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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs. This binary checks for style issues such as incorrect or missing JSDoc usage, and missing goog.require() statements. It does not do more advanced checks such as typechecking.

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/*
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Norris Boyd
 *   Roger Lawrence
 *   Mike McCabe
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package com.google.javascript.rhino;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Ascii;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableList;
import com.google.errorprone.annotations.DoNotCall;
import com.google.javascript.rhino.StaticSourceFile.SourceKind;
import com.google.javascript.rhino.jstype.JSType;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.function.Function;
import javax.annotation.CheckReturnValue;
import javax.annotation.Nullable;

/**
 * This class implements the root of the intermediate representation.
 *
 */

public class Node implements Serializable {

  private static final long serialVersionUID = 1L;

  private enum Prop {
    // Contains non-JSDoc comment
    NON_JSDOC_COMMENT,
    // Contains a JSDocInfo object
    JSDOC_INFO,
    // The name node is a variable length argument placeholder.
    VAR_ARGS,
    // Whether incrdecr is pre (false) or post (true)
    INCRDECR,
    // Set to indicate a quoted object lit key
    QUOTED,
    // The name node is an optional argument.
    OPT_ARG,
    // A synthetic block. Used to make processing simpler, and does not represent a real block in
    // the source.
    SYNTHETIC,
    // Used to indicate BLOCK that is added
    ADDED_BLOCK,
    // The original name of the node, before renaming.
    ORIGINALNAME,
    // Function or constructor call side effect flags.
    SIDE_EFFECT_FLAGS,
    // The variable or property is constant.
    // TODO(lukes): either document the differences or otherwise reconcile with CONSTANT_VAR_FLAGS
    IS_CONSTANT_NAME,
    // The variable creates a namespace.
    IS_NAMESPACE,
    // The ES5 directives on this node.
    DIRECTIVES,
    // ES5 distinguishes between direct and indirect calls to eval.
    DIRECT_EVAL,
    // A CALL without an explicit "this" value.
    FREE_CALL,
    // A StaticSourceFile indicating the file where this node lives.
    SOURCE_FILE,
    // The id of the input associated with this node.
    INPUT_ID,
    // Whether a STRING node contains a \v vertical tab escape. This is a total hack. See comments
    // in IRFactory about this.
    SLASH_V,
    // For passes that work only on changed funs.
    CHANGE_TIME,
    // An object that's used for goog.object.reflect-style reflection.
    REFLECTED_OBJECT,
    // Set if class member definition is static
    STATIC_MEMBER,
    // Set if the node is a Generator function or member method.
    GENERATOR_FN,
    // Set if the node is an arrow function.
    ARROW_FN,
    // http://tc39.github.io/ecmascript-asyncawait/
    ASYNC_FN,
    // Set if a yield is a "yield all"
    YIELD_ALL,
    // Set if a export is a "default" export
    EXPORT_DEFAULT,
    // Set if an export is a "*"
    EXPORT_ALL_FROM,
    // A variable is inferred or declared as const meaning it is only ever assigned once at its
    // declaration site.
    // This is an int prop that holds a bitset of {@link ConstantVarFlags} values.
    CONSTANT_VAR_FLAGS,
    // Used by the ES6-to-ES3 translator.
    IS_GENERATOR_MARKER,
    // Used by the ES6-to-ES3 translator.
    IS_GENERATOR_SAFE,
    // A computed property that has the method syntax
    //   ( [prop]() {...} )
    // rather than the property definition syntax
    //   ( [prop]: value ).
    COMPUTED_PROP_METHOD,
    // A computed property in a getter, e.g. var obj = { get [prop]() {...} };
    COMPUTED_PROP_GETTER,
    // A computed property in a setter, e.g. var obj = 32;
    COMPUTED_PROP_SETTER,
    // A computed property that's a variable, e.g. [prop]: string;
    COMPUTED_PROP_VARIABLE,
    // Used to attach TypeDeclarationNode ASTs to Nodes which represent a typed NAME or FUNCTION.
    DECLARED_TYPE_EXPR,
    // The type of an expression before the cast. This will be present only if the expression is
    // casted.
    TYPE_BEFORE_CAST,
    // The node is an optional parameter or property in ES6 Typed syntax.
    OPT_ES6_TYPED,
    // Generic type list in ES6 typed syntax.
    GENERIC_TYPE,
    // "implements" clause in ES6 typed syntax.
    IMPLEMENTS,
    // This node is a TypeScript ConstructSignature
    CONSTRUCT_SIGNATURE,
    // TypeScript accessibility modifiers (public, protected, private)
    ACCESS_MODIFIER,
    // Indicates the node should not be indexed by analysis tools.
    NON_INDEXABLE,
    // Parse results stored on SCRIPT nodes to allow replaying parse warnings/errors when cloning
    // cached ASTs.
    PARSE_RESULTS,
    // Indicates that a SCRIPT node is a goog.module. Remains set after the goog.module is
    // desugared.
    GOOG_MODULE,
    // Node is a goog.require() as desugared by goog.module()
    GOOG_MODULE_REQUIRE,
    // Attaches a FeatureSet to SCRIPT nodes.
    FEATURE_SET,
    // Indicates that a STRING node represents a namespace from goog.module() or goog.require()
    // call.
    IS_MODULE_NAME,
    // Indicates a namespace that was provided at some point in the past.
    WAS_PREVIOUSLY_PROVIDED,
    // Indicates that a SCRIPT represents a transpiled file
    TRANSPILED,
    // For passes that work only on deleted funs.
    DELETED,
    // Indicates that the node is an alias or a name from goog.require'd module or ES6
    // module. Aliases are desugared and inlined by compiler passes but we need to preserve them for
    // building index.
    MODULE_ALIAS,
    // Mark a parameter as unused. Used to defer work from RemovedUnusedVars to OptimizeParameters.
    IS_UNUSED_PARAMETER,
    // Mark a property as a module export so that collase properties can act on it.
    MODULE_EXPORT,
    // Indicates that a property {x:x} was originally parsed as {x}.
    IS_SHORTHAND_PROPERTY,
    // Indicates that a SCRIPT node is or was an ES module. Remains set after the module is
    // rewritten.
    ES6_MODULE,
    // Record the type associated with a @typedef to enable looking up typedef in the AST possible
    // without saving the type scope.
    TYPEDEF_TYPE,
    // Original name of a goog.define call.
    DEFINE_NAME,
  }

  /**
   * Get the NonJSDoc comment string attached to this node.
   *
   * @return the information or empty string if no nonJSDoc is attached to this node
   */
  public final String getNonJSDocCommentString() {
    if (getProp(Prop.NON_JSDOC_COMMENT) == null) {
      return "";
    }
    return ((NonJSDocComment) getProp(Prop.NON_JSDOC_COMMENT)).getCommentString();
  }

  public final NonJSDocComment getNonJSDocComment() {
    return (NonJSDocComment) getProp(Prop.NON_JSDOC_COMMENT);
  }

  /** Sets the NonJSDoc comment attached to this node. */
  public final Node setNonJSDocComment(NonJSDocComment comment) {
    putProp(Prop.NON_JSDOC_COMMENT, comment);
    return this;
  }

  // TODO(sdh): Get rid of these by using accessor methods instead.
  // These export instances of a private type, which is awkward but a side effect is that it
  // prevents anyone from introducing problemmatic uses of the general-purpose accessors.
  public static final Prop JSDOC_INFO_PROP = Prop.JSDOC_INFO;
  public static final Prop INCRDECR_PROP = Prop.INCRDECR;
  public static final Prop QUOTED_PROP = Prop.QUOTED;
  public static final Prop ORIGINALNAME_PROP = Prop.ORIGINALNAME;
  public static final Prop IS_CONSTANT_NAME = Prop.IS_CONSTANT_NAME;
  public static final Prop IS_NAMESPACE = Prop.IS_NAMESPACE;
  public static final Prop DIRECT_EVAL = Prop.DIRECT_EVAL;
  public static final Prop FREE_CALL = Prop.FREE_CALL;
  public static final Prop SLASH_V = Prop.SLASH_V;
  public static final Prop REFLECTED_OBJECT = Prop.REFLECTED_OBJECT;
  public static final Prop STATIC_MEMBER = Prop.STATIC_MEMBER;
  public static final Prop GENERATOR_FN = Prop.GENERATOR_FN;
  public static final Prop YIELD_ALL = Prop.YIELD_ALL;
  public static final Prop EXPORT_DEFAULT = Prop.EXPORT_DEFAULT;
  public static final Prop EXPORT_ALL_FROM = Prop.EXPORT_ALL_FROM;
  public static final Prop COMPUTED_PROP_METHOD = Prop.COMPUTED_PROP_METHOD;
  public static final Prop COMPUTED_PROP_GETTER = Prop.COMPUTED_PROP_GETTER;
  public static final Prop COMPUTED_PROP_SETTER = Prop.COMPUTED_PROP_SETTER;
  public static final Prop COMPUTED_PROP_VARIABLE = Prop.COMPUTED_PROP_VARIABLE;
  public static final Prop OPT_ES6_TYPED = Prop.OPT_ES6_TYPED;
  public static final Prop GENERIC_TYPE_LIST = Prop.GENERIC_TYPE;
  public static final Prop IMPLEMENTS = Prop.IMPLEMENTS;
  public static final Prop CONSTRUCT_SIGNATURE = Prop.CONSTRUCT_SIGNATURE;
  public static final Prop ACCESS_MODIFIER = Prop.ACCESS_MODIFIER;
  public static final Prop PARSE_RESULTS = Prop.PARSE_RESULTS;
  public static final Prop GOOG_MODULE = Prop.GOOG_MODULE;
  public static final Prop FEATURE_SET = Prop.FEATURE_SET;
  public static final Prop IS_MODULE_NAME = Prop.IS_MODULE_NAME;
  public static final Prop WAS_PREVIOUSLY_PROVIDED = Prop.WAS_PREVIOUSLY_PROVIDED;
  public static final Prop TRANSPILED = Prop.TRANSPILED;
  public static final Prop MODULE_ALIAS = Prop.MODULE_ALIAS;
  public static final Prop MODULE_EXPORT = Prop.MODULE_EXPORT;
  public static final Prop IS_SHORTHAND_PROPERTY = Prop.IS_SHORTHAND_PROPERTY;
  public static final Prop ES6_MODULE = Prop.ES6_MODULE;

  private static final String propToString(Prop propType) {
    return Ascii.toLowerCase(String.valueOf(propType));
  }

  /**
   * Represents a node in the type declaration AST.
   */
  public static final class TypeDeclarationNode extends Node {

    private static final long serialVersionUID = 1L;
    private String str; // This is used for specialized signatures.

    public TypeDeclarationNode(Token nodeType, String str) {
      super(nodeType);
      this.str = str;
    }

    public TypeDeclarationNode(Token nodeType) {
      super(nodeType);
    }

    public TypeDeclarationNode(Token nodeType, Node child) {
      super(nodeType, child);
    }

    /**
     * returns the string content.
     * @return non null.
     */
    @Override
    public String getString() {
      return str;
    }

    @Override
    public TypeDeclarationNode cloneNode(boolean cloneTypeExprs) {
      return copyNodeFields(new TypeDeclarationNode(token, str), cloneTypeExprs);
    }
  }

  private static final class NumberNode extends Node {

    private static final long serialVersionUID = 1L;

    NumberNode(double number) {
      super(Token.NUMBER);
      this.number = number;
    }

    public NumberNode(double number, int lineno, int charno) {
      super(Token.NUMBER, lineno, charno);
      this.number = number;
    }

    @Override
    public double getDouble() {
      return this.number;
    }

    @Override
    public void setDouble(double d) {
      this.number = d;
    }

    @Override
    public boolean isEquivalentTo(
        Node node, boolean compareType, boolean recur, boolean jsDoc, boolean sideEffect) {
      boolean equiv = super.isEquivalentTo(node, compareType, recur, jsDoc, sideEffect);
      if (equiv) {
        double thisValue = getDouble();
        double thatValue = ((NumberNode) node).getDouble();
        if (thisValue == thatValue) {
          // detect the difference between 0.0 and -0.0.
          return (thisValue != 0.0) || (1 / thisValue == 1 / thatValue);
        }
      }
      return false;
    }

    private double number;

