coregrind/m_seqmatch.c

   1
   2 /*--------------------------------------------------------------------*/
   3 /*--- A simple sequence matching facility.                         ---*/
   4 /*---                                                 m_seqmatch.c ---*/
   5 /*--------------------------------------------------------------------*/
   6
   7 /*
   8    This file is part of Valgrind, a dynamic binary instrumentation
   9    framework.
  10
  11    Copyright (C) 2008-2017 OpenWorks Ltd
  12       info@open-works.co.uk
  13
  14    This program is free software; you can redistribute it and/or
  15    modify it under the terms of the GNU General Public License as
  16    published by the Free Software Foundation; either version 2 of the
  17    License, or (at your option) any later version.
  18
  19    This program is distributed in the hope that it will be useful, but
  20    WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22    General Public License for more details.
  23
  24    You should have received a copy of the GNU General Public License
  25    along with this program; if not, write to the Free Software
  26    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  27    02111-1307, USA.
  28
  29    The GNU General Public License is contained in the file COPYING.
  30 */
  31
  32 #include "pub_core_basics.h"
  33 #include "pub_core_libcassert.h"
  34 #include "pub_core_libcbase.h"    // VG_(strlen)
  35 #include "pub_core_seqmatch.h"    // self
  36
  37 /* ---------------------------------------------------------------------
  38    A simple sequence matching facility
  39    ------------------------------------------------------------------ */
  40
  41 /* See detailed comment in include/pub_tool_seqmatch.h about this. */
  42 Bool VG_(generic_match) (
  43         Bool matchAll,
  44         const void* patt,  SizeT szbPatt,  UWord nPatt,  UWord ixPatt,
  45         const void* input, SizeT szbInput, UWord nInput, UWord ixInput,
  46         Bool (*pIsStar)(const void*),
  47         Bool (*pIsQuery)(const void*),
  48         Bool (*pattEQinp)(const void*,const void*,void*,UWord),
  49         void* inputCompleter, Bool (*haveInputInpC)(void*,UWord)
  50      )
  51 {
  52    /* This is the spec, written in my favourite formal specification
  53       language.  It specifies non-greedy matching of '*'s.
  54
  55       ma ('*':ps) (i:is) = ma ps (i:is) || ma ('*':ps) is
  56       ma ('*':ps) []     = ma ps []
  57
  58       ma ('?':ps) (i:is) = ma ps is
  59       ma ('?':ps) []     = False
  60
  61       ma (p:ps)   (i:is) = p == i && ma ps is
  62
  63       ma (p:ps)   []     = False
  64       ma []       (i:is) = False -- m-all, True for m-prefix
  65       ma []       []     = True
  66    */
  67    Bool  havePatt, haveInput;
  68    const HChar *currPatt, *currInput;
  69   tailcall:
  70    vg_assert(nPatt >= 0 && nPatt  < 1000000); /* arbitrary */
  71    vg_assert(inputCompleter
  72              || (nInput >= 0  && nInput < 1000000)); /* arbitrary */
  73    vg_assert(ixPatt >= 0  && ixPatt <= nPatt);
  74    vg_assert(ixInput >= 0 && (inputCompleter || ixInput <= nInput));
  75
  76    havePatt  = ixPatt < nPatt;
  77    haveInput = inputCompleter ?
  78       (*haveInputInpC)(inputCompleter, ixInput)
  79       : ixInput < nInput;
  80
  81    /* No specific need to set NULL when !have{Patt,Input}, but guards
  82       against inadvertantly dereferencing an out of range pointer to
  83       the pattern or input arrays. */
  84    currPatt  = havePatt  ? ((const HChar*)patt) + szbPatt * ixPatt    : NULL;
  85    currInput = haveInput && !inputCompleter ?
  86       ((const HChar*)input) + szbInput * ixInput : NULL;
  87
  88    // Deal with the complex case first: wildcards.  Do frugal
  89    // matching.  When encountering a '*', first skip no characters
  90    // at all, and see if the rest of the match still works.  Only if
  91    // that fails do we then skip a character, and retry at the next
  92    // position.
  93    //
  94    // ma ('*':ps) (i:is) = ma ps (i:is) || ma ('*':ps) is
  95    //
  96    // If we're out of input, check the rest of the pattern matches
  97    // the empty input.  This really means can only be be empty or
  98    // composed entirely of '*'s.
  99    //
 100    // ma ('*':ps) []     = ma ps []
 101    //
 102    if (havePatt && pIsStar(currPatt)) {
 103       if (haveInput) {
 104          // ma ('*':ps) (i:is) = ma ps (i:is) || ma ('*':ps) is
 105          // we unavoidably have to make a real recursive call for the
 106          // first half of the OR, since this isn't straight tail-recursion.
 107          if (VG_(generic_match)( matchAll,
 108                                  patt, szbPatt, nPatt,  ixPatt+1,
 109                                  input,szbInput,nInput, ixInput+0,
 110                                  pIsStar,pIsQuery,pattEQinp,
 111                                  inputCompleter,haveInputInpC) ) {
 112             return True;
 113          }
 114          // but we can tail-recurse for the second call
 115          ixInput++; goto tailcall;
 116       } else {
 117          // ma ('*':ps) []     = ma ps []
 118          ixPatt++; goto tailcall;
 119       }
 120    }
 121
 122    // simpler cases now.  Deal with '?' wildcards.
