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, see <http://www.gnu.org/licenses/>.
  26
  27    The GNU General Public License is contained in the file COPYING.
  28 */
  29
  30 #include "pub_core_basics.h"
  31 #include "pub_core_libcassert.h"
  32 #include "pub_core_libcbase.h"    // VG_(strlen)
  33 #include "pub_core_seqmatch.h"    // self
  34
  35 /* ---------------------------------------------------------------------
  36    A simple sequence matching facility
  37    ------------------------------------------------------------------ */
  38
  39 /* See detailed comment in include/pub_tool_seqmatch.h about this. */
  40 Bool VG_(generic_match) (
  41         Bool matchAll,
  42         const void* patt,  SizeT szbPatt,  UWord nPatt,  UWord ixPatt,
  43         const void* input, SizeT szbInput, UWord nInput, UWord ixInput,
  44         Bool (*pIsStar)(const void*),
  45         Bool (*pIsQuery)(const void*),
  46         Bool (*pattEQinp)(const void*,const void*,void*,UWord),
  47         void* inputCompleter, Bool (*haveInputInpC)(void*,UWord)
  48      )
  49 {
  50    /* This is the spec, written in my favourite formal specification
  51       language.  It specifies non-greedy matching of '*'s.
  52
  53       ma ('*':ps) (i:is) = ma ps (i:is) || ma ('*':ps) is
  54       ma ('*':ps) []     = ma ps []
  55
  56       ma ('?':ps) (i:is) = ma ps is
  57       ma ('?':ps) []     = False
  58
  59       ma (p:ps)   (i:is) = p == i && ma ps is
  60
  61       ma (p:ps)   []     = False
  62       ma []       (i:is) = False -- m-all, True for m-prefix
  63       ma []       []     = True
  64    */
  65    Bool  havePatt, haveInput;
  66    const HChar *currPatt, *currInput;
  67   tailcall:
  68    vg_assert(nPatt >= 0 && nPatt  < 1000000); /* arbitrary */
  69    vg_assert(inputCompleter
  70              || (nInput >= 0  && nInput < 1000000)); /* arbitrary */
  71    vg_assert(ixPatt >= 0  && ixPatt <= nPatt);
  72    vg_assert(ixInput >= 0 && (inputCompleter || ixInput <= nInput));
  73
  74    havePatt  = ixPatt < nPatt;
  75    haveInput = inputCompleter ?
  76       (*haveInputInpC)(inputCompleter, ixInput)
  77       : ixInput < nInput;
  78
  79    /* No specific need to set NULL when !have{Patt,Input}, but guards
  80       against inadvertantly dereferencing an out of range pointer to
  81       the pattern or input arrays. */
  82    currPatt  = havePatt  ? ((const HChar*)patt) + szbPatt * ixPatt    : NULL;
  83    currInput = haveInput && !inputCompleter ?
  84       ((const HChar*)input) + szbInput * ixInput : NULL;
  85
  86    // Deal with the complex case first: wildcards.  Do frugal
  87    // matching.  When encountering a '*', first skip no characters
  88    // at all, and see if the rest of the match still works.  Only if
  89    // that fails do we then skip a character, and retry at the next
  90    // position.
  91    //
  92    // ma ('*':ps) (i:is) = ma ps (i:is) || ma ('*':ps) is
  93    //
  94    // If we're out of input, check the rest of the pattern matches
  95    // the empty input.  This really means can only be be empty or
  96    // composed entirely of '*'s.
  97    //
  98    // ma ('*':ps) []     = ma ps []
  99    //
 100    if (havePatt && pIsStar(currPatt)) {
 101       if (haveInput) {
 102          // ma ('*':ps) (i:is) = ma ps (i:is) || ma ('*':ps) is
 103          // we unavoidably have to make a real recursive call for the
 104          // first half of the OR, since this isn't straight tail-recursion.
 105          if (VG_(generic_match)( matchAll,
 106                                  patt, szbPatt, nPatt,  ixPatt+1,
 107                                  input,szbInput,nInput, ixInput+0,
 108                                  pIsStar,pIsQuery,pattEQinp,
 109                                  inputCompleter,haveInputInpC) ) {
 110             return True;
 111          }
 112          // but we can tail-recurse for the second call
 113          ixInput++; goto tailcall;
 114       } else {
 115          // ma ('*':ps) []     = ma ps []
 116          ixPatt++; goto tailcall;
 117       }
 118    }
 119
 120    // simpler cases now.  Deal with '?' wildcards.
