/* -*- 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.Node;
import org.mozilla.javascript.Token;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
/**
* Represents a scope in the lexical scope chain. Base type for
* all {@link AstNode} implementations that can introduce a new scope.
*/
public class Scope extends Jump {
// Use LinkedHashMap so that the iteration order is the insertion order
protected Map<String,Symbol> symbolTable;
protected Scope parentScope;
protected ScriptNode top; // current script or function scope
private List<Scope> childScopes;
{
this.type = Token.BLOCK;
}
public Scope() {
}
public Scope(int pos) {
this.position = pos;
}
public Scope(int pos, int len) {
this(pos);
this.length = len;
}
public Scope getParentScope() {
return parentScope;
}
/**
* Sets parent scope
*/
public void setParentScope(Scope parentScope) {
this.parentScope = parentScope;
this.top = parentScope == null ? (ScriptNode)this : parentScope.top;
}
/**
* Used only for code generation.
*/
public void clearParentScope() {
this.parentScope = null;
}
/**
* Return a list of the scopes whose parent is this scope.
* @return the list of scopes we enclose, or {@code null} if none
*/
public List<Scope> getChildScopes() {
return childScopes;
}
/**
* Add a scope to our list of child scopes.
* Sets the child's parent scope to this scope.
* @throws IllegalStateException if the child's parent scope is
* non-{@code null}
*/
public void addChildScope(Scope child) {
if (childScopes == null) {
childScopes = new ArrayList<Scope>();
}
childScopes.add(child);
child.setParentScope(this);
}
/**
* Used by the parser; not intended for typical use.
* Changes the parent-scope links for this scope's child scopes
* to the specified new scope. Copies symbols from this scope
* into new scope.
*
* @param newScope the scope that will replace this one on the
* scope stack.
*/
public void replaceWith(Scope newScope) {
if (childScopes != null) {
for (Scope kid : childScopes) {
newScope.addChildScope(kid); // sets kid's parent
}
childScopes.clear();
childScopes = null;
}
if (symbolTable != null && !symbolTable.isEmpty()) {
joinScopes(this, newScope);
}
}
/**
* Returns current script or function scope
*/
public ScriptNode getTop() {
return top;
}
/**
* Sets top current script or function scope
*/
public void setTop(ScriptNode top) {
this.top = top;
}
/**
* Creates a new scope node, moving symbol table information
* from "scope" to the new node, and making "scope" a nested
* scope contained by the new node.
* Useful for injecting a new scope in a scope chain.
*/
public static Scope splitScope(Scope scope) {
Scope result = new Scope(scope.getType());
result.symbolTable = scope.symbolTable;
scope.symbolTable = null;
result.parent = scope.parent;
result.setParentScope(scope.getParentScope());
result.setParentScope(result);
scope.parent = result;
result.top = scope.top;
return result;
}
/**
* Copies all symbols from source scope to dest scope.
*/
public static void joinScopes(Scope source, Scope dest) {
Map<String,Symbol> src = source.ensureSymbolTable();
Map<String,Symbol> dst = dest.ensureSymbolTable();
if (!Collections.disjoint(src.keySet(), dst.keySet())) {
codeBug();
}
for (Map.Entry<String, Symbol> entry: src.entrySet()) {
Symbol sym = entry.getValue();
sym.setContainingTable(dest);
dst.put(entry.getKey(), sym);
}
}
/**
* Returns the scope in which this name is defined
* @param name the symbol to look up
* @return this {@link Scope}, one of its parent scopes, or {@code null} if
* the name is not defined any this scope chain
*/
public Scope getDefiningScope(String name) {
for (Scope s = this; s != null; s = s.parentScope) {
Map<String,Symbol> symbolTable = s.getSymbolTable();
if (symbolTable != null && symbolTable.containsKey(name)) {
return s;
}
}
return null;
}
/**
* Looks up a symbol in this scope.
* @param name the symbol name
* @return the Symbol, or {@code null} if not found
*/
public Symbol getSymbol(String name) {
return symbolTable == null ? null : symbolTable.get(name);
}
/**
* Enters a symbol into this scope.
*/
public void putSymbol(Symbol symbol) {
if (symbol.getName() == null)
throw new IllegalArgumentException("null symbol name");
ensureSymbolTable();
symbolTable.put(symbol.getName(), symbol);
symbol.setContainingTable(this);
top.addSymbol(symbol);
}
/**
* Returns the symbol table for this scope.
* @return the symbol table. May be {@code null}.
*/
public Map<String,Symbol> getSymbolTable() {
return symbolTable;
}
/**
* Sets the symbol table for this scope. May be {@code null}.
*/
public void setSymbolTable(Map<String, Symbol> table) {
symbolTable = table;
}
private Map<String,Symbol> ensureSymbolTable() {
if (symbolTable == null) {
symbolTable = new LinkedHashMap<String,Symbol>(5);
}
return symbolTable;
}
/**
* Returns a copy of the child list, with each child cast to an
* {@link AstNode}.
* @throws ClassCastException if any non-{@code AstNode} objects are
* in the child list, e.g. if this method is called after the code
* generator begins the tree transformation.
*/
public List<AstNode> getStatements() {
List<AstNode> stmts = new ArrayList<AstNode>();
Node n = getFirstChild();
while (n != null) {
stmts.add((AstNode)n);
n = n.getNext();
}
return stmts;
}
@Override
public String toSource(int depth) {
StringBuilder sb = new StringBuilder();
sb.append(makeIndent(depth));
sb.append("{\n");
for (Node kid : this) {
sb.append(((AstNode)kid).toSource(depth+1));
}
sb.append(makeIndent(depth));
sb.append("}\n");
return sb.toString();
}
@Override
public void visit(NodeVisitor v) {
if (v.visit(this)) {
for (Node kid : this) {
((AstNode)kid).visit(v);
}
}
}
}