 123    //
 124    // ma ('?':ps) (i:is) = ma ps is
 125    // ma ('?':ps) []     = False
 126    if (havePatt && pIsQuery(currPatt)) {
 127       if (haveInput) {
 128          ixPatt++; ixInput++; goto tailcall;
 129       } else {
 130          return False;
 131       }
 132    }
 133
 134    // obvious case with literal chars in the pattern
 135    //
 136    // ma (p:ps)   (i:is) = p == i && ma ps is
 137    if (havePatt && haveInput) {
 138       if (!pattEQinp(currPatt,currInput,inputCompleter,ixInput)) return False;
 139       ixPatt++; ixInput++; goto tailcall;
 140    }
 141
 142    // if we run out of input before we run out of pattern, we must fail
 143    // ma (p:ps)   []     = False
 144    if (havePatt && !haveInput) return False;
 145
 146    // if we run out of pattern before we run out of input, the
 147    // verdict depends on the matching mode.  If we are trying to
 148    // match exactly (the pattern must consume the entire input)
 149    // then the outcome is failure.  However, if we're merely attempting
 150    // to match some prefix of the input, then we have been successful.
 151    //
 152    // ma []       (i:is) = False -- m-all, True for m-prefix
 153    if (!havePatt && haveInput) {
 154       return matchAll ? False // match-all
 155                       : True; // match-prefix
 156    }
 157
 158    // finally, if both sequence and input are both completely
 159    // consumed, then we were successful, regardless of matching mode.
 160    if (!havePatt && !haveInput) return True;
 161
 162    // end of cases
 163    vg_assert(0);
 164 }
 165
 166
 167 /* And a parameterization of the above, to make it do
 168    string matching.
 169 */
 170 static Bool charIsStar  ( const void* pV ) { return *(const HChar*)pV == '*'; }
 171 static Bool charIsQuery ( const void* pV ) { return *(const HChar*)pV == '?'; }
 172 static Bool char_p_EQ_i ( const void* pV, const void* cV,
 173                           void* null_completer, UWord ixcV ) {
 174    HChar p = *(const HChar*)pV;
 175    HChar c = *(const HChar*)cV;
 176    vg_assert(p != '*' && p != '?');
 177    return p == c;
 178 }
 179 Bool VG_(string_match) ( const HChar* patt, const HChar* input )
 180 {
 181    return VG_(generic_match)(
 182              True/* match-all */,
 183              patt,  sizeof(HChar), VG_(strlen)(patt), 0,
 184              input, sizeof(HChar), VG_(strlen)(input), 0,
 185              charIsStar, charIsQuery, char_p_EQ_i,
 186              NULL, NULL
 187           );
 188 }
 189
 190
 191 // test cases for the matcher (in match-all mode)
 192 // typedef struct { char* patt; char* input; Bool xres; } Test;
 193 //
 194 //static Test tests[] =
 195 //  {
 196 //    { ""          ,""   , True },
 197 //    { "a"         ,""   , False },
 198 //    { "a"         ,"b"  , False },
 199 //    { "a"         ,"a"  , True },
 200 //    { "a"         ,"aa" , False },
 201 //    { "*"         ,""   , True },
 202 //    { "**"        ,""   , True },
 203 //    { "*"         ,"abc", True },
 204 //    { "*a"        ,"abc", False },
 205 //    { "*b"        ,"abc", False },
 206 //    { "*bc"       ,"abc", True },
 207 //    { "a*b"       ,"abc", False },
 208 //    { "a*c"       ,"abc", True },
 209 //    { "*c"        ,"abc", True },
 210 //    { "c*c"       ,"abc", False },
 211 //    { "abc*"      ,"abc", True },
 212 //    { "abc**"     ,"abc", True },
 213 //    { "**abc"     ,"abc", True },
 214 //    { "**a*b*c**" ,"abc", True },
 215 //    { "**a*b*d**" ,"abc", False },
 216 //    { "a?b"       ,"abc", False },
 217 //    { "a?c"       ,"abc", True },
 218 //    { "?"         ,""   , False },
 219 //    { "?"         ,"a"  , True },
 220 //    { "?"         ,"ab" , False },
 221 //    { "abcd"      ,"abc", False },
 222 //    { "ab"        ,"abc", False },
 223 //    { NULL        ,NULL , False }
 224 //  };
 225 //
 226 //int main ( void )
 227 //{
 228 //   Test* t;
 229 //   for (t = tests; t->patt; t++) {
 230 //     printf("%-10s %-6s  %s\n",
 231 //            t->patt, t->input,
 232 //            match_string_all((UChar*)t->patt,(UChar*)t->input,True)
 233 //            == t->xres
 234 //               ? "pass" : "FAIL" );
 235 //   }
 236 //   return 0;
 237 //}
 238
 239 /*--------------------------------------------------------------------*/
 240 /*--- end                                             m_seqmatch.c ---*/
 241 /*--------------------------------------------------------------------*/