Implement Pattern / Matcher classes based on the PikeVM

Based on the just-implemented PikeVM, let's test it with a specific
regular expression. At this point, no parsing is implemented but instead
an explicit program executing a(bb)?a is hardcoded.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

test/regex/Pattern.java

@@ -19,7 +19,7 @@ import java.util.List;
  * @author zsombor and others
  * 
  */
-public abstract class Pattern {
+public abstract class Pattern implements PikeVMOpcodes {
 
   public static final int UNIX_LINES       = 1;
   public static final int CASE_INSENSITIVE = 2;
@@ -46,6 +46,23 @@ public abstract class Pattern {
     try {
       return new TrivialPattern(regex, flags);
     } catch (UnsupportedOperationException handledBelow) { }
+    if (flags != 0) {
+      throw new UnsupportedOperationException("TODO");
+    }
+    if ("a(bb)?a".equals(regex)) {
+      int[] program = new int[] {
+        SAVE_OFFSET, 0,
+        CHAR, 'a',
+        SPLIT, 14,
+        SAVE_OFFSET, 2,
+        CHAR, 'b',
+        CHAR, 'b',
+        SAVE_OFFSET, 3,
+        /* 14 */ CHAR, 'a',
+        SAVE_OFFSET, 1
+      };
+      return new RegexPattern(regex, flags, new PikeVM(program, 1));
+    }
     throw new UnsupportedOperationException("Cannot handle regex " + regex);
   }
 

test/regex/RegexMatcher.java

@@ -0,0 +1,55 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package regex;
+
+/**
+ * A minimal implementation of a regular expression matcher.
+ * 
+ * @author Johannes Schindelin
+ */
+public class RegexMatcher extends Matcher {
+  private final PikeVM vm;
+  private char[] array;
+  int[] groupStart, groupEnd;
+
+  RegexMatcher(PikeVM vm, CharSequence string) {
+    super(string);
+    this.vm = vm;
+  }
+
+  private final PikeVM.Result adapter = new PikeVM.Result() {
+    public void set(int[] start, int[] end) {
+      RegexMatcher.this.start = start[0];
+      RegexMatcher.this.end = end[0];
+      RegexMatcher.this.groupStart = start;
+      RegexMatcher.this.groupEnd = end;
+    }
+  };
+
+  public Matcher reset() {
+    start = end = -1;
+    return this;
+  }
+
+  public Matcher reset(CharSequence input) {
+    this.input = input;
+    array = input.toString().toCharArray();
+    return reset();
+  }
+
+  public boolean matches() {
+    return vm.matches(array, 0, array.length, true, true, adapter);
+  }
+
+  public boolean find(int offset) {
+    throw new UnsupportedOperationException("TODO");
+  }
+}

test/regex/RegexPattern.java

@@ -0,0 +1,29 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package regex;
+
+/**
+ * A minimal implementation of a regular expression engine.
+ * 
+ * @author Johannes Schindelin
+ */
+public class RegexPattern extends Pattern {
+  private PikeVM vm;
+
+  public RegexMatcher matcher(CharSequence string) {
+    return new RegexMatcher(vm, string);
+  }
+
+  RegexPattern(String regex, int flags, PikeVM vm) {
+    super(regex, flags);
+    this.vm = vm;
+  }
+}