Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_nodes.dart

Index: sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_nodes.dart b/sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_nodes.dart
deleted file mode 100644
index 9048405f357a9a5e2644ad3e0d5dc3fa1b62d43d..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_nodes.dart
+++ /dev/null
@@ -1,1544 +0,0 @@
-// Copyright (c) 2014, 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.
-
-library backend_ast_nodes;
-
-import '../constants/values.dart' as values;
-import '../dart_types.dart' as types;
-import '../elements/elements.dart' as elements;
-import '../tree/tree.dart' as tree;
-import '../util/characters.dart' as characters;
-
-/// The following nodes correspond to [tree.Send] expressions:
-/// [FieldExpression], [IndexExpression], [Assignment], [Increment],
-/// [CallFunction], [CallMethod], [CallNew], [CallStatic], [UnaryOperator],
-/// [BinaryOperator], and [TypeOperator].
-abstract class Node {}
-
-/// Receiver is an [Expression] or the [SuperReceiver].
-abstract class Receiver extends Node {}
-
-/// Argument is an [Expression] or a [NamedArgument].
-abstract class Argument extends Node {}
-
-abstract class Expression extends Node implements Receiver, Argument {
-  bool get assignable => false;
-}
-
-abstract class Statement extends Node {}
-
-/// Used as receiver in expressions that dispatch to the super class.
-/// For instance, an expression such as `super.f()` is represented
-/// by a [CallMethod] node with [SuperReceiver] as its receiver.
-class SuperReceiver extends Receiver {
-  static final SuperReceiver _instance = new SuperReceiver._create();
-
-  factory SuperReceiver() => _instance;
-  SuperReceiver._create();
-}
-
-/// Named arguments may occur in the argument list of
-/// [CallFunction], [CallMethod], [CallNew], and [CallStatic].
-class NamedArgument extends Argument {
-  final String name;
-  final Expression expression;
-
-  NamedArgument(this.name, this.expression);
-}
-
-class TypeAnnotation extends Node {
-  final String name;
-  final List<TypeAnnotation> typeArguments;
-
-  types.DartType dartType;
-
-  TypeAnnotation(this.name, [this.typeArguments = const <TypeAnnotation>[]]);
-}
-
-// STATEMENTS
-
-
-class Block extends Statement {
-  final List<Statement> statements;
-
-  Block(this.statements);
-}
-
-class Break extends Statement {
-  final String label;
-
-  Break([this.label]);
-}
-
-class Continue extends Statement {
-  final String label;
-
-  Continue([this.label]);
-}
-
-class EmptyStatement extends Statement {
-  static final EmptyStatement _instance = new EmptyStatement._create();
-
-  factory EmptyStatement() => _instance;
-  EmptyStatement._create();
-}
-
-class ExpressionStatement extends Statement {
-  final Expression expression;
-
-  ExpressionStatement(this.expression);
-}
-
-class For extends Statement {
-  final Node initializer;
-  final Expression condition;
-  final List<Expression> updates;
-  final Statement body;
-
-  /// Initializer must be [VariableDeclarations] or [Expression] or null.
-  For(this.initializer, this.condition, this.updates, this.body) {
-    assert(initializer == null
-        || initializer is VariableDeclarations
-        || initializer is Expression);
-  }
-}
-
-class ForIn extends Statement {
-  final Node leftHandValue;
-  final Expression expression;
-  final Statement body;
-
-  /// [leftHandValue] must be [Identifier] or [VariableDeclarations] with
-  /// exactly one definition, and that variable definition must have no
-  /// initializer.
-  ForIn(Node leftHandValue, this.expression, this.body)
-      : this.leftHandValue = leftHandValue {
-    assert(leftHandValue is Identifier
-        || (leftHandValue is VariableDeclarations
-            && leftHandValue.declarations.length == 1
-            && leftHandValue.declarations[0].initializer == null));
-  }
-}
-
-class While extends Statement {
-  final Expression condition;
-  final Statement body;
-
-  While(this.condition, this.body);
-}
-
-class DoWhile extends Statement {
-  final Statement body;
-  final Expression condition;
-
-  DoWhile(this.body, this.condition);
-}
-
-class If extends Statement {
-  final Expression condition;
-  final Statement thenStatement;
-  final Statement elseStatement;
-
-  If(this.condition, this.thenStatement, [this.elseStatement]);
-}
-
-class LabeledStatement extends Statement {
-  final String label;
-  final Statement statement;
-
-  LabeledStatement(this.label, this.statement);
-}
-
-class Rethrow extends Statement {
-}
-
-class Return extends Statement {
-  final Expression expression;
-
-  Return([this.expression]);
-}
-
-class Switch extends Statement {
-  final Expression expression;
-  final List<SwitchCase> cases;
-
-  Switch(this.expression, this.cases);
-}
-
-/// A sequence of case clauses followed by a sequence of statements.
-/// Represents the default case if [expressions] is null.
-///
-/// NOTE:
-/// Control will never fall through to the following SwitchCase, even if
-/// the list of statements is empty. An empty list of statements will be
-/// unparsed to a semicolon to guarantee this behaviour.
-class SwitchCase extends Node {
-  final List<Expression> expressions;
-  final List<Statement> statements;
-
-  SwitchCase(this.expressions, this.statements);
-  SwitchCase.defaultCase(this.statements) : expressions = null;
-
-  bool get isDefaultCase => expressions == null;
-}
-
-/// A try statement. The try, catch and finally blocks will automatically
-/// be printed inside a block statement if necessary.
-class Try extends Statement {
-  final Statement tryBlock;
-  final List<CatchBlock> catchBlocks;
-  final Statement finallyBlock;
-
-  Try(this.tryBlock, this.catchBlocks, [this.finallyBlock]) {
-    assert(catchBlocks.length > 0 || finallyBlock != null);
-  }
-}
-
-class CatchBlock extends Node {
-  final TypeAnnotation onType;
-  final String exceptionVar;
-  final String stackVar;
-  final Statement body;
-
-  /// At least onType or exceptionVar must be given.
-  /// stackVar may only be given if exceptionVar is also given.