    @Override
    public NumberNode cloneNode(boolean cloneTypeExprs) {
      return copyNodeFields(new NumberNode(number), cloneTypeExprs);
    }
  }

  private static final class StringNode extends Node {

    private static final long serialVersionUID = 1L;

    // Only for cloneNode
    private StringNode(Token token) {
      super(token);
    }

    StringNode(Token token, String str) {
      super(token);
      setString(str);
    }

    StringNode(Token token, String str, int lineno, int charno) {
      super(token, lineno, charno);
      setString(str);
    }

    /**
     * returns the string content.
     * @return non null.
     */
    @Override
    public String getString() {
      return this.str;
    }

    /**
     * sets the string content.
     * @param str the new value.  Non null.
     */
    @Override
    public void setString(String str) {
      if (null == str) {
        throw new IllegalArgumentException("StringNode: str is null");
      }
      // Intern the string reference so that serialization won't save repeated strings.
      this.str = str.intern();
    }

    @Override
    @SuppressWarnings("ReferenceEquality")
    public boolean isEquivalentTo(
        Node node, boolean compareType, boolean recur, boolean jsDoc, boolean sideEffect) {
      // NOTE: we take advantage of the string interning done in #setString and use
      // '==' rather than 'equals' here to avoid doing unnecessary string equalities.
      return (super.isEquivalentTo(node, compareType, recur, jsDoc, sideEffect)
          && this.str == (((StringNode) node).str));
    }

    /**
     * If the property is not defined, this was not a quoted key.  The
     * Prop.QUOTED int property is only assigned to STRING tokens used as
     * object lit keys.
     * @return true if this was a quoted string key in an object literal.
     */
    @Override
    public boolean isQuotedString() {
      return getBooleanProp(Prop.QUOTED);
    }

    /**
     * This should only be called for STRING nodes created in object lits.
     */
    @Override
    public void setQuotedString() {
      putBooleanProp(Prop.QUOTED, true);
    }

    private String str;

    @Override
    public StringNode cloneNode(boolean cloneTypeExprs) {
      StringNode clone = new StringNode(token);
      clone.str = str;
      return copyNodeFields(clone, cloneTypeExprs);
    }

    @GwtIncompatible("ObjectInputStream")
    private void readObject(java.io.ObjectInputStream in) throws Exception {
      in.defaultReadObject();

      this.str = this.str.intern();
    }
  }

  private static final class TemplateLiteralSubstringNode extends Node {

    private static final long serialVersionUID = 1L;
    // The "cooked" version of the template literal substring. May be null.
    @Nullable
    private String cooked;
    // The raw version of the template literal substring, is not null
    private String raw;

    // Only for cloneNode
    private TemplateLiteralSubstringNode() {
      super(Token.TEMPLATELIT_STRING);
    }

    TemplateLiteralSubstringNode(@Nullable String cooked, String raw) {
      super(Token.TEMPLATELIT_STRING);
      this.cooked = cooked;
      setRaw(raw);
    }

    TemplateLiteralSubstringNode(@Nullable String cooked, String raw,
        int lineno, int charno) {
      super(Token.TEMPLATELIT_STRING, lineno, charno);
      this.cooked = cooked;
      setRaw(raw);
    }

    /**
     * returns the raw string content.
     * @return non null.
     */
    @Override
    public String getRawString() {
      return this.raw;
    }

    /**
     * @return the cooked string content.
     */
    @Override @Nullable
    public String getCookedString() {
      return this.cooked;
    }

    /**
     * sets the raw string content.
     * @param str the new value. Non null.
     */
    public void setRaw(String str) {
      if (null == str) {
        throw new IllegalArgumentException("TemplateLiteralSubstringNode: raw str is null");
      }
      // Intern the string reference so that serialization won't save repeated strings.
      this.raw = str.intern();
    }

    @Override
    @SuppressWarnings("ReferenceEquality")
    public boolean isEquivalentTo(
        Node node, boolean compareType, boolean recur, boolean jsDoc, boolean sideEffect) {
      // NOTE: we take advantage of the string interning done in #setRaw and use
      // '==' rather than 'equals' here to avoid doing unnecessary string equalities.
      return (super.isEquivalentTo(node, compareType, recur, jsDoc, sideEffect)
          && this.raw == ((TemplateLiteralSubstringNode) node).raw
          && Objects.equal(this.cooked, ((TemplateLiteralSubstringNode) node).cooked));
    }

    @Override
    public TemplateLiteralSubstringNode cloneNode(boolean cloneTypeExprs) {
      TemplateLiteralSubstringNode clone = new TemplateLiteralSubstringNode();
      clone.raw = raw;
      clone.cooked = cooked;
      return copyNodeFields(clone, cloneTypeExprs);
    }
  }

  private abstract static class PropListItem implements Serializable {
    final @Nullable PropListItem next;
    final byte propType;

    PropListItem(byte propType, @Nullable PropListItem next) {
      this.propType = propType;
      this.next = next;
    }

    public abstract int getIntValue();
    public abstract Object getObjectValue();
    public abstract PropListItem chain(@Nullable PropListItem next);
  }

  // A base class for Object storing props
  private static final class ObjectPropListItem extends PropListItem {
    private final Object objectValue;

    ObjectPropListItem(byte propType, Object objectValue, @Nullable PropListItem next) {
      super(propType, next);
      this.objectValue = objectValue;
    }

    @Override
    public int getIntValue() {
      throw new UnsupportedOperationException();
    }

    @Override
    public Object getObjectValue() {
      return objectValue;
    }

    @Override
    public String toString() {
      return String.valueOf(objectValue);
    }

    @Override
    public PropListItem chain(@Nullable PropListItem next) {
      return new ObjectPropListItem(propType, objectValue, next);
    }
  }

  // A base class for int storing props
  private static final class IntPropListItem extends PropListItem {
    final int intValue;

    IntPropListItem(byte propType, int intValue, @Nullable PropListItem next) {
      super(propType, next);
      this.intValue = intValue;
    }

    @Override
    public int getIntValue() {
      return intValue;
    }

    @Override
    public Object getObjectValue() {
      throw new UnsupportedOperationException();
    }

    @Override
    public String toString() {
      return String.valueOf(intValue);
    }

    @Override
    public PropListItem chain(@Nullable PropListItem next) {
      return new IntPropListItem(propType, intValue, next);
    }
  }

  public Node(Token nodeType) {
    token = nodeType;
    parent = null;
    sourcePosition = -1;
  }

  public Node(Token nodeType, Node child) {
    checkArgument(child.parent == null, "new child has existing parent");
    checkArgument(child.next == null, "new child has existing next sibling");
    checkArgument(child.previous == null, "new child has existing previous sibling");

    token = nodeType;
    parent = null;
    first = child;
    child.next = null;
    child.previous = first;
    child.parent = this;
    sourcePosition = -1;
  }

  public Node(Token nodeType, Node left, Node right) {
    checkArgument(left.parent == null, "first new child has existing parent");
    checkArgument(left.next == null, "first new child has existing next sibling");
    checkArgument(left.previous == null, "first new child has existing previous sibling");
    checkArgument(right.parent == null, "second new child has existing parent");
    checkArgument(right.next == null, "second new child has existing next sibling");
    checkArgument(right.previous == null, "second new child has existing previous sibling");
    token = nodeType;
    parent = null;
    first = left;
    left.next = right;
    left.previous = right;
    left.parent = this;
    right.next = null;
    right.previous = left;
    right.parent = this;
    sourcePosition = -1;
  }

  public Node(Token nodeType, Node left, Node mid, Node right) {
    checkArgument(left.parent == null);
    checkArgument(left.next == null);
    checkArgument(left.previous == null);
    checkArgument(mid.parent == null);
    checkArgument(mid.next == null);
    checkArgument(mid.previous == null);
    checkArgument(right.parent == null);
    checkArgument(right.next == null);
    checkArgument(right.previous == null);
    token = nodeType;
    parent = null;
    first = left;
    left.next = mid;
    left.previous = right;
    left.parent = this;
    mid.next = right;
    mid.previous = left;
    mid.parent = this;
    right.next = null;
    right.previous = mid;
    right.parent = this;
    sourcePosition = -1;
  }

  Node(Token nodeType, Node left, Node mid, Node mid2, Node right) {
    checkArgument(left.parent == null);
    checkArgument(left.next == null);
    checkArgument(left.previous == null);
    checkArgument(mid.parent == null);
    checkArgument(mid.next == null);
    checkArgument(mid.previous == null);
    checkArgument(mid2.parent == null);
    checkArgument(mid2.next == null);
    checkArgument(mid2.previous == null);
    checkArgument(right.parent == null);
    checkArgument(right.next == null);
    checkArgument(right.previous == null);
    token = nodeType;
    parent = null;
    first = left;
    left.next = mid;
    left.previous = right;
    left.parent = this;
    mid.next = mid2;
    mid.previous = left;
    mid.parent = this;
    mid2.next = right;
    mid2.previous = mid;
    mid2.parent = this;
    right.next = null;
    right.previous = mid2;
    right.parent = this;
    sourcePosition = -1;
  }

  public Node(Token nodeType, int lineno, int charno) {
    token = nodeType;
    parent = null;
    sourcePosition = mergeLineCharNo(lineno, charno);
  }

  public Node(Token nodeType, Node child, int lineno, int charno) {
    this(nodeType, child);
    sourcePosition = mergeLineCharNo(lineno, charno);
  }

  public static Node newNumber(double number) {
    return new NumberNode(number);
  }

  public static Node newNumber(double number, int lineno, int charno) {
    return new NumberNode(number, lineno, charno);
  }

  public static Node newString(String str) {
    return new StringNode(Token.STRING, str);
  }

  public static Node newString(Token token, String str) {
    return new StringNode(token, str);
  }

  public static Node newString(String str, int lineno, int charno) {
    return new StringNode(Token.STRING, str, lineno, charno);
  }

  public static Node newString(Token token, String str, int lineno, int charno) {
    return new StringNode(token, str, lineno, charno);
  }

  public static Node newTemplateLitString(String cooked, String raw) {
    return new TemplateLiteralSubstringNode(cooked, raw);
  }

  public final Token getToken() {
    return token;
  }

  public final void setToken(Token token) {
    this.token = token;
  }

  public final boolean hasChildren() {
    return first != null;
  }

  public final Node getOnlyChild() {
    checkState(hasOneChild());
    return first;
  }

  @Nullable
  public final Node getFirstChild() {
    return first;
  }

  /**
   * Get the first child of the first child. This method assumes that the first child exists.
   *
   * @return The first child of the first child.
   */
  @Nullable
  public final Node getFirstFirstChild() {
    return first.first;
  }

  @Nullable
  public final Node getSecondChild() {
    return first.next;
  }

  @Nullable
  public final Node getLastChild() {
    return first != null ? first.previous : null;
  }

  @Nullable
  public final Node getNext() {
    return next;
  }

  @Nullable
  public final Node getPrevious() {
    return this == parent.first ? null : previous;
  }

  @Nullable
  private final Node getPrevious(@Nullable Node firstSibling) {
    return this == firstSibling ? null : previous;
  }

  @Nullable
  public final Node getChildBefore(Node child) {
    return child.getPrevious(first);
  }

  /**
   * Gets the ith child, note that this is O(N) where N is the number of children.
   *
   * @param i The index
   * @return The ith child
   */
  public final Node getChildAtIndex(int i) {
    Node n = first;
    while (i > 0) {
      n = n.next;
      i--;
    }
    return n;
  }

