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/* -*- tab-width: 2; indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
File Name: 12.10-1.js
ECMA Section: 12.10 The with statement
Description:
WithStatement :
with ( Expression ) Statement
The with statement adds a computed object to the front of the scope chain
of the current execution context, then executes a statement with this
augmented scope chain, then restores the scope chain.
Semantics
The production WithStatement : with ( Expression ) Statement is evaluated
as follows:
1. Evaluate Expression.
2. Call GetValue(Result(1)).
3. Call ToObject(Result(2)).
4. Add Result(3) to the front of the scope chain.
5. Evaluate Statement using the augmented scope chain from step 4.
6. Remove Result(3) from the front of the scope chain.
7. Return Result(5).
Discussion
Note that no matter how control leaves the embedded Statement, whether
normally or by some form of abrupt completion, the scope chain is always
restored to its former state.
Author: christine@netscape.com
Date: 12 november 1997
*/
var SECTION = "12.10-1";
var VERSION = "ECMA_1";
startTest();
var TITLE = "The with statement";
writeHeaderToLog( SECTION + " "+ TITLE);
// although the scope chain changes, the this value is immutable for a given
// execution context.
new TestCase( SECTION,
"with( new Number() ) { this +'' }",
GLOBAL,
eval("with( new Number() ) { this +'' }") );
// the object's functions and properties should override those of the
// global object.
new TestCase(
SECTION,
"var MYOB = new WithObject(true); with (MYOB) { parseInt() }",
true,
eval("var MYOB = new WithObject(true); with (MYOB) { parseInt() }") );
new TestCase(
SECTION,
"var MYOB = new WithObject(false); with (MYOB) { NaN }",
false,
eval("var MYOB = new WithObject(false); with (MYOB) { NaN }") );
new TestCase(
SECTION,
"var MYOB = new WithObject(NaN); with (MYOB) { Infinity }",
Number.NaN,
eval("var MYOB = new WithObject(NaN); with (MYOB) { Infinity }") );
new TestCase(
SECTION,
"var MYOB = new WithObject(false); with (MYOB) { }; Infinity",
Number.POSITIVE_INFINITY,
eval("var MYOB = new WithObject(false); with (MYOB) { }; Infinity") );
new TestCase(
SECTION,
"var MYOB = new WithObject(0); with (MYOB) { delete Infinity; Infinity }",
Number.POSITIVE_INFINITY,
eval("var MYOB = new WithObject(0); with (MYOB) { delete Infinity; Infinity }") );
// let us leave the with block via a break.
new TestCase(
SECTION,
"var MYOB = new WithObject(0); while (true) { with (MYOB) { Infinity; break; } } Infinity",
Number.POSITIVE_INFINITY,
eval("var MYOB = new WithObject(0); while (true) { with (MYOB) { Infinity; break; } } Infinity") );
test();
function WithObject( value ) {
this.prop1 = 1;
this.prop2 = new Boolean(true);
this.prop3 = "a string";
this.value = value;
// now we will override global functions
this.parseInt = new Function( "return this.value" );
this.NaN = value;
this.Infinity = value;
this.unescape = new Function( "return this.value" );
this.escape = new Function( "return this.value" );
this.eval = new Function( "return this.value" );
this.parseFloat = new Function( "return this.value" );
this.isNaN = new Function( "return this.value" );
this.isFinite = new Function( "return this.value" );
}
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