implement enough of java.util.regex to ensure String methods work for trivial regular expressions

classpath/java/util/regex/Matcher.java

@@ -1,4 +1,4 @@
-/* Copyright (c) 2008, Avian Contributors
+/* Copyright (c) 2008-2009, Avian Contributors
 
    Permission to use, copy, modify, and/or distribute this software
    for any purpose with or without fee is hereby granted, provided
@@ -11,17 +11,29 @@
 package java.util.regex;
 
 /**
- * This implementation is a skeleton, useful only for compilation. At runtime it
- * is need to be replaced by a working implementation, for example one from the
- * Apache Harmony project.
- * 
- * @author zsombor
+ * This is a work in progress.
  * 
+ * @author zsombor and others
  */
 public class Matcher {
+  private final Pattern pattern;
+  private CharSequence input;
+  private int start;
+  private int end;
+
+  Matcher(Pattern pattern, CharSequence input) {
+    this.pattern = pattern;
+    this.input = input;
+  }
 
   public boolean matches() {
-    throw new UnsupportedOperationException();
+    if (pattern.pattern().equals(input.toString())) {
+      start = 0;
+      end = input.length();
+      return true;
+    } else {
+      return false;
+    }
   }
 
   public boolean requireEnd() {
@@ -37,15 +49,18 @@ public class Matcher {
   }
 
   public Matcher reset() {
-    throw new UnsupportedOperationException();
+    return reset(input);
   }
 
   public Matcher reset(CharSequence input) {
-    throw new UnsupportedOperationException();
+    this.input = input;
+    start = 0;
+    end = 0;
+    return this;
   }
 
   public int start() {
-    throw new UnsupportedOperationException();
+    return start;
   }
 
   public int start(int group) {
@@ -69,15 +84,44 @@ public class Matcher {
   }
 
   public String replaceAll(String replacement) {
-    throw new UnsupportedOperationException();
+    return replace(replacement, Integer.MAX_VALUE);
   }
 
   public String replaceFirst(String replacement) {
-    throw new UnsupportedOperationException();
+    return replace(replacement, 1);
+  }
+
+  private String replace(String replacement, int limit) {
+    reset();
+
+    StringBuilder sb = null;
+    int index = 0;
+    int count = 0;
+    while (count < limit && index < input.length()) {
+      if (find(index)) {
+        if (sb == null) {
+          sb = new StringBuilder();
+        }
+        if (start > index) {
+          sb.append(input.subSequence(index, start));
+        }
+        sb.append(replacement);
+        index = end;
+        ++ count;
+      } else if (index == 0) {
+        return input.toString();
+      } else {
+        break;
+      }
+    }
+    if (index < input.length()) {
+      sb.append(input.subSequence(index, input.length()));
+    }
+    return sb.toString();
   }
 
   public int end() {
-    throw new UnsupportedOperationException();
+    return end;
   }
 
   public int end(int group) {
@@ -85,11 +129,19 @@ public class Matcher {
   }
 
   public boolean find() {
-    throw new UnsupportedOperationException();
+    return find(end);
   }
 
   public boolean find(int start) {
-    throw new UnsupportedOperationException();
+    String p = pattern.pattern();
+    int i = Pattern.indexOf(input, p, start);
+    if (i >= 0) {
+      this.start = i;
+      this.end = i + p.length();
+      return true;
+    } else {
+      return false;
+    }
   }
 
   public int groupCount() {