rhino1.7.7.src.org.mozilla.javascript.ast.AstNode Maven / Gradle / Ivy
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/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.javascript.ast;
import org.mozilla.javascript.Kit;
import org.mozilla.javascript.Node;
import org.mozilla.javascript.Token;
import java.io.Serializable;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Base class for AST node types. The goal of the AST is to represent the
* physical source code, to make it useful for code-processing tools such
* as IDEs or pretty-printers. The parser must not rewrite the parse tree
* when producing this representation.
*
* The {@code AstNode} hierarchy sits atop the older {@link Node} class,
* which was designed for code generation. The {@code Node} class is a
* flexible, weakly-typed class suitable for creating and rewriting code
* trees, but using it requires you to remember the exact ordering of the
* child nodes, which are kept in a linked list. The {@code AstNode}
* hierarchy is a strongly-typed facade with named accessors for children
* and common properties, but under the hood it's still using a linked list
* of child nodes. It isn't a very good idea to use the child list directly
* unless you know exactly what you're doing.
*
* Note that {@code AstNode} records additional information, including
* the node's position, length, and parent node. Also, some {@code AstNode}
* subclasses record some of their child nodes in instance members, since
* they are not needed for code generation. In a nutshell, only the code
* generator should be mixing and matching {@code AstNode} and {@code Node}
* objects.
*
* All offset fields in all subclasses of AstNode are relative to their
* parent. For things like paren, bracket and keyword positions, the
* position is relative to the current node. The node start position is
* relative to the parent node.
*
* During the actual parsing, node positions are absolute; adding the node to
* its parent fixes up the offsets to be relative. By the time you see the AST
* (e.g. using the {@code Visitor} interface), the offsets are relative.
*
* {@code AstNode} objects have property lists accessible via the
* {@link #getProp} and {@link #putProp} methods. The property lists are
* integer-keyed with arbitrary {@code Object} values. For the most part the
* parser generating the AST avoids using properties, preferring fields for
* elements that are always set. Property lists are intended for user-defined
* annotations to the tree. The Rhino code generator acts as a client and
* uses node properties extensively. You are welcome to use the property-list
* API for anything your client needs.
*
* This hierarchy does not have separate branches for expressions and
* statements, as the distinction in JavaScript is not as clear-cut as in
* Java or C++.
*/
public abstract class AstNode extends Node implements Comparable {
protected int position = -1;
protected int length = 1;
protected AstNode parent;
private static Map operatorNames =
new HashMap();
static {
operatorNames.put(Token.IN, "in");
operatorNames.put(Token.TYPEOF, "typeof");
operatorNames.put(Token.INSTANCEOF, "instanceof");
operatorNames.put(Token.DELPROP, "delete");
operatorNames.put(Token.COMMA, ",");
operatorNames.put(Token.COLON, ":");
operatorNames.put(Token.OR, "||");
operatorNames.put(Token.AND, "&&");
operatorNames.put(Token.INC, "++");
operatorNames.put(Token.DEC, "--");
operatorNames.put(Token.BITOR, "|");
operatorNames.put(Token.BITXOR, "^");
operatorNames.put(Token.BITAND, "&");
operatorNames.put(Token.EQ, "==");
operatorNames.put(Token.NE, "!=");
operatorNames.put(Token.LT, "<");
operatorNames.put(Token.GT, ">");
operatorNames.put(Token.LE, "<=");
operatorNames.put(Token.GE, ">=");
operatorNames.put(Token.LSH, "<<");
operatorNames.put(Token.RSH, ">>");
operatorNames.put(Token.URSH, ">>>");
operatorNames.put(Token.ADD, "+");
operatorNames.put(Token.SUB, "-");
operatorNames.put(Token.MUL, "*");
operatorNames.put(Token.DIV, "/");
operatorNames.put(Token.MOD, "%");
operatorNames.put(Token.NOT, "!");
operatorNames.put(Token.BITNOT, "~");
operatorNames.put(Token.POS, "+");
operatorNames.put(Token.NEG, "-");
operatorNames.put(Token.SHEQ, "===");
operatorNames.put(Token.SHNE, "!==");
operatorNames.put(Token.ASSIGN, "=");
operatorNames.put(Token.ASSIGN_BITOR, "|=");
operatorNames.put(Token.ASSIGN_BITAND, "&=");
operatorNames.put(Token.ASSIGN_LSH, "<<=");
operatorNames.put(Token.ASSIGN_RSH, ">>=");
operatorNames.put(Token.ASSIGN_URSH, ">>>=");
operatorNames.put(Token.ASSIGN_ADD, "+=");
operatorNames.put(Token.ASSIGN_SUB, "-=");
operatorNames.put(Token.ASSIGN_MUL, "*=");
operatorNames.put(Token.ASSIGN_DIV, "/=");
operatorNames.put(Token.ASSIGN_MOD, "%=");
operatorNames.put(Token.ASSIGN_BITXOR, "^=");
operatorNames.put(Token.VOID, "void");
}
public static class PositionComparator implements Comparator, Serializable {
private static final long serialVersionUID = 1L;
/**
* Sorts nodes by (relative) start position. The start positions are
* relative to their parent, so this comparator is only meaningful for
* comparing siblings.
