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
+ * This is a work in progress.
- * is need to be replaced by a working implementation, for example one from the
- * Apache Harmony project.
- * 
- * @author zsombor
  * 
+ * @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() {

classpath/java/util/regex/Pattern.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
@@ -10,12 +10,14 @@
 
 package java.util.regex;
 
+import java.util.Iterator;
+import java.util.List;
+import java.util.LinkedList;
+
 /**
- * This implementation is a skeleton, useful only for compilation. At runtime it
+ * This is a work in progress.
- * is need to be replaced by a working implementation, for example one from the
- * Apache Harmony project.
  * 
- * @author zsombor
+ * @author zsombor and others
  * 
  */
 public class Pattern {
@@ -29,12 +31,41 @@ public class Pattern {
   public static final int UNICODE_CASE     = 64;
   public static final int CANON_EQ         = 128;
 
-  private int             patternFlags;
+  private final int patternFlags;
-  private String          pattern;
+  private final String pattern;
 
   protected Pattern(String pattern, int flags) {
     this.pattern = pattern;
     this.patternFlags = flags;
+
+    if (! trivial(pattern)) {
+      throw new UnsupportedOperationException
+        ("only trivial regular expressions are supported so far");
+    }
+  }
+
+  private static boolean trivial(String pattern) {
+    for (int i = 0; i < pattern.length(); ++i) {
+      char c = pattern.charAt(i);
+      switch (c) {
+      case '\\':
+      case '.':
+      case '*':
+      case '+':
+      case '?':
+      case '|':
+      case '[':
+      case ']':
+      case '{':
+      case '}':
+      case '(':
+      case ')':
+      case '^':
+      case '$':
+        return false;
+      }
+    }
+    return true;
   }
 
   public static Pattern compile(String regex) {
@@ -50,7 +81,7 @@ public class Pattern {
   }
 
   public Matcher matcher(CharSequence input) {
-    throw new UnsupportedOperationException();
+    return new Matcher(this, input);
   }
 
   public static boolean matches(String regex, CharSequence input) {
@@ -66,10 +97,72 @@ public class Pattern {
   }
 
   public String[] split(CharSequence input) {
-    throw new UnsupportedOperationException();
+    return split(input, 0);
   }
 
   public String[] split(CharSequence input, int limit) {
-    throw new UnsupportedOperationException();
+    boolean strip;
+    if (limit < 0) {
+      strip = false;
+      limit = Integer.MAX_VALUE;
+    } else if (limit == 0) {
+      strip = true;
+      limit = Integer.MAX_VALUE;
+    } else {
+      strip = false;
+    }
+
+    List<CharSequence> list = new LinkedList();
+    int index = 0;
+    int trailing = 0;
+    while (index < input.length() && list.size() < limit) {
+      int i = indexOf(input, pattern, index);
+      if (i >= 0) {
+        if (i == index) {
+          ++ trailing;
+        } else {
+          trailing = 0;
+        }
+
+        list.add(input.subSequence(index, i));
+        index = i + pattern.length();
+      } else {
+        break;
+      }
+    }
+
+    if (strip && index == input.length()) {
+      ++ trailing;
+    } else {
+      trailing = 0;
+    }
+    list.add(input.subSequence(index, input.length()));
+
+    String[] result = new String[list.size() - trailing];
+    int i = 0;
+    for (Iterator<CharSequence> it = list.iterator();
+         it.hasNext() && i < result.length; ++ i)
+    {
+      result[i] = it.next().toString();
+    }
+    return result;
+  }
+
+  static int indexOf(CharSequence haystack, CharSequence needle, int start) {
+    if (needle.length() == 0) return start;
+
+    for (int i = start; i < haystack.length() - needle.length() + 1; ++i) {
+      int j = 0;
+      for (; j < needle.length(); ++j) {
+        if (haystack.charAt(i + j) != needle.charAt(j)) {
+          break;
+        }
+      }
+      if (j == needle.length()) {
+        return i;
+      }
+    }
+
+    return -1;
   }
 }

test/Strings.java

@@ -9,9 +9,20 @@ public class Strings {
                                    115, 46, 83, 121, 109, 98, 111, 108 })
       .equals("com.ecovate.nat.bus.Symbol"));
     
-    // We don't yet have a regex implementation, so this test will fail:
+    final String months = "Jan\u00aeFeb\u00aeMar\u00ae";
-//     final String months = "Jan\u00aeFeb\u00aeMar\u00ae";
+    expect(months.split("\u00ae").length == 3);
-//     expect(months.split("\u00ae").length == 3);
+    expect(months.replaceAll("\u00ae", ".").equals("Jan.Feb.Mar."));
+
+    expect("foo_foofoo__foo".replaceAll("_", "__")
+           .equals("foo__foofoo____foo"));
+
+    expect("foo_foofoo__foo".replaceFirst("_", "__")
+           .equals("foo__foofoo__foo"));
+
+    expect("stereomime".matches("stereomime"));
+    expect(! "stereomime".matches("stereomim"));
+    expect(! "stereomime".matches("tereomime"));
+    expect(! "stereomime".matches("sterEomime"));
 
     StringBuilder sb = new StringBuilder();
     sb.append('$');