  /**
   * Gets the index of a child, note that this is O(N) where N is the number of children.
   *
   * @param child The child
   * @return The index of the child
   */
  public final int getIndexOfChild(Node child) {
    Node n = first;
    int i = 0;
    while (n != null) {
      if (child == n) {
        return i;
      }

      n = n.next;
      i++;
    }
    return -1;
  }

  public final void addChildToFront(Node child) {
    checkArgument(child.parent == null);
    checkArgument(child.next == null);
    checkArgument(child.previous == null);
    child.parent = this;
    child.next = first;
    if (first == null) {
      // NOTE: child.next remains null
      child.previous = child;
    } else {
      Node last = first.previous;
      // NOTE: last.next remains null
      child.previous = last;
      child.next = first;
      first.previous = child;
    }
    first = child;
  }

  public final void addChildToBack(Node child) {
    checkArgument(
        child.parent == null,
        "Cannot add already-owned child node.\nChild: %s\nExisting parent: %s\nNew parent: %s",
        child, child.parent, this);
    checkArgument(child.next == null);
    checkArgument(child.previous == null);

    if (first == null) {
      // NOTE: child.next remains null
      child.previous = child;
      first = child;
    } else {
      Node last = first.previous;
      last.next = child;
      // NOTE: child.next remains null
      child.previous = last;
      first.previous = child;
    }

    child.parent = this;
  }

  /**
   * Add all children to the front of this node.
   *
   * @param children first of a list of sibling nodes who have no parent.
   *    NOTE: Usually you would get this argument from a removeChildren() call.
   *    A single detached node will not work because its sibling pointers will not be
   *    correctly initialized.
   */
  public final void addChildrenToFront(@Nullable Node children) {
    if (children == null) {
      return; // removeChildren() returns null when there are none
    }
    // NOTE: If there is only one sibling, its previous pointer must point to itself.
    // Null indicates a fully detached node.
    checkNotNull(children.previous, children);
    for (Node child = children; child != null; child = child.next) {
      checkArgument(child.parent == null);
      child.parent = this;
    }

    Node lastSib = children.previous;
    if (first != null) {
      Node last = first.previous;
      // NOTE: last.next remains null
      children.previous = last;
      lastSib.next = first;
      first.previous = lastSib;
    }
    first = children;
  }

  public final void addChildrenToBack(Node children) {
    addChildrenAfter(children, getLastChild());
  }

  /**
   * Add 'child' before 'node'.
   */
  public final void addChildBefore(Node newChild, Node node) {
    checkArgument(node.parent == this, "The existing child node of the parent should not be null.");
    checkArgument(newChild.next == null, "The new child node has next siblings.");
    checkArgument(newChild.previous == null, "The new child node has previous siblings.");
    checkArgument(newChild.parent == null, "The new child node already has a parent.");
    if (first == node) {
      Node last = first.previous;
      // NOTE: last.next remains null
      newChild.parent = this;
      newChild.next = first;
      newChild.previous = last;
      first.previous = newChild;
      first = newChild;
    } else {
      addChildAfter(newChild, node.previous);
    }
  }

  /**
   * Add 'newChild' after 'node'.  If 'node' is null, add it to the front of this node.
   */
  public final void addChildAfter(Node newChild, @Nullable Node node) {
    checkArgument(newChild.next == null, "The new child node has next siblings.");
    checkArgument(newChild.previous == null, "The new child node has previous siblings.");
    // NOTE: newChild.next remains null
    newChild.previous = newChild;
    addChildrenAfter(newChild, node);
  }

  /**
   * Add all children after 'node'. If 'node' is null, add them to the front of this node.
   *
   * @param children first of a list of sibling nodes who have no parent.
   *    NOTE: Usually you would get this argument from a removeChildren() call.
   *    A single detached node will not work because its sibling pointers will not be
   *    correctly initialized.
   */
  public final void addChildrenAfter(@Nullable Node children, @Nullable Node node) {
    if (children == null) {
      return; // removeChildren() returns null when there are none
    }
    checkArgument(node == null || node.parent == this);
    // NOTE: If there is only one sibling, its previous pointer must point to itself.
    // Null indicates a fully detached node.
    checkNotNull(children.previous, children);
    if (node == null) {
      addChildrenToFront(children);
      return;
    }

    for (Node child = children; child != null; child = child.next) {
      checkArgument(child.parent == null);
      child.parent = this;
    }

    Node lastSibling = children.previous;
    Node nodeAfter = node.next;
    lastSibling.next = nodeAfter;
    if (nodeAfter == null) {
      first.previous = lastSibling;
    } else {
      nodeAfter.previous = lastSibling;
    }
    node.next = children;
    children.previous = node;
  }

  /** Detach a child from its parent and siblings. */
  public final void removeChild(Node child) {
    checkState(child.parent == this, "%s is not the parent of %s", this, child);
    checkNotNull(child.previous);

    Node last = first.previous;
    Node prevSibling = child.previous;
    Node nextSibling = child.next;
    if (first == child) {
      first = nextSibling;
      if (nextSibling != null) {
        nextSibling.previous = last;
      }
      // last.next remains null
    } else if (child == last) {
      first.previous = prevSibling;
      prevSibling.next = null;
    } else {
      prevSibling.next = nextSibling;
      nextSibling.previous = prevSibling;
    }

    child.next = null;
    child.previous = null;
    child.parent = null;
  }

  /**
   * Detaches Node and replaces it with newNode.
   */
  public final void replaceWith(Node newNode) {
    parent.replaceChild(this, newNode);
  }

  /** Detaches child from Node and replaces it with newChild. */
  public final void replaceChild(Node child, Node newChild) {
    checkArgument(newChild.next == null, "The new child node has next siblings.");
    checkArgument(newChild.previous == null, "The new child node has previous siblings.");
    checkArgument(newChild.parent == null, "The new child node already has a parent.");
    checkState(child.parent == this, "%s is not the parent of %s", this, child);

    // Copy over important information.
    newChild.useSourceInfoIfMissingFrom(child);
    newChild.parent = this;

    Node nextSibling = child.next;
    Node prevSibling = child.previous;

    Node last = first.previous;

    if (child == prevSibling) {  // first and only child
      first = newChild;
      first.previous = newChild;
    } else {
      if (child == first) {
        first = newChild;
        // prevSibling == last, and last.next remains null
      } else {
        prevSibling.next = newChild;
      }

      if (child == last) {
        first.previous = newChild;
      } else {
        nextSibling.previous = newChild;
      }

      newChild.previous = prevSibling;
    }
    newChild.next = nextSibling;  // maybe null

    child.next = null;
    child.previous = null;
    child.parent = null;
  }

  public final void replaceChildAfter(Node prevChild, Node newChild) {
    checkNotNull(prevChild.next, "prev doesn't have a sibling to replace.");
    replaceChild(prevChild.next, newChild);
  }

  /** Detaches the child after the given child, or the first child if prev is null. */
  public final void replaceFirstOrChildAfter(@Nullable Node prev, Node newChild) {
    Node target = prev == null ? first : prev.next;
    checkNotNull(target, "prev doesn't have a sibling to replace.");
    replaceChild(target, newChild);
  }

  @VisibleForTesting
  @Nullable
  final PropListItem lookupProperty(Prop prop) {
    byte propType = (byte) prop.ordinal();
    PropListItem x = propListHead;
    while (x != null && propType != x.propType) {
      x = x.next;
    }
    return x;
  }

  /**
   * Clone the properties from the provided node without copying
   * the property object.  The receiving node may not have any
   * existing properties.
   * @param other The node to clone properties from.
   * @return this node.
   */
  public final Node clonePropsFrom(Node other) {
    checkState(this.propListHead == null, "Node has existing properties.");
    this.propListHead = other.propListHead;
    return this;
  }

  public final boolean hasProps() {
    return propListHead != null;
  }

  public final void removeProp(Prop propType) {
    PropListItem result = removeProp(propListHead, (byte) propType.ordinal());
    if (result != propListHead) {
      propListHead = result;
    }
  }

  /**
   * @param item The item to inspect
   * @param propType The property to look for
   * @return The replacement list if the property was removed, or 'item' otherwise.
   */
  @Nullable
  private final PropListItem removeProp(@Nullable PropListItem item, byte propType) {
    if (item == null) {
      return null;
    } else if (item.propType == propType) {
      return item.next;
    } else {
      PropListItem result = removeProp(item.next, propType);
      if (result != item.next) {
        return item.chain(result);
      } else {
        return item;
      }
    }
  }

  @Nullable
  public final Object getProp(Prop propType) {
    PropListItem item = lookupProperty(propType);
    if (item == null) {
      return null;
    }
    return item.getObjectValue();
  }

  public final boolean getBooleanProp(Prop propType) {
    return getIntProp(propType) != 0;
  }

  /**
   * Returns the integer value for the property, or 0 if the property
   * is not defined.
   */
  public final int getIntProp(Prop propType) {
    PropListItem item = lookupProperty(propType);
    if (item == null) {
      return 0;
    }
    return item.getIntValue();
  }

  public final int getExistingIntProp(Prop propType) {
    PropListItem item = lookupProperty(propType);
    if (item == null) {
      throw new IllegalStateException("missing prop: " + propType);
    }
    return item.getIntValue();
  }

  public final void putProp(Prop propType, @Nullable Object value) {
    removeProp(propType);
    if (value != null) {
      propListHead = createProp((byte) propType.ordinal(), value, propListHead);
    }
  }

  public final void putBooleanProp(Prop propType, boolean value) {
    putIntProp(propType, value ? 1 : 0);
  }

  public final void putIntProp(Prop propType, int value) {
    removeProp(propType);
    if (value != 0) {
      propListHead = createProp((byte) propType.ordinal(), value, propListHead);
    }
  }

  /**
   * Sets the syntactical type specified on this node.
   * @param typeExpression
   */
  public final void setDeclaredTypeExpression(TypeDeclarationNode typeExpression) {
    putProp(Prop.DECLARED_TYPE_EXPR, typeExpression);
  }

  /**
   * Returns the syntactical type specified on this node. Not to be confused with {@link
   * #getJSType()} which returns the compiler-inferred type.
   */
  @Nullable
  public final TypeDeclarationNode getDeclaredTypeExpression() {
    return (TypeDeclarationNode) getProp(Prop.DECLARED_TYPE_EXPR);
  }

  final PropListItem createProp(byte propType, Object value, @Nullable PropListItem next) {
    return new ObjectPropListItem(propType, value, next);
  }

  final PropListItem createProp(byte propType, int value, @Nullable PropListItem next) {
    return new IntPropListItem(propType, value, next);
  }

  /**
   * Sets the type of this node before casting.
   */
  public final void setJSTypeBeforeCast(JSType type) {
    putProp(Prop.TYPE_BEFORE_CAST, type);
  }

  /**
   * Returns the type of this node before casting. This annotation will only exist on the first
   * child of a CAST node after type checking.
   */
  @Nullable
  public final JSType getJSTypeBeforeCast() {
    return (JSType) getProp(Prop.TYPE_BEFORE_CAST);
  }

  // Gets all the property types, in sorted order.
  private byte[] getSortedPropTypes() {
    int count = 0;
    for (PropListItem x = propListHead; x != null; x = x.next) {
      count++;
    }

    byte[] keys = new byte[count];
    for (PropListItem x = propListHead; x != null; x = x.next) {
      count--;
      keys[count] = x.propType;
    }

    Arrays.sort(keys);
    return keys;
  }

  /** Can only be called when getType() == TokenStream.NUMBER */
  public double getDouble() {
    if (this.token == Token.NUMBER) {
      throw new IllegalStateException(
          "Number node not created with Node.newNumber");
    } else {
      throw new UnsupportedOperationException(this + " is not a number node");
    }
  }

  /**
   * Can only be called when getType() == Token.NUMBER
   *
   * @param value value to set.
   */
  public void setDouble(double value) {
    if (this.token == Token.NUMBER) {
      throw new IllegalStateException(
          "Number node not created with Node.newNumber");
    } else {
      throw new UnsupportedOperationException(this + " is not a string node");
    }
  }

  /** Can only be called when node has String context. */
  public String getString() {
    if (this.token == Token.STRING) {
      throw new IllegalStateException(
          "String node not created with Node.newString");
    } else {
      throw new UnsupportedOperationException(this + " is not a string node");
    }
  }