*/
public int compare(AstNode n1, AstNode n2) {
return n1.position - n2.position;
}
}
public AstNode() {
super(Token.ERROR);
}
/**
* Constructs a new AstNode
* @param pos the start position
*/
public AstNode(int pos) {
this();
position = pos;
}
/**
* Constructs a new AstNode
* @param pos the start position
* @param len the number of characters spanned by the node in the source
* text
*/
public AstNode(int pos, int len) {
this();
position = pos;
length = len;
}
/**
* Returns relative position in parent
*/
public int getPosition() {
return position;
}
/**
* Sets relative position in parent
*/
public void setPosition(int position) {
this.position = position;
}
/**
* Returns the absolute document position of the node.
* Computes it by adding the node's relative position
* to the relative positions of all its parents.
*/
public int getAbsolutePosition() {
int pos = position;
AstNode parent = this.parent;
while (parent != null) {
pos += parent.getPosition();
parent = parent.getParent();
}
return pos;
}
/**
* Returns node length
*/
public int getLength() {
return length;
}
/**
* Sets node length
*/
public void setLength(int length) {
this.length = length;
}
/**
* Sets the node start and end positions.
* Computes the length as ({@code end} - {@code position}).
*/
public void setBounds(int position, int end) {
setPosition(position);
setLength(end - position);
}
/**
* Make this node's position relative to a parent.
* Typically only used by the parser when constructing the node.
* @param parentPosition the absolute parent position; the
* current node position is assumed to be absolute and is
* decremented by parentPosition.
*/
public void setRelative(int parentPosition) {
this.position -= parentPosition;
}
/**
* Returns the node parent, or {@code null} if it has none
*/
public AstNode getParent() {
return parent;
}
/**
* Sets the node parent. This method automatically adjusts the
* current node's start position to be relative to the new parent.
* @param parent the new parent. Can be {@code null}.
*/
public void setParent(AstNode parent) {
if (parent == this.parent) {
return;
}
// Convert position back to absolute.
if (this.parent != null) {
setRelative(-this.parent.getPosition());
}
this.parent = parent;
if (parent != null) {
setRelative(parent.getPosition());
}
}
/**
* Adds a child or function to the end of the block.
* Sets the parent of the child to this node, and fixes up
* the start position of the child to be relative to this node.
* Sets the length of this node to include the new child.
* @param kid the child
* @throws IllegalArgumentException if kid is {@code null}
*/
public void addChild(AstNode kid) {
assertNotNull(kid);
int end = kid.getPosition() + kid.getLength();
setLength(end - this.getPosition());
addChildToBack(kid);
kid.setParent(this);
}
/**
* Returns the root of the tree containing this node.
* @return the {@link AstRoot} at the root of this node's parent
* chain, or {@code null} if the topmost parent is not an {@code AstRoot}.
*/
public AstRoot getAstRoot() {
AstNode parent = this; // this node could be the AstRoot
while (parent != null && !(parent instanceof AstRoot)) {
parent = parent.getParent();
}
return (AstRoot)parent;
}
/**
* Emits source code for this node. Callee is responsible for calling this
* function recursively on children, incrementing indent as appropriate.
*
* Note: if the parser was in error-recovery mode, some AST nodes may have
* {@code null} children that are expected to be non-{@code null}
* when no errors are present. In this situation, the behavior of the
* {@code toSource} method is undefined: {@code toSource}
* implementations may assume that the AST node is error-free, since it is
* intended to be invoked only at runtime after a successful parse.
