Cache values of fields and lists in summary implementations.

pkg/analyzer/tool/summary/generate.dart

Index: pkg/analyzer/tool/summary/generate.dart
diff --git a/pkg/analyzer/tool/summary/generate.dart b/pkg/analyzer/tool/summary/generate.dart
index 5d412e4bfde5907b0e813a1efaea0e002b5baf13..19180745cd4ad9b1451700c7b7b0c5fb0b2b45bf 100644
--- a/pkg/analyzer/tool/summary/generate.dart
+++ b/pkg/analyzer/tool/summary/generate.dart
@@ -281,6 +281,8 @@ class _CodeGenerator {
       out();
       _generateReader(cls);
       out();
+      _generateImpl(cls);
+      out();
     }
   }
 
@@ -441,41 +443,21 @@ class _CodeGenerator {
     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');
@@ -492,8 +474,8 @@ class _CodeGenerator {
         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) {
@@ -514,33 +496,68 @@ class _CodeGenerator {
         } 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.