[llvm-dev] FW: RFC: FileCheck Enhancements

[Elena Lepilkina via llvm-dev]

As I understood, I should do first of all patch with patterns implementation only with simple parameters without modifiers? And after add this feature separately?

-----Original Message-----
From: vsk at apple.com [mailto:vsk at apple.com] 
Sent: Tuesday, September 13, 2016 4:05 AM
To: Elena Lepilkina <Elena.Lepilkina at synopsys.com>
Cc: Mehdi Amini <mehdi.amini at apple.com>; llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] RFC: FileCheck Enhancements

That's a good example. While '{{REGEX}}' usually creates a new matching group, we could introduce some new syntax to make it possible to use pattern arguments inside of regexes. E.g for an argument named 'x', writing 'x' in a pattern definition preserves the current behavior, and writing '#x' concatenates the value of 'x' with any surrounding regexes (resulting in just one matching group).

So, to match one or more things you could write:

  CHECK-DEFINE-PATTERN: one_or_more(x): #x {{+}}
  CHECK: [[@one_or_more("1")]]

Without the '#', you'd see a syntax error because '+' isn't a valid regex.

I like this approach because it doesn't require changing the definitions of REGEX or POSIX_REGEX. It'd be interesting to hear what other people think.

We should be able to hash this out in parallel to the work on D22403, since the plan is to defer work on pattern arguments until basic support for pattern definitions has landed.

Revised grammar (** proposal **):

  ACTION <- CHECK ':' MATCH '\n' ;
  ACTION <- CHECK-DEFINE-PATTERN ':' IDENT PARAMLIST? ':' PATTERN_ELEMENT* '\n' ;
  PARAMLIST <- '(' IDENT (',' IDENT)* ')' ;
  PATTERN_ELEMENT <- '#'? IDENT ;
  PATTERN_ELEMENT <- REGEX ;
  MATCH <- (TEXT | REGEX | PATTERN_USE | VAR)* ;
  REGEX <- '{{' POSIX_REGEX '}}' ;
  PATTERN_USE <- '[[' '@' IDENT ARGLIST? ']]' ;
  VAR <- '[[' IDENT ':' POSIX_REGEX ']]' ;
  VAR <- '[[' IDENT '@' IDENT ARGLIST? ']]' ;
  ARGLIST <- '(' ARG (',' ARG)* ')' ;
  ARG <- "([^"]|\\")*" ;


best,
vedant

> On Sep 12, 2016, at 5:57 AM, Elena Lepilkina <Elena.Lepilkina at synopsys.com> wrote:
> 
> Hi,
> 
> I have question again about modifiers for pattern parameters.
> 
> Vedant suggested such way.
> 
>>  CHECK-DEFINE-PATTERN: one_or_more(x): x {{+}}
> 
> But I have some doubts. This should be equal to x+. This approach differs from standard one.
> In FileCheck I can write
> 
> CHECK: {{x|y}}{{something}}
> 
> This line will be equal to regex (x|y)(something).
> 
> But if I use suggested approach and write same string in pattern CHECK-DEFINE-PATTERN: example: {{x|y}}{{something}}, it will be equal to (x|ysomething).
> As user I expected behavior as in first check.
> 
> Thanks, Elena.
> 
> 
> 
> 
>