TRegexp.cxx

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// @(#)root/base:$Id: TRegexp.cxx 35844 2010-09-28 15:10:29Z rdm $
// Author: Fons Rademakers   04/08/95

/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TRegexp                                                              //
//                                                                      //
// Regular expression class.                                            //
//                                                                      //
//   '^'             // start-of-line anchor                            //
//   '$'             // end-of-line anchor                              //
//   '.'             // matches any character                           //
//   '['             // start a character class                         //
//   ']'             // end a character class                           //
//   '^'             // negates character class if 1st character        //
//   '*'             // Kleene closure (matches 0 or more)              //
//   '+'             // Positive closure (1 or more)                    //
//   '?'             // Optional closure (0 or 1)                       //
//                                                                      //
//   Standard classes like [:alnum:], [:alpha:], etc. are not supported,//
//   only [a-zA-Z], [^ntf] and so on.                                   //
//                                                                      //
//////////////////////////////////////////////////////////////////////////

#include "TRegexp.h"
#include "TString.h"
#include "TError.h"

const unsigned TRegexp::fgMaxpat = 2048;


ClassImp(TRegexp)

//______________________________________________________________________________
TRegexp::TRegexp(const char *re, Bool_t wildcard)
{
   // Create a regular expression from the input string. If wildcard is true
   // then the input string contains a wildcard expression (see MakeWildcard()).

   if (wildcard)
      GenPattern(MakeWildcard(re));
   else
      GenPattern(re);
}

//______________________________________________________________________________
TRegexp::TRegexp(const TString& re)
{
   // Create a regular expression from a TString.

   GenPattern(re.Data());
}

//______________________________________________________________________________
TRegexp::TRegexp(const TRegexp& r)
{
   // Copy ctor.

   CopyPattern(r);
}

//______________________________________________________________________________
TRegexp::~TRegexp()
{
   // Destructor.
   delete [] fPattern;
}

//______________________________________________________________________________
TRegexp& TRegexp::operator=(const TRegexp& r)
{
   // Assignment operator.

   if (this != &r) {
      delete [] fPattern;
      CopyPattern(r);
   }
   return *this;
}

//______________________________________________________________________________
TRegexp& TRegexp::operator=(const char *str)
{
   // Assignment operator taking a char* and assigning it to a regexp.

   delete [] fPattern;
   GenPattern(str);
   return *this;
}

//______________________________________________________________________________
TRegexp& TRegexp::operator=(const TString &str)
{
   // Assignment operator taking a TString.

   delete [] fPattern;
   GenPattern(str.Data());
   return *this;
}

//______________________________________________________________________________
void TRegexp::GenPattern(const char *str)
{
   // Generate the regular expression pattern.

   fPattern = new Pattern_t[fgMaxpat];
   int error = ::Makepat(str, fPattern, fgMaxpat);
   fStat = (error < 3) ? (EStatVal) error : kToolong;
}

//______________________________________________________________________________
void TRegexp::CopyPattern(const TRegexp& r)
{
   // Copy the regular expression pattern.

   fPattern = new Pattern_t[fgMaxpat];
   memcpy(fPattern, r.fPattern, fgMaxpat * sizeof(Pattern_t));
   fStat = r.fStat;
}

//______________________________________________________________________________
const char *TRegexp::MakeWildcard(const char *re)
{
   // This routine transforms a wildcarding regular expression into
   // a general regular expression used for pattern matching.
   // When using wildcards the regular expression is assumed to be
   // preceded by a "^" (BOL) and terminated by a "$" (EOL). Also, all
   // "*"'s and "?"'s (closures) are assumed to be preceded by a "." (i.e. any
   // character, except "/"'s) and all .'s are escaped (so *.ps is different
   // from *.eps). The special treatment of "/" allows the easy matching of
   // pathnames, e.g. "*.root" will match "aap.root", but not "pipo/aap.root".

   static char buf[fgMaxpat];
   char *s = buf;
   if (!re) return "";
   int len = strlen(re);
   int slen = 0;

   if (!len) return "";