-  CatchBlock(this.body, {this.onType, this.exceptionVar, this.stackVar}) {
-    // Must specify at least a type or an exception binding.
-    assert(onType != null || exceptionVar != null);
-
-    // We cannot bind the stack trace without binding the exception too.
-    assert(stackVar == null || exceptionVar != null);
-  }
-}
-
-class VariableDeclarations extends Statement {
-  final TypeAnnotation type;
-  final bool isFinal;
-  final bool isConst;
-  final List<VariableDeclaration> declarations;
-
-  VariableDeclarations(this.declarations,
-                      { this.type,
-                        this.isFinal: false,
-                        this.isConst: false }) {
-    // Cannot be both final and const.
-    assert(!isFinal || !isConst);
-  }
-}
-
-class VariableDeclaration extends Node {
-  final String name;
-  final Expression initializer;
-
-  elements.Element element;
-
-  VariableDeclaration(this.name, [this.initializer]);
-}
-
-
-class FunctionDeclaration extends Statement {
-  final FunctionExpression function;
-
-  TypeAnnotation get returnType => function.returnType;
-  Parameters get parameters => function.parameters;
-  String get name => function.name;
-  Statement get body => function.body;
-
-  FunctionDeclaration(this.function);
-}
-
-class Parameters extends Node {
-  final List<Parameter> requiredParameters;
-  final List<Parameter> optionalParameters;
-  final bool hasNamedParameters;
-
-  Parameters(this.requiredParameters,
-             [ this.optionalParameters,
-               this.hasNamedParameters = false ]);
-
-  Parameters.named(this.requiredParameters, this.optionalParameters)
-      : hasNamedParameters = true;
-
-  Parameters.positional(this.requiredParameters, this.optionalParameters)
-        : hasNamedParameters = false;
-
-  bool get hasOptionalParameters =>
-      optionalParameters != null && optionalParameters.length > 0;
-}
-
-class Parameter extends Node {
-  final String name;
-
-  /// Type of parameter, or return type of function parameter.
-  final TypeAnnotation type;
-
-  Expression defaultValue;
-
-  /// Parameters to function parameter. Null for non-function parameters.
-  final Parameters parameters;
-
-  elements.FormalElement element;
-
-  Parameter(this.name, {this.type, this.defaultValue})
-      : parameters = null;
-
-  Parameter.function(this.name,
-                     TypeAnnotation returnType,
-                     this.parameters,
-                     [ this.defaultValue ]) : type = returnType {
-    assert(parameters != null);
-  }
-
-  /// True if this is a function parameter.
-  bool get isFunction => parameters != null;
-}
-
-// EXPRESSIONS
-
-class FunctionExpression extends Expression {
-  final TypeAnnotation returnType;
-  String name;
-  final Parameters parameters;
-  final Statement body;
-  final bool isGetter;
-  final bool isSetter;
-
-  elements.FunctionElement element;
-
-  FunctionExpression(this.parameters,
-                     this.body,
-                     { this.name,
-                       this.returnType,
-                       this.isGetter: false,
-                       this.isSetter: false }) {
-    // Function must have a name if it has a return type
-    assert(returnType == null || name != null);
-  }
-}
-
-class Conditional extends Expression {
-  final Expression condition;
-  final Expression thenExpression;
-  final Expression elseExpression;
-
-  Conditional(this.condition, this.thenExpression, this.elseExpression);
-}
-
-/// An identifier expression.
-/// The unparser does not concern itself with scoping rules, and it is the
-/// responsibility of the AST creator to ensure that the identifier resolves
-/// to the proper definition.
-/// For the time being, this class is also used to reference static fields and
-/// top-level variables that are qualified with a class and/or library name,
-/// assuming the [element] is set. This is likely to change when the old backend
-/// is replaced.
-class Identifier extends Expression {
-  final String name;
-
-  elements.Element element;
-
-  Identifier(this.name);
-
-  bool get assignable => true;
-}
-
-class Literal extends Expression {
-  final values.PrimitiveConstantValue value;
-
-  Literal(this.value);
-}
-
-class LiteralList extends Expression {
-  final bool isConst;
-  final TypeAnnotation typeArgument;
-  final List<Expression> values;
-
-  LiteralList(this.values, { this.typeArgument, this.isConst: false });
-}
-
-class LiteralMap extends Expression {
-  final bool isConst;
-  final List<TypeAnnotation> typeArguments;
-  final List<LiteralMapEntry> entries;
-
-  LiteralMap(this.entries, { this.typeArguments, this.isConst: false }) {
-    assert(this.typeArguments == null
-        || this.typeArguments.length == 0
-        || this.typeArguments.length == 2);
-  }
-}
-
-class LiteralMapEntry extends Node {
-  final Expression key;
-  final Expression value;
-
-  LiteralMapEntry(this.key, this.value);
-}
-
-class LiteralSymbol extends Expression {
-  final String id;
-
-  /// [id] should not include the # symbol
-  LiteralSymbol(this.id);
-}
-
-/// A type literal. This is distinct from [Identifier] since the unparser
-/// needs to this distinguish a static invocation from a method invocation
-/// on a type literal.
-class LiteralType extends Expression {
-  final String name;
-
-  types.DartType type;
-
-  LiteralType(this.name);
-}
-
-/// Reference to a type variable.
-/// This is distinct from [Identifier] since the unparser needs to this
-/// distinguish a function invocation `T()` from a type variable invocation
-/// `(T)()` (the latter is invalid, but must be generated anyway).
-class ReifyTypeVar extends Expression {
-  final String name;
-
-  elements.TypeVariableElement element;
-
-  ReifyTypeVar(this.name);
-}
-
-/// StringConcat is used in place of string interpolation and juxtaposition.
-/// Semantically, each subexpression is evaluated and converted to a string
-/// by `toString()`. These string are then concatenated and returned.
-/// StringConcat unparses to a string literal, possibly with interpolations.
-/// The unparser will flatten nested StringConcats.
-/// A StringConcat node may have any number of children, including zero and one.
-class StringConcat extends Expression {
-  final List<Expression> expressions;
-
-  StringConcat(this.expressions);
-}
-
-/// Expression of form `e.f`.