  /**
   * Can only be called for a Token.STRING or Token.NAME.
   *
   * @param value the value to set.
   */
  public void setString(String value) {
    if (this.token == Token.STRING || this.token == Token.NAME) {
      throw new IllegalStateException(
          "String node not created with Node.newString");
    } else {
      throw new UnsupportedOperationException(this + " is not a string node");
    }
  }

  /** Can only be called when getType() == Token.TEMPLATELIT_STRING */
  public String getRawString() {
    if (this.token == Token.TEMPLATELIT_STRING) {
      throw new IllegalStateException(
          "Template Literal String node not created with Node.newTemplateLitString");
    } else {
      throw new UnsupportedOperationException(this + " is not a template literal string node");
    }
  }

  /** Can only be called when getType() == Token.TEMPLATELIT_STRING */
  @Nullable
  public String getCookedString() {
    if (this.token == Token.TEMPLATELIT_STRING) {
      throw new IllegalStateException(
          "Template Literal String node not created with Node.newTemplateLitString");
    } else {
      throw new UnsupportedOperationException(this + " is not a template literal string node");
    }
  }

  @Override
  public final String toString() {
    return toString(true, true, true);
  }

  public final String toString(
      boolean printSource,
      boolean printAnnotations,
      boolean printType) {
    StringBuilder sb = new StringBuilder();
    toString(sb, printSource, printAnnotations, printType);
    return sb.toString();
  }

  private void toString(
      StringBuilder sb,
      boolean printSource,
      boolean printAnnotations,
      boolean printType) {
    sb.append(token);
    if (this instanceof StringNode) {
      sb.append(' ');
      sb.append(getString());
    } else if (token == Token.FUNCTION) {
      sb.append(' ');
      // In the case of JsDoc trees, the first child is often not a string
      // which causes exceptions to be thrown when calling toString or
      // toStringTree.
      if (first == null || first.token != Token.NAME) {
        sb.append("");
      } else {
        sb.append(first.getString());
      }
    } else if (token == Token.NUMBER) {
      sb.append(' ');
      sb.append(getDouble());
    }
    if (printSource) {
      int lineno = getLineno();
      if (lineno != -1) {
        sb.append(' ');
        sb.append(lineno);
      }
      if (length != 0) {
        sb.append(" [length: ");
        sb.append(length);
        sb.append(']');
      }
    }

    if (printAnnotations) {
      byte[] keys = getSortedPropTypes();
      for (int i = 0; i < keys.length; i++) {
        Prop type = Prop.values()[keys[i]];
        PropListItem x = lookupProperty(type);
        sb.append(" [");
        sb.append(propToString(type));
        sb.append(": ");
        sb.append(x);
        sb.append(']');
      }
    }

    if (printType && jstype != null) {
      String typeString = jstype.toString();
      if (typeString != null) {
        sb.append(" : ");
        sb.append(typeString);
      }
    }
  }

  @CheckReturnValue
  public final String toStringTree() {
    return toStringTreeImpl();
  }

  private String toStringTreeImpl() {
    try {
      StringBuilder s = new StringBuilder();
      appendStringTree(s);
      return s.toString();
    } catch (IOException e) {
      throw new RuntimeException("Should not happen\n" + e);
    }
  }

  public final void appendStringTree(Appendable appendable) throws IOException {
    toStringTreeHelper(this, 0, appendable);
  }

  private static void toStringTreeHelper(Node n, int level, Appendable sb)
      throws IOException {
    for (int i = 0; i != level; ++i) {
      sb.append("    ");
    }
    sb.append(n.toString());
    sb.append('\n');
    for (Node cursor = n.first; cursor != null; cursor = cursor.next) {
      toStringTreeHelper(cursor, level + 1, sb);
    }
  }

  transient Token token;           // Type of the token of the node; NAME for example
  @Nullable transient Node next; // next sibling, a linked list
  @Nullable transient Node previous; // previous sibling, a circular linked list
  @Nullable transient Node first; // first element of a linked list of children
  // We get the last child as first.previous. But last.next is null, not first.

  /**
   * Linked list of properties. Since vast majority of nodes would have no more than 2 properties,
   * linked list saves memory and provides fast lookup. If this does not holds, propListHead can be
   * replaced by UintMap.
   */
  @Nullable private transient PropListItem propListHead;

  /**
   * COLUMN_BITS represents how many of the lower-order bits of
   * sourcePosition are reserved for storing the column number.
   * Bits above these store the line number.
   * This gives us decent position information for everything except
   * files already passed through a minimizer, where lines might
   * be longer than 4096 characters.
   */
  public static final int COLUMN_BITS = 12;

  /**
   * MAX_COLUMN_NUMBER represents the maximum column number that can
   * be represented.  JSCompiler's modifications to Rhino cause all
   * tokens located beyond the maximum column to MAX_COLUMN_NUMBER.
   */
  public static final int MAX_COLUMN_NUMBER = (1 << COLUMN_BITS) - 1;

  /**
   * COLUMN_MASK stores a value where bits storing the column number
   * are set, and bits storing the line are not set.  It's handy for
   * separating column number from line number.
   */
  public static final int COLUMN_MASK = MAX_COLUMN_NUMBER;

  /**
   * Source position of this node. The position is encoded with the
   * column number in the low 12 bits of the integer, and the line
   * number in the rest.  Create some handy constants so we can change this
   * size if we want.
   */
  private transient int sourcePosition;

  /** The length of the code represented by the node. */
  private transient int length;

  @Nullable private transient JSType jstype;

  @Nullable protected transient Node parent;

  //==========================================================================
  // Source position management

  public final void setStaticSourceFileFrom(Node other) {
    // Make sure source file prop nodes are not duplicated.
    if (other.propListHead != null
        && (this.propListHead == null
            || (this.propListHead.propType == Prop.SOURCE_FILE.ordinal()
               && this.propListHead.next == null))) {
      // Either the node has only Prop.SOURCE_FILE as a property or has not properties.
      PropListItem tail = other.propListHead;
      while (tail.next != null) {
        tail = tail.next;
      }
      if (tail.propType == Prop.SOURCE_FILE.ordinal()) {
        propListHead = tail;
        return;
      }
    }
    setStaticSourceFile(other.getStaticSourceFile());
  }

  public final Node setStaticSourceFile(@Nullable StaticSourceFile file) {
    this.putProp(Prop.SOURCE_FILE, file);
    return this;
  }

  /** Sets the source file to a non-extern file of the given name. */
  public final void setSourceFileForTesting(String name) {
    this.putProp(Prop.SOURCE_FILE, new SimpleSourceFile(name, SourceKind.STRONG));
  }

  // TODO(johnlenz): make this final
  @Nullable
  public String getSourceFileName() {
    StaticSourceFile file = getStaticSourceFile();
    return file == null ? null : file.getName();
  }

  /** Returns the source file associated with this input. */
  @Nullable
  public StaticSourceFile getStaticSourceFile() {
    return ((StaticSourceFile) this.getProp(Prop.SOURCE_FILE));
  }

  /**
   * @param inputId
   */
  public void setInputId(InputId inputId) {
    this.putProp(Prop.INPUT_ID, inputId);
  }

  /** @return The Id of the CompilerInput associated with this Node. */
  @Nullable
  public InputId getInputId() {
    return ((InputId) this.getProp(Prop.INPUT_ID));
  }

  /** The original name of this node, if the node has been renamed. */
  @Nullable
  public String getOriginalName() {
    return (String) this.getProp(Prop.ORIGINALNAME);
  }

  public void setOriginalName(String originalName) {
    this.putProp(Prop.ORIGINALNAME, originalName);
  }

  /**
   * Whether this node should be indexed by static analysis / code indexing tools.
   */
  public final boolean isIndexable() {
    return !this.getBooleanProp(Prop.NON_INDEXABLE);
  }

  public final void makeNonIndexable() {
    this.putBooleanProp(Prop.NON_INDEXABLE, true);
  }

  public final void makeNonIndexableRecursive() {
    this.makeNonIndexable();
    for (Node child : children()) {
      child.makeNonIndexableRecursive();
    }
  }

  public final boolean isFromExterns() {
    StaticSourceFile file = getStaticSourceFile();
    return file == null ? false : file.isExtern();
  }

  public final int getLength() {
    return this.length;
  }

  public final void setLength(int length) {
    this.length = length;
  }

  /** Useful to set length of a transpiled node tree to map back to the length of original node. */
  public final void setLengthForTree(int length) {
    this.length = length;

    for (Node child = first; child != null; child = child.next) {
      child.setLengthForTree(length);
    }
  }

  public final int getLineno() {
    return extractLineno(sourcePosition);
  }

  // Returns the 0-based column number
  public final int getCharno() {
    return extractCharno(sourcePosition);
  }

  // TODO(johnlenz): make this final
  public int getSourceOffset() {
    StaticSourceFile file = getStaticSourceFile();
    if (file == null) {
      return -1;
    }
    int lineno = getLineno();
    if (lineno == -1) {
      return -1;
    }
    return file.getLineOffset(lineno) + getCharno();
  }

  public final int getSourcePosition() {
    return sourcePosition;
  }

  public final void setLineno(int lineno) {
      int charno = getCharno();
      if (charno == -1) {
        charno = 0;
      }
      sourcePosition = mergeLineCharNo(lineno, charno);
  }

  public final void setCharno(int charno) {
      sourcePosition = mergeLineCharNo(getLineno(), charno);
  }

  public final void setSourceEncodedPosition(int sourcePosition) {
    this.sourcePosition = sourcePosition;
  }

  public final void setSourceEncodedPositionForTree(int sourcePosition) {
    this.sourcePosition = sourcePosition;

    for (Node child = first; child != null; child = child.next) {
      child.setSourceEncodedPositionForTree(sourcePosition);
    }
  }

  /**
   * Merges the line number and character number in one integer. The Character
   * number takes the first 12 bits and the line number takes the rest. If
   * the character number is greater than 212-1 it is
   * adjusted to 212-1.
   */
  protected static int mergeLineCharNo(int lineno, int charno) {
    if (lineno < 0 || charno < 0) {
      return -1;
    } else if ((charno & ~COLUMN_MASK) != 0) {
      return lineno << COLUMN_BITS | COLUMN_MASK;
    } else {
      return lineno << COLUMN_BITS | (charno & COLUMN_MASK);
    }
  }

  /**
   * Extracts the line number and character number from a merged line char
   * number (see {@link #mergeLineCharNo(int, int)}).
   */
  protected static int extractLineno(int lineCharNo) {
    if (lineCharNo == -1) {
      return -1;
    } else {
      return lineCharNo >>> COLUMN_BITS;
    }
  }

  /**
   * Extracts the character number and character number from a merged line
   * char number (see {@link #mergeLineCharNo(int, int)}).
   */
  protected static int extractCharno(int lineCharNo) {
    if (lineCharNo == -1) {
      return -1;
    } else {
      return lineCharNo & COLUMN_MASK;
    }
  }

  //==========================================================================
  // Iteration

  /**
   * 

Return an iterable object that iterates over this node's children. * The iterator does not support the optional operation * {@link Iterator#remove()}.

* *

To iterate over a node's children, one can write

*
Node n = ...;
   * for (Node child : n.children()) { ...
*/ public final Iterable children() { if (first == null) { return Collections.emptySet(); } else { return new SiblingNodeIterable(first); } } /** *

Return an iterable object that iterates over this node's siblings, * including this Node but not any siblings that are before this one. * *

The iterator does not support the optional * operation {@link Iterator#remove()}.

