Cache values of fields and lists in summary implementations.

pkg/analyzer/tool/summary/generate.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * This file contains code to generate serialization/deserialization logic for
  * summaries based on an "IDL" description of the summary format (written in
  * stylized Dart).
  *
  * For each class in the "IDL" input, two corresponding classes are generated:
@@ skipping 263 matching lines @@
     });
     for (var cls in _idl.classes.values) {
       List<String> builderParams = _generateBuilder(cls);
       out();
       _generateEncodeFunction(cls, builderParams);
       out();
       _generateInterface(cls);
       out();
       _generateReader(cls);
       out();
+      _generateImpl(cls);
+      out();
     }
   }
 
   /**
    * Enclose [s] in quotes, escaping as necessary.
    */
   String quoted(String s) {
     return JSON.encode(s);
   }
 
@@ skipping 140 matching lines @@
       out('$builderName builder = new $builderName();');
       for (idlModel.FieldDeclaration field in cls.fields) {
         String fieldName = field.name;
         out('builder.$fieldName = $fieldName;');
       }
       out('return builder;');
     });
     out('}');
   }
 
-  void _generateInterface(idlModel.ClassDeclaration cls) {
+  void _generateImpl(idlModel.ClassDeclaration cls) {
     String name = cls.name;
-    outDoc(cls.documentation);
-    out('abstract class $name extends base.SummaryClass {');
-    indent(() {
-      if (cls.isTopLevel) {
-        out('factory $name.fromBuffer(List<int> buffer) {');
-        indent(() {
-          out('fb.BufferPointer rootRef = new fb.BufferPointer.fromBytes(buffer);');
-          out('return const _${name}Reader().read(rootRef);');
-        });
-        out('}');
-      }
-      cls.fields.asMap().forEach((index, field) {
-        String fieldName = field.name;
-        idlModel.FieldType type = field.type;
-        out();
-        outDoc(field.documentation);
-        out('${dartType(type)} get $fieldName;');
-      });
-    });
-    out('}');
-  }
-
-  void _generateReader(idlModel.ClassDeclaration cls) {
-    String name = cls.name;
-    String readerName = '_${name}Reader';
-    out('class $readerName extends fb.TableReader<$readerName> implements $name {');
+    String implName = '_${name}Impl';
+    out('class $implName implements $name {');
     indent(() {
       out('final fb.BufferPointer _bp;');
       out();
-      out('const $readerName([this._bp]);');
+      out('$implName(this._bp);');
       out();
-      out('@override');
-      out('$readerName createReader(fb.BufferPointer bp) => new $readerName(bp);');
+      // Write cache fields.
+      for (idlModel.FieldDeclaration field in cls.fields) {
+        String returnType = dartType(field.type);
+        String fieldName = field.name;
+        out('$returnType _$fieldName;');
+      }
       out();
       // Write toMap().
       out('@override');
       out('Map<String, Object> toMap() => {');
       indent(() {
         for (idlModel.FieldDeclaration field in cls.fields) {
           String fieldName = field.name;
           out('${quoted(fieldName)}: $fieldName,');
         }
       });
       out('};');
       // Write getters.
       cls.fields.asMap().forEach((index, field) {
         String fieldName = field.name;
         idlModel.FieldType type = field.type;
         String typeName = type.typeName;
-        // Prepare "readLines" or "readCode" + "def" + "readSuffix"
-        List<String> readLines;
+        // Prepare "readExpr" or "readCode" + "def"
+        String readExpr;
         String readCode;
         String def = defaultValue(type);
         if (type.isList) {
           if (typeName == 'int') {
             String itemCode = 'const fb.Int32Reader()';
             readCode = 'const fb.ListReader<int>($itemCode)';
           } else if (typeName == 'String') {
             String itemCode = 'const fb.StringReader()';
             readCode = 'const fb.ListReader<String>($itemCode)';
           } else {
             String itemCode = '$typeName>(const _${typeName}Reader()';
             readCode = 'const fb.ListReader<$itemCode)';
           }
         } else if (typeName == 'bool') {
           readCode = 'const fb.BoolReader()';
         } else if (typeName == 'int') {
           readCode = 'const fb.Int32Reader()';
         } else if (typeName == 'String') {
           readCode = 'const fb.StringReader()';
         } else if (_idl.enums.containsKey(typeName)) {
-          readLines = <String>[
-            'int index = const fb.Int32Reader().vTableGet(_bp, $index, 0);',
-            'return $typeName.values[index];'
-          ];
+          readExpr =
+              '$typeName.values[const fb.Int32Reader().vTableGet(_bp, $index, 0)]';
         } else if (_idl.classes.containsKey(typeName)) {
           readCode = 'const _${typeName}Reader()';
         }
-        assert(readCode != null || readLines != null);
+        if (readExpr == null) {
+          assert(readCode != null);
+          readExpr = '$readCode.vTableGet(_bp, $index, $def)';
+        }
         // Write the getter implementation.
         out();
         out('@override');
         String returnType = dartType(type);
-        if (readLines != null) {
-          out('$returnType get $fieldName {');
-          indent(() {
-            readLines.forEach(out);
-          });
-          out('}');
-        } else {
-          String expr = '$readCode.vTableGet(_bp, $index, $def)';
-          out('$returnType get $fieldName => $expr;');
-        }
+        out('$returnType get $fieldName {');
+        indent(() {
+          out('_$fieldName ??= $readExpr;');
+          out('return _$fieldName;');
+        });
+        out('}');
       });
     });
     out('}');
   }
 
+  void _generateInterface(idlModel.ClassDeclaration cls) {
+    String name = cls.name;
+    outDoc(cls.documentation);
+    out('abstract class $name extends base.SummaryClass {');
+    indent(() {
+      if (cls.isTopLevel) {
+        out('factory $name.fromBuffer(List<int> buffer) {');
+        indent(() {
+          out('fb.BufferPointer rootRef = new fb.BufferPointer.fromBytes(buffer);');
+          out('return const _${name}Reader().read(rootRef);');
+        });
+        out('}');
+      }
+      cls.fields.asMap().forEach((index, field) {
+        String fieldName = field.name;
+        idlModel.FieldType type = field.type;
+        out();
+        outDoc(field.documentation);
+        out('${dartType(type)} get $fieldName;');
+      });
+    });
+    out('}');
+  }
+
+  void _generateReader(idlModel.ClassDeclaration cls) {
+    String name = cls.name;
+    String readerName = '_${name}Reader';
+    String implName = '_${name}Impl';
+    out('class $readerName extends fb.TableReader<$implName> {');
+    indent(() {
+      out('const $readerName();');
+      out();
+      out('@override');
+      out('$implName createObject(fb.BufferPointer bp) => new $implName(bp);');
+    });
+    out('}');
+  }
+
   /**
    * Return the documentation text of the given [node], or `null` if the [node]
    * does not have a comment.  Each line is `\n` separated.
    */
   String _getNodeDoc(LineInfo lineInfo, AnnotatedNode node) {
     Comment comment = node.documentationComment;
     if (comment != null &&
         comment.isDocumentation &&
         comment.tokens.length == 1 &&
         comment.tokens.first.type == TokenType.MULTI_LINE_COMMENT) {
       Token token = comment.tokens.first;
       int column = lineInfo.getLocation(token.offset).columnNumber;
       String indent = ' ' * (column - 1);
       return token.lexeme.split('\n').map((String line) {
         if (line.startsWith(indent)) {
           line = line.substring(indent.length);
         }
         return line;
       }).join('\n');
     }
     return null;
   }
 }