src/com/stevesoft/pat/FastMulti.java

   1 //\r
   2 // This software is now distributed according to\r
   3 // the Lesser Gnu Public License.  Please see\r
   4 // http://www.gnu.org/copyleft/lesser.txt for\r
   5 // the details.\r
   6 //    -- Happy Computing!\r
   7 //\r
   8 package com.stevesoft.pat;\r
   9 import java.util.Hashtable;\r
  10 \r
  11 /** A special case of Multi, implemented when minChars().equals(maxChars()),\r
  12   * and some other conditions spelled out in RegOpt.safe4fm "Safe for\r
  13   * FastMulti."  It avoids stack growth problems as well as being slightly\r
  14   * faster.\r
  15   */\r
  16 class FastMulti extends PatternSub {\r
  17     patInt fewestMatches,mostMatches;\r
  18     public patInt minChars() {\r
  19         return sub.countMinChars().mul(fewestMatches);\r
  20     }\r
  21     public patInt maxChars() {\r
  22         return sub.countMaxChars().mul(mostMatches);\r
  23     }\r
  24     public boolean matchFewest = false;\r
  25 \r
  26     FastMulti(patInt a,patInt b,Pattern p) throws RegSyntax {\r
  27         if(p == null) RegSyntaxError.endItAll("Null length pattern "+\r
  28                 "followed by *, +, or other Multi.");\r
  29         fewestMatches = a;\r
  30         mostMatches = b;\r
  31         sub = p;\r
  32         step = p.countMinChars().intValue();\r
  33         sub.setParent(null);\r
  34     }\r
  35     public String toString() {\r
  36         return sub.toString()+"{"\r
  37             +fewestMatches+","+mostMatches+"}"+\r
  38             (matchFewest ? "?" : "")+"(?# <= fast multi)"+\r
  39             nextString();\r
  40     }\r
  41     int step = -1;\r
  42     public int matchInternal(int pos,Pthings pt) {\r
  43         int m=-1;\r
  44         int i=pos;\r
  45         int endstr = pt.src.length()-step;\r
  46         patInt matches = new patInt(0);\r
  47         if(matchFewest) {\r
  48             if(fewestMatches.lessEq(matches)) {\r
  49                 int ii = nextMatch(i,pt);\r
  50                 if(ii >= 0) return ii;\r
  51             }\r
  52             while(i >= 0 && i <= endstr) {\r
  53                 i=sub.matchInternal(i,pt);\r
  54                 if(i >= 0) {\r
  55                     matches.inc();\r
  56                     if(fewestMatches.lessEq(matches)) {\r
  57                         int ii = nextMatch(i,pt);\r
  58                         if(ii >= 0) return ii;\r
  59                     }\r
  60                     if(matches.equals(mostMatches))\r
  61                         return -1;\r
  62                 }\r
  63             }\r
  64             return -1;\r
  65         }\r
  66         int nMatches = 0;\r
  67         while(fewestMatches.intValue() > nMatches) {\r
  68             i=sub.matchInternal(i,pt);\r
  69             if(i >= 0)\r
  70                 nMatches++;\r
  71             else\r
  72                 return -1;\r
  73         }\r
  74         m=i;\r
  75         if(mostMatches.finite()) {\r
  76             while(nMatches < mostMatches.intValue()) {\r
  77                 i = sub.matchInternal(i,pt);\r
  78                 if(i>=0) {\r
  79                     m=i;\r
  80                     nMatches++;\r
  81                 } else break;\r
  82             }\r
  83         } else {\r
  84             while(true) {\r
  85                 i = sub.matchInternal(i,pt);\r
  86                 if(i>=0) {\r
  87                     m=i;\r
  88                     nMatches++;\r
  89                 } else break;\r
  90             }\r
  91         }\r
  92         while(m >= pos) {\r
  93             int r=nextMatch(m,pt);\r
  94             if(r >= 0) return r;\r
  95             m -= step;\r
  96             nMatches--;\r
  97             if(nMatches < fewestMatches.intValue())\r
  98                 return -1;\r
  99         }\r
 100         return -1;\r
 101     }\r
 102     public Pattern clone1(Hashtable h) {\r
 103         try {\r
 104             FastMulti fm = new FastMulti(fewestMatches,mostMatches,sub.clone(h));\r
 105             fm.matchFewest = matchFewest;\r
 106             return fm;\r
 107         } catch(RegSyntax rs) {\r
 108             return null;\r
 109         }\r
 110     }\r
 111 }\r