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  1. import java.util.regex.*;
  2.  
  3. public class Main {
  4.     private static Pattern combineRe(Pattern p1, Pattern p2){
  5.         return Pattern.compile(combineRE(p1.pattern(), p2.pattern()));
  6.     }
  7.     private static String combineRE(String p1, String p2){
  8.         int groups1 = 0, groups2=0;
  9.         StringBuilder newP = new StringBuilder("(?=");
  10.         newP.append(p1);
  11.         newP.append("$)(?=");
  12.  
  13.         Pattern capturingGroup = Pattern.compile("(?<!\\\\)(\\\\\\\\)*\\((?!\\?)");
  14.         Matcher m = capturingGroup.matcher(p1);
  15.         while(m.find()) groups1 ++;
  16.  
  17.         m = capturingGroup.matcher(p2);
  18.  
  19.         while(m.find()) groups2 ++;
  20.         String new2 = p2;
  21.  
  22.         for(int i=1; i<=groups2; i++)
  23.             new2 = new2.replaceAll("(?<!\\\\)\\\\"+i, "\\\\" + (i+groups1));
  24.  
  25.         newP.append(new2);
  26.         newP.append("$).*");
  27.         return newP.toString();
  28.     }
  29.     public static void main(String[] args){
  30.         reComboTestCase[] cases = {
  31.             new reComboTestCase(
  32.                 "(?=.*)([ab])\\1"
  33.                 , "([c]*)\\1bb"
  34.                 , new String[] { "aa" }
  35.                 , new String[] { "ccccbb" }
  36.                 , new String[] { "bb" }
  37.             )
  38.             , new reComboTestCase(
  39.                 "a."
  40.                 , ".b"
  41.                 , new String[] { "aa", "ac" }
  42.                 , new String[] { "bb", "cb"}
  43.                 , new String[] { "ab" }
  44.             )
  45.         };
  46.  
  47.         for (int i=0; i<cases.length; i++)
  48.             cases[i].test(i);
  49.     }
  50.     private static class reComboTestCase{
  51.         String p1;
  52.         String p2;
  53.         String[] left; //Strings that should match p1 but not p2
  54.         String[] right; //Strings that should match p2 but not p1
  55.         String[] intersect; //Strings that should match both
  56.         public reComboTestCase(String p1, String p2, String[] left, String[] right, String[] intersect) {
  57.             this.p1 = p1;
  58.             this.p2 = p2;
  59.             this.left = left;
  60.             this.right = right;
  61.             this.intersect = intersect;
  62.         }
  63.         public void test(int n){
  64.             System.out.printf("TEST %d:\n", n);
  65.             System.out.printf("\t   P1: %s\n", p1);
  66.             System.out.printf("\t   P2: %s\n", p2);
  67.             String combo = Main.combineRE(p1,p2);
  68.             System.out.printf("\tCombo: %s\n", combo);
  69.             Pattern one = Pattern.compile(p1);
  70.             Pattern two = Pattern.compile(p2);
  71.             Pattern three = Pattern.compile(combo);
  72.             System.out.printf("\t%100s: %5s %5s %5s\n", "LEFT", "ONE", "TWO", "COMBO");
  73.             for(int i=0; i<left.length; i++)
  74.                 System.out.printf("\t%100s: %5s %5s %5s\n"
  75.                     , left[i]
  76.                     , one.matcher(left[i]).matches()
  77.                     , two.matcher(left[i]).matches()
  78.                     , three.matcher(left[i]).matches()
  79.                 );
  80.             System.out.printf("\t%100s: %5s %5s %5s\n", "RIGHT", "ONE", "TWO", "COMBO");
  81.             for(int i=0; i<right.length; i++)
  82.                 System.out.printf("\t%100s: %5s %5s %5s\n"
  83.                     , left[i]
  84.                     , one.matcher(right[i]).matches()
  85.                     , two.matcher(right[i]).matches()
  86.                     , three.matcher(right[i]).matches()
  87.                 );
  88.             System.out.printf("\t%100s: %5s %5s %5s\n", "INTERSECT", "ONE", "TWO", "COMBO");
  89.             for(int i=0; i<intersect.length; i++)
  90.                 System.out.printf("\t%100s: %5s %5s %5s\n"
  91.                     , left[i]
  92.                     , one.matcher(intersect[i]).matches()
  93.                     , two.matcher(intersect[i]).matches()
  94.                     , three.matcher(intersect[i]).matches()
  95.                 );
  96.  
  97.         }
  98.     }
  99. }
Success #stdin #stdout 0.09s 380544KB
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Standard input is empty
stdout
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TEST 0:
	   P1: (?=.*)([ab])\1
	   P2: ([c]*)\1bb
	Combo: (?=(?=.*)([ab])\1$)(?=([c]*)\2bb$).*
	                                                                                                LEFT:   ONE   TWO COMBO
	                                                                                                  aa:  true false false
	                                                                                               RIGHT:   ONE   TWO COMBO
	                                                                                                  aa: false  true false
	                                                                                           INTERSECT:   ONE   TWO COMBO
	                                                                                                  aa:  true  true  true
TEST 1:
	   P1: a.
	   P2: .b
	Combo: (?=a.$)(?=.b$).*
	                                                                                                LEFT:   ONE   TWO COMBO
	                                                                                                  aa:  true false false
	                                                                                                  ac:  true false false
	                                                                                               RIGHT:   ONE   TWO COMBO
	                                                                                                  aa: false  true false
	                                                                                                  ac: false  true false
	                                                                                           INTERSECT:   ONE   TWO COMBO
	                                                                                                  aa:  true  true  true
https://ideone.com/Wm8cRc
language:
Java (HotSpot 12)
created:
11 years ago
visibility:
public

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