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) {

modules/angular2/test/change_detection/parser/parser_spec.ts

@@ -43,10 +43,14 @@ export function main() {
 
   function emptyLocals() { return new Locals(null, MapWrapper.create()); }
 
-  function expectEval(text, passedInContext = null, passedInLocals = null) {
+  function evalAction(text, passedInContext = null, passedInLocals = null) {
     var c = isBlank(passedInContext) ? td() : passedInContext;
     var l = isBlank(passedInLocals) ? emptyLocals() : passedInLocals;
-    return expect(parseAction(text).eval(c, l));
+    return parseAction(text).eval(c, l);
+  }
+
+  function expectEval(text, passedInContext = null, passedInLocals = null) {
+    return expect(evalAction(text, passedInContext, passedInLocals));
   }
 
   function expectEvalError(text, passedInContext = null, passedInLocals = null) {
@@ -280,6 +284,28 @@ export function main() {
         });
       });
 
+      describe("if", () => {
+        it('should parse if statements', () => {
+
+          var fixtures = [
+            ['if (true) a = 0', 0, null],
+            ['if (false) a = 0', null, null],
+            ['if (a == null) b = 0', null, 0],
+            ['if (true) { a = 0; b = 0 }', 0, 0],
+            ['if (true) { a = 0; b = 0 } else { a = 1; b = 1; }', 0, 0],
+            ['if (false) { a = 0; b = 0 } else { a = 1; b = 1; }', 1, 1],
+            ['if (false) { } else { a = 1; b = 1; }', 1, 1],
+          ];
+
+          fixtures.forEach(fix => {
+            var testData = td(null, null);
+            evalAction(fix[0], testData);
+            expect(testData.a).toEqual(fix[1]);
+            expect(testData.b).toEqual(fix[2]);
+          });
+        });
+      });
+
       describe("assignment", () => {
         it("should support field assignments", () => {
           var context = td();

modules/angular2/test/change_detection/parser/unparser.ts

@@ -6,6 +6,8 @@ import {
   Binary,
   Chain,
   Conditional,
+  EmptyExpr,
+  If,
   Pipe,
   FunctionCall,
   ImplicitReceiver,
@@ -21,7 +23,7 @@ import {
 } from 'angular2/src/change_detection/parser/ast';
 
 
-import {StringWrapper, RegExpWrapper} from 'angular2/src/facade/lang';
+import {StringWrapper, RegExpWrapper, isPresent} from 'angular2/src/facade/lang';
 
 var quoteRegExp = RegExpWrapper.create('"');
 
@@ -53,10 +55,11 @@ export class Unparser implements AstVisitor {
   }
 
   visitChain(ast: Chain) {
-    ast.expressions.forEach(expression => {
-      this._visit(expression);
-      this._expression += ';'
-    });
+    var len = ast.expressions.length;
+    for (let i = 0; i < len; i++) {
+      this._visit(ast.expressions[i]);
+      this._expression += i == len - 1 ? ';' : '; ';
+    }
   }
 
   visitConditional(ast: Conditional) {
@@ -67,6 +70,17 @@ export class Unparser implements AstVisitor {
     this._visit(ast.falseExp);
   }
 
+  visitIf(ast: If) {
+    this._expression += 'if (';
+    this._visit(ast.condition);
+    this._expression += ') ';
+    this._visitExpOrBlock(ast.trueExp);
+    if (isPresent(ast.falseExp)) {
+      this._expression += ' else ';
+      this._visitExpOrBlock(ast.falseExp);
+    }
+  }
+
   visitPipe(ast: Pipe) {
     this._expression += '(';
     this._visit(ast.exp);
@@ -179,4 +193,11 @@ export class Unparser implements AstVisitor {
   }
 
   private _visit(ast: AST) { ast.visit(this); }
+
+  private _visitExpOrBlock(ast: AST) {
+    var isBlock = ast instanceof Chain || ast instanceof EmptyExpr;
+    if (isBlock) this._expression += '{ ';
+    this._visit(ast);
+    if (isBlock) this._expression += ' }';
+  }
 }

modules/angular2/test/change_detection/parser/unparser_spec.ts

@@ -8,6 +8,8 @@ import {
   Binary,
   Chain,
   Conditional,
+  EmptyExpr,
+  If,
   Pipe,
   ImplicitReceiver,
   Interpolation,
@@ -93,6 +95,17 @@ export function main() {
 
     it('should support SafeMethodCall', () => { check('a?.b(c, d)', SafeMethodCall); });
 
+    it('should support if statements', () => {
+      var ifs = [
+        'if (true) a()',
+        'if (true) a() else b()',
+        'if (a()) { b = 1; c = 2; }',
+        'if (a()) b = 1 else { c = 2; d = e(); }'
+      ];
+
+      ifs.forEach(ifStmt => check(ifStmt, If));
+    });
+
     it('should support complex expression', () => {
       var originalExp = 'a + 3 * fn([(c + d | e).f], {a: 3})[g].h && i';
       var ast = parseBinding(originalExp).ast;
@@ -108,5 +121,12 @@ export function main() {
       expect(ast).toBeAnInstanceOf(Interpolation);
       expect(unparser.unparse(ast)).toEqual('a {{ b }} c');
     });
+
+    it('should support EmptyExpr', () => {
+      var ast = parser.parseAction('if (true) { }', null).ast;
+      expect(ast).toBeAnInstanceOf(If);
+      expect((<If>ast).trueExp).toBeAnInstanceOf(EmptyExpr);
+      expect(unparser.unparse(ast)).toEqual('if (true) {  }');
+    });
   });
 }