* *

To iterate over a node's siblings including itself, one can write

*
Node n = ...;
   * for (Node sibling : n.siblings()) { ...
*/ public final Iterable siblings() { return new SiblingNodeIterable(this); } /** * @see Node#siblings() */ private static final class SiblingNodeIterable implements Iterable { private final Node start; SiblingNodeIterable(Node start) { this.start = start; } @Override public Iterator iterator() { return new SiblingNodeIterator(start); } } /** * @see Node#siblings() */ private static final class SiblingNodeIterator implements Iterator { @Nullable private Node current; SiblingNodeIterator(Node start) { this.current = start; } @Override public boolean hasNext() { return current != null; } @Override public Node next() { if (current == null) { throw new NoSuchElementException(); } Node n = current; current = current.getNext(); return n; } @Override public void remove() { throw new UnsupportedOperationException(); } } // ========================================================================== // Accessors @Nullable final PropListItem getPropListHeadForTesting() { return propListHead; } final void setPropListHead(@Nullable PropListItem propListHead) { this.propListHead = propListHead; } @Nullable public final Node getParent() { return parent; } @Nullable public final Node getGrandparent() { return parent == null ? null : parent.parent; } /** * Gets the ancestor node relative to this. * * @param level 0 = this, 1 = the parent, etc. */ @Nullable public final Node getAncestor(int level) { checkArgument(level >= 0); Node node = this; while (node != null && level-- > 0) { node = node.getParent(); } return node; } /** @return True if this Node is {@code node} or a descendant of {@code node}. */ public final boolean isDescendantOf(Node node) { for (Node n = this; n != null; n = n.parent) { if (n == node) { return true; } } return false; } public final boolean isOnlyChildOf(Node possibleParent) { return possibleParent == getParent() && getPrevious() == null && getNext() == null; } public final boolean isFirstChildOf(Node possibleParent) { return possibleParent == getParent() && getPrevious() == null; } public final boolean isSecondChildOf(Node possibleParent) { Node previousNode = getPrevious(); return previousNode != null && previousNode.isFirstChildOf(possibleParent); } /** * Iterates all of the node's ancestors excluding itself. */ public final AncestorIterable getAncestors() { return new AncestorIterable(this.getParent()); } /** * Iterator to go up the ancestor tree. */ public static final class AncestorIterable implements Iterable { @Nullable private Node cur; /** @param cur The node to start. */ AncestorIterable(@Nullable Node cur) { this.cur = cur; } @Override public Iterator iterator() { return new Iterator() { @Override public boolean hasNext() { return cur != null; } @Override public Node next() { if (!hasNext()) { throw new NoSuchElementException(); } Node n = cur; cur = cur.getParent(); return n; } @Override public void remove() { throw new UnsupportedOperationException(); } }; } } /** * Check for one child more efficiently than by iterating over all the * children as is done with Node.getChildCount(). * * @return Whether the node has exactly one child. */ public final boolean hasOneChild() { return first != null && first.next == null; } /** * Check for two children more efficiently than {@code getChildCount() == 2} * * @return Whether the node has exactly two children. */ public final boolean hasTwoChildren() { return first != null && first.next != null && first.next == getLastChild(); } /** * Check for zero or one child more efficiently than by iterating over all the * children as is done with Node.getChildCount(). * * @return Whether the node has no children or exactly one child. */ public final boolean hasZeroOrOneChild() { return first == getLastChild(); } /** * Check for more than one child more efficiently than by iterating over all * the children as is done with Node.getChildCount(). * * @return Whether the node more than one child. */ public final boolean hasMoreThanOneChild() { return first != null && first.next != null; } /** * Check for has exactly the number of specified children. * * @return Whether the node has exactly the number of children specified. */ public final boolean hasXChildren(int x) { int c = 0; for (Node n = first; n != null && c <= x; n = n.next) { c++; } return c == x; } public final int getChildCount() { int c = 0; for (Node n = first; n != null; n = n.next) { c++; } return c; } // Intended for testing and verification only. public final boolean hasChild(Node child) { for (Node n = first; n != null; n = n.next) { if (child == n) { return true; } } return false; } /** Checks equivalence without going into child nodes */ public final boolean isEquivalentToShallow(Node node) { return isEquivalentTo(node, false, false, false, false); } /** Returns true if this node is equivalent semantically to another including side effects. */ public final boolean isEquivalentWithSideEffectsTo(Node node) { return isEquivalentTo(node, false, true, false, true); } /** Returns true if this node is equivalent semantically to another including side effects. */ public final boolean isEquivalentWithSideEffectsToShallow(Node node) { return isEquivalentTo(node, false, false, false, true); } /** * Returns true if this node is equivalent semantically to another and the types are equivalent. */ public final boolean isEquivalentToTyped(Node node) { return isEquivalentTo(node, true, true, true, false); } /** Returns true if this node is equivalent semantically to another */ public final boolean isEquivalentTo(Node node) { return isEquivalentTo(node, false, true, false, false); } /** * @param compareType Whether to compare the JSTypes of the nodes. * @param recurse Whether to compare the children of the current node. If not, only the count of * the children are compared. * @param jsDoc Whether to check that the JsDoc of the nodes are equivalent. * @return Whether this node is equivalent semantically to the provided node. */ final boolean isEquivalentTo(Node node, boolean compareType, boolean recurse, boolean jsDoc) { return isEquivalentTo(node, compareType, recurse, jsDoc, false); } /** * @param compareType Whether to compare the JSTypes of the nodes. * @param recurse Whether to compare the children of the current node. If not, only the count * of the children are compared. * @param jsDoc Whether to check that the JsDoc of the nodes are equivalent. * @param sideEffect Whether to check that the side-effect flags of the nodes are equivalent. * @return Whether this node is equivalent semantically to the provided node. */ public boolean isEquivalentTo( Node node, boolean compareType, boolean recurse, boolean jsDoc, boolean sideEffect) { if (token != node.token || getChildCount() != node.getChildCount() || this.getClass() != node.getClass()) { return false; } if (compareType && !JSType.isEquivalent(getJSType(), node.getJSType())) { return false; } if (jsDoc && !JSDocInfo.areEquivalent(getJSDocInfo(), node.getJSDocInfo())) { return false; } TypeDeclarationNode thisTDN = this.getDeclaredTypeExpression(); TypeDeclarationNode thatTDN = node.getDeclaredTypeExpression(); if ((thisTDN != null || thatTDN != null) && (thisTDN == null || thatTDN == null || !thisTDN.isEquivalentTo(thatTDN, compareType, recurse, jsDoc))) { return false; } for (Function getter : PROP_GETTERS_FOR_EQUALITY) { if (!Objects.equal(getter.apply(this), getter.apply(node))) { return false; } } if (sideEffect) { if (this.getSideEffectFlags() != node.getSideEffectFlags()) { return false; } if (this.isUnusedParameter() != node.isUnusedParameter()) { return false; } } if (recurse) { for (Node n = first, n2 = node.first; n != null; n = n.next, n2 = n2.next) { if (!n.isEquivalentTo(n2, compareType, recurse, jsDoc, sideEffect)) { return false; } } } return true; } /** * Accessors for {@link Node} properties that should also be compared when comparing nodes for * equality. * *

We'd prefer to list the props that should be ignored rather than the ones that should be * checked, but that was too difficult initially. In general these properties are ones that show * up as keywords / symbols which don't have their own nodes. * *

