/*
* Copyright 2006 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import com.google.common.base.Preconditions;
import com.google.javascript.rhino.InputId;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
/**
* <p>The syntactic scope creator scans the parse tree to create a Scope object
* containing all the variable declarations in that scope.</p>
*
* <p>This implementation is not thread-safe.</p>
*
*/
class SyntacticScopeCreator implements ScopeCreator {
private final AbstractCompiler compiler;
private Scope scope;
private InputId inputId;
private final RedeclarationHandler redeclarationHandler;
// The arguments variable is special, in that it's declared in every local
// scope, but not explicitly declared.
private static final String ARGUMENTS = "arguments";
/**
* Creates a ScopeCreator.
*/
SyntacticScopeCreator(AbstractCompiler compiler) {
this.compiler = compiler;
this.redeclarationHandler = new DefaultRedeclarationHandler();
}
SyntacticScopeCreator(
AbstractCompiler compiler, RedeclarationHandler redeclarationHandler) {
this.compiler = compiler;
this.redeclarationHandler = redeclarationHandler;
}
@Override
public Scope createScope(Node n, Scope parent) {
inputId = null;
if (parent == null) {
scope = Scope.createGlobalScope(n);
} else {
scope = new Scope(parent, n);
}
scanRoot(n);
inputId = null;
Scope returnedScope = scope;
scope = null;
return returnedScope;
}
private void scanRoot(Node n) {
if (n.isFunction()) {
if (inputId == null) {
inputId = NodeUtil.getInputId(n);
// TODO(johnlenz): inputId maybe null if the FUNCTION node is detached
// from the AST.
// Is it meaningful to build a scope for detached FUNCTION node?
}
final Node fnNameNode = n.getFirstChild();
final Node args = fnNameNode.getNext();
final Node body = args.getNext();
// Bleed the function name into the scope, if it hasn't
// been declared in the outer scope.
String fnName = fnNameNode.getString();
if (!fnName.isEmpty() && NodeUtil.isFunctionExpression(n)) {
declareVar(fnNameNode);
}
// Args: Declare function variables
Preconditions.checkState(args.isParamList());
for (Node a = args.getFirstChild(); a != null;
a = a.getNext()) {
Preconditions.checkState(a.isName());
declareVar(a);
}
// Body
scanVars(body);
} else {
// It's the global block
Preconditions.checkState(scope.getParent() == null);
scanVars(n);
}
}
/**
* Scans and gather variables declarations under a Node
*/
private void scanVars(Node n) {
switch (n.getType()) {
case Token.VAR:
// Declare all variables. e.g. var x = 1, y, z;
for (Node child = n.getFirstChild();
child != null;) {
Node next = child.getNext();
declareVar(child);
child = next;
}
return;
case Token.FUNCTION:
if (NodeUtil.isFunctionExpression(n)) {
return;
}
String fnName = n.getFirstChild().getString();
if (fnName.isEmpty()) {
// This is invalid, but allow it so the checks can catch it.
return;
}
declareVar(n.getFirstChild());
return; // should not examine function's children
case Token.CATCH:
Preconditions.checkState(n.getChildCount() == 2);
Preconditions.checkState(n.getFirstChild().isName());
// the first child is the catch var and the second child
// is the code block
final Node var = n.getFirstChild();
final Node block = var.getNext();
declareVar(var);
scanVars(block);
return; // only one child to scan
case Token.SCRIPT:
inputId = n.getInputId();
Preconditions.checkNotNull(inputId);
break;
}
// Variables can only occur in statement-level nodes, so
// we only need to traverse children in a couple special cases.
if (NodeUtil.isControlStructure(n) || NodeUtil.isStatementBlock(n)) {
for (Node child = n.getFirstChild();
child != null;) {
Node next = child.getNext();
scanVars(child);
child = next;
}
}
}
/**
* Interface for injectable duplicate handling.
*/
interface RedeclarationHandler {
void onRedeclaration(
Scope s, String name, Node n, CompilerInput input);
}
/**
* The default handler for duplicate declarations.
*/
private static class DefaultRedeclarationHandler implements RedeclarationHandler {
@Override
public void onRedeclaration(
Scope s, String name, Node n, CompilerInput input) {}
}
/**
* Declares a variable.
*
* @param n The node corresponding to the variable name.
*/
private void declareVar(Node n) {
Preconditions.checkState(n.isName());
CompilerInput input = compiler.getInput(inputId);
String name = n.getString();
if (scope.isDeclared(name, false)
|| (scope.isLocal() && name.equals(ARGUMENTS))) {
redeclarationHandler.onRedeclaration(
scope, name, n, input);
} else {
scope.declare(name, n, null, input);
}
}
/**
* Generates an untyped global scope from the root of AST of compiler (which
* includes externs).
*
* @param compiler The compiler for which the scope is generated.
* @return The new untyped global scope generated as a result of this call.
*/
static Scope generateUntypedTopScope(AbstractCompiler compiler) {
return new SyntacticScopeCreator(compiler).createScope(compiler.getRoot(),
null);
}
@Override
public boolean hasBlockScope() {
return false;
}
}