[jira] [Created] (WEEX-217) WXTransform should not crash while parsing 'translate(0)'

["Gabriel Li (JIRA)" <ji...@apache.org>]

Gabriel Li created WEEX-217:
-------------------------------

             Summary: WXTransform should not crash while parsing 'translate(0)'
                 Key: WEEX-217
                 URL: https://issues.apache.org/jira/browse/WEEX-217
             Project: Weex
          Issue Type: Bug
          Components: iOS
            Reporter: Gabriel Li
            Assignee: Adam Feng


According to the latest published W3C specification about [CSS Transforms|https://www.w3.org/TR/css-transforms-1/)]:
{code:java}
translate() = translate( <length-percentage> [, <length-percentage> ]? )
specifies a 2D translation by the vector [tx, ty], where tx is the first translation-value parameter and ty is the optional second translation-value parameter. If <ty> is not provided, ty has zero as a value.
{code}
, _translate(tx)_ is equal to _translate(tx, 0)_. In the previous _version of Weex_, we removed the array length check in method [WXTransform parseTranslate:]
{code:java}
- (void)parseTranslate:(NSArray *)value
{
    [self parseTranslatex:@[value[0]]];
    [self parseTranslatey:@[value[1]]];
}{code}
so if the parser encounter a '_translate(0)_', the array contains only one single value inside, parseTranslate will fetch the element at index 1 from the array, which causes a typical _out-of-bounds_ exception, and lead to an app crash eventually.

As we known in many js packing procedures, '_translate(x, 0)_' will be compressed/minified to the form 'translate(x)', Weex should avoid such inconsistent implementations and conforms the W3C specifications.



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