[Mono-dev] [PATCH] String.Split() broken behavior

[Tyler Larson]

Hey Mono team:

This is my first time contributing, so please bear with me if I do 
something dumb.

I've provided a patch for incorrect behavior in the String.Split() 
function. In particular, String.Split(char[],int,StringSplitOptions) 
behaves incorrectly when instructed to remove empty entries while also 
limiting the size of the resultant array.

Take for example, the following code:
 ",a,,b,c".Split(new char[]{','},3,StringSplitOptions.RemoveEmptyEntries);

The existing implementation split the string into the following 3 
components:  {[], [], [a,,b,c]}
Then it scans the array and removes all empty entries, returning simply 
{[a,,b,c]}

The correct behavior would be to remove empty entries while the string 
was being split, and always return the maximum number of elements 
possible. The *correct* result to the preceding example would be:
{[a],[b],[c]}

In order to do this correctly and efficiently, the InternalSplit 
function had to be modified to be able to remove empty entries during 
the split procedure; this included changing the signature to accept an 
"options" parameter.

This patch also removes the need for further optimization of the 
String.Split() call.


I'm a bit unsure about the coding style required; the .c file seemed to 
be a bit of a combination of a few coding styles all together. Also, the 
new InternalSplit function in this patch contains the line:
 remempty = options & 0x01;

where 0x01 refers to the StringSplitOptions.RemoveEmptyEntries flag. I'm 
sure there's a "better" way of indicating this; either by referencing 
the enum somehow or with a #define somewhere. I don't know how you do 
that sort of thing here.

The patch, as provided, DOES fix the broken code and works without any 
trouble, but I would appreciate it if someone more familiar with the 
Mono project would go over the changes and bring those style bits a bit 
more into conformance with what is expected.

Cheers

-Tyler Larson



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