   for (int i = 0; i < len; i++) {
      if ((unsigned)slen > fgMaxpat - 10) {
         Error("MakeWildcard", "regexp too large");
         break;
      }
      if (i == 0 && re[i] != '^') {
         *s++ = '^';
         slen++;
      }
      if (re[i] == '*') {
#ifndef R__WIN32
         //const char *wc = "[a-zA-Z0-9-+_\\.,: []<>]";
         const char *wc = "[^/]";
#else
         //const char *wc = "[a-zA-Z0-9-+_., []<>]";
         const char *wc = "[^\\/:]";
#endif
         strcpy(s, wc);
         s += strlen(wc);
         slen += strlen(wc);
      }
      if (re[i] == '.') {
         *s++ = '\\';
         slen++;
      }
      if (re[i] == '?') {
#ifndef R__WIN32
         //const char *wc = "[a-zA-Z0-9-+_\\.,: []<>]";
         const char *wc = "[^/]";
#else
         //const char *wc = "[a-zA-Z0-9-+_., []<>]";
         const char *wc = "[^\\/:]";
#endif
         strcpy(s, wc);
         s += strlen(wc);
         slen += strlen(wc);
      } else {
         *s++ = re[i];
         slen++;
      }
      if (i == len-1 && re[i] != '$') {
         *s++ = '$';
         slen++;
      }
   }
   *s = '\0';
   return buf;
}

//______________________________________________________________________________
Ssiz_t TRegexp::Index(const TString& string, Ssiz_t* len, Ssiz_t i) const
{
   // Find the first occurance of the regexp in string and return the position.
   // Len is length of the matched string and i is the offset at which the
   // matching should start.

   if (fStat != kOK)
      Error("TRegexp::Index", "Bad Regular Expression");

   const char* startp;
   const char* s = string.Data();
   Ssiz_t slen = string.Length();
   if (slen < i) return kNPOS;
   const char* endp = ::Matchs(s+i, slen-i, fPattern, &startp);
   if (endp) {
      *len = endp - startp;
      return startp - s;
   } else {
      *len = 0;
      return kNPOS;
   }
}

//______________________________________________________________________________
TRegexp::EStatVal TRegexp::Status()
{
   // Check status of regexp.

   EStatVal temp = fStat;
   fStat = kOK;
   return temp;
}

//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TString member functions, put here so the linker will include        //
// them only if regular expressions are used.                           //
//                                                                      //
//////////////////////////////////////////////////////////////////////////

//______________________________________________________________________________
Ssiz_t TString::Index(const TRegexp& r, Ssiz_t start) const
{
   // Find the first occurance of the regexp in string and return the position.
   // Start is the offset at which the search should start.

   Ssiz_t len;
   return r.Index(*this, &len, start); // len not used
}

//______________________________________________________________________________
Ssiz_t TString::Index(const TRegexp& r, Ssiz_t* extent, Ssiz_t start) const
{
   // Find the first occurance of the regexp in string and return the position.
   // Extent is length of the matched string and start is the offset at which
   // the matching should start.

   return r.Index(*this, extent, start);
}

//______________________________________________________________________________
TSubString TString::operator()(const TRegexp& r, Ssiz_t start) const
{
   // Return the substring found by applying the regexp starting at start.

   Ssiz_t len;
   Ssiz_t begin = Index(r, &len, start);
   return TSubString(*this, begin, len);
}

//______________________________________________________________________________
TSubString TString::operator()(const TRegexp& r) const
{
   // Return the substring found by applying the regexp.

   return (*this)(r,0);
}

//__________________________________________________________________________________
Bool_t TString::Tokenize(TString &tok, Ssiz_t &from, const char *delim) const
{
   // Search for tokens delimited by regular expression 'delim' (default " ")
   // in this string; search starts at 'from' and the token is returned in 'tok'.
   // Returns in 'from' the next position after the delimiter.
   // Returns kTRUE if a token is found, kFALSE if not or if some inconsistency
   // occured.
   // This method allows to loop over tokens in this way:
   //
   //    TString myl = "tok1 tok2|tok3";
   //    TString tok;
   //    Ssiz_t from = 0;
   //    while (myl.Tokenize(tok, from, "[ |]")) {
   //       // Analyse tok
   //       ...
   //    }
   //
   // more convenient of the other Tokenize method when saving the tokens is not
   // needed.

   Bool_t found = kFALSE;

   // Reset the token
   tok = "";

   // Make sure inputs make sense
   Int_t len = Length();
   if (len <= 0 || from > (len - 1) || from < 0)
      return found;

   TRegexp rg(delim);

   while (tok.IsNull()) {
      // Find delimiter
      Int_t ext = 0;
      Int_t pos = Index(rg, &ext, from);

      // Assign to token
      if (pos == kNPOS || pos > from) {
         Ssiz_t last = (pos != kNPOS) ? (pos - 1) : len;
         tok = (*this)(from, last-from+1);
      }
      found = kTRUE;

      // Update start-of-search index
      from = pos + ext;
      if (pos == kNPOS) {
         from = pos;
         if (tok.IsNull()) {
            // Empty, last token
            found = kFALSE;
            break;
         }
      }
   }
   // Make sure that 'from' has a meaningful value
   from = (from < len) ? from : len;

   // Done
   return found;
}

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