1+ /*
2+ * Copyright 2014 The Closure Compiler Authors.
3+ *
4+ * Licensed under the Apache License, Version 2.0 (the "License");
5+ * you may not use this file except in compliance with the License.
6+ * You may obtain a copy of the License at
7+ *
8+ * http://www.apache.org/licenses/LICENSE-2.0
9+ *
10+ * Unless required by applicable law or agreed to in writing, software
11+ * distributed under the License is distributed on an "AS IS" BASIS,
12+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13+ * See the License for the specific language governing permissions and
14+ * limitations under the License.
15+ */
16+
17+ package com .google .javascript .jscomp ;
18+
19+ import com .google .common .collect .Lists ;
20+ import com .google .javascript .jscomp .Es6ToEs3Converter .UniqueNameGenerator ;
21+ import com .google .javascript .jscomp .NodeTraversal .AbstractPostOrderCallback ;
22+ import com .google .javascript .jscomp .Scope .Var ;
23+ import com .google .javascript .rhino .Node ;
24+
25+ import java .util .HashMap ;
26+ import java .util .HashSet ;
27+ import java .util .Iterator ;
28+ import java .util .Map ;
29+ import java .util .Set ;
30+
31+ /**
32+ * Renames declarations and references in function bodies to avoid shadowing
33+ * names referenced in default parameters.
34+ *
35+ * @author [email protected] (Michael Zhou) 36+ */
37+ public class Es6HandleDefaultParameters extends AbstractPostOrderCallback
38+ implements HotSwapCompilerPass {
39+
40+ private final AbstractCompiler compiler ;
41+ private final UniqueNameGenerator unique ;
42+
43+ public Es6HandleDefaultParameters (AbstractCompiler compiler , UniqueNameGenerator unique ) {
44+ this .compiler = compiler ;
45+ this .unique = unique ;
46+ }
47+
48+ @ Override
49+ public void visit (NodeTraversal t , Node n , Node parent ) {
50+ // Arrow functions without blocked body cannot have declarations in the body
51+ if (!n .isFunction () || !n .getLastChild ().isBlock ()) {
52+ return ;
53+ }
54+
55+ Node paramList = n .getChildAtIndex (1 );
56+ CollectReferences collector = new CollectReferences ();
57+ for (Node child : paramList .children ()) {
58+ if (child .isName () && child .hasChildren ()) {
59+ NodeTraversal .traverse (compiler , child .getFirstChild (), collector );
60+ }
61+ }
62+
63+ Node block = paramList .getNext ();
64+ Scope fBlockScope = new Es6SyntacticScopeCreator (compiler ).createScope (block , null );
65+ Map <String , String > currFuncRenameMap = new HashMap <>();
66+ for (Iterator <Var > it = fBlockScope .getVars (); it .hasNext ();) {
67+ Var var = it .next ();
68+ String oldName = var .getName ();
69+ if (collector .currFuncReferences .contains (oldName )
70+ && !currFuncRenameMap .containsKey (oldName )) {
71+ currFuncRenameMap .put (oldName , unique .generate (oldName ));
72+ }
73+ }
74+ new NodeTraversal (compiler ,
75+ new RenameReferences (fBlockScope , currFuncRenameMap ))
76+ .traverseInnerNode (block , block .getParent (), fBlockScope .getParent ());
77+ }
78+
79+ @ Override
80+ public void process (Node externs , Node root ) {
81+ NodeTraversal .traverseRoots (compiler , Lists .newArrayList (externs , root ), this );
82+ }
83+
84+ @ Override
85+ public void hotSwapScript (Node scriptRoot , Node originalRoot ) {
86+ NodeTraversal .traverse (compiler , scriptRoot , this );
87+ }
88+
89+ /**
90+ * Collects all references in a naive way.
91+ */
92+ private class CollectReferences extends NodeTraversal .AbstractPostOrderCallback {
93+
94+ private final Set <String > currFuncReferences = new HashSet <>();
95+
96+ @ Override
97+ public void visit (NodeTraversal t , Node n , Node parent ) {
98+ if (!NodeUtil .isReferenceName (n )) {
99+ return ;
100+ }
101+ currFuncReferences .add (n .getString ());
102+ }
103+ }
104+
105+ /**
106+ * Renames declarations / references when necessary.
107+ *
108+ * TODO(moz): See if we can just use the one in Es6RewriteLetConst.
109+ */
110+ private class RenameReferences extends AbstractPostOrderCallback {
111+
112+ private final Scope fBlockScope ;
113+ private final Map <String , String > currParamListMap ;
114+
115+ private RenameReferences (Scope scope , Map <String , String > map ) {
116+ fBlockScope = scope ;
117+ currParamListMap = map ;
118+ }
119+
120+ @ Override
121+ public void visit (NodeTraversal t , Node n , Node parent ) {
122+ if (!NodeUtil .isReferenceName (n )) {
123+ return ;
124+ }
125+
126+ Scope scope = t .getScope ();
127+ String oldName = n .getString ();
128+ if (scope .getRootNode () != fBlockScope .getRootNode ()
129+ && scope .isDeclared (oldName , false )) {
130+ return ;
131+ }
132+ if (currParamListMap .containsKey (oldName )) {
133+ n .setString (currParamListMap .get (oldName ));
134+ compiler .reportCodeChange ();
135+ }
136+ }
137+ }
138+ }
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