Question

I m looking for a way of pattern matching the "geometry" of an array, the order in which the elements appear, not the contents of each element directly.

Let me outline what I mean by some examples. Given the target array:

array( T_STRING , T_VARIABLE , ASSIGN , T_STRING , LPAREN , T_VARIABLE , COMMA , T_VARIABLE , RPAREN );
//as a matter of fact, these would be the tokens for the PHP code "foo $var = Foo($arg1,$arg2)

Then the following "pattern" would match, returning the 0-based indexes of the matches, as well as the indexes of the groupings, just like preg_match_all() would do for strings:

array( T_STRING ,  ? ,  ( ,  T_VARIABLE ,  ASSIGN   ) ,  ? ,
     T_STRING ,  LPAREN ,  ( ,  T_VARIABLE ,  COMMA ,  ? ,  ) ,  ? ,  RPAREN );

This is only a simplified PoC, the way I intend to use it is much more complicated, and I don t want to use the full parser generator from PEAR (the lemon port to PHP), which would be overkill.

Are you aware of a function (possibly not an internal PHP function) or project which does just that?

Thank you.

Answer 1

When ever I hear "pattern matching" I think "regex".

Push that array to a string and match against the pattern you re looking for using regex. You may be able to a symbol replacement to make the regex small and manageable:

Your array above could be reduced to a string like this:

$arrayPattern =  SVASL_PVCVR_P

Now you can use RegEx to match against it.

if (preg_match( /VA/ , $arrayPattern)) 
  print "You ve got a Variable followed by an Assign!";

Just a thought....

Answer 2

If you are you looking for Code Analysis, then these slides of Sebastian Bergmann might be of use to you. Starting with slide 17 is examples for analysis by tokens.

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