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exported xmlExpExpDerive(), added it to the testRegexp command line tool

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* testRegexp.c xmlregexp.c include/libxml/xmlregexp.h: exported
  xmlExpExpDerive(), added it to the testRegexp command line
  tool when providing multiple expressions.
Daniel
This commit is contained in:
Daniel Veillard
2005-08-22 14:43:43 +00:00
parent 355a023866
commit 0090bd524f
4 changed files with 162 additions and 16 deletions
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37
xmlregexp.c
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@ -6819,6 +6819,43 @@ xmlExpExpDeriveInt(xmlExpCtxtPtr ctxt, xmlExpNodePtr exp, xmlExpNodePtr sub) {
return(ret);
}
/**
* xmlExpExpDerive:
* @ctxt: the expressions context
* @exp: the englobing expression
* @sub: the subexpression
*
* Evaluates the expression resulting from @exp consuming a sub expression @sub
* Based on algebraic derivation and sometimes direct Brzozowski derivation
* it usually tatkes less than linear time and can handle expressions generating
* infinite languages.
*
* Returns the resulting expression or NULL in case of internal error, the
* result must be freed
*/
xmlExpNodePtr
xmlExpExpDerive(xmlExpCtxtPtr ctxt, xmlExpNodePtr exp, xmlExpNodePtr sub) {
if ((exp == NULL) || (ctxt == NULL) || (sub == NULL))
return(NULL);
/*
* O(1) speedups
*/
if (IS_NILLABLE(sub) && (!IS_NILLABLE(exp))) {
#ifdef DEBUG_DERIV
printf("Sub nillable and not exp : can't subsume\n");
#endif
return(forbiddenExp);
}
if (xmlExpCheckCard(exp, sub) == 0) {
#ifdef DEBUG_DERIV
printf("sub generate longuer sequances than exp : can't subsume\n");
#endif
return(forbiddenExp);
}
return(xmlExpExpDeriveInt(ctxt, exp, sub));
}
/**
* xmlExpSubsume:
* @ctxt: the expressions context