Accessor functions are used rather than {@link Prop}s to encode the correct way of reading * the prop. */ private static final ImmutableList> PROP_GETTERS_FOR_EQUALITY = ImmutableList.of( Node::isArrowFunction, Node::isAsyncFunction, Node::isAsyncGeneratorFunction, Node::isGeneratorFunction, Node::isStaticMember, Node::isYieldAll, (n) -> n.getIntProp(Prop.SLASH_V), (n) -> n.getIntProp(Prop.INCRDECR), (n) -> n.getIntProp(Prop.QUOTED), (n) -> n.getBooleanProp(Prop.FREE_CALL), (n) -> n.getBooleanProp(Prop.COMPUTED_PROP_METHOD), (n) -> n.getBooleanProp(Prop.COMPUTED_PROP_GETTER), (n) -> n.getBooleanProp(Prop.COMPUTED_PROP_SETTER)); /** * This function takes a set of GETPROP nodes and produces a string that is each property * separated by dots. If the node ultimately under the left sub-tree is not a simple name, this is * not a valid qualified name. * * @return a null if this is not a qualified name, or a dot-separated string of the name and * properties. */ @Nullable public final String getQualifiedName() { switch (token) { case NAME: String name = getString(); return name.isEmpty() ? null : name; case GETPROP: StringBuilder builder = getQualifiedNameForGetProp(0); return builder != null ? builder.toString() : null; case THIS: return "this"; case SUPER: return "super"; default: return null; } } @Nullable public final QualifiedName getQualifiedNameObject() { return isQualifiedName() ? new QualifiedName.NodeQname(this) : null; } /** * Helper method for {@link #getQualifiedName} to handle GETPROP nodes. * * @param reserve The number of characters of space to reserve in the StringBuilder * @return {@code null} if this is not a qualified name or a StringBuilder if it is a complex * qualified name. */ @Nullable private StringBuilder getQualifiedNameForGetProp(int reserve) { String propName = getLastChild().getString(); reserve += 1 + propName.length(); // +1 for the '.' StringBuilder builder; if (first.isGetProp()) { builder = first.getQualifiedNameForGetProp(reserve); if (builder == null) { return null; } } else { String left = first.getQualifiedName(); if (left == null) { return null; } builder = new StringBuilder(left.length() + reserve); builder.append(left); } builder.append('.').append(propName); return builder; } /** * This function takes a set of GETPROP nodes and produces a string that is each property * separated by dots. If the node ultimately under the left sub-tree is not a simple name, this is * not a valid qualified name. This method returns the original name of each segment rather than * the renamed version. * * @return a null if this is not a qualified name, or a dot-separated string of the name and * properties. */ @Nullable public final String getOriginalQualifiedName() { if (token == Token.NAME || getBooleanProp(Prop.IS_MODULE_NAME)) { String name = getOriginalName(); if (name == null) { name = getString(); } return name.isEmpty() ? null : name; } else if (token == Token.GETPROP) { String left = getFirstChild().getOriginalQualifiedName(); if (left == null) { return null; } String right = getLastChild().getOriginalName(); if (right == null) { right = getLastChild().getString(); } return left + "." + right; } else if (token == Token.THIS) { return "this"; } else if (token == Token.SUPER) { return "super"; } else { return null; } } /** * Returns whether a node corresponds to a simple or a qualified name, such as * x or a.b.c or this.a. */ public final boolean isQualifiedName() { switch (this.getToken()) { case NAME: return !getString().isEmpty(); case THIS: case SUPER: return true; case GETPROP: return getFirstChild().isQualifiedName(); case MEMBER_FUNCTION_DEF: // These are explicitly *not* qualified name components. default: return false; } } /** * Returns whether a node matches a simple name, such as * x, returns false if this is not a NAME node. */ public final boolean matchesName(String name) { if (token != token.NAME) { return false; } String internalString = getString(); return !internalString.isEmpty() && name.equals(internalString); } /** * Check that if two NAME node match, returns false if either node is * not a NAME node. As a empty string is not considered a * valid Name (it is an AST placeholder), empty strings are never * considered to be matches. */ @SuppressWarnings("ReferenceEquality") public final boolean matchesName(Node n) { if (token != token.NAME || n.token != Token.NAME) { return false; } // ==, rather than equal as it is intern'd in setString String internalString = getString(); return internalString != "" && internalString == n.getString(); } /** * Returns whether a node matches a simple or a qualified name, such as * x or a.b.c or this.a. */ public final boolean matchesQualifiedName(String name) { return matchesQualifiedName(name, name.length()); } /** * Returns whether a node matches a simple or a qualified name, such as * x or a.b.c or this.a. */ private boolean matchesQualifiedName(String qname, int endIndex) { int start = qname.lastIndexOf('.', endIndex - 1) + 1; switch (this.getToken()) { case NAME: case IMPORT_STAR: String name = getString(); return start == 0 && !name.isEmpty() && name.length() == endIndex && qname.startsWith(name); case THIS: return start == 0 && 4 == endIndex && qname.startsWith("this"); case SUPER: return start == 0 && 5 == endIndex && qname.startsWith("super"); case GETPROP: String prop = getLastChild().getString(); return start > 1 && prop.length() == endIndex - start && prop.regionMatches(0, qname, start, endIndex - start) && getFirstChild().matchesQualifiedName(qname, start - 1); case MEMBER_FUNCTION_DEF: // These are explicitly *not* qualified name components. default: return false; } } /** * Returns whether a node matches a simple or a qualified name, such as x or * a.b.c or this.a. */ @SuppressWarnings("ReferenceEquality") public final boolean matchesQualifiedName(Node n) { if (n.token != token) { return false; } switch (token) { case NAME: // ==, rather than equal as it is intern'd in setString String internalString = getString(); return internalString != "" && internalString == n.getString(); case THIS: case SUPER: return true; case GETPROP: // ==, rather than equal as it is intern'd in setString return getLastChild().getString() == n.getLastChild().getString() && getFirstChild().matchesQualifiedName(n.getFirstChild()); case MEMBER_FUNCTION_DEF: // These are explicitly *not* qualified name components. default: return false; } } /** * Returns whether a node corresponds to a simple or a qualified name without * a "this" reference, such as a.b.c, but not this.a * . */ @SuppressWarnings("ReferenceEquality") public final boolean isUnscopedQualifiedName() { switch (this.getToken()) { case NAME: // Both string are intern'd. return getString() != ""; case GETPROP: return getFirstChild().isUnscopedQualifiedName(); default: return false; } } public final boolean isValidAssignmentTarget() { switch (this.getToken()) { case NAME: case GETPROP: case GETELEM: case ARRAY_PATTERN: case OBJECT_PATTERN: return true; default: return false; } } // ========================================================================== // Mutators /** * Removes this node from its parent. Equivalent to: * node.getParent().removeChild(); */ public final Node detachFromParent() { return detach(); } /** * Removes this node from its parent. Equivalent to: * node.getParent().removeChild(); */ public final Node detach() { checkNotNull(parent); parent.removeChild(this); return this; } /** * Removes the first child of Node. Equivalent to: node.removeChild(node.getFirstChild()); * * @return The removed Node. */ @Nullable public final Node removeFirstChild() { Node child = first; if (child != null) { removeChild(child); } return child; } /** @return A Node that is the head of the list of children. */ @Nullable public final Node removeChildren() { Node children = first; for (Node child = first; child != null; child = child.next) { child.parent = null; } first = null; return children; } /** * Removes all children from this node and isolates the children from each * other. */ public final void detachChildren() { for (Node child = first; child != null;) { Node nextChild = child.next; child.parent = null; child.next = null; child.previous = null; child = nextChild; } first = null; } public final Node removeChildAfter(Node prev) { Node target = prev.next; checkNotNull(target, "no next sibling."); removeChild(target); return target; } /** Remove the child after the given child, or the first child if given null. */ public final Node removeFirstOrChildAfter(@Nullable Node prev) { checkArgument(prev == null || prev.parent == this, "invalid node."); Node target = prev == null ? first : prev.next; checkNotNull(target, "no next sibling."); removeChild(target); return target; } /** * @return A detached clone of the Node, specifically excluding its children. */ @CheckReturnValue public final Node cloneNode() { return cloneNode(false); } /** * @return A detached clone of the Node, specifically excluding its children. */ @CheckReturnValue protected Node cloneNode(boolean cloneTypeExprs) { return copyNodeFields(new Node(token), cloneTypeExprs); } final T copyNodeFields(T dst, boolean cloneTypeExprs) { dst.setSourceEncodedPosition(this.sourcePosition); dst.setLength(this.getLength()); dst.setJSType(this.jstype); dst.setPropListHead(this.propListHead); // TODO(johnlenz): Remove this once JSTypeExpression are immutable if (cloneTypeExprs) { JSDocInfo info = this.getJSDocInfo(); if (info != null) { this.setJSDocInfo(info.clone(true)); } } return dst; } /** * @return A detached clone of the Node and all its children. */ @CheckReturnValue public final Node cloneTree() { return cloneTree(false); } @CheckReturnValue public final Node cloneTree(boolean cloneTypeExprs) { Node result = cloneNode(cloneTypeExprs); Node firstChild = null; Node lastChild = null; if (this.hasChildren()) { for (Node n2 = getFirstChild(); n2 != null; n2 = n2.next) { Node n2clone = n2.cloneTree(cloneTypeExprs); n2clone.parent = result; if (firstChild == null) { firstChild = n2clone; lastChild = firstChild; } else { lastChild.next = n2clone; n2clone.previous = lastChild; lastChild = n2clone; } } firstChild.previous = lastChild; lastChild.next = null; result.first = firstChild; } return result; } /** * Overwrite all the source information in this node with * that of {@code other}. */ public final Node useSourceInfoFrom(Node other) { setStaticSourceFileFrom(other); putProp(Prop.ORIGINALNAME, other.getProp(Prop.ORIGINALNAME)); sourcePosition = other.sourcePosition; length = other.length; return this; } public final Node srcref(Node other) { return useSourceInfoFrom(other); } /** * Overwrite all the source information in this node and its subtree with * that of {@code other}. */ public final Node useSourceInfoFromForTree(Node other) { useSourceInfoFrom(other); for (Node child = first; child != null; child = child.next) { child.useSourceInfoFromForTree(other); } return this; } public final Node srcrefTree(Node other) { return useSourceInfoFromForTree(other); } /** * Overwrite all the source information in this node with * that of {@code other} iff the source info is missing. */ public final Node useSourceInfoIfMissingFrom(Node other) { if (getStaticSourceFile() == null) { setStaticSourceFileFrom(other); sourcePosition = other.sourcePosition; length = other.length; } // TODO(lharker): should this be inside the above if condition? // If the node already has a source file, it seems strange to // go ahead and set the original name anyway. if (getProp(Prop.ORIGINALNAME) == null) { putProp(Prop.ORIGINALNAME, other.getProp(Prop.ORIGINALNAME)); } return this; } /** * Overwrite all the source information in this node and its subtree with * that of {@code other} iff the source info is missing. */ public final Node useSourceInfoIfMissingFromForTree(Node other) { useSourceInfoIfMissingFrom(other); for (Node child = first; child != null; child = child.next) { child.useSourceInfoIfMissingFromForTree(other); } return this; } //========================================================================== // Custom annotations /** * Returns the compiled inferred type on this node. Not to be confused with {@link * #getDeclaredTypeExpression()} which returns the syntactically specified type. */ @Nullable public final JSType getJSType() { return jstype; } /** Returns the compiled inferred type on this node, or throws an NPE if there isn't one. */ public final JSType getJSTypeRequired() { checkNotNull(jstype, "no jstype: %s", this); return jstype; } public final Node setJSType(@Nullable JSType jstype) { this.jstype = jstype; return this; } /** * Get the {@link JSDocInfo} attached to this node. * * @return the information or {@code null} if no JSDoc is attached to this node */ @Nullable public final JSDocInfo getJSDocInfo() { return (JSDocInfo) getProp(Prop.JSDOC_INFO); } /** * Sets the {@link JSDocInfo} attached to this node. */ public final Node setJSDocInfo(JSDocInfo info) { putProp(Prop.JSDOC_INFO, info); return this; } /** This node was last changed at {@code time} */ public final void setChangeTime(int time) { putIntProp(Prop.CHANGE_TIME, time); } /** Returns the time of the last change for this node */ public final int getChangeTime() { return getIntProp(Prop.CHANGE_TIME); } public final void setDeleted(boolean deleted) { putBooleanProp(Prop.DELETED, deleted); } public final boolean isDeleted() { return getBooleanProp(Prop.DELETED); } /** If this node represents a typedef declaration, the associated JSType */ public final void setTypedefTypeProp(JSType type) { putProp(Prop.TYPEDEF_TYPE, type); } /** If this node represents a typedef declaration, the associated JSType */ public final JSType getTypedefTypeProp() { return (JSType) getProp(Prop.TYPEDEF_TYPE); } /** @param unused Whether a parameter was function to be unused. Set by RemoveUnusedVars */ public final void setUnusedParameter(boolean unused) { putBooleanProp(Prop.IS_UNUSED_PARAMETER, unused); } /** * @return Whether a parameter was function to be unused. Set by RemoveUnusedVars */ public final boolean isUnusedParameter() { return getBooleanProp(Prop.IS_UNUSED_PARAMETER); } /** Sets the isShorthandProperty annotation. */ public final void setShorthandProperty(boolean shorthand) { putBooleanProp(Prop.IS_SHORTHAND_PROPERTY, shorthand); } /** Whether this {x:x} property was originally parsed as {x}. */ public final boolean isShorthandProperty() { return getBooleanProp(Prop.IS_SHORTHAND_PROPERTY); } /** * Sets whether this node is a variable length argument node. This * method is meaningful only on {@link Token#NAME} nodes * used to define a {@link Token#FUNCTION}'s argument list. */ public final void setVarArgs(boolean varArgs) { putBooleanProp(Prop.VAR_ARGS, varArgs); } /** * Returns whether this node is a variable length argument node. This * method's return value is meaningful only on {@link Token#NAME} nodes * used to define a {@link Token#FUNCTION}'s argument list. */ public final boolean isVarArgs() { return getBooleanProp(Prop.VAR_ARGS); } /** * Sets whether this node is an optional argument node. This * method is meaningful only on {@link Token#NAME} nodes * used to define a {@link Token#FUNCTION}'s argument list. */ public final void setOptionalArg(boolean optionalArg) { putBooleanProp(Prop.OPT_ARG, optionalArg); } /** * Returns whether this node is an optional argument node. This * method's return value is meaningful only on {@link Token#NAME} nodes * used to define a {@link Token#FUNCTION}'s argument list. */ public final boolean isOptionalArg() { return getBooleanProp(Prop.OPT_ARG); } /** * Returns whether this node is an optional node in the ES6 Typed syntax. */ public final boolean isOptionalEs6Typed() { return getBooleanProp(Prop.OPT_ES6_TYPED); } /** * Sets whether this is a synthetic block that should not be considered * a real source block. */ public final void setIsSyntheticBlock(boolean val) { checkState(token == Token.BLOCK); putBooleanProp(Prop.SYNTHETIC, val); } /** * Returns whether this is a synthetic block that should not be considered * a real source block. */ public final boolean isSyntheticBlock() { return getBooleanProp(Prop.SYNTHETIC); } /** * Sets the ES5 directives on this node. */ public final void setDirectives(Set val) { putProp(Prop.DIRECTIVES, val); } /** Returns the set of ES5 directives for this node. */ @SuppressWarnings("unchecked") @Nullable public final Set getDirectives() { return (Set) getProp(Prop.DIRECTIVES); } /** * Sets whether this is an added block that should not be considered * a real source block. Eg: In "if (true) x;", the "x;" is put under an added * block in the AST. */ public final void setIsAddedBlock(boolean val) { putBooleanProp(Prop.ADDED_BLOCK, val); } /** * Returns whether this is an added block that should not be considered * a real source block. */ public final boolean isAddedBlock() { return getBooleanProp(Prop.ADDED_BLOCK); } /** * Sets whether this node is a static member node. This * method is meaningful only on {@link Token#GETTER_DEF}, * {@link Token#SETTER_DEF} or {@link Token#MEMBER_FUNCTION_DEF} nodes contained * within {@link Token#CLASS}. */ public final void setStaticMember(boolean isStatic) { putBooleanProp(Prop.STATIC_MEMBER, isStatic); } /** * Returns whether this node is a static member node. This * method is meaningful only on {@link Token#GETTER_DEF}, * {@link Token#SETTER_DEF} or {@link Token#MEMBER_FUNCTION_DEF} nodes contained * within {@link Token#CLASS}. */ public final boolean isStaticMember() { return getBooleanProp(Prop.STATIC_MEMBER); } /** * Sets whether this node is a generator node. This * method is meaningful only on {@link Token#FUNCTION} or * {@link Token#MEMBER_FUNCTION_DEF} nodes. */ public final void setIsGeneratorFunction(boolean isGenerator) { putBooleanProp(Prop.GENERATOR_FN, isGenerator); } /** * Returns whether this node is a generator function node. */ public final boolean isGeneratorFunction() { return getBooleanProp(Prop.GENERATOR_FN); } /** * Sets whether this node subtree contains YIELD nodes. * *

