feat(Parser): support if statements in actions

fixes #2022

modules/angular2/src/change_detection/parser/ast.ts

@@ -60,6 +60,20 @@ export class Conditional extends AST {
   visit(visitor: AstVisitor) { return visitor.visitConditional(this); }
 }
 
+export class If extends AST {
+  constructor(public condition: AST, public trueExp: AST, public falseExp?: AST) { super(); }
+
+  eval(context, locals) {
+    if (this.condition.eval(context, locals)) {
+      this.trueExp.eval(context, locals);
+    } else if (isPresent(this.falseExp)) {
+      this.falseExp.eval(context, locals);
+    }
+  }
+
+  visit(visitor: AstVisitor) { return visitor.visitIf(this); }
+}
+
 export class AccessMember extends AST {
   constructor(public receiver: AST, public name: string, public getter: Function,
               public setter: Function) {
@@ -321,6 +335,7 @@ export interface AstVisitor {
   visitBinary(ast: Binary): any;
   visitChain(ast: Chain): any;
   visitConditional(ast: Conditional): any;
+  visitIf(ast: If): any;
   visitPipe(ast: Pipe): any;
   visitFunctionCall(ast: FunctionCall): any;
   visitImplicitReceiver(ast: ImplicitReceiver): any;
@@ -398,6 +413,8 @@ export class AstTransformer implements AstVisitor {
   visitChain(ast: Chain) { throw new BaseException('Not implemented'); }
 
   visitAssignment(ast: Assignment) { throw new BaseException('Not implemented'); }
+
+  visitIf(ast: If) { throw new BaseException('Not implemented'); }
 }
 
 var _evalListCache = [

modules/angular2/src/change_detection/parser/lexer.ts

@@ -59,6 +59,10 @@ export class Token {
 
   isKeywordTrue(): boolean { return (this.type == TOKEN_TYPE_KEYWORD && this.strValue == "true"); }
 
+  isKeywordIf(): boolean { return (this.type == TOKEN_TYPE_KEYWORD && this.strValue == "if"); }
+
+  isKeywordElse(): boolean { return (this.type == TOKEN_TYPE_KEYWORD && this.strValue == "else"); }
+
   isKeywordFalse(): boolean {
     return (this.type == TOKEN_TYPE_KEYWORD && this.strValue == "false");
   }
@@ -463,4 +467,5 @@ var OPERATORS = SetWrapper.createFromList([
 ]);
 
 
-var KEYWORDS = SetWrapper.createFromList(['var', 'null', 'undefined', 'true', 'false']);
+var KEYWORDS =
+    SetWrapper.createFromList(['var', 'null', 'undefined', 'true', 'false', 'if', 'else']);

modules/angular2/src/change_detection/parser/parser.ts

@@ -33,6 +33,7 @@ import {
   Binary,
   PrefixNot,
   Conditional,
+  If,
   Pipe,
   Assignment,
   Chain,
@@ -412,6 +413,19 @@ class _ParseAST {
       this.advance();
       return new LiteralPrimitive(false);
 
+    } else if (this.parseAction && this.next.isKeywordIf()) {
+      this.advance();
+      this.expectCharacter($LPAREN);
+      let condition = this.parseExpression();
+      this.expectCharacter($RPAREN);
+      let ifExp = this.parseExpressionOrBlock();
+      let elseExp;
+      if (this.next.isKeywordElse()) {
+        this.advance();
+        elseExp = this.parseExpressionOrBlock();
+      }
+      return new If(condition, ifExp, elseExp)
+
     } else if (this.optionalCharacter($LBRACKET)) {
       var elements = this.parseExpressionList($RBRACKET);
       this.expectCharacter($RBRACKET);
@@ -494,6 +508,37 @@ class _ParseAST {
     return positionals;
   }
 
+  parseExpressionOrBlock(): AST {
+    if (this.optionalCharacter($LBRACE)) {
+      let block = this.parseBlockContent();
+      this.expectCharacter($RBRACE);
+      return block;
+    }
+
+    return this.parseExpression();
+  }
+
+  parseBlockContent(): AST {
+    if (!this.parseAction) {
+      this.error("Binding expression cannot contain chained expression");
+    }
+    var exprs = [];
+    while (this.index < this.tokens.length && !this.next.isCharacter($RBRACE)) {
+      var expr = this.parseExpression();
+      ListWrapper.push(exprs, expr);
+
+      if (this.optionalCharacter($SEMICOLON)) {
+        while (this.optionalCharacter($SEMICOLON)) {
+        }  // read all semicolons
+      }
+    }
+    if (exprs.length == 0) return new EmptyExpr();
+    if (exprs.length == 1) return exprs[0];
+
+    return new Chain(exprs);
+  }
+
+
   /**
    * An identifier, a keyword, a string with an optional `-` inbetween.
    */

modules/angular2/src/change_detection/proto_change_detector.ts

@@ -10,6 +10,7 @@ import {
   Binary,
   Chain,
   Conditional,
+  If,
   Pipe,
   FunctionCall,
   ImplicitReceiver,
@@ -201,6 +202,8 @@ class _ConvertAstIntoProtoRecords implements AstVisitor {
 
   visitChain(ast: Chain) { throw new BaseException('Not supported'); }
 
+  visitIf(ast: If) { throw new BaseException('Not supported'); }
+
   _visitAll(asts: List<any>) {
     var res = ListWrapper.createFixedSize(asts.length);
     for (var i = 0; i < asts.length; ++i) {