*
* @param depth the current recursion depth, typically beginning at 0
* when called on the root node.
*/
public abstract String toSource(int depth);
/**
* Prints the source indented to depth 0.
*/
public String toSource() {
return this.toSource(0);
}
/**
* Constructs an indentation string.
* @param indent the number of indentation steps
*/
public String makeIndent(int indent) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < indent; i++) {
sb.append(" ");
}
return sb.toString();
}
/**
* Returns a short, descriptive name for the node, such as
* "ArrayComprehension".
*/
public String shortName() {
String classname = getClass().getName();
int last = classname.lastIndexOf(".");
return classname.substring(last + 1);
}
/**
* Returns the string name for this operator.
* @param op the token type, e.g. {@link Token#ADD} or {@link Token#TYPEOF}
* @return the source operator string, such as "+" or "typeof"
*/
public static String operatorToString(int op) {
String result = operatorNames.get(op);
if (result == null)
throw new IllegalArgumentException("Invalid operator: " + op);
return result;
}
/**
* Visits this node and its children in an arbitrary order.
*
* It's up to each node subclass to decide the order for processing
* its children. The subclass also decides (and should document)
* which child nodes are not passed to the {@code NodeVisitor}.
* For instance, nodes representing keywords like {@code each} or
* {@code in} may not be passed to the visitor object. The visitor
* can simply query the current node for these children if desired.
*
* Generally speaking, the order will be deterministic; the order is
* whatever order is decided by each child node. Normally child nodes
* will try to visit their children in lexical order, but there may
* be exceptions to this rule.
*
* @param visitor the object to call with this node and its children
*/
public abstract void visit(NodeVisitor visitor);
// subclasses with potential side effects should override this
@Override
public boolean hasSideEffects()
{
switch (getType()) {
case Token.ASSIGN:
case Token.ASSIGN_ADD:
case Token.ASSIGN_BITAND:
case Token.ASSIGN_BITOR:
case Token.ASSIGN_BITXOR:
case Token.ASSIGN_DIV:
case Token.ASSIGN_LSH:
case Token.ASSIGN_MOD:
case Token.ASSIGN_MUL:
case Token.ASSIGN_RSH:
case Token.ASSIGN_SUB:
case Token.ASSIGN_URSH:
case Token.BLOCK:
case Token.BREAK:
case Token.CALL:
case Token.CATCH:
case Token.CATCH_SCOPE:
case Token.CONST:
case Token.CONTINUE:
case Token.DEC:
case Token.DELPROP:
case Token.DEL_REF:
case Token.DO:
case Token.ELSE:
case Token.ENTERWITH:
case Token.ERROR: // Avoid cascaded error messages
case Token.EXPORT:
case Token.EXPR_RESULT:
case Token.FINALLY:
case Token.FUNCTION:
case Token.FOR:
case Token.GOTO:
case Token.IF:
case Token.IFEQ:
case Token.IFNE:
case Token.IMPORT:
case Token.INC:
case Token.JSR:
case Token.LABEL:
case Token.LEAVEWITH:
case Token.LET:
case Token.LETEXPR:
case Token.LOCAL_BLOCK:
case Token.LOOP:
case Token.NEW:
case Token.REF_CALL:
case Token.RETHROW:
case Token.RETURN:
case Token.RETURN_RESULT:
case Token.SEMI:
case Token.SETELEM:
case Token.SETELEM_OP:
case Token.SETNAME:
case Token.SETPROP:
case Token.SETPROP_OP:
case Token.SETVAR:
case Token.SET_REF:
case Token.SET_REF_OP:
case Token.SWITCH:
case Token.TARGET:
case Token.THROW:
case Token.TRY:
case Token.VAR:
case Token.WHILE:
case Token.WITH:
case Token.WITHEXPR:
case Token.YIELD:
return true;
default:
return false;
}
}
/**
* Bounces an IllegalArgumentException up if arg is {@code null}.
* @param arg any method argument
* @throws IllegalArgumentException if the argument is {@code null}
*/
protected void assertNotNull(Object arg) {
if (arg == null)
throw new IllegalArgumentException("arg cannot be null");
}
/**
* Prints a comma-separated item list into a {@link StringBuilder}.
