/*
* Copyright 2015 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.Predicates;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.JSDocInfo.Visibility;
import com.google.javascript.rhino.Node;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
/**
* Inline aliases created by exports of modules before type checking.
*
* <p>The old type inference doesn't deal as well with aliased types as with unaliased ones, such as
* in extends clauses (@extends {alias}) and templated types (alias<T>). This pass inlines these
* aliases to make type checking's job easier.
*
* <p>This alias inliner is not very aggressive. It will only inline explicitly const aliases but
* not effectively const ones (for example ones that are only ever assigned a value once). This is
* done to be conservative since it's not a good idea to be making dramatic AST changes before type
* checking. There is a more aggressive alias inliner that runs at the start of optimization.
*
* @author blickly@gmail.com (Ben Lickly)
*/
final class InlineAliases implements CompilerPass {
static final DiagnosticType ALIAS_CYCLE =
DiagnosticType.error("JSC_ALIAS_CYCLE", "Alias path contains a cycle: {0} to {1}");
private final AbstractCompiler compiler;
private final Map<String, String> aliases = new LinkedHashMap<>();
private GlobalNamespace namespace;
InlineAliases(AbstractCompiler compiler) {
this.compiler = compiler;
}
@Override
public void process(Node externs, Node root) {
namespace = new GlobalNamespace(compiler, root);
NodeTraversal.traverseEs6(compiler, root, new AliasesCollector());
NodeTraversal.traverseEs6(compiler, root, new AliasesInliner());
}
private class AliasesCollector extends AbstractPostOrderCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case VAR:
if (n.hasOneChild() && t.inGlobalScope()) {
visitAliasDefinition(n.getFirstChild(), NodeUtil.getBestJSDocInfo(n.getFirstChild()));
}
break;
case ASSIGN:
if (parent != null && parent.isExprResult() && t.inGlobalScope()) {
visitAliasDefinition(n.getFirstChild(), n.getJSDocInfo());
}
break;
default:
break;
}
}
/**
* Maybe record that given lvalue is an alias of the qualified name on its rhs.
* Note that since we are doing a post-order traversal, any previous aliases contained in
* the rhs will have already been substituted by the time we record the new alias.
*/
private void visitAliasDefinition(Node lhs, JSDocInfo info) {
if (info != null && info.hasConstAnnotation() && !info.hasTypeInformation()
&& lhs.isQualifiedName()) {
Node rhs = NodeUtil.getRValueOfLValue(lhs);
if (rhs != null && rhs.isQualifiedName()) {
GlobalNamespace.Name lhsName = namespace.getOwnSlot(lhs.getQualifiedName());
GlobalNamespace.Name rhsName = namespace.getOwnSlot(rhs.getQualifiedName());
if (lhsName != null
&& lhsName.isInlinableGlobalAlias()
&& rhsName != null
&& rhsName.isInlinableGlobalAlias()
&& !isPrivate(rhsName.getDeclaration().getNode())) {
aliases.put(lhs.getQualifiedName(), rhs.getQualifiedName());
}
}
}
}
private boolean isPrivate(Node nameNode) {
if (nameNode.isQualifiedName()
&& compiler.getCodingConvention().isPrivate(nameNode.getQualifiedName())) {
return true;
}
JSDocInfo info = NodeUtil.getBestJSDocInfo(nameNode);
return info != null && info.getVisibility().equals(Visibility.PRIVATE);
}
}
private class AliasesInliner extends AbstractPostOrderCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case NAME:
case GETPROP:
if (n.isQualifiedName() && aliases.containsKey(n.getQualifiedName())) {
String leftmostName = NodeUtil.getRootOfQualifiedName(n).getString();
Var v = t.getScope().getVar(leftmostName);
if (v != null && v.isLocal()) {
// Shadow of alias. Don't rewrite
return;
}
if (NodeUtil.isVarOrSimpleAssignLhs(n, parent)) {
// Alias definition. Don't rewrite
return;
}
Node newNode = NodeUtil.newQName(compiler, resolveAlias(n.getQualifiedName(), n))
.useSourceInfoFromForTree(n);
parent.replaceChild(n, newNode);
t.reportCodeChange();
}
break;
default:
break;
}
maybeRewriteJsdoc(n.getJSDocInfo());
}
/**
* Use the alias table to look up the resolved name of the given alias. If the result is also an
* alias repeat until the real name is resolved.
* @param n
*/
private String resolveAlias(String name, Node n) {
Set<String> aliasPath = new LinkedHashSet<>();
while (aliases.containsKey(name)) {
if (!aliasPath.add(name)) {
compiler.report(JSError.make(n, ALIAS_CYCLE, aliasPath.toString(), name));
// Cut the cycle so that it doesn't get reported more than once.
aliases.remove(name);
break;
}
name = aliases.get(name);
}
return name;
}
private void maybeRewriteJsdoc(JSDocInfo info) {
if (info == null) {
return;
}
for (Node typeNode : info.getTypeNodes()) {
NodeUtil.visitPreOrder(typeNode, fixJsdocTypeNodes, Predicates.<Node>alwaysTrue());
}
}
private final NodeUtil.Visitor fixJsdocTypeNodes =
new NodeUtil.Visitor() {
@Override
public void visit(Node aliasReference) {
if (!aliasReference.isString()) {
return;
}
String fullTypeName = aliasReference.getString();
int dotIndex = 0;
do {
dotIndex = fullTypeName.indexOf('.', dotIndex + 1);
String aliasName =
dotIndex == -1 ? fullTypeName : fullTypeName.substring(0, dotIndex);
if (aliases.containsKey(aliasName)) {
String replacement =
resolveAlias(aliasName, aliasReference)
+ fullTypeName.substring(aliasName.length());
aliasReference.setString(replacement);
return;
}
} while (dotIndex != -1);
}
};
}
}