-class FieldExpression extends Expression {
-  final Receiver object;
-  final String fieldName;
-
-  FieldExpression(this.object, this.fieldName);
-
-  bool get assignable => true;
-}
-
-/// Expression of form `e1[e2]`.
-class IndexExpression extends Expression {
-  final Receiver object;
-  final Expression index;
-
-  IndexExpression(this.object, this.index);
-
-  bool get assignable => true;
-}
-
-/// Expression of form `e(..)`
-/// Note that if [callee] is a [FieldExpression] this will translate into
-/// `(e.f)(..)` and not `e.f(..)`. Use a [CallMethod] to generate
-/// the latter type of expression.
-class CallFunction extends Expression {
-  final Expression callee;
-  final List<Argument> arguments;
-
-  CallFunction(this.callee, this.arguments);
-}
-
-/// Expression of form `e.f(..)`.
-class CallMethod extends Expression {
-  final Receiver object;
-  final String methodName;
-  final List<Argument> arguments;
-
-  CallMethod(this.object, this.methodName, this.arguments);
-}
-
-/// Expression of form `new T(..)`, `new T.f(..)`, `const T(..)`,
-/// or `const T.f(..)`.
-class CallNew extends Expression {
-  final bool isConst;
-  final TypeAnnotation type;
-  final String constructorName;
-  final List<Argument> arguments;
-
-  elements.FunctionElement constructor;
-  types.DartType dartType;
-
-  CallNew(this.type,
-          this.arguments,
-         { this.constructorName,
-           this.isConst: false });
-}
-
-/// Expression of form `T.f(..)`.
-class CallStatic extends Expression {
-  final String className;
-  final String methodName;
-  final List<Argument> arguments;
-
-  elements.Element element;
-
-  CallStatic(this.className, this.methodName, this.arguments);
-}
-
-/// Expression of form `!e` or `-e` or `~e`.
-class UnaryOperator extends Expression {
-  final String operatorName;
-  final Receiver operand;
-
-  UnaryOperator(this.operatorName, this.operand) {
-    assert(isUnaryOperator(operatorName));
-  }
-}
-
-/// Expression of form `e1 + e2`, `e1 - e2`, etc.
-/// This node also represents application of the logical operators && and ||.
-class BinaryOperator extends Expression {
-  final Receiver left;
-  final String operator;
-  final Expression right;
-
-  BinaryOperator(this.left, this.operator, this.right) {
-    assert(isBinaryOperator(operator));
-  }
-}
-
-/// Expression of form `e is T` or `e is! T` or `e as T`.
-class TypeOperator extends Expression {
-  final Expression expression;
-  final String operator;
-  final TypeAnnotation type;
-
-  TypeOperator(this.expression, this.operator, this.type) {
-    assert(operator == 'is'
-        || operator == 'as'
-        || operator == 'is!');
-  }
-}
-
-class Increment extends Expression {
-  final Expression expression;
-  final String operator;
-  final bool isPrefix;
-
-  Increment(this.expression, this.operator, this.isPrefix) {
-    assert(operator == '++' || operator == '--');
-    assert(expression.assignable);
-  }
-
-  Increment.prefix(Expression expression, String operator)
-      : this(expression, operator, true);
-
-  Increment.postfix(Expression expression, String operator)
-      : this(expression, operator, false);
-}
-
-class Assignment extends Expression {
-  static final _operators =
-      new Set.from(['=', '|=', '^=', '&=', '<<=', '>>=',
-                    '+=', '-=', '*=', '/=', '%=', '~/=']);
-
-  final Expression left;
-  final String operator;
-  final Expression right;
-
-  Assignment(this.left, this.operator, this.right) {
-    assert(_operators.contains(operator));
-    assert(left.assignable);
-  }
-}
-
-class Throw extends Expression {
-  final Expression expression;
-
-  Throw(this.expression);
-}
-
-class This extends Expression {
-  static final This _instance = new This._create();
-
-  factory This() => _instance;
-  This._create();
-}
-
-// UNPARSER
-
-bool isUnaryOperator(String op) {
-  return op == '!' || op == '-' || op == '~';
-}
-bool isBinaryOperator(String op) {
-  return BINARY_PRECEDENCE.containsKey(op);
-}
-/// True if the given operator can be converted to a compound assignment.
-bool isCompoundableOperator(String op) {
-  switch (BINARY_PRECEDENCE[op]) {
-    case BITWISE_OR:
-    case BITWISE_XOR:
-    case BITWISE_AND:
-    case SHIFT:
-    case ADDITIVE:
-    case MULTIPLICATIVE:
-      return true;
-    default:
-      return false;
-  }
-}
-
-
-// Precedence levels
-const int EXPRESSION = 1;
-const int CONDITIONAL = 2;
-const int LOGICAL_OR = 3;
-const int LOGICAL_AND = 4;
-const int EQUALITY = 6;
-const int RELATIONAL = 7;
-const int BITWISE_OR = 8;
-const int BITWISE_XOR = 9;
-const int BITWISE_AND = 10;
-const int SHIFT = 11;
-const int ADDITIVE = 12;
-const int MULTIPLICATIVE = 13;
-const int UNARY = 14;
-const int POSTFIX_INCREMENT = 15;
-const int TYPE_LITERAL = 19;
-const int PRIMARY = 20;
-
-/// Precedence level required for the callee in a [FunctionCall].
-const int CALLEE = 21;
-
-const Map<String,int> BINARY_PRECEDENCE = const {
-  '&&': LOGICAL_AND,
-  '||': LOGICAL_OR,
-
-  '==': EQUALITY,
-  '!=': EQUALITY,
-
-  '>': RELATIONAL,
-  '>=': RELATIONAL,
-  '<': RELATIONAL,
-  '<=': RELATIONAL,
-
-  '|': BITWISE_OR,
-  '^': BITWISE_XOR,
-  '&': BITWISE_AND,
-
-  '>>': SHIFT,
-  '<<': SHIFT,
-
-  '+': ADDITIVE,
-  '-': ADDITIVE,
-
-  '*': MULTIPLICATIVE,
-  '%': MULTIPLICATIVE,
-  '/': MULTIPLICATIVE,
-  '~/': MULTIPLICATIVE,
-};
-
-/// Return true if binary operators with the given precedence level are
-/// (left) associative. False if they are non-associative.
-bool isAssociativeBinaryOperator(int precedence) {
-  return precedence != EQUALITY && precedence != RELATIONAL;
-}
-
-/// True if [x] is a letter, digit, or underscore.
-/// Such characters may not follow a shorthand string interpolation.
-bool isIdentifierPartNoDollar(dynamic x) {
-  if (x is! int) {
-    return false;
-  }
-  return (characters.$0 <= x && x <= characters.$9) ||
-         (characters.$A <= x && x <= characters.$Z) ||
-         (characters.$a <= x && x <= characters.$z) ||
-         (x == characters.$_);
-}
-
-/// The unparser will apply the following syntactic rewritings:
-///   Use short-hand function returns:
-///     foo(){return E} ==> foo() => E;
-///   Remove empty else branch:
-///     if (E) S else ; ==> if (E) S
-///   Flatten nested blocks:
-///     {S; {S; S}; S} ==> {S; S; S; S}
-///   Remove empty statements from block:
-///     {S; ; S} ==> {S; S}
-///   Unfold singleton blocks:
-///     {S} ==> S
-///   Empty block to empty statement:
-///     {} ==> ;
-///   Introduce not-equals operator:
-///     !(E == E) ==> E != E
-///   Introduce is-not operator:
-///     !(E is T) ==> E is!T
-///
-/// The following transformations will NOT be applied here:
-///   Use implicit this:
-///     this.foo ==> foo              (preconditions too complex for unparser)
-///   Merge adjacent variable definitions:
-///     var x; var y  ==> var x,y;    (hoisting will be done elsewhere)
-///   Merge adjacent labels:
-///     foo: bar: S ==> foobar: S     (scoping is categorically ignored)
-///
-/// The following transformations might be applied here in the future:
-///   Use implicit dynamic types:
-///     dynamic x = E ==> var x = E
-///     <dynamic>[]   ==> []
-class Unparser {
-  StringSink output;
-
-  Unparser(this.output);
-
-
-  void write(String s) {
-    output.write(s);
-  }
-
-  /// Outputs each element from [items] separated by [separator].
-  /// The actual printing must be performed by the [callback].
-  void writeEach(String separator, Iterable items, void callback(any)) {
-    bool first = true;
-    for (var x in items) {
-      if (first) {
-        first = false;
-      } else {
-        write(separator);
-      }
-      callback(x);
-    }
-  }
-
-  void writeOperator(String operator) {
-    write(" "); // TODO(sigurdm,kmillikin): Minimize use of whitespace.
-    write(operator);
-    write(" ");
-  }
-
-  /// Unfolds singleton blocks and returns the inner statement.
-  /// If an empty block is found, the [EmptyStatement] is returned instead.
-  Statement unfoldBlocks(Statement stmt) {
-    while (stmt is Block && stmt.statements.length == 1) {
-      Statement inner = (stmt as Block).statements[0];
-      if (definesVariable(inner)) {
-        return stmt; // Do not unfold block with lexical scope.
-      }
-      stmt = inner;
-    }
-    if (stmt is Block && stmt.statements.length == 0)
-      return new EmptyStatement();
-    return stmt;
-  }
-
-  void writeArgument(Argument arg) {
-    if (arg is NamedArgument) {
-      write(arg.name);
-      write(':');
-      writeExpression(arg.expression);
-    } else {
-      writeExpression(arg);
-    }
-  }
-
-  /// Prints the expression [e].
-  void writeExpression(Expression e) {
-    writeExp(e, EXPRESSION);
-  }
-
-  /// Prints [e] as an expression with precedence of at least [minPrecedence],
-  /// using parentheses if necessary to raise the precedence level.
-  /// Abusing terminology slightly, the function accepts a [Receiver] which
-  /// may also be the [SuperReceiver] object.
-  void writeExp(Receiver e, int minPrecedence, {beginStmt:false}) {
-    // TODO(kmillikin,sigurdm): it might be faster to use a Visitor.
-    void withPrecedence(int actual, void action()) {
-      if (actual < minPrecedence) {
-        write("(");
-        beginStmt = false;
-        action();
-        write(")");
-      } else {
-        action();
-      }
-    }
-    if (e is SuperReceiver) {
-      write('super');
-    } else if (e is FunctionExpression) {
-      assert(!e.isGetter && !e.isSetter);
-      Statement stmt = unfoldBlocks(e.body);
-      int precedence = stmt is Return ? EXPRESSION : PRIMARY;
-      withPrecedence(precedence, () {
-        // A named function expression at the beginning of a statement
-        // can be mistaken for a function declaration.
-        // (Note: Functions with a return type also have a name)
-        bool needParen = beginStmt && e.name != null;
-        if (needParen) {
-          write('(');
-        }
-        if (e.returnType != null) {
-          writeType(e.returnType);
-          write(' ');
-        }
-        if (e.name != null) {
-          write(e.name);
-        }
-        writeParameters(e.parameters);
-        // TODO(sigurdm,kmillikin): Print {} for "return null;"
-        if (stmt is Return) {
-          write('=> ');
-          writeExp(stmt.expression, EXPRESSION);
-        } else {
-          writeBlock(stmt);
-        }
-        if (needParen) {
-          write(')');
-        }
-      });
-    } else if (e is Conditional) {
-      withPrecedence(CONDITIONAL, () {
-        writeExp(e.condition, LOGICAL_OR, beginStmt: beginStmt);
-        write(' ? ');
-        writeExp(e.thenExpression, EXPRESSION);
-        write(' : ');
-        writeExp(e.elseExpression, EXPRESSION);
-      });
-    } else if (e is Identifier) {
-      write(e.name);
-    } else if (e is Literal) {
-      if (e.value.isString) {
-        writeStringLiteral(e);
-      }
-      else if (e.value.isDouble) {
-        double v = e.value.primitiveValue;
-        if (v == double.INFINITY) {
-          withPrecedence(MULTIPLICATIVE, () {
-            write('1/0.0');
-          });
-        } else if (v == double.NEGATIVE_INFINITY) {
-          withPrecedence(MULTIPLICATIVE, () {
-            write('-1/0.0');
-          });
-        } else if (v.isNaN) {
-          withPrecedence(MULTIPLICATIVE, () {
-            write('0/0.0');
-          });
-        } else {
-          write(v.toString());
-        }
-      } else {
-        // TODO(sigurdm): Use [ConstExp] to generate valid code for any
-        // constant.
-        write(e.value.unparse());
-      }
-    } else if (e is LiteralList) {
-      if (e.isConst) {
-        write(' const ');
-      }
-      if (e.typeArgument != null) {
-        write('<');
-        writeType(e.typeArgument);
-        write('>');
-      }
-      write('[');
-      writeEach(',', e.values, writeExpression);
-      write(']');
-    }
-    else if (e is LiteralMap) {
-      // The curly brace can be mistaken for a block statement if we
-      // are at the beginning of a statement.
-      bool needParen = beginStmt;
-      if (e.isConst) {
-        write(' const ');
-        needParen = false;
-      }
-      if (e.typeArguments.length > 0) {
-        write('<');
-        writeEach(',', e.typeArguments, writeType);
-        write('>');
-        needParen = false;
-      }
-      if (needParen) {
-        write('(');
-      }
-      write('{');
-      writeEach(',', e.entries, (LiteralMapEntry en) {
-        writeExp(en.key, EXPRESSION);
-        write(' : ');
-        writeExp(en.value, EXPRESSION);
-      });
-      write('}');
-      if (needParen) {
-        write(')');
-      }
-    } else if (e is LiteralSymbol) {
-      write('#');
-      write(e.id);
-    } else if (e is LiteralType) {
-      withPrecedence(TYPE_LITERAL, () {
-        write(e.name);
-      });
-    } else if (e is ReifyTypeVar) {
-      withPrecedence(PRIMARY, () {
-        write(e.name);
-      });
-    } else if (e is StringConcat) {
-      writeStringLiteral(e);
-    } else if (e is UnaryOperator) {
-      Receiver operand = e.operand;
-      // !(x == y) ==> x != y.
-      if (e.operatorName == '!' &&
-          operand is BinaryOperator && operand.operator == '==') {
-        withPrecedence(EQUALITY, () {
-          writeExp(operand.left, RELATIONAL);
-          writeOperator('!=');
-          writeExp(operand.right, RELATIONAL);
-        });
-      }
-      // !(x is T) ==> x is!T
-      else if (e.operatorName == '!' &&
-          operand is TypeOperator && operand.operator == 'is') {
-        withPrecedence(RELATIONAL, () {
-          writeExp(operand.expression, BITWISE_OR, beginStmt: beginStmt);
-          write(' is!');
-          writeType(operand.type);
-        });
-      }
-      else {
-        withPrecedence(UNARY, () {
-          writeOperator(e.operatorName);
-          writeExp(e.operand, UNARY);
-        });
-      }
-    } else if (e is BinaryOperator) {
-      int precedence = BINARY_PRECEDENCE[e.operator];
-      withPrecedence(precedence, () {
-        // All binary operators are left-associative or non-associative.
-        // For each operand, we use either the same precedence level as
-        // the current operator, or one higher.
-        int deltaLeft = isAssociativeBinaryOperator(precedence) ? 0 : 1;
-        writeExp(e.left, precedence + deltaLeft, beginStmt: beginStmt);
-        writeOperator(e.operator);
-        writeExp(e.right, precedence + 1);
-      });
-    } else if (e is TypeOperator) {
-      withPrecedence(RELATIONAL, () {
-        writeExp(e.expression, BITWISE_OR, beginStmt: beginStmt);
-        write(' ');
-        write(e.operator);
-        write(' ');
-        writeType(e.type);
-      });
-    } else if (e is Assignment) {
-      withPrecedence(EXPRESSION, () {
-        writeExp(e.left, PRIMARY, beginStmt: beginStmt);
-        writeOperator(e.operator);
-        writeExp(e.right, EXPRESSION);
-      });
-    } else if (e is FieldExpression) {
-      withPrecedence(PRIMARY, () {
-        writeExp(e.object, PRIMARY, beginStmt: beginStmt);
-        write('.');
-        write(e.fieldName);
-      });
-    } else if (e is IndexExpression) {
-      withPrecedence(CALLEE, () {
-        writeExp(e.object, PRIMARY, beginStmt: beginStmt);
-        write('[');
-        writeExp(e.index, EXPRESSION);
-        write(']');
-      });
-    } else if (e is CallFunction) {
-      withPrecedence(CALLEE, () {
-        writeExp(e.callee, CALLEE, beginStmt: beginStmt);
-        write('(');
-        writeEach(',', e.arguments, writeArgument);
-        write(')');
-      });
-    } else if (e is CallMethod) {
-      withPrecedence(CALLEE, () {
-        writeExp(e.object, PRIMARY, beginStmt: beginStmt);
-        write('.');
-        write(e.methodName);
-        write('(');
-        writeEach(',', e.arguments, writeArgument);
-        write(')');
-      });
-    } else if (e is CallNew) {
-      withPrecedence(CALLEE, () {
-        write(' ');
-        write(e.isConst ? 'const ' : 'new ');
-        writeType(e.type);
-        if (e.constructorName != null) {
-          write('.');
-          write(e.constructorName);
-        }
-        write('(');
-        writeEach(',', e.arguments, writeArgument);
-        write(')');
-      });
-    } else if (e is CallStatic) {
-      withPrecedence(CALLEE, () {
-        write(e.className);
-        write('.');
-        write(e.methodName);
-        write('(');
-        writeEach(',', e.arguments, writeArgument);
-        write(')');
-      });
-    } else if (e is Increment) {
-      int precedence = e.isPrefix ? UNARY : POSTFIX_INCREMENT;
-      withPrecedence(precedence, () {
-        if (e.isPrefix) {
-          write(e.operator);
-          writeExp(e.expression, PRIMARY);
-        } else {
-          writeExp(e.expression, PRIMARY, beginStmt: beginStmt);
-          write(e.operator);
-        }
-      });
-    } else if (e is Throw) {
-      withPrecedence(EXPRESSION, () {
-        write('throw ');
-        writeExp(e.expression, EXPRESSION);
-      });
-    } else if (e is This) {
-      write('this');
-    } else {
-      throw "Unexpected expression: $e";
-    }
-  }
-
-  void writeParameters(Parameters params) {
-    write('(');
-    bool first = true;
-    writeEach(',', params.requiredParameters, (Parameter p) {
-      if (p.type != null) {
-        writeType(p.type);
-        write(' ');
-      }
-      write(p.name);
-      if (p.parameters != null) {
-        writeParameters(p.parameters);
-      }
-    });
-    if (params.hasOptionalParameters) {
-      if (params.requiredParameters.length > 0) {
-        write(',');
-      }
-      write(params.hasNamedParameters ? '{' : '[');
-      writeEach(',', params.optionalParameters, (Parameter p) {
-        if (p.type != null) {
-          writeType(p.type);
-          write(' ');
-        }
-        write(p.name);
-        if (p.parameters != null) {
-          writeParameters(p.parameters);
-        }
-        if (p.defaultValue != null) {
-          write(params.hasNamedParameters ? ':' : '=');
-          writeExp(p.defaultValue, EXPRESSION);
-        }
-      });
-      write(params.hasNamedParameters ? '}' : ']');
-    }
-    write(')');
-  }
-
-  void writeStatement(Statement stmt, {bool shortIf: true}) {
-    stmt = unfoldBlocks(stmt);
-    if (stmt is Block) {
-      write('{');
-      stmt.statements.forEach(writeBlockMember);
-      write('}');
-    } else if (stmt is Break) {
-      write('break');
-      if (stmt.label != null) {
-        write(' ');
-        write(stmt.label);
-      }
-      write(';');
-    } else if (stmt is Continue) {
-      write('continue');
-      if (stmt.label != null) {
-        write(' ');
-        write(stmt.label);
-      }
-      write(';');
-    } else if (stmt is EmptyStatement) {
-      write(';');
-    } else if (stmt is ExpressionStatement) {
-      writeExp(stmt.expression, EXPRESSION, beginStmt:true);
-      write(';');
-    } else if (stmt is For) {
-      write('for(');
-      Node init = stmt.initializer;
-      if (init is Expression) {
-        writeExp(init, EXPRESSION);
-      } else if (init is VariableDeclarations) {
-        writeVariableDefinitions(init);
-      }
-      write(';');
-      if (stmt.condition != null) {
-        writeExp(stmt.condition, EXPRESSION);
-      }
-      write(';');
-      writeEach(',', stmt.updates, writeExpression);
-      write(')');
-      writeStatement(stmt.body, shortIf: shortIf);
-    } else if (stmt is ForIn) {
-      write('for(');
-      Node lhv = stmt.leftHandValue;
-      if (lhv is Identifier) {
-        write(lhv.name);
-      } else {
-        writeVariableDefinitions(lhv as VariableDeclarations);
-      }
-      write(' in ');
-      writeExp(stmt.expression, EXPRESSION);
-      write(')');
-      writeStatement(stmt.body, shortIf: shortIf);
-    } else if (stmt is While) {
-      write('while(');
-      writeExp(stmt.condition, EXPRESSION);
-      write(')');
-      writeStatement(stmt.body, shortIf: shortIf);
-    } else if (stmt is DoWhile) {
-      write('do ');
-      writeStatement(stmt.body);
-      write('while(');
-      writeExp(stmt.condition, EXPRESSION);
-      write(');');
-    } else if (stmt is If) {
-      // if (E) S else ; ==> if (E) S
-      Statement elsePart = unfoldBlocks(stmt.elseStatement);
-      if (elsePart is EmptyStatement) {
-        elsePart = null;
-      }
-      if (!shortIf && elsePart == null) {
-        write('{');
-      }
-      write('if(');
-      writeExp(stmt.condition, EXPRESSION);
-      write(')');
-      writeStatement(stmt.thenStatement, shortIf: elsePart == null);
-      if (elsePart != null) {
-        write('else ');
-        writeStatement(elsePart, shortIf: shortIf);
-      }
-      if (!shortIf && elsePart == null) {
-        write('}');
-      }
-    } else if (stmt is LabeledStatement) {
-      write(stmt.label);
-      write(':');
-      writeStatement(stmt.statement, shortIf: shortIf);
-    } else if (stmt is Rethrow) {
-      write('rethrow;');
-    } else if (stmt is Return) {
-      write('return');
-      if (stmt.expression != null) {
-        write(' ');
-        writeExp(stmt.expression, EXPRESSION);
-      }
-      write(';');
-    } else if (stmt is Switch) {
-      write('switch(');
-      writeExp(stmt.expression, EXPRESSION);
-      write('){');
-      for (SwitchCase caze in stmt.cases) {
-        if (caze.isDefaultCase) {
-          write('default:');
-        } else {
-          for (Expression exp in caze.expressions) {
-            write('case ');
-            writeExp(exp, EXPRESSION);
-            write(':');
-          }
-        }
-        if (caze.statements.isEmpty) {
-          write(';'); // Prevent fall-through.