It's used in the translation of generators. */ public final void setGeneratorMarker(boolean isGeneratorMarker) { putBooleanProp(Prop.IS_GENERATOR_MARKER, isGeneratorMarker); } /** * Returns whether this node was marked as containing YIELD nodes. * *

It's used in the translation of generators. */ public final boolean isGeneratorMarker() { return getBooleanProp(Prop.IS_GENERATOR_MARKER); } /** * @see #isGeneratorSafe() */ public final void setGeneratorSafe(boolean isGeneratorSafe) { putBooleanProp(Prop.IS_GENERATOR_SAFE, isGeneratorSafe); } /** * Used when translating ES6 generators. If this returns true, this Node * was generated by the compiler, and it is safe to copy this node to the * transpiled output with no further changes. */ public final boolean isGeneratorSafe() { return getBooleanProp(Prop.IS_GENERATOR_SAFE); } /** * Sets whether this node is a arrow function node. This * method is meaningful only on {@link Token#FUNCTION} */ public final void setIsArrowFunction(boolean isArrow) { checkState(isFunction()); putBooleanProp(Prop.ARROW_FN, isArrow); } /** * Returns whether this node is a arrow function node. */ public final boolean isArrowFunction() { return isFunction() && getBooleanProp(Prop.ARROW_FN); } /** * Sets whether this node is an async function node. This * method is meaningful only on {@link Token#FUNCTION} */ public void setIsAsyncFunction(boolean isAsync) { checkState(isFunction()); putBooleanProp(Prop.ASYNC_FN, isAsync); } /** * Returns whether this is an async function node. */ public final boolean isAsyncFunction() { return isFunction() && getBooleanProp(Prop.ASYNC_FN); } /** Returns whether this is an async generator function node. */ public final boolean isAsyncGeneratorFunction() { return isAsyncFunction() && isGeneratorFunction(); } /** * Sets whether this node is a generator node. This * method is meaningful only on {@link Token#FUNCTION} or * {@link Token#MEMBER_FUNCTION_DEF} nodes. */ public final void setYieldAll(boolean isGenerator) { putBooleanProp(Prop.YIELD_ALL, isGenerator); } /** * Returns whether this node is a generator node. This * method is meaningful only on {@link Token#FUNCTION} or * {@link Token#MEMBER_FUNCTION_DEF} nodes. */ public final boolean isYieldAll() { return getBooleanProp(Prop.YIELD_ALL); } /** Returns any goog.define'd name corresponding to this NAME or GETPROP node. */ public final String getDefineName() { return (String) getProp(Prop.DEFINE_NAME); } /** Sets the goog.define name for a NAME or GETPROP node. */ public final void setDefineName(String name) { putProp(Prop.DEFINE_NAME, name); } /** * Marks this function or constructor call's side effect flags. * This property is only meaningful for {@link Token#CALL} and * {@link Token#NEW} nodes. */ public final void setSideEffectFlags(int flags) { checkState( this.isCall() || this.isNew() || this.isTaggedTemplateLit(), "Side-effect flags can only be set on invocation nodes; got %s", this); // We invert the flags before setting because we also invert the them when getting; they go // full circle. // // We apply the mask after inversion so that if all flags are being set (all 1s), it's // equivalent to storing a 0, the default value of an int-prop, which has no memory cost. putIntProp(Prop.SIDE_EFFECT_FLAGS, ~flags & SideEffectFlags.USED_BITS_MASK); } public final void setSideEffectFlags(SideEffectFlags flags) { setSideEffectFlags(flags.valueOf()); } /** * Returns the side effects flags for this node. */ public final int getSideEffectFlags() { // Int props default to 0, but we want the default for side-effect flags to be all 1s. // Therefore, we invert the value returned here. This is correct for non-defaults because we // also invert when setting the flags. return ~getIntProp(Prop.SIDE_EFFECT_FLAGS) & SideEffectFlags.USED_BITS_MASK; } /** * A helper class for getting and setting invocation side-effect flags. * *

The following values are of interest: * *

    *
  1. Is global state mutated? ({@code MUTATES_GLOBAL_STATE}) *
  2. Is the receiver (`this`) mutated? ({@code MUTATES_THIS}) *
  3. Are any arguments mutated? ({@code MUTATES_ARGUMENTS}) *
  4. Does the call throw an error? ({@code THROWS}) *
  5. Is the return an escaped (mutable by other code) value? ({@code ESCAPED_RETURN}) *
* * @author [email protected] (John Lenz) */ public static final class SideEffectFlags { public static final int MUTATES_GLOBAL_STATE = 1; public static final int MUTATES_THIS = 2; public static final int MUTATES_ARGUMENTS = 4; public static final int THROWS = 8; public static final int ESCAPED_RETURN = 16; private static final int USED_BITS_MASK = (1 << 5) - 1; // TODO(nickreid): Delete one of these values. They should be symmetric with respect to // inversion. We need better noenclature to describe ESCAPED_RETURN. public static final int NO_SIDE_EFFECTS = ESCAPED_RETURN; public static final int ALL_SIDE_EFFECTS = MUTATES_GLOBAL_STATE | MUTATES_THIS | MUTATES_ARGUMENTS | THROWS | ESCAPED_RETURN; // A bitfield indicating the flag statuses. All bits set to 1 means "global state changes and // unknown locality of result". private int value = ALL_SIDE_EFFECTS; public SideEffectFlags() { } public SideEffectFlags(int value) { this.value = value; } public int valueOf() { return value; } /** All side-effect occur and the returned results are non-local. */ public SideEffectFlags setAllFlags() { value = ALL_SIDE_EFFECTS; return this; } /** No side-effects occur and the returned results are local. */ public SideEffectFlags clearAllFlags() { value = NO_SIDE_EFFECTS & ~ESCAPED_RETURN; return this; } /** * Preserve the return result flag, but clear the others: * no global state change, no throws, no this change, no arguments change */ public void clearSideEffectFlags() { value &= ESCAPED_RETURN; } public SideEffectFlags setMutatesGlobalState() { // Modify global means everything must be assumed to be modified. value |= MUTATES_GLOBAL_STATE | MUTATES_ARGUMENTS | MUTATES_THIS; return this; } public SideEffectFlags setThrows() { value |= THROWS; return this; } public SideEffectFlags setMutatesThis() { value |= MUTATES_THIS; return this; } public SideEffectFlags setMutatesArguments() { value |= MUTATES_ARGUMENTS; return this; } public SideEffectFlags setReturnsTainted() { value |= ESCAPED_RETURN; return this; } @Override @DoNotCall // For debugging only. public String toString() { StringBuilder builder = new StringBuilder("Side effects: "); if ((value & MUTATES_THIS) != 0) { builder.append("this "); } if ((value & MUTATES_GLOBAL_STATE) != 0) { builder.append("global "); } if ((value & THROWS) != 0) { builder.append("throw "); } if ((value & MUTATES_ARGUMENTS) != 0) { builder.append("args "); } if ((value & ESCAPED_RETURN) != 0) { builder.append("return "); } return builder.toString(); } } /** * @return Whether the only side-effect is "modifies this" */ public final boolean isOnlyModifiesThisCall() { int consideredFlags = getSideEffectFlags(); consideredFlags |= SideEffectFlags.NO_SIDE_EFFECTS; // Set non-side-effect bits to 1. // TODO(nickreid): Delete this; check if MUTATES_THIS is actually set. This was left in to // maintain existing behaviour but it makes the name of this method misleading. consideredFlags &= ~SideEffectFlags.MUTATES_THIS; return consideredFlags == SideEffectFlags.NO_SIDE_EFFECTS; } /** * @return Whether the only side-effect is "modifies arguments" */ public final boolean isOnlyModifiesArgumentsCall() { int consideredFlags = getSideEffectFlags(); consideredFlags |= SideEffectFlags.NO_SIDE_EFFECTS; // Set non-side-effect bits to 1. // TODO(nickreid): Delete this; check if MUTATES_ARGUMENTS is actually set. This was left in to // maintain existing behaviour but it makes the name of this method misleading. consideredFlags &= ~SideEffectFlags.MUTATES_ARGUMENTS; return consideredFlags == SideEffectFlags.NO_SIDE_EFFECTS; } /** * Returns true if this node is a function or constructor call that * has no side effects. */ public final boolean isNoSideEffectsCall() { int consideredFlags = getSideEffectFlags(); consideredFlags |= SideEffectFlags.NO_SIDE_EFFECTS; // Set non-side-effect bits to 1. return consideredFlags == SideEffectFlags.NO_SIDE_EFFECTS; } /** * Returns true if this node is a function or constructor call that * returns a primitive or a local object (an object that has no other * references). */ public final boolean isLocalResultCall() { return !allBitsSet(getSideEffectFlags(), SideEffectFlags.ESCAPED_RETURN); } /** Returns true if this is a new/call that may mutate its arguments. */ public final boolean mayMutateArguments() { return allBitsSet(getSideEffectFlags(), SideEffectFlags.MUTATES_ARGUMENTS); } /** Returns true if this is a new/call that may mutate global state or throw. */ public final boolean mayMutateGlobalStateOrThrow() { return anyBitSet( getSideEffectFlags(), SideEffectFlags.MUTATES_GLOBAL_STATE | SideEffectFlags.THROWS); } /** Returns true iff all the set bits in {@code mask} are also set in {@code value}. */ private static boolean allBitsSet(int value, int mask) { return (value & mask) == mask; } /** Returns true iff any the bit set in {@code mask} is also set in {@code value}. */ private static boolean anyBitSet(int value, int mask) { return (value & mask) != 0; } /** * Constants for the {@link Prop#CONSTANT_VAR_FLAGS} bit set property. * *
    *
  • {@link ConstantVarFlags#DECLARED} means the name was declared using annotation or syntax * indicating it must be constant *
  • {@link ConstantVarFlags#INFERRED} means the compiler can see that it is assigned exactly * once, whether or not it was declared to be constant. *
* *

Either, both, or neither may be set for any name. */ private static final class ConstantVarFlags { // each constant should be a distinct power of 2. static final int DECLARED = 1; static final int INFERRED = 2; private ConstantVarFlags() {} } private final int getConstantVarFlags() { return getIntProp(Prop.CONSTANT_VAR_FLAGS); } private final void setConstantVarFlag(int flag, boolean value) { int flags = getConstantVarFlags(); if (value) { flags = flags | flag; } else { flags = flags & ~flag; } putIntProp(Prop.CONSTANT_VAR_FLAGS, flags); } /** * Returns whether this variable is declared as a constant. * *

The compiler considers a variable to be declared if: * *

    *
  • it is declared with the {@code const} keyword, or *
  • It is declared with a jsdoc {@code @const} annotation, or *
  • The current coding convention considers it to be a constant. *
* *

Only valid to call on a {@linkplain #isName name} node. */ public final boolean isDeclaredConstantVar() { checkState( isName() || isImportStar(), "Should only be called on name or import * nodes. Found %s", this); return anyBitSet(getConstantVarFlags(), ConstantVarFlags.DECLARED); } /** * Sets this variable to be a declared constant. * *

See {@link #isDeclaredConstantVar} for the rules. */ public final void setDeclaredConstantVar(boolean value) { checkState( isName() || isImportStar(), "Should only be called on name or import * nodes. Found %s", this); setConstantVarFlag(ConstantVarFlags.DECLARED, value); } /** * Returns whether this variable is inferred to be constant. * *

The compiler infers a variable to be a constant if: * *

    *
  • It is assigned at its declaration site, and *
  • It is never reassigned during its lifetime, and *
  • It is not defined by an extern. *
* *

Only valid to call on a {@linkplain #isName name} node. */ public final boolean isInferredConstantVar() { checkState( isName() || isImportStar(), "Should only be called on name or import * nodes. Found %s", this); return anyBitSet(getConstantVarFlags(), ConstantVarFlags.INFERRED); } /** * Sets this variable to be an inferred constant. * * *

