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sdk/lib/_internal/compiler/implementation/compiler.dart

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compiler.dart b/sdk/lib/_internal/compiler/implementation/compiler.dart
index 636fcc530952bc44532781cfc2215c708c93adf1..220b9fe613f88d1786b292099b0f0d550a55915c 100644
--- a/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -103,6 +103,32 @@ abstract class Backend {
   void registerInstantiatedClass(ClassElement cls, Enqueuer enqueuer) {}
 }
 
+class CommentTokenMapEntry {

[ahe, 2013/01/03 13:04:09]

Document class please. How about:

/// An entry in [CommentTokenMap].

+  final key;

[ahe, 2013/01/03 13:04:09]

Add types one these two fields please.

+  final value;
+
+  CommentTokenMapEntry(this.key, this.value);
+}
+
+/**
+ * Map of tokens and the first associated comment.

[ahe, 2013/01/03 13:04:09]

One line comment?

+ */
+class CommentTokenMap  {
+  Link<CommentTokenMapEntry> entries = const Link<CommentTokenMapEntry>();
+
+  Token operator[] (Token key) {
+    for (CommentTokenMapEntry entry in entries) {

[ahe, 2013/01/03 13:04:09]

This seems like a sub-optimal implementation. I would like to understand why
this is doesn't cause quadratic runtime before approving this change.

+      if (entry.key == key) {
+        return entry.value;
+      }
+    }
+  }
+
+  void operator[]= (Token key, Token value) {
+    entries = entries.prepend(new CommentTokenMapEntry(key, value));
+  }
+}
+
 abstract class Compiler implements DiagnosticListener {
   final Map<String, LibraryElement> libraries;
   final Stopwatch totalCompileTime = new Stopwatch();
@@ -111,6 +137,11 @@ abstract class Compiler implements DiagnosticListener {
   String assembledCode;
   Types types;
 
+  /**
+   * Map from token to the first preceeding comment token.
+   */
+  final CommentTokenMap commentMap = new CommentTokenMap();
+
   final bool enableMinification;
   final bool enableTypeAssertions;
   final bool enableUserAssertions;
@@ -125,6 +156,11 @@ abstract class Compiler implements DiagnosticListener {
   final bool rejectDeprecatedFeatures;
   final bool checkDeprecationInSdk;
 
+  /**
+   * If [:true:], comment tokens are collected in [commentMap] during scanning.
+   */
+  final bool preserveComments;
+
   bool disableInlining = false;
 
   final Tracer tracer;
@@ -247,6 +283,7 @@ abstract class Compiler implements DiagnosticListener {
             this.analyzeAll: false,
             this.rejectDeprecatedFeatures: false,
             this.checkDeprecationInSdk: false,
+            this.preserveComments: false,
             List<String> strips: const []})
       : libraries = new Map<String, LibraryElement>(),
         progress = new Stopwatch() {
@@ -898,6 +935,28 @@ abstract class Compiler implements DiagnosticListener {
       => interceptorsLibrary.findLocal(name);
 
   bool get isMockCompilation => false;
+
+  Token processAndStripComments(Token currentToken) {
+    Token firstToken = currentToken;
+    Token prevToken;
+    while (currentToken.kind != EOF_TOKEN) {
+      if (identical(currentToken.kind, COMMENT_TOKEN)) {
+        Token firstCommentToken = currentToken;
+        while (identical(currentToken.kind, COMMENT_TOKEN)) {
+          currentToken = currentToken.next;
+        }
+        commentMap[currentToken] = firstCommentToken;
+        if (prevToken == null) {
+          firstToken = currentToken;
+        } else {
+          prevToken.next = currentToken;
+        }
+      }
+      prevToken = currentToken;
+      currentToken = currentToken.next;
+    }
+    return firstToken;
+  }
 }
 
 class CompilerTask {