dart2js: In minified mode shorter getter and setter names.

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

Index: sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart b/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
index 98344a1e0a202b35b5f63fdd6c8f6749dda38fc8..4c537497f728daf359803c901e2872106ba4be92 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
@@ -16,6 +16,9 @@ class MinifyNamer extends Namer {
   String get isolatePropertiesName => 'p';
   bool get shouldMinify => true;
 
+  final String getterPrefix = 'g';
+  final String setterPrefix = 's';
+
   const ALPHABET_CHARACTERS = 52;  // a-zA-Z.
   const ALPHANUMERIC_CHARACTERS = 62;  // a-zA-Z0-9.
 
@@ -69,11 +72,17 @@ class MinifyNamer extends Namer {
         'refY', 'RGBA', 'root', 'rows', 'save', 'seed', 'seek', 'self', 'send',
         'show', 'SINE', 'size', 'span', 'stat', 'step', 'stop', 'tags', 'text',
         'Text', 'time', 'type', 'view', 'warn', 'wrap', 'ZERO'];
+
     for (var name in reservedNativeProperties) {
       if (name.length < 2) {
         instanceNameMap[name] = name;
       }
       usedInstanceNames.add(name);
+      // Getter and setter names are autogenerated by prepending 'g' and 's' to
+      // field names.  Therefore there are some field names we don't want to
+      // use.
+      if (name.startsWith('g')) usedInstanceNames.add(name.substring(1));

[karlklose, 2013/02/12 14:41:19]

Can you use _hasBannedPrefix here?

[erikcorry, 2013/02/12 14:50:40]

Yes, but the substring(1) still retains implicit knowledge about what the prefix
is (or rather, its length).

+      if (name.startsWith('s')) usedInstanceNames.add(name.substring(1));
     }
 
     // This list of popular instance variable names generated with:
@@ -152,7 +161,9 @@ class MinifyNamer extends Namer {
           h2 ~/= ALPHANUMERIC_CHARACTERS;
         }
         final candidate = new String.fromCharCodes(codes);
-        if (!usedNames.contains(candidate) && !jsReserved.contains(candidate)) {
+        if (!usedNames.contains(candidate) &&
+            !jsReserved.contains(candidate) &&
+            !_hasBannedPrefix(candidate)) {
           return candidate;
         }
         // Try again with a slightly different hash.  After around 10 turns
@@ -168,9 +179,20 @@ class MinifyNamer extends Namer {
     while (usedNames.contains("$startLetter$i")) {
       i++;
     }
+    // We don't need to check for banned prefix because the name is in the form
+    // xnnn, where nnn is a number.  There can be no getter or setter called
+    // gnnn since that would imply a numeric field name.
     return "$startLetter$i";
   }
 
+  // Instance members starting with g and s are reserved for getters and

[karlklose, 2013/02/12 14:41:19]

Use /// to turn comment into dart doc.

[erikcorry, 2013/02/12 14:50:40]

Done.

+  // setters.
+  bool _hasBannedPrefix(String name) {
+    int code = name.codeUnitAt(0);
+    if (code == $g || code == $s) return true;

[karlklose, 2013/02/12 14:41:19]

'return (code == $g || code == $s)'?

[erikcorry, 2013/02/12 14:50:40]

Done.

+    return false;
+  }
+
   int _calculateHash(String name) {
     int h = 0;
     for (int i = 0; i < name.length; i++) {