See {@link #isInferredConstantVar} for the rules. */ public final void setInferredConstantVar(boolean value) { checkState( isName() || isImportStar(), "Should only be called on name or import * nodes. Found %s", this); setConstantVarFlag(ConstantVarFlags.INFERRED, value); } /** * This should only be called for STRING nodes children of OBJECTLIT. */ public boolean isQuotedString() { return false; } /** * This should only be called for STRING nodes children of OBJECTLIT. */ public void setQuotedString() { throw new IllegalStateException(this + " is not a StringNode"); } /*** AST type check methods ***/ public final boolean isAdd() { return this.token == Token.ADD; } public final boolean isSub() { return this.token == Token.SUB; } public final boolean isAnd() { return this.token == Token.AND; } public final boolean isArrayLit() { return this.token == Token.ARRAYLIT; } public final boolean isArrayPattern() { return this.token == Token.ARRAY_PATTERN; } public final boolean isAssign() { return this.token == Token.ASSIGN; } public final boolean isAssignAdd() { return this.token == Token.ASSIGN_ADD; } public final boolean isNormalBlock() { return isBlock(); } public final boolean isBlock() { return this.token == Token.BLOCK; } public final boolean isRoot() { return this.token == Token.ROOT; } public final boolean isAwait() { return this.token == Token.AWAIT; } public final boolean isBreak() { return this.token == Token.BREAK; } public final boolean isCall() { return this.token == Token.CALL; } public final boolean isCase() { return this.token == Token.CASE; } public final boolean isCast() { return this.token == Token.CAST; } public final boolean isCatch() { return this.token == Token.CATCH; } public final boolean isClass() { return this.token == Token.CLASS; } public final boolean isClassMembers() { return this.token == Token.CLASS_MEMBERS; } public final boolean isComma() { return this.token == Token.COMMA; } public final boolean isComputedProp() { return this.token == Token.COMPUTED_PROP; } public final boolean isContinue() { return this.token == Token.CONTINUE; } public final boolean isConst() { return this.token == Token.CONST; } public final boolean isDebugger() { return this.token == Token.DEBUGGER; } public final boolean isDec() { return this.token == Token.DEC; } public final boolean isDefaultCase() { return this.token == Token.DEFAULT_CASE; } public final boolean isDefaultValue() { return this.token == Token.DEFAULT_VALUE; } public final boolean isDelProp() { return this.token == Token.DELPROP; } public final boolean isDestructuringLhs() { return this.token == Token.DESTRUCTURING_LHS; } public final boolean isDestructuringPattern() { return isObjectPattern() || isArrayPattern(); } public final boolean isDo() { return this.token == Token.DO; } public final boolean isEmpty() { return this.token == Token.EMPTY; } public final boolean isExport() { return this.token == Token.EXPORT; } public final boolean isExportSpec() { return this.token == Token.EXPORT_SPEC; } public final boolean isExportSpecs() { return this.token == Token.EXPORT_SPECS; } public final boolean isExprResult() { return this.token == Token.EXPR_RESULT; } public final boolean isFalse() { return this.token == Token.FALSE; } public final boolean isVanillaFor() { return this.token == Token.FOR; } public final boolean isForIn() { return this.token == Token.FOR_IN; } public final boolean isForOf() { return this.token == Token.FOR_OF; } public final boolean isForAwaitOf() { return this.token == Token.FOR_AWAIT_OF; } public final boolean isFunction() { return this.token == Token.FUNCTION; } public final boolean isGetterDef() { return this.token == Token.GETTER_DEF; } public final boolean isGetElem() { return this.token == Token.GETELEM; } public final boolean isGetProp() { return this.token == Token.GETPROP; } public final boolean isHook() { return this.token == Token.HOOK; } public final boolean isIf() { return this.token == Token.IF; } public final boolean isImport() { return this.token == Token.IMPORT; } public final boolean isImportStar() { return this.token == Token.IMPORT_STAR; } public final boolean isImportSpec() { return this.token == Token.IMPORT_SPEC; } public final boolean isImportSpecs() { return this.token == Token.IMPORT_SPECS; } public final boolean isIn() { return this.token == Token.IN; } public final boolean isInc() { return this.token == Token.INC; } public final boolean isInstanceOf() { return this.token == Token.INSTANCEOF; } public final boolean isInterfaceMembers() { return this.token == Token.INTERFACE_MEMBERS; } public final boolean isRecordType() { return this.token == Token.RECORD_TYPE; } public final boolean isCallSignature() { return this.token == Token.CALL_SIGNATURE; } public final boolean isIndexSignature() { return this.token == Token.INDEX_SIGNATURE; } public final boolean isLabel() { return this.token == Token.LABEL; } public final boolean isLabelName() { return this.token == Token.LABEL_NAME; } public final boolean isLet() { return this.token == Token.LET; } public final boolean isMemberFunctionDef() { return this.token == Token.MEMBER_FUNCTION_DEF; } public final boolean isMemberVariableDef() { return this.token == Token.MEMBER_VARIABLE_DEF; } public final boolean isModuleBody() { return this.token == Token.MODULE_BODY; } public final boolean isName() { return this.token == Token.NAME; } public final boolean isNE() { return this.token == Token.NE; } public final boolean isNew() { return this.token == Token.NEW; } public final boolean isNot() { return this.token == Token.NOT; } public final boolean isNull() { return this.token == Token.NULL; } public final boolean isNumber() { return this.token == Token.NUMBER; } public final boolean isObjectLit() { return this.token == Token.OBJECTLIT; } public final boolean isObjectPattern() { return this.token == Token.OBJECT_PATTERN; } public final boolean isOr() { return this.token == Token.OR; } public final boolean isParamList() { return this.token == Token.PARAM_LIST; } public final boolean isRegExp() { return this.token == Token.REGEXP; } public final boolean isRest() { return this.token == Token.ITER_REST || this.token == Token.OBJECT_REST; } public final boolean isReturn() { return this.token == Token.RETURN; } public final boolean isScript() { return this.token == Token.SCRIPT; } public final boolean isSetterDef() { return this.token == Token.SETTER_DEF; } public final boolean isSpread() { return this.token == Token.ITER_SPREAD || this.token == Token.OBJECT_SPREAD; } public final boolean isString() { return this.token == Token.STRING; } public final boolean isStringKey() { return this.token == Token.STRING_KEY; } public final boolean isSuper() { return this.token == Token.SUPER; } public final boolean isSwitch() { return this.token == Token.SWITCH; } public final boolean isTaggedTemplateLit() { return this.token == Token.TAGGED_TEMPLATELIT; } public final boolean isTemplateLit() { return this.token == Token.TEMPLATELIT; } public final boolean isTemplateLitString() { return this.token == Token.TEMPLATELIT_STRING; } public final boolean isTemplateLitSub() { return this.token == Token.TEMPLATELIT_SUB; } public final boolean isThis() { return this.token == Token.THIS; } public final boolean isThrow() { return this.token == Token.THROW; } public final boolean isTrue() { return this.token == Token.TRUE; } public final boolean isTry() { return this.token == Token.TRY; } public final boolean isTypeOf() { return this.token == Token.TYPEOF; } public final boolean isVar() { return this.token == Token.VAR; } public final boolean isVoid() { return this.token == Token.VOID; } public final boolean isWhile() { return this.token == Token.WHILE; } public final boolean isWith() { return this.token == Token.WITH; } public final boolean isYield() { return this.token == Token.YIELD; } // see writeObject() and readObject() for how this field is used in (de)serialization. // TODO(bradfordcsmith): We are assuming that we will never have multiple (de)serializations // happening at the same time. private static List incompleteNodes = null; @GwtIncompatible("ObjectOutputStream") private void writeObject(java.io.ObjectOutputStream out) throws Exception { // Do not call out.defaultWriteObject() as all the fields are transient and this class does not // have a superclass. checkState(Token.values().length < Byte.MAX_VALUE - Byte.MIN_VALUE); out.writeByte(token.ordinal()); writeEncodedInt(out, sourcePosition); writeEncodedInt(out, length); boolean isStartingNode = false; if (incompleteNodes == null) { // The first node to get serialized is responsible for completing serialization // of all the other nodes whose serialization it triggers. // This allows us to avoid deep recursion that would happen otherwise due to // node -> type obj -> another node -> type obj... isStartingNode = true; incompleteNodes = new ArrayList<>(); } incompleteNodes.add(this); // Serialize the embedded children linked list here to limit the depth of recursion (and avoid // serializing redundant information like the previous reference) Node currentChild = first; while (currentChild != null) { out.writeObject(currentChild); currentChild = currentChild.next; } // Null marks the end of the children. out.writeObject(null); out.writeObject(propListHead); if (isStartingNode) { List nodeList = Node.incompleteNodes; Node.incompleteNodes = null; for (Node n : nodeList) { out.writeObject(n.jstype); } } } @GwtIncompatible("ObjectInputStream") private void readObject(java.io.ObjectInputStream in) throws Exception { // Do not call in.defaultReadObject() as all the fields are transient and this class does not // have a superclass. token = Token.values()[in.readUnsignedByte()]; sourcePosition = readEncodedInt(in); length = readEncodedInt(in); boolean isStartingNode = false; if (incompleteNodes == null) { // The first node to get deserialized is responsible for completing deserialization // of all the other nodes whose deserialization it triggers. // This allows us to avoid deep recursion that would happen otherwise due to // node -> type obj -> another node -> type obj... isStartingNode = true; incompleteNodes = new ArrayList<>(); } incompleteNodes.add(this); // Deserialize the children list restoring the value of the previous reference. first = (Node) in.readObject(); if (first != null) { checkState(first.parent == null); first.parent = this; Node currentChild; Node lastChild = first; while ((currentChild = (Node) in.readObject()) != null) { checkState(currentChild.parent == null); currentChild.parent = this; // previous is never null, either it points to the previous sibling or if it is the first // sibling it points to the last one. checkState(currentChild.previous == null); currentChild.previous = lastChild; checkState(lastChild.next == null); lastChild.next = currentChild; lastChild = currentChild; } // Close the reverse circular list. checkState(first.previous == null); first.previous = lastChild; } propListHead = (PropListItem) in.readObject(); if (isStartingNode) { List nodeList = Node.incompleteNodes; Node.incompleteNodes = null; for (Node n : nodeList) { n.jstype = (JSType) in.readObject(); } } } /** * Encode integers using variable length encoding. * * Encodes an integer as a sequence of 7-bit values with a continuation bit. For example the * number 3912 (0111 0100 1000) is encoded in two bytes as follows 0xC80E (1100 1000 0000 1110), * i.e. first byte will be the lower 7 bits with a continuation bit set and second byte will * consist of the upper 7 bits with the continuation bit unset. * * This encoding aims to reduce the serialized footprint for the most common values, reducing the * footprint for all positive values that are smaller than 2^21 (~2000000): * 0 - 127 are encoded in one byte * 128 - 16384 are encoded in two bytes * 16385 - 2097152 are encoded in three bytes * 2097153 - 268435456 are encoded in four bytes. * values greater than 268435456 and negative values are encoded in 5 bytes. * * Most values for the length field will be encoded with one byte and most values for * sourcePosition will be encoded with 2 or 3 bytes. (Value -1, which is used to mark absence will * use 5 bytes, and could be accommodated in the present scheme by an offset of 1 if it leads to * size improvements). */ @GwtIncompatible("ObjectOutput") private void writeEncodedInt(ObjectOutput out, int value) throws IOException { while (value > 0X7f || value < 0) { out.writeByte(((value & 0X7f) | 0x80)); value >>>= 7; } out.writeByte(value); } @GwtIncompatible("ObjectInput") private int readEncodedInt(ObjectInput in) throws IOException { int value = 0; int shift = 0; byte current; while ((current = in.readByte()) < 0) { value |= (current & 0x7f) << shift; shift += 7; } value |= current << shift; return value; } }





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