1 files changed, 142 insertions, 0 deletions
diff --git a/libjava/gnu/regexp/CharIndexedReader.java b/libjava/gnu/regexp/CharIndexedReader.java
new file mode 100644
index 0000000..aa0fa5a
--- /dev/null
+++ b/libjava/gnu/regexp/CharIndexedReader.java
@@ -0,0 +1,142 @@
+/*
+ *  gnu/regexp/CharIndexedReader.java
+ *  Copyright (C) 2001 Lee Sau Dan
+ *  Based on gnu.regexp.CharIndexedInputStream by Wes Biggs
+ *
+ *  This library is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published
+ *  by the Free Software Foundation; either version 2.1 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+package gnu.regexp;
+import java.io.Reader;
+import java.io.BufferedReader;
+import java.io.IOException;
+
+// TODO: move(x) shouldn't rely on calling next() x times
+
+class CharIndexedReader implements CharIndexed {
+    private static final int BUFFER_INCREMENT = 1024;
+    private static final int UNKNOWN = Integer.MAX_VALUE; // value for end
+    
+    private final BufferedReader br;
+    // so that we don't try to reset() right away
+    private int index = -1;
+
+    private int bufsize = BUFFER_INCREMENT;
+
+    private int end = UNKNOWN;
+
+    private char cached = OUT_OF_BOUNDS;
+
+    // Big enough for a \r\n pair
+    // lookBehind[0] = most recent
+    // lookBