Add JavaScript AST.

lib/compiler/implementation/js/nodes.dart

+// Copyright (c) 2012, 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.
+
+interface NodeVisitor<T> {
+  T visitProgram(Program program);
+
+  T visitBlock(Block block);
+  T visitExpressionStatement(ExpressionStatement expressionStatement);
+  T visitNOP(NOP nop);
+  T visitIf(If node);
+  T visitFor(For loop);
+  T visitForIn(ForIn loop);
+  T visitWhile(While loop);
+  T visitDo(Do loop);
+  T visitContinue(Continue cont);
+  T visitBreak(Break node);
+  T visitReturn(Return node);
+  T visitThrow(Throw node);
+  T visitTry(Try node);
+  T visitCatch(Catch node);
+  T visitWith(With node);
+  T visitSwitch(Switch node);
+  T visitCase(Case node);
+  T visitDefault(Default node);
+  T visitFunctionDeclaration(FunctionDeclaration declaration);
+  T visitLabeled(Labeled node);
+  T visitStatementBlob(StatementBlob node);
+
+  T visitExpressionBlob(ExpressionBlob blob);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

LiteralExpression.

[floitsch, 2012/08/09 16:24:07]

Done.

+  T visitVariableDeclarationList(VariableDeclarationList list);
+  T visitSequence(Sequence sequence);
+  T visitVassign(Vassign vassign);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Expand name. What's a "Vassign"?

[floitsch, 2012/08/09 16:24:07]

Simplified.

+  T visitInit(Init init);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Initialize? Initializer? Initialization?

+  T visitAccsign(Accsign accsign);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Wut?

+  T visitVassignOp(VassignOp vassignOp);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

VariableAssignOperation? Operator?

+  T visitAccsignOp(AccsignOp accsignOp);
+  T visitConditional(Conditional cond);
+  T visitNew(New node);
+  T visitCall(Call call);
+  T visitBinary(Binary binary);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Perhaps BinaryOperation? But not necessarily, just "binary" does make sense.

[floitsch, 2012/08/09 16:24:07]

Prefer to call it Binary. Otherwise Prefix and Postfix would need "Operation"
too.

+  T visitUnary(Unary unary);
+  T visitPostfix(Postfix postfix);
+
+  T visitRef(Ref ref);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Wut?

+  T visitThis(This node);
+  T visitDecl(Decl decl);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Declaration.

+  T visitParam(Param param);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Parameter ... you get the idea. Don't abbreviate names.

+  T visitAccess(Access access);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

What is an "Access"? Better name?

+
+  T visitNamedFunction(NamedFunction namedFunction);
+  T visitFun(Fun fun);
+
+  T visitBoolLiteral(BoolLiteral node);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

I prefer "LiteralBool", but that's subjective.

[floitsch, 2012/08/09 16:24:07]

Done.

+  T visitStringLiteral(StringLiteral node);
+  T visitNumberLiteral(NumberLiteral node);
+  T visitNullLiteral(NullLiteral node);
+
+  T visitArrayLiteral(ArrayLiteral node);
+  T visitArrayElement(ArrayElement node);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

What is an ArrayElement?

[floitsch, 2012/08/09 16:24:07]

An element in an ArrayInitializer. Couldn't find a better name.

+  T visitObjectLiteral(ObjectLiteral node);
+  T visitPropertyInit(PropertyInit node);
+  T visitRegExpLiteral(RegExpLiteral node);
+}
+
+class BaseVisitor<T> implements NodeVisitor {
+  T visitNode(Node node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  T visitProgram(Program node) => visitNode(node);
+
+  T visitStatement(Statement node) => visitNode(node);
+  T visitLoop(Loop node) => visitStatement(node);
+  T visitInterruption(Statement node) => visitStatement(node);
+
+  T visitBlock(Block node) => visitStatement(node);
+  T visitExpressionStatement(ExpressionStatement node)
+      => visitStatement(node);
+  T visitNOP(NOP node) => visitStatement(node);
+  T visitIf(If node) => visitStatement(node);
+  T visitFor(For node) => visitLoop(node);
+  T visitForIn(ForIn node) => visitLoop(node);
+  T visitWhile(While node) => visitLoop(node);
+  T visitDo(Do node) => visitLoop(node);
+  T visitContinue(Continue node) => visitInterruption(node);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

I'd prefer visitControlFlow or visitJump. Interrupts are something different.

[floitsch, 2012/08/09 16:24:07]

Done.

+  T visitBreak(Break node) => visitInterruption(node);
+  T visitReturn(Return node) => visitInterruption(node);
+  T visitThrow(Throw node) => visitInterruption(node);
+  T visitTry(Try node) => visitStatement(node);
+  T visitWith(With node) => visitStatement(node);
+  T visitSwitch(Switch node) => visitStatement(node);
+  T visitFunctionDeclaration(FunctionDeclaration node)
+      => visitStatement(node);
+  T visitLabeled(Labeled node) => visitStatement(node);
+  T visitStatementBlob(StatementBlob node) => visitStatement(node);
+
+  T visitCatch(Catch node) => visitNode(node);
+  T visitCase(Case node) => visitNode(node);
+  T visitDefault(Default node) => visitNode(node);
+
+  T visitExpression(Expression node) => visitNode(node);
+  T visitAssign(Assign node) => visitExpression(node);
+
+  T visitExpressionBlob(ExpressionBlob node) => visitExpression(node);
+  T visitVariableDeclarationList(VariableDeclarationList node)
+      => visitExpression(node);
+  T visitSequence(Sequence node) => visitExpression(node);
+  T visitVassign(Vassign node) => visitAssign(node);
+  T visitInit(Init node) {
+    if (node.value != null) {
+      visitAssign(node);
+    } else {
+      visitExpression(node);
+    }
+  }
+  T visitAccsign(Accsign node) => visitAssign(node);
+  T visitVassignOp(VassignOp node) => visitVassign(node);
+  T visitAccsignOp(AccsignOp node) => visitAccsign(node);
+  T visitConditional(Conditional node) => visitExpression(node);
+  T visitNew(New node) => visitExpression(node);
+  T visitCall(Call node) => visitExpression(node);
+  T visitBinary(Binary node) => visitCall(node);
+  T visitUnary(Unary node) => visitCall(node);
+  T visitPostfix(Postfix node) => visitCall(node);
+  T visitAccess(Access node) => visitExpression(node);
+
+  T visitRef(Ref node) => visitExpression(node);
+  T visitDecl(Decl node) => visitRef(node);
+  T visitParam(Param node) => visitDecl(node);
+  T visitThis(This node) => visitParam(node);
+
+  T visitNamedFunction(NamedFunction node) => visitExpression(node);
+  T visitFun(Fun node) => visitExpression(node);
+
+  T visitLiteral(Literal node) => visitExpression(node);
+
+  T visitBoolLiteral(BoolLiteral node) => visitLiteral(node);
+  T visitStringLiteral(StringLiteral node) => visitLiteral(node);
+  T visitNumberLiteral(NumberLiteral node) => visitLiteral(node);
+  T visitNullLiteral(NullLiteral node) => visitLiteral(node);
+
+  T visitArrayLiteral(ArrayLiteral node) => visitExpression(node);
+  T visitArrayElement(ArrayElement node) => visitNode(node);
+  T visitObjectLiteral(ObjectLiteral node) => visitExpression(node);
+  T visitPropertyInit(PropertyInit node) => visitNode(node);
+  T visitRegExpLiteral(RegExpLiteral node) => visitExpression(node);
+}
+
+class Node implements Hashable {
+  // I don't really like static state, but the alternatives seem even more
+  // annoying.
+  static int nodeCounter = 0;
+
+  final int nodeId;
+  Dynamic sourcePosition;

[kasperl, 2012/08/07 07:46:45]

var

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Or something better, if possible.

[floitsch, 2012/08/09 16:24:07]

Done.

[floitsch, 2012/08/09 16:24:07]

Not sure that is easy. I don't think the AST should know how the source-position
is encoded.

+  Dynamic endSourcePosition;
+
+  Node() : nodeId = nodeCounter++ & 0x7FFFFFFF;
+
+  abstract accept(NodeVisitor visitor);
+  abstract void visitChildren(NodeVisitor visitor);
+  int hashCode() => nodeId;
+}
+
+class Program extends Node {
+  List<Statement> body;
+  Program(this.body);
+
+  accept(NodeVisitor visitor) => visitor.visitProgram(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (Statement statement in body) statement.accept(visitor);
+  }
+}
+
+abstract class Statement extends Node {
+}
+
+class Block extends Statement {
+  List<Statement> elements;

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

elements -> statements?

[floitsch, 2012/08/09 16:24:07]

Done.

+  Block(this.elements);
+  Block.empty() : this.elements = <Statement>[];
+
+  accept(NodeVisitor visitor) => visitor.visitBlock(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (Statement statement in elements) statement.accept(visitor);
+  }
+}
+
+class ExpressionStatement extends Statement {
+  Expression expr;

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Don't abbreviate.

[floitsch, 2012/08/09 16:24:07]

Done.

+  ExpressionStatement(this.expr);
+
+  accept(NodeVisitor visitor) => visitor.visitExpressionStatement(this);
+  void visitChildren(NodeVisitor visitor) { expr.accept(visitor); }
+}
+
+class NOP extends Statement {

[kasperl, 2012/08/07 07:46:45]

I would call this EmptyStatement. I don't like the abbreviation.

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

+1

[floitsch, 2012/08/09 16:24:07]

Done.

+  NOP();
+
+  accept(NodeVisitor visitor) => visitor.visitNOP(this);
+  void visitChildren(NodeVisitor visitor) {}
+}
+
+class If extends Statement {
+  Node test;

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

"Expression test;" ?

[floitsch, 2012/08/09 16:24:07]

Done.

+  Node then;
+  Node otherwise;
+  If(this.test, this.then, this.otherwise);
+  If.then(this.test, this.then) : this.otherwise = new NOP();

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Could you reuse an empty statement, or would it be too horrible that they have
the same id?

[floitsch, 2012/08/09 16:24:07]

I think of an AST as a tree, and not as a DAG. We can revisit this decision,
though.

+  bool get hasElse() => otherwise is !NOP;
+
+  accept(NodeVisitor visitor) => visitor.visitIf(this);
+  void visitChildren(NodeVisitor visitor) {
+    test.accept(visitor);
+    then.accept(visitor);
+    otherwise.accept(visitor);
+  }
+}
+
+abstract class Loop extends Statement {
+  Statement body;
+  Loop(this.body);
+}
+
+class For extends Loop {
+  Expression init;
+  Expression test;

[kasperl, 2012/08/07 07:46:45]

test -> condition?

[floitsch, 2012/08/09 16:24:07]

Done.

+  Expression incr;

[kasperl, 2012/08/07 07:46:45]

incr -> update?

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

What Kasper said!

[floitsch, 2012/08/09 16:24:07]

Done.

[floitsch, 2012/08/09 16:24:07]

Done.

+  For(this.init, this.test, this.incr, Statement body) : super(body);
+
+  accept(NodeVisitor visitor) => visitor.visitFor(this);
+  void visitChildren(NodeVisitor visitor) {
+    if (init !== null) init.accept(visitor);
+    if (test !== null) test.accept(visitor);
+    if (incr !== null) incr.accept(visitor);
+    body.accept(visitor);
+  }
+}
+
+class ForIn extends Loop {
+  Expression lhs;

[kasperl, 2012/08/07 07:46:45]

I would try to cut down on the abbreviations (if possible).

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

I'd say cut it all the way down to zero, and it better be possible!

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

The lhs can be a declaration:
 for (var i in beep) ...
so Expression is probably too strict.

[floitsch, 2012/08/09 16:24:07]

trying :)

[floitsch, 2012/08/09 16:24:07]

var x is a an expression in this AST.

[floitsch, 2012/08/09 16:24:07]

Done.

+  Expression obj;
+  ForIn(this.lhs, this.obj, Statement body) : super(body);
+
+  accept(NodeVisitor visitor) => visitor.visitForIn(this);
+  void visitChildren(NodeVisitor visitor) {
+    lhs.accept(visitor);
+    obj.accept(visitor);
+    body.accept(visitor);
+  }
+}
+
+class While extends Loop {
+  Node test;
+  While(this.test, Statement body) : super(body);
+
+  accept(NodeVisitor visitor) => visitor.visitWhile(this);
+  void visitChildren(NodeVisitor visitor) {
+    test.accept(visitor);
+    body.accept(visitor);
+  }
+}
+
+class Do extends Loop {
+  Node test;
+  Do(Statement body, this.test) : super(body);
+
+  accept(NodeVisitor visitor) => visitor.visitDo(this);
+  void visitChildren(NodeVisitor visitor) {
+    body.accept(visitor);
+    test.accept(visitor);
+  }
+}
+
+class Continue extends Statement {
+  String id;  // Can be null.

[kasperl, 2012/08/07 07:46:45]

Can more of these fields be final? Seems like that should work just fine in
almost all cases.

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

id -> targetLabel.
Ditto for break.

[floitsch, 2012/08/09 16:24:07]

Done.

+  Continue(this.id);
+
+  accept(NodeVisitor visitor) => visitor.visitContinue(this);
+  void visitChildren(NodeVisitor visitor) {}
+}
+
+class Break extends Statement {
+  String id;  // Can be null.
+  Break(this.id);
+
+  accept(NodeVisitor visitor) => visitor.visitBreak(this);
+  void visitChildren(NodeVisitor visitor) {}
+}
+
+class Return extends Statement {
+  Expression expr;  // Can be null.
+  Return(this.expr);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

make this.expr optional.

[floitsch, 2012/08/09 16:24:07]

Done.

+
+  accept(NodeVisitor visitor) => visitor.visitReturn(this);
+  void visitChildren(NodeVisitor visitor) {
+    expr.accept(visitor);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

if (expr !== null) expr.accept(visitor);

[floitsch, 2012/08/09 16:24:07]

Done.

+  }
+}
+
+class Throw extends Statement {
+  Expression expr;
+  Throw(this.expr);
+
+  accept(NodeVisitor visitor) => visitor.visitThrow(this);
+  void visitChildren(NodeVisitor visitor) {
+    expr.accept(visitor);
+  }
+}
+
+class Try extends Statement {
+  Block body;
+  Catch catchPart;
+  Block finallyPart;

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Add comment saying that either, but not both, of catchPart and finallyPart can
be null.
Perhaps make a check for it in the constructor.

[floitsch, 2012/08/09 16:24:07]

Done.

+  Try(this.body, this.catchPart, this.finallyPart);
+
+  accept(NodeVisitor visitor) => visitor.visitTry(this);
+  void visitChildren(NodeVisitor visitor) {
+    body.accept(visitor);
+    if (catchPart !== null) catchPart.accept(visitor);
+    if (finallyPart !== null) finallyPart.accept(visitor);
+  }
+}
+
+class Catch extends Node {
+  Decl decl;
+  Block body;
+  Catch(this.decl, this.body);
+
+  accept(NodeVisitor visitor) => visitor.visitCatch(this);
+  void visitChildren(NodeVisitor visitor) {
+    decl.accept(visitor);
+    body.accept(visitor);
+  }
+}
+
+class With extends Statement {

[kasperl, 2012/08/07 07:46:45]

Do we need this?

[floitsch, 2012/08/09 16:24:07]

Done.

+  Expression object;
+  Statement body;
+  With(this.object, this.body);
+
+  accept(NodeVisitor visitor) => visitor.visitWith(this);
+  void visitChildren(NodeVisitor visitor) {
+    object.accept(visitor);
+    body.accept(visitor);
+  }
+}
+
+class Switch extends Statement {
+  Expression key;
+  List<SwitchClause> cases;
+  Switch(this.key, this.cases);
+
+  accept(NodeVisitor visitor) => visitor.visitSwitch(this);
+  void visitChildren(NodeVisitor visitor) {
+    key.accept(visitor);
+    for (SwitchClause clause in cases) clause.accept(visitor);
+  }
+}
+
+abstract class SwitchClause extends Node {
+  Block body;
+  SwitchClause(this.body);
+}
+
+class Case extends SwitchClause {
+  Expression expr;
+  Case(this.expr, Block body) : super(body);
+
+  accept(NodeVisitor visitor) => visitor.visitCase(this);
+  void visitChildren(NodeVisitor visitor) {
+    expr.accept(visitor);
+    body.accept(visitor);
+  }
+}
+
+class Default extends SwitchClause {
+  Default(Block body) : super(body);
+
+  accept(NodeVisitor visitor) => visitor.visitDefault(this);
+  void visitChildren(NodeVisitor visitor) {
+    body.accept(visitor);
+  }
+}
+
+class FunctionDeclaration extends Statement {
+  Decl id;
+  Fun fun;
+  FunctionDeclaration(this.id, this.fun);
+
+  accept(NodeVisitor visitor) => visitor.visitFunctionDeclaration(this);
+  void visitChildren(NodeVisitor visitor) {
+    id.accept(visitor);
+    fun.accept(visitor);
+  }
+}
+
+class Labeled extends Statement {

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

LabeledStatement (Labeled isn't a noun phrase).

[floitsch, 2012/08/09 16:24:07]

Done.

+  String id;

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

id -> label.

[floitsch, 2012/08/09 16:24:07]

Done.

+  Statement body;
+  Labeled(this.id, this.body);
+
+  accept(NodeVisitor visitor) => visitor.visitLabeled(this);
+  void visitChildren(NodeVisitor visitor) {
+    body.accept(visitor);
+  }
+}
+
+class StatementBlob extends Statement {
+  String blob;
+  StatementBlob(this.blob);
+
+  accept(NodeVisitor visitor) => visitor.visitStatementBlob(this);
+  void visitChildren(NodeVisitor visitor) { }
+}
+
+abstract class Expression extends Node {
+  abstract int get precedenceLevel();
+}
+
+class ExpressionBlob extends Expression {

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

ExpressionBlob -> LiteralExpression.
blob -> source.
What is "data"? Needs explanation.

[floitsch, 2012/08/09 16:24:07]

blob -> template.
data -> inputs.
done.

+  String blob;
+  List<Expression> data;
+  ExpressionBlob(this.blob);
+  ExpressionBlob.withData(this.blob, this.data);
+
+  accept(NodeVisitor visitor) => visitor.visitExpressionBlob(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (Expression expr in data) expr.accept(visitor);
+  }
+
+  int get precedenceLevel() => EXPRESSION;

[kasperl, 2012/08/07 07:46:45]

Put this in Expression?

[floitsch, 2012/08/09 16:24:07]

It's not duplicated that often, and I prefer to be forced to think about it at
every Expression.

+}
+
+class VariableDeclarationList extends Expression {
+  List<Init> declarations;
+  VariableDeclarationList(this.declarations);
+
+  accept(NodeVisitor visitor) => visitor.visitVariableDeclarationList(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (Init init in declarations) init.accept(visitor);
+  }
+
+  int get precedenceLevel() => EXPRESSION;
+}
+
+class Sequence extends Expression {
+  List<Expression> expressions;
+  Sequence(this.expressions);
+
+  accept(NodeVisitor visitor) => visitor.visitSequence(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (Expression expr in expressions) expr.accept(visitor);
+  }
+
+  int get precedenceLevel() => EXPRESSION;
+}
+
+class Assign extends Expression {
+  abstract Expression get lhs();

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Getters below constructors. Only fields above.

[floitsch, 2012/08/09 16:24:07]

Done.

+  Expression value;  // May be null, for [Init]s.
+  Assign(this.value);
+
+  int get precedenceLevel() => ASSIGNMENT;
+}
+
+class Vassign extends Assign {

[kasperl, 2012/08/07 07:46:45]

Vassign? Maybe think of a better name.

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

No "maybe". Do! I'm guessing "VariableAssignment"

[floitsch, 2012/08/09 16:24:07]

Removed.

+  Ref lhs;
+  Vassign(this.lhs, Expression value): super(value);
+
+  accept(NodeVisitor visitor) => visitor.visitVassign(this);
+  void visitChildren(NodeVisitor visitor) {
+    lhs.accept(visitor);
+    value.accept(visitor);
+  }
+}
+
+class Init extends Vassign {
+  /** [value] may be null. */
+  Init(Decl decl, Expression value) : super(decl, value);
+
+  Ref get decl() => lhs;
+
+  accept(NodeVisitor visitor) => visitor.visitInit(this);
+  void visitChildren(NodeVisitor visitor) {
+    decl.accept(visitor);
+    if (value !== null) value.accept(visitor);
+  }
+}
+
+class VassignOp extends Vassign {

[kasperl, 2012/08/07 07:46:45]

Vassign.

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Is this, e.g.,
 v += 42;
?
Is it necessary to have it separate from Vassign?

+  Ref target;
+  VassignOp(Ref lhs, String op, Expression value)
+      : target = new Ref(op), super(lhs, value);
+
+  String get op() => target.id;
+
+  accept(NodeVisitor visitor) => visitor.visitVassignOp(this);
+  void visitChildren(NodeVisitor visitor) {
+    lhs.accept(visitor);
+    target.accept(visitor);
+    value.accept(visitor);
+  }
+}
+
+class Accsign extends Assign {

[kasperl, 2012/08/07 07:46:45]

Accsign?

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

What is an Access? I'm *guessing* it's, e.g., x.y. Is it also x['z']?

Why have different Vassign and Accsign classes, and not just one Assign that has
an expression as LHS?

+  Access lhs;
+  Accsign(this.lhs, Expression value): super(value);
+
+  accept(NodeVisitor visitor) => visitor.visitAccsign(this);
+  void visitChildren(NodeVisitor visitor) {
+    lhs.accept(visitor);
+    value.accept(visitor);
+  }
+}
+
+class AccsignOp extends Accsign {
+  Ref target;
+  AccsignOp(Access lhs, String op, Expression value)
+      : target = new Ref(op), super(lhs, value);
+
+  String get op() => target.id;
+
+  accept(NodeVisitor visitor) => visitor.visitAccsignOp(this);
+  void visitChildren(NodeVisitor visitor) {
+    lhs.accept(visitor);
+    target.accept(visitor);
+    value.accept(visitor);
+  }
+}
+
+class Conditional extends Expression {
+  Expression test;
+  Expression then;
+  Expression otherwise;
+  Conditional(this.test, this.then, this.otherwise);
+
+  accept(NodeVisitor visitor) => visitor.visitConditional(this);
+  void visitChildren(NodeVisitor visitor) {
+    test.accept(visitor);
+    then.accept(visitor);
+    otherwise.accept(visitor);
+  }
+
+  int get precedenceLevel() => ASSIGNMENT;
+}
+
+class New extends Expression {

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Could "New" extend "Call"? They have the same fields and precedence, it's just a
"special kind of call"?

[floitsch, 2012/08/09 16:24:07]

Nice suggestion. done.

+  Expression cls;
+  List<Expression> arguments;
+  New(this.cls, this.arguments);
+
+  accept(NodeVisitor visitor) => visitor.visitNew(this);
+  void visitChildren(NodeVisitor visitor) {
+    cls.accept(visitor);
+    for (Expression arg in arguments) arg.accept(visitor);
+  }
+
+  int get precedenceLevel() => CALL;
+}
+
+class Call extends Expression {
+  Expression target;
+  List<Expression> arguments;
+  Call(this.target, this.arguments);
+
+  accept(NodeVisitor visitor) => visitor.visitCall(this);
+  void visitChildren(NodeVisitor visitor) {
+    target.accept(visitor);
+    for (Expression arg in arguments) arg.accept(visitor);
+  }
+
+  int get precedenceLevel() => CALL;
+}
+
+class Binary extends Call {
+  Binary(String op, Expression left, Expression right)
+      : super(new Ref(op), <Expression>[left, right]);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

That seems wrong. The "op" is not referencing a variable.

Also: new Ref.operator(op)

[floitsch, 2012/08/09 16:24:07]

Depends on how you look at operators. For Schemers and MLers its natural to see
the '+' operator as a reference to the plus-function.
Keeping it to simplify the AST.
done.

+
+  String get op() {
+    return (target as Ref).id;
+  }
+  Expression get left() => arguments[0];
+  Expression get right() => arguments[1];
+
+  accept(NodeVisitor visitor) => visitor.visitBinary(this);
+  // Inherit visitChildren from [Call].
+
+  int get precedenceLevel() {
+    switch (op) {
+      case "*":
+      case "/":
+      case "%":
+        return MULTIPLICATIVE;
+      case "+":
+      case "-":
+        return ADDITIVE;
+      case "<<":
+      case ">>":
+      case ">>>":
+        return SHIFT;
+      case "<":
+      case ">":
+      case "<=":
+      case ">=":
+      case "instanceof":
+      case "in":
+        return RELATIONAL;
+      case "==":
+      case "===":
+      case "!=":
+      case "!==":
+        return EQUALITY;
+      case "&":
+        return BIT_AND;
+      case "^":
+        return BIT_XOR;
+      case "|":
+        return BIT_OR;
+      case "&&":
+        return LOGICAL_AND;
+      case "||":
+        return LOGICAL_OR;
+      default:
+        throw new CompilerCancelledException(
+            "Internal Error: Unhandled binary operator: $op");
+    }
+  }
+}
+
+class Unary extends Call {
+  Unary(String op, Expression arg) : super(new Ref(op), <Expression>[arg]);

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

new Ref.unaryOperator(op) ?

[floitsch, 2012/08/09 16:24:07]

Done.

+
+  String get op() {
+    return (target as Ref).id;
+  }
+  Expression get arg() => arguments[0];
+
+  accept(NodeVisitor visitor) => visitor.visitUnary(this);
+  // Inherit visitChildren from [Call].
+
+  int get precedenceLevel() => UNARY;
+}
+
+class Postfix extends Call {
+  Postfix(String op, Expression arg) : super(new Ref(op), <Expression>[arg]);
+
+  String get op() {
+    return (target as Ref).id;
+  }
+  Expression get arg() => arguments[0];
+
+  accept(NodeVisitor visitor) => visitor.visitPostfix(this);
+  // Inherit visitChildren from [Call].
+
+  int get precedenceLevel() => UNARY;
+}
+
+class Ref extends Expression {
+  final String id;
+  final bool isOperator = false;
+  final bool isUnaryOperator = false;
+
+  Ref(this.id);
+  Ref.operator(this.id) : isOperator = true;
+  Ref.unaryOperator(this.id) : isOperator = true, isUnaryOperator = true;
+
+  accept(NodeVisitor visitor) => visitor.visitRef(this);
+  void visitChildren(NodeVisitor visitor) {}
+
+  int get precedenceLevel() => PRIMARY;
+}
+
+class Decl extends Ref {

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Extends Ref? I thought both referred to a variable, but this way, a Ref seems
just to *be* the variable.

[floitsch, 2012/08/09 16:24:07]

As discussed.
Added VariableReference super class.
Ref then became VariableUse and Decl became VariableDeclaration (both inheriting
from VariableReference).

+  Decl(String id) : super(id);
+
+  accept(NodeVisitor visitor) => visitor.visitDecl(this);
+  // Inherit visitChildren from [Ref].
+}
+
+class Param extends Decl {
+  Param(String id) : super(id);
+
+  accept(NodeVisitor visitor) => visitor.visitParam(this);
+  // Inherit visitChildren from [Ref].
+}
+
+class This extends Param {
+  This() : super("this");

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Clever.

+
+  accept(NodeVisitor visitor) => visitor.visitThis(this);
+  // Inherit visitChildren from [Ref].
+}
+
+class NamedFunction extends Expression {
+  Decl id;
+  Fun fun;
+  NamedFunction(this.id, this.fun);
+
+  accept(NodeVisitor visitor) => visitor.visitNamedFunction(this);
+  void visitChildren(NodeVisitor visitor) {
+    id.accept(visitor);
+    fun.accept(visitor);
+  }
+
+  int get precedenceLevel() => CALL;
+}
+
+class Fun extends Expression {

[kasperl, 2012/08/07 07:46:45]

Function?

[floitsch, 2012/08/09 16:24:07]

This would shadow the global Function type.

+  List<Param> params;
+  Block body;
+  Fun(this.params, this.body);
+
+  accept(NodeVisitor visitor) => visitor.visitFun(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (Param param in params) param.accept(visitor);
+    body.accept(visitor);
+  }
+
+  int get precedenceLevel() => CALL;
+}
+
+class Access extends Expression {
+  Expression receiver;
+  Expression selector;
+  Access(this.receiver, this.selector);
+  Access.field(this.receiver, String fieldName)
+      : selector = new StringLiteral("'$fieldName'");
+
+  accept(NodeVisitor visitor) => visitor.visitAccess(this);
+  void visitChildren(NodeVisitor visitor) {
+    receiver.accept(visitor);
+    selector.accept(visitor);
+  }
+
+  int get precedenceLevel() => CALL;
+}
+
+abstract class Literal extends Expression {
+  void visitChildren(NodeVisitor visitor) {}
+
+  int get precedenceLevel() => PRIMARY;
+}
+
+class BoolLiteral extends Literal {
+  final bool value;
+  BoolLiteral(this.value);
+
+  accept(NodeVisitor visitor) => visitor.visitBoolLiteral(this);
+  // [visitChildren] inherited from [Literal].
+}
+
+class NullLiteral extends Literal {
+  NullLiteral();
+
+  accept(NodeVisitor visitor) => visitor.visitNullLiteral(this);
+  // [visitChildren] inherited from [Literal].
+}
+
+class StringLiteral extends Literal {
+  final String value;
+  StringLiteral(this.value);
+
+  accept(NodeVisitor visitor) => visitor.visitStringLiteral(this);
+  // [visitChildren] inherited from [Literal].
+}
+
+class NumberLiteral extends Literal {
+  final String value;
+  NumberLiteral(this.value);
+
+  accept(NodeVisitor visitor) => visitor.visitNumberLiteral(this);
+  // [visitChildren] inherited from [Literal].
+}
+
+// Despite being called "Literal" the [ArrayLiteral] does not inherit from
+// [Literal].

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Why not?

[floitsch, 2012/08/09 16:24:07]

Changed name to ArrayInitialization.

+class ArrayLiteral extends Expression {
+  int length;
+  List<ArrayElement> elements;
+  ArrayLiteral(this.length, this.elements);
+
+  accept(NodeVisitor visitor) => visitor.visitArrayLiteral(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (ArrayElement element in elements) element.accept(visitor);
+  }
+
+  int get precedenceLevel() => PRIMARY;
+}
+
+class ArrayElement extends Node {
+  int index;

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

When is that useful?

[floitsch, 2012/08/09 16:24:07]

added comment. An ArrayInitialization has a sparse list of its elements.

+  Expression value;
+  ArrayElement(this.index, this.value);
+
+  accept(NodeVisitor visitor) => visitor.visitArrayElement(this);
+  void visitChildren(NodeVisitor visitor) {
+    value.accept(visitor);
+  }
+}
+
+// Despite being called "Literal" the [ObjectLiteral] does not inherit from
+// [Literal].
+class ObjectLiteral extends Expression {
+  List<PropertyInit> properties;

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Just "Property". The "Init" makes no sense.

[floitsch, 2012/08/09 16:24:07]

Done.

+  ObjectLiteral(this.properties);
+
+  accept(NodeVisitor visitor) => visitor.visitObjectLiteral(this);
+  void visitChildren(NodeVisitor visitor) {
+    for (PropertyInit init in properties) init.accept(visitor);
+  }
+
+  int get precedenceLevel() => PRIMARY;
+}
+
+class PropertyInit extends Node {
+  Literal name;
+  Expression value;
+  PropertyInit(this.name, this.value);
+
+  accept(NodeVisitor visitor) => visitor.visitPropertyInit(this);
+  void visitChildren(NodeVisitor visitor) {
+    name.accept(visitor);
+    value.accept(visitor);
+  }
+}
+
+// Despite being called "Literal" the [RegExpLiteral] does not inherit from
+// [Literal].

[Lasse Reichstein Nielsen, 2012/08/08 11:16:38]

Why not, it doesn't even need to extend visitChildren?

[floitsch, 2012/08/09 16:24:07]

As discussed. It is evaluated and thus has a side-effect.

+class RegExpLiteral extends Expression {
+  /** Contains the pattern and the flags.*/
+  String pattern;
+  RegExpLiteral(this.pattern);
+
+  accept(NodeVisitor visitor) => visitor.visitRegExpLiteral(this);
+  void visitChildren(NodeVisitor visitor) {}
+
+  int get precedenceLevel() => PRIMARY;
+}