-        } else {
-          caze.statements.forEach(writeBlockMember);
-        }
-      }
-      write('}');
-    } else if (stmt is Try) {
-      write('try');
-      writeBlock(stmt.tryBlock);
-      for (CatchBlock block in stmt.catchBlocks) {
-        if (block.onType != null) {
-          write('on ');
-          writeType(block.onType);
-        }
-        if (block.exceptionVar != null) {
-          write('catch(');
-          write(block.exceptionVar);
-          if (block.stackVar != null) {
-            write(',');
-            write(block.stackVar);
-          }
-          write(')');
-        }
-        writeBlock(block.body);
-      }
-      if (stmt.finallyBlock != null) {
-        write('finally');
-        writeBlock(stmt.finallyBlock);
-      }
-    } else if (stmt is VariableDeclarations) {
-      writeVariableDefinitions(stmt);
-      write(';');
-    } else if (stmt is FunctionDeclaration) {
-      assert(!stmt.function.isGetter && !stmt.function.isSetter);
-      if (stmt.returnType != null) {
-        writeType(stmt.returnType);
-        write(' ');
-      }
-      write(stmt.name);
-      writeParameters(stmt.parameters);
-      Statement body = unfoldBlocks(stmt.body);
-      if (body is Return) {
-        write('=> ');
-        writeExp(body.expression, EXPRESSION);
-        write(';');
-      } else {
-        writeBlock(body);
-      }
-    } else {
-      throw "Unexpected statement: $stmt";
-    }
-  }
-
-  /// Writes a variable definition statement without the trailing semicolon
-  void writeVariableDefinitions(VariableDeclarations vds) {
-    if (vds.isConst)
-      write('const ');
-    else if (vds.isFinal)
-      write('final ');
-    if (vds.type != null) {
-      writeType(vds.type);
-      write(' ');
-    }
-    if (!vds.isConst && !vds.isFinal && vds.type == null) {
-      write('var ');
-    }
-    writeEach(',', vds.declarations, (VariableDeclaration vd) {
-      write(vd.name);
-      if (vd.initializer != null) {
-        write('=');
-        writeExp(vd.initializer, EXPRESSION);
-      }
-    });
-  }
-
-  /// True of statements that introduce variables in the scope of their
-  /// surrounding block. Blocks containing such statements cannot be unfolded.
-  static bool definesVariable(Statement s) {
-    return s is VariableDeclarations || s is FunctionDeclaration;
-  }
-
-  /// Writes the given statement in a context where only blocks are allowed.
-  void writeBlock(Statement stmt) {
-    if (stmt is Block) {
-      writeStatement(stmt);
-    } else {
-      write('{');
-      writeBlockMember(stmt);
-      write('}');
-    }
-  }
-
-  /// Outputs a statement that is a member of a block statement (or a similar
-  /// sequence of statements, such as in switch statement).
-  /// This will flatten blocks and skip empty statement.
-  void writeBlockMember(Statement stmt) {
-    if (stmt is Block && !stmt.statements.any(definesVariable)) {
-      stmt.statements.forEach(writeBlockMember);
-    } else if (stmt is EmptyStatement) {
-      // do nothing
-    } else {
-      writeStatement(stmt);
-    }
-  }
-
-  void writeType(TypeAnnotation type) {
-    write(type.name);
-    if (type.typeArguments != null && type.typeArguments.length > 0) {
-      write('<');
-      writeEach(',', type.typeArguments, writeType);
-      write('>');
-    }
-  }
-
-  /// A list of string quotings that the printer may use to quote strings.
-  // Ignore multiline quotings for now. Would need to make sure that no
-  // newline (potentially prefixed by whitespace) follows the quoting.
-  // TODO(sigurdm,kmillikin): Include multiline quotation schemes.
-  static const _QUOTINGS = const <tree.StringQuoting>[
-      const tree.StringQuoting(characters.$DQ, raw: false, leftQuoteLength: 1),
-      const tree.StringQuoting(characters.$DQ, raw: true, leftQuoteLength: 1),
-      const tree.StringQuoting(characters.$SQ, raw: false, leftQuoteLength: 1),
-      const tree.StringQuoting(characters.$SQ, raw: true, leftQuoteLength: 1),
-  ];
-
-  static StringLiteralOutput analyzeStringLiteral(Expression node) {
-    // TODO(sigurdm,kmillikin): This might be a bit too expensive. Benchmark.
-    // Flatten the StringConcat tree.
-    List parts = []; // Expression or int (char node)
-    void collectParts(Expression e) {
-      if (e is StringConcat) {
-        e.expressions.forEach(collectParts);
-      } else if (e is Literal && e.value.isString) {
-        for (int char in e.value.primitiveValue) {
-          parts.add(char);
-        }
-      } else {
-        parts.add(e);
-      }
-    }
-    collectParts(node);
-
-    // We use a dynamic algorithm to compute the optimal way of printing
-    // the string literal.
-    //
-    // Using string juxtapositions, it is possible to switch from one quoting
-    // to another, e.g. the constant "''''" '""""' uses this trick.
-    //
-    // As we move through the string from left to right, we maintain a strategy
-    // for each StringQuoting Q, denoting the best way to print the current
-    // prefix so that we end with a string literal quoted with Q.
-    // At every step, each strategy is either:
-    //  1) Updated to include the cost of printing the next character.
-    //  2) Abandoned because it is cheaper to use another strategy as prefix,
-    //     and then switching quotation using a juxtaposition.
-
-    int getQuoteCost(tree.StringQuoting quot) {
-      return quot.leftQuoteLength + quot.rightQuoteLength;
-    }
-
-    // Create initial scores for each StringQuoting and index them
-    // into raw/non-raw and single-quote/double-quote.
-    List<OpenStringChunk> best = <OpenStringChunk>[];
-    List<int> raws = <int>[];
-    List<int> nonRaws = <int>[];
-    List<int> sqs = <int>[];
-    List<int> dqs = <int>[];
-    for (tree.StringQuoting q in _QUOTINGS) {
-      OpenStringChunk chunk = new OpenStringChunk(null, q, getQuoteCost(q));
-      int index = best.length;
-      best.add(chunk);
-
-      if (q.raw) {
-        raws.add(index);
-      } else {
-        nonRaws.add(index);
-      }
-      if (q.quote == characters.$SQ) {
-        sqs.add(index);
-      } else {
-        dqs.add(index);
-      }
-    }
-
-
-    /// Applies additional cost to each track in [penalized], and considers
-    /// switching from each [penalized] to a [nonPenalized] track.
-    void penalize(List<int> penalized,
-                  List<int> nonPenalized,
-                  int endIndex,
-                  num cost(tree.StringQuoting q)) {
-      for (int j in penalized) {
-        // Check if another track can benefit from switching from this track.