 121    //
 122    // ma ('?':ps) (i:is) = ma ps is
 123    // ma ('?':ps) []     = False
 124    if (havePatt && pIsQuery(currPatt)) {
 125       if (haveInput) {
 126          ixPatt++; ixInput++; goto tailcall;
 127       } else {
 128          return False;
 129       }
 130    }
 131
 132    // obvious case with literal chars in the pattern
 133    //
 134    // ma (p:ps)   (i:is) = p == i && ma ps is
 135    if (havePatt && haveInput) {
 136       if (!pattEQinp(currPatt,currInput,inputCompleter,ixInput)) return False;
 137       ixPatt++; ixInput++; goto tailcall;
 138    }
 139
 140    // if we run out of input before we run out of pattern, we must fail
 141    // ma (p:ps)   []     = False
 142    if (havePatt && !haveInput) return False;
 143
 144    // if we run out of pattern before we run out of input, the
 145    // verdict depends on the matching mode.  If we are trying to
 146    // match exactly (the pattern must consume the entire input)
 147    // then the outcome is failure.  However, if we're merely attempting
 148    // to match some prefix of the input, then we have been successful.
 149    //
 150    // ma []       (i:is) = False -- m-all, True for m-prefix
 151    if (!havePatt && haveInput) {
 152       return matchAll ? False // match-all
 153                       : True; // match-prefix
 154    }
 155
 156    // finally, if both sequence and input are both completely
 157    // consumed, then we were successful, regardless of matching mode.
 158    if (!havePatt && !haveInput) return True;
 159
 160    // end of cases
 161    vg_assert(0);
 162 }
 163
 164
 165 /* And a parameterization of the above, to make it do
 166    string matching.
 167 */
 168 static Bool charIsStar  ( const void* pV ) { return *(const HChar*)pV == '*'; }
 169 static Bool charIsQuery ( const void* pV ) { return *(const HChar*)pV == '?'; }
 170 static Bool char_p_EQ_i ( const void* pV, const void* cV,
 171                           void* null_completer, UWord ixcV ) {
 172    HChar p = *(const HChar*)pV;
 173    HChar c = *(const HChar*)cV;
 174    vg_assert(p != '*' && p != '?');
 175    return p == c;
 176 }
 177 Bool VG_(string_match) ( const HChar* patt, const HChar* input )
 178 {
 179    return VG_(generic_match)(
 180              True/* match-all */,
 181              patt,  sizeof(HChar), VG_(strlen)(patt), 0,
 182              input, sizeof(HChar), VG_(strlen)(input), 0,
 183              charIsStar, charIsQuery, char_p_EQ_i,
 184              NULL, NULL
 185           );
 186 }
 187
 188
 189 // test cases for the matcher (in match-all mode)
 190 // typedef struct { char* patt; char* input; Bool xres; } Test;
 191 //
 192 //static Test tests[] =
 193 //  {
 194 //    { ""          ,""   , True },
 195 //    { "a"         ,""   , False },
 196 //    { "a"         ,"b"  , False },
 197 //    { "a"         ,"a"  , True },
 198 //    { "a"         ,"aa" , False },
 199 //    { "*"         ,""   , True },
 200 //    { "**"        ,""   , True },
 201 //    { "*"         ,"abc", True },
 202 //    { "*a"        ,"abc", False },
 203 //    { "*b"        ,"abc", False },
 204 //    { "*bc"       ,"abc", True },
 205 //    { "a*b"       ,"abc", False },
 206 //    { "a*c"       ,"abc", True },
 207 //    { "*c"        ,"abc", True },
 208 //    { "c*c"       ,"abc", False },
 209 //    { "abc*"      ,"abc", True },
 210 //    { "abc**"     ,"abc", True },
 211 //    { "**abc"     ,"abc", True },
 212 //    { "**a*b*c**" ,"abc", True },
 213 //    { "**a*b*d**" ,"abc", False },
 214 //    { "a?b"       ,"abc", False },
 215 //    { "a?c"       ,"abc", True },
 216 //    { "?"         ,""   , False },
 217 //    { "?"         ,"a"  , True },
 218 //    { "?"         ,"ab" , False },
 219 //    { "abcd"      ,"abc", False },
 220 //    { "ab"        ,"abc", False },
 221 //    { NULL        ,NULL , False }
 222 //  };
 223 //
 224 //int main ( void )
 225 //{
 226 //   Test* t;
 227 //   for (t = tests; t->patt; t++) {
 228 //     printf("%-10s %-6s  %s\n",
 229 //            t->patt, t->input,
 230 //            match_string_all((UChar*)t->patt,(UChar*)t->input,True)
 231 //            == t->xres
 232 //               ? "pass" : "FAIL" );
 233 //   }
 234 //   return 0;
 235 //}
 236
 237 /*--------------------------------------------------------------------*/
 238 /*--- end                                             m_seqmatch.c ---*/
 239 /*--------------------------------------------------------------------*/