Introduce a shadow hierarchy and factory class for use by fasta's BodyBuilder.

pkg/front_end/lib/src/fasta/kernel/ast_factory.dart

+import 'package:kernel/ast.dart' show DartType;

[ahe, 2017/03/24 12:00:40]

Missing copyright.

[Paul Berry, 2017/03/24 14:55:23]

Done.

+
+import '../builder/ast_factory.dart' as builder;

[ahe, 2017/03/24 12:00:40]

Could you rename this file to kernel_ast_factory.dart? It makes it easier for me
in Emacs :-)

[Paul Berry, 2017/03/24 14:55:24]

Done.

+import '../builder/shadow_ast.dart' as builder;
+import 'shadow_ast.dart';
+
+/// Concrete implementation of [builder.AstFactory] for building a kernel AST.
+class AstFactory implements builder.AstFactory {

[ahe, 2017/03/24 12:00:40]

KernelAstFactory?

[Paul Berry, 2017/03/24 14:55:24]

Done.

+  @override
+  Block block(List<builder.Statement> statements, int charOffset) {
+    return new Block(statements)..fileOffset = charOffset;
+  }
+
+  @override
+  IntLiteral intLiteral(value, int charOffset) {
+    return new IntLiteral(value)..fileOffset = charOffset;
+  }
+
+  @override
+  ListLiteral listLiteral(List<builder.Expression> expressions,
+      DartType typeArgument, bool isConst, int charOffset) {
+    return new ListLiteral(expressions,
+        typeArgument: typeArgument, isConst: isConst)..fileOffset = charOffset;
+  }
+
+  @override
+  NullLiteral nullLiteral(int charOffset) {
+    return new NullLiteral()..fileOffset = charOffset;
+  }
+
+  @override
+  ReturnStatement returnStatement(
+      builder.Expression expression, int charOffset) {
+    return new ReturnStatement(expression)..fileOffset = charOffset;
+  }
+
+  @override
+  VariableDeclaration variableDeclaration(String name,
+      {DartType type,
+      builder.Expression initializer,
+      int charOffset,
+      bool isFinal: false,
+      bool isConst: false}) {
+    return new VariableDeclaration(name,
+        type: type,
+        initializer: initializer,
+        isFinal: isFinal,
+        isConst: isConst)..fileEqualsOffset = charOffset;
+  }
+}