On Tue, 21 Dec 2010, Frank Shearar wrote:

> One of the failing Decompiler tests is when we check 
> MethodPragmaTest>>testCompileCharacter:
>
> testCompileCharacter
> 	self assertPragma: 'foo: $a' givesKeyword: #foo: arguments: #( $a ).
> 	self assertPragma: 'foo: $ ' givesKeyword: #foo: arguments: #( $  ).
>
> As bytecodes, this method looks like this:
>
> 37 <70> self
> 38 <21> pushConstant: 'foo: $a'
> 39 <22> pushConstant: #foo:
> 40 <23> pushConstant: #($a)
> 41 <83 60> send: assertPragma:givesKeyword:arguments:
> 43 <87> pop
> 44 <70> self
> 45 <24> pushConstant: 'foo: $ '
> 46 <22> pushConstant: #foo:
> 47 <25> pushConstant: {Character space}
> 48 <83 60> send: assertPragma:givesKeyword:arguments:
> 50 <87> pop
> 51 <78> returnSelf
>
> And when decompiled, we have:
>
> testCompileCharacter
> 	self
> 		assertPragma: 'foo: $a'
> 		givesKeyword: #foo:
> 		arguments: #($a ).
> 	self
> 		assertPragma: 'foo: $ '
> 		givesKeyword: #foo:
> 		arguments: ((Array new: 1) at: 1 put: Character space; 
> yourself)
>
> Notice that the literal #( $  ) has expanded into an Array declaration etc.
>
> When we compile this decompiled string, we end up with the rather different
>
> 	self
> 	pushConstant: ''foo: $a''
> 	pushConstant: #foo:
> 	pushConstant: #($a)
> 	send: #assertPragma:givesKeyword:arguments: (3 args)
> 	pop
> 	self
> 	pushConstant: ''foo: $ ''
> 	pushConstant: #foo:
> 	pushLit: Array
> 	pushConstant: 1
> 	send: #new: (1 arg)
> 	dup
> 	pushConstant: 1
> 	pushLit: Character
> 	send: #space (0 args)
> 	send: #at:put: (2 args)
> 	pop
> 	send: #yourself (0 args)
> 	send: #assertPragma:givesKeyword:arguments: (3 args)
> 	pop
> 	returnSelf
>
> The decompiler turns that pushConstant: into a whole bunch of stuff because 
> it interprets #( $  ) as (Array new: 1) at: 1 put: Character space; yourself.
>
> (The same thing happens for SyntaxMorph>>replaceSel:menuItem: and 
> SyntaxMorph>>replaceKeyWord:menuItem. It looks like $  is being interpreted 
> as Character space, and then decompiled to pushLit: Character send: #space.)
>
> That's all fine, but what happens is that when you compile the decompiled 
> method (and then decompile _that_ method), you can't have the 
> newly-decompiled method match the original decompiled method. The parse tree 
> are different: where the original has a LiteralNode, the new version has a 
> CascadeNode.

It's easy to fix it, just change Character >> shouldBePrintedAsLiteral to
^value between: 32 and: 255. Though it may break other stuff. See here:
http://bugs.squeak.org/view.php?id=2254
http://bugs.squeak.org/view.php?id=4322
Btw the 33-255 range is funny, because 127 is a control character.


Levente

>
> frank
>
>