* @param items a list to print
* @param sb a {@link StringBuilder} into which to print
*/
protected void printList(List items,
StringBuilder sb) {
int max = items.size();
int count = 0;
for (AstNode item : items) {
sb.append(item.toSource(0));
if (count++ < max-1) {
sb.append(", ");
} else if (item instanceof EmptyExpression) {
sb.append(",");
}
}
}
/**
* @see Kit#codeBug
*/
public static RuntimeException codeBug()
throws RuntimeException
{
throw Kit.codeBug();
}
// TODO(stevey): think of a way to have polymorphic toString
// methods while keeping the ability to use Node.toString for
// dumping the IR with Token.printTrees. Most likely: change
// Node.toString to be Node.dumpTree and change callers to use that.
// For now, need original toString, to compare output to old Rhino's.
// @Override
// public String toString() {
// return this.getClass().getName() + ": " +
// Token.typeToName(getType());
// }
/**
* Returns the innermost enclosing function, or {@code null} if not in a
* function. Begins the search with this node's parent.
* @return the {@link FunctionNode} enclosing this node, else {@code null}
*/
public FunctionNode getEnclosingFunction() {
AstNode parent = this.getParent();
while (parent != null && !(parent instanceof FunctionNode)) {
parent = parent.getParent();
}
return (FunctionNode)parent;
}
/**
* Returns the innermost enclosing {@link Scope} node, or {@code null}
* if we're not nested in a scope. Begins the search with this node's parent.
* Note that this is not the same as the defining scope for a {@link Name}.
*
* @return the {@link Scope} enclosing this node, else {@code null}
*/
public Scope getEnclosingScope() {
AstNode parent = this.getParent();
while (parent != null && !(parent instanceof Scope)) {
parent = parent.getParent();
}
return (Scope)parent;
}
/**
* Permits AST nodes to be sorted based on start position and length.
* This makes it easy to sort Comment and Error nodes into a set of
* other AST nodes: just put them all into a {@link java.util.SortedSet},
* for instance.
* @param other another node
* @return -1 if this node's start position is less than {@code other}'s
* start position. If tied, -1 if this node's length is less than
* {@code other}'s length. If the lengths are equal, sorts abitrarily
* on hashcode unless the nodes are the same per {@link #equals}.
*/
public int compareTo(AstNode other) {
if (this.equals(other)) return 0;
int abs1 = this.getAbsolutePosition();
int abs2 = other.getAbsolutePosition();
if (abs1 < abs2) return -1;
if (abs2 < abs1) return 1;
int len1 = this.getLength();
int len2 = other.getLength();
if (len1 < len2) return -1;
if (len2 < len1) return 1;
return this.hashCode() - other.hashCode();
}
/**
* Returns the depth of this node. The root is depth 0, its
* children are depth 1, and so on.
* @return the node depth in the tree
*/
public int depth() {
return parent == null ? 0 : 1 + parent.depth();
}
protected static class DebugPrintVisitor implements NodeVisitor {
private StringBuilder buffer;
private static final int DEBUG_INDENT = 2;
public DebugPrintVisitor(StringBuilder buf) {
buffer = buf;
}
@Override
public String toString() {
return buffer.toString();
}
private String makeIndent(int depth) {
StringBuilder sb = new StringBuilder(DEBUG_INDENT * depth);
for (int i = 0; i < (DEBUG_INDENT * depth); i++) {
sb.append(" ");
}
return sb.toString();
}
public boolean visit(AstNode node) {
int tt = node.getType();
String name = Token.typeToName(tt);
buffer.append(node.getAbsolutePosition()).append("\t");
buffer.append(makeIndent(node.depth()));
buffer.append(name).append(" ");
buffer.append(node.getPosition()).append(" ");
buffer.append(node.getLength());
if (tt == Token.NAME) {
buffer.append(" ").append(((Name)node).getIdentifier());
}
buffer.append("\n");
return true; // process kids
}
}
/**
* Return the line number recorded for this node.
* If no line number was recorded, searches the parent chain.
* @return the nearest line number, or -1 if none was found
*/
@Override
public int getLineno() {
if (lineno != -1)
return lineno;
if (parent != null)
return parent.getLineno();
return -1;
}
/**
* Returns a debugging representation of the parse tree
* starting at this node.
* @return a very verbose indented printout of the tree.
* The format of each line is: abs-pos name position length [identifier]
*/
public String debugPrint() {
DebugPrintVisitor dpv = new DebugPrintVisitor(new StringBuilder(1000));
visit(dpv);
return dpv.toString();
}
}