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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.

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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 com.google.common.collect.ImmutableList;
import org.jspecify.nullness.Nullable;

/**
 * Abstraction over a qualified name. Unifies Node-based qualified names and string-based names,
 * allowing to lazily parse strings and represent a pre-parsed qualified name without the overhead
 * of a whole Node. Essentially, a qualified name is a linked list of {@linkplain #getComponent
 * components}, starting from the outermost property access and ending with the root of the name,
 * which is a {@linkplain #isSimple simple name} with no {@linkplain #getOwner owner}.
 */
public abstract class QualifiedName {

  // All subclasses must be defined in this file.
  private QualifiedName() {}

  public static QualifiedName of(String string) {
    int lastIndex = 0;
    int index;
    ImmutableList.Builder builder = ImmutableList.builder();
    do {
      index = string.indexOf('.', lastIndex);
      String term = string.substring(lastIndex, index < 0 ? string.length() : index);
      builder.add(RhinoStringPool.addOrGet(term));
      lastIndex = index + 1;
    } while (index >= 0);
    ImmutableList terms = builder.build();
    return new StringListQname(terms, terms.size());
  }

  /**
   * Returns the qualified name of the owner, or null for simple names. For the name "foo.bar.baz",
   * this returns an object representing "foo.bar".
   */
  public abstract @Nullable QualifiedName getOwner();

  /**
   * Returns outer-most term of this qualified name, or the entire name for simple names. For the
   * name "foo.bar.baz", this returns "baz".
   */
  public abstract String getComponent();

  /** Returns true if this is a simple name. */
  public abstract boolean isSimple();

  // TODO(sdh): We'll probably want a getRoot() method, which would be useful once this is
  // integrated
  // further into TypedScopeCreator.

  /** Appends the joined qualified name to the given StringBuilder. */
  abstract void appendTo(StringBuilder sb);

  /** Checks whether the given node matches this name. */
  public abstract boolean matches(Node n);

  /** Returns the root of this name, e.g. "foo" from "foo.bar.baz". */
  public String getRoot() {
    QualifiedName name = this;
    while (!name.isSimple()) {
      name = name.getOwner();
    }
    return name.getComponent();
  }

  /**
   * Returns the components of this name as an iterable of strings, starting at the root. For the
   * qualified name foo.bar.baz, this returns ["foo", "bar", "baz"].
   */
  public Iterable components() {
    ImmutableList.Builder components = ImmutableList.builder();
    buildComponents(components);
    return components.build();
  }

  private void buildComponents(ImmutableList.Builder builder) {
    QualifiedName owner = getOwner();
    if (owner != null) {
      owner.buildComponents(builder);
    }
    builder.add(getComponent());
  }

  /** Returns the qualified name as a string. */
  public String join() {
    StringBuilder sb = new StringBuilder();
    appendTo(sb);
    return sb.toString();
  }

  /**
   * Returns a new qualified name object with {@code this} name as the owner and the given string as
   * the property name.
   */
  public QualifiedName getprop(String propertyName) {
    return new GetpropQname(this, propertyName);
  }

  /** A qualified name based on a list of string terms. */
  private static class StringListQname extends QualifiedName {
    final ImmutableList terms;
    final int size;

    StringListQname(ImmutableList terms, int size) {
      this.terms = terms;
      this.size = size;
    }

    @Override
    public @Nullable QualifiedName getOwner() {
      return size > 1 ? new StringListQname(terms, size - 1) : null;
    }

    @Override
    public String getComponent() {
      return terms.get(size - 1);
    }

    @Override
    public boolean isSimple() {
      return size == 1;
    }

    @Override
    void appendTo(StringBuilder sb) {
      for (int i = 0; i < size; i++) {
        if (i > 0) {
          sb.append('.');
        }
        sb.append(terms.get(i));
      }
    }

    @Override
    public Iterable components() {
      return terms.subList(0, size);
    }

    @Override
    public boolean matches(Node n) {
      int pos = size - 1;
      while (pos > 0 && n.isGetProp()) {
        if (!RhinoStringPool.uncheckedEquals(n.getString(), terms.get(pos))) {
          return false;
        }
        pos--;
        n = n.getFirstChild();
      }
      if (pos > 0) {
        return false;
      }

      String term = this.terms.get(0);
      switch (n.getToken()) {
        case NAME:
        case MEMBER_FUNCTION_DEF:
          return RhinoStringPool.uncheckedEquals(term, n.getString());
        case THIS:
          return RhinoStringPool.uncheckedEquals(term, THIS);
        case SUPER:
          return RhinoStringPool.uncheckedEquals(term, SUPER);
        default:
          return false;
      }
    }
  }

  /** A qualified name built with an extra property access on an existing qualified name. */
  private static class GetpropQname extends QualifiedName {
    final QualifiedName owner;
    final String prop;

    GetpropQname(QualifiedName owner, String prop) {
      this.owner = owner;
      this.prop = RhinoStringPool.addOrGet(prop);
    }

    @Override
    public QualifiedName getOwner() {
      return owner;
    }

    @Override
    public String getComponent() {
      return prop;
    }

    @Override
    public boolean isSimple() {
      return false;
    }

    @Override
    void appendTo(StringBuilder sb) {
      owner.appendTo(sb);
      sb.append('.').append(prop);
    }

    @Override
    public boolean matches(Node n) {
      return n.isGetProp()
          && RhinoStringPool.uncheckedEquals(n.getString(), prop)
          && owner.matches(n.getFirstChild());
    }
  }

  /**
   * A qualified name from a node. The precondition that the node is actually a qualified name is
   * not actually checked here, though it will throw IllegalStateException eventually if it is not.
   */
  static final class NodeQname extends QualifiedName {
    private final Node node;

    NodeQname(Node n) {
      this.node = n;
    }

    @Override
    public @Nullable QualifiedName getOwner() {
      return node.isGetProp() ? new NodeQname(node.getFirstChild()) : null;
    }

    @Override
    public String getComponent() {
      switch (node.getToken()) {
        case THIS:
          return THIS;
        case SUPER:
          return SUPER;
        case NAME:
        case GETPROP:
        case MEMBER_FUNCTION_DEF:
          return node.getString();
        default:
          throw new IllegalStateException("Not a qualified name: " + node);
      }
    }

    @Override
    public boolean isSimple() {
      return !node.isGetProp();
    }

    @Override
    void appendTo(StringBuilder sb) {
      sb.append(join());
    }

    @Override
    public String join() {
      return node.getQualifiedName();
    }

    @Override
    public boolean matches(Node n) {
      return n.matchesQualifiedName(node);
    }
  }

  private static final String THIS = RhinoStringPool.addOrGet("this");
  private static final String SUPER = RhinoStringPool.addOrGet("super");
}




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