-        for (int k in nonPenalized) {
-          num newCost = best[j].cost
-                      + 1             // Whitespace in string juxtaposition
-                      + getQuoteCost(best[k].quoting);
-          if (newCost < best[k].cost) {
-            best[k] = new OpenStringChunk(
-                best[j].end(endIndex),
-                best[k].quoting,
-                newCost);
-          }
-        }
-        best[j].cost += cost(best[j].quoting);
-      }
-    }
-
-    // Iterate through the string and update the score for each StringQuoting.
-    for (int i = 0; i < parts.length; i++) {
-      var part = parts[i];
-      if (part is int) {
-        int char = part;
-        switch (char) {
-          case characters.$$:
-          case characters.$BACKSLASH:
-            penalize(nonRaws, raws, i, (q) => 1);
-            break;
-          case characters.$DQ:
-            penalize(dqs, sqs, i, (q) => q.raw ? double.INFINITY : 1);
-            break;
-          case characters.$SQ:
-            penalize(sqs, dqs, i, (q) => q.raw ? double.INFINITY : 1);
-            break;
-          case characters.$LF:
-          case characters.$CR:
-          case characters.$FF:
-          case characters.$BS:
-          case characters.$VTAB:
-          case characters.$TAB:
-          case characters.$EOF:
-            penalize(raws, nonRaws, i, (q) => double.INFINITY);
-            break;
-        }
-      } else {
-        // Penalize raw literals for string interpolation.
-        penalize(raws, nonRaws, i, (q) => double.INFINITY);
-
-        // Splitting a string can sometimes allow us to use a shorthand
-        // string interpolation that would otherwise be illegal.
-        // E.g. "...${foo}x..." -> "...$foo" 'x...'
-        // If are other factors that make splitting advantageous,
-        // we can gain even more by doing the split here.
-        if (part is Identifier &&
-            !part.name.contains(r'$') &&
-            i + 1 < parts.length &&
-            isIdentifierPartNoDollar(parts[i+1])) {
-          for (int j in nonRaws) {
-            for (int k = 0; k < best.length; k++) {
-              num newCost = best[j].cost
-                          + 1             // Whitespace in string juxtaposition
-                          - 2             // Save two curly braces
-                          + getQuoteCost(best[k].quoting);
-              if (newCost < best[k].cost) {
-                best[k] = new OpenStringChunk(
-                    best[j].end(i+1),
-                    best[k].quoting,
-                    newCost);
-              }
-            }
-          }
-        }
-      }
-    }
-
-    // Select the cheapest strategy
-    OpenStringChunk bestChunk = best[0];
-    for (OpenStringChunk chunk in best) {
-      if (chunk.cost < bestChunk.cost) {
-        bestChunk = chunk;
-      }
-    }
-
-    return new StringLiteralOutput(parts, bestChunk.end(parts.length));
-  }
-
-  void writeStringLiteral(Expression node) {
-    StringLiteralOutput output = analyzeStringLiteral(node);
-    List parts = output.parts;
-    void printChunk(StringChunk chunk) {
-      int startIndex;
-      if (chunk.previous != null) {
-        printChunk(chunk.previous);
-        write(' '); // String juxtaposition requires a space between literals.
-        startIndex = chunk.previous.endIndex;
-      } else {
-        startIndex = 0;
-      }
-      if (chunk.quoting.raw) {
-        write('r');
-      }
-      write(chunk.quoting.quoteChar);
-      bool raw = chunk.quoting.raw;
-      int quoteCode = chunk.quoting.quote;
-      for (int i=startIndex; i<chunk.endIndex; i++) {
-        var part = parts[i];
-        if (part is int) {
-          int char = part;
-          write(getEscapedCharacter(char, quoteCode, raw));
-        } else if (part is Identifier &&
-                   !part.name.contains(r'$') &&
-                   (i == chunk.endIndex - 1 ||
-                    !isIdentifierPartNoDollar(parts[i+1]))) {
-          write(r'$');
-          write(part.name);
-        } else {
-          write(r'${');
-          writeExpression(part);
-          write('}');
-        }
-      }
-      write(chunk.quoting.quoteChar);
-    }
-    printChunk(output.chunk);
-  }
-
-  static String getEscapedCharacter(int char, int quoteCode, bool raw) {
-    switch (char) {
-      case characters.$$:
-        return raw ? r'$' : r'\$';
-      case characters.$BACKSLASH:
-        return raw ? r'\' : r'\\';
-      case characters.$DQ:
-        return quoteCode == char ? r'\"' : r'"';
-      case characters.$SQ:
-        return quoteCode == char ? r"\'" : r"'";
-      case characters.$LF:
-        return r'\n';
-      case characters.$CR:
-        return r'\r';
-      case characters.$FF:
-        return r'\f';
-      case characters.$BS:
-        return r'\b';
-      case characters.$TAB:
-        return r'\t';
-      case characters.$VTAB:
-        return r'\v';
-      case characters.$EOF:
-        return r'\x00';
-      default:
-        return new String.fromCharCode(char);
-    }
-  }
-
-}
-
-/// The contents of a string literal together with a strategy for printing it.
-class StringLiteralOutput {
-  /// Mix of [Expression] and `int`. Each expression is a string interpolation,
-  /// and each `int` is the character code of a character in a string literal.
-  final List parts;
-  final StringChunk chunk;
-
-  StringLiteralOutput(this.parts, this.chunk);
-}
-
-
-/// Strategy for printing a prefix of a string literal.
-/// A chunk represents the substring going from [:previous.endIndex:] to
-/// [endIndex] (or from 0 to [endIndex] if [previous] is null).
-class StringChunk {
-  final StringChunk previous;
-  final tree.StringQuoting quoting;
-  final int endIndex;
-
-  StringChunk(this.previous, this.quoting, this.endIndex);
-}
-
-/// [StringChunk] that has not yet been assigned an [endIndex].
-/// It additionally has a [cost] denoting the number of auxilliary characters
-/// (quotes, spaces, etc) needed to print the literal using this strategy
-class OpenStringChunk {
-  final StringChunk previous;
-  final tree.StringQuoting quoting;
-  num cost;
-
-  OpenStringChunk(this.previous, this.quoting, this.cost);
-
-  StringChunk end(int endIndex) {
-    return new StringChunk(previous, quoting, endIndex);
-  }
-}