As throw

lib/src/builders/expression.dart

@@ -29,6 +29,7 @@ part 'expression/invocation.dart';
 part 'expression/negate.dart';
 part 'expression/operators.dart';
 part 'expression/return.dart';
+part 'expression/throw.dart';
 part 'expression/yield.dart';
 
 final _false =
@@ -205,6 +206,9 @@ abstract class AbstractExpressionMixin implements ExpressionBuilder {
   @override
   StatementBuilder asYieldStar() => new _AsYield(this, true);
 
+  @override
+  ExpressionBuilder asThrow() => new _ThrowExpression(this);
+
   @override
   WhileStatementBuilder asWhile({bool asDo: false}) {
     return new WhileStatementBuilder(asDo, this);
@@ -371,6 +375,9 @@ abstract class ExpressionBuilder
   /// [Statement] AST instead of an expression.
   StatementBuilder asStatement();
 
+  /// Returns as an [ExpressionBuilder] that throws this expression as an error.
+  ExpressionBuilder asThrow();
+
   /// Returns as a [StatementBuilder] that assigns to a new `var` [variable].
   ///
   /// If [type] is supplied, the resulting statement is `{type} {variable} =`.

lib/src/builders/expression/throw.dart

@@ -0,0 +1,22 @@
+// Copyright (c) 2016, 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.
+
+part of code_builder.src.builders.expression;
+
+class _ThrowExpression extends AbstractExpressionMixin with TopLevelMixin {
+  final ExpressionBuilder _value;
+
+  _ThrowExpression(this._value);
+
+  @override
+  ExpressionBuilder asThrow() => this;
+
+  @override
+  AstNode buildAst([Scope scope]) => buildExpression(scope);
+
+  @override
+  Expression buildExpression([Scope scope]) {
+    return astFactory.throwExpression($throw, _value.buildExpression(scope));
+  }
+}

lib/src/builders/field.dart

@@ -106,9 +106,7 @@ abstract class FieldBuilder
   TopLevelVariableDeclaration buildTopLevel([Scope scope]);
 }
 
-class _FieldBuilderImpl extends TopLevelMixin
-    with HasAnnotationsMixin
-    implements FieldBuilder {
+class _FieldBuilderImpl extends HasAnnotationsMixin implements FieldBuilder {
   final Keyword _keyword;
   final String _name;
   final TypeBuilder _type;
@@ -157,6 +155,11 @@ class _FieldBuilderImpl extends TopLevelMixin
     );
   }
 
+  @override
+  CompilationUnitMember buildTopLevelAst([Scope scope]) {
+    return buildTopLevel(scope);
+  }
+
   VariableDeclarationList _buildVariableList([Scope scope]) {
     return astFactory.variableDeclarationList(
       null,

lib/src/tokens.dart

@@ -187,6 +187,9 @@ final Token $static = new KeywordToken(Keyword.STATIC, 0);
 /// The `this` token.
 final Token $this = new KeywordToken(Keyword.THIS, 0);
 
+/// The `throw` token.
+final Token $throw = new KeywordToken(Keyword.THROW, 0);
+
 /// The `true` token.
 final Token $true = new KeywordToken(Keyword.TRUE, 0);
 

test/builders/expression_test.dart

@@ -404,4 +404,15 @@ void main() {
       '''),
     );
   });
+
+  test('should throw an exception', () {
+    expect(
+        new TypeBuilder('StateError')
+            .newInstance([literal('Hey! No!')])
+            .asThrow()
+            .asStatement(),
+        equalsSource('''
+    throw new StateError('Hey! No!');
+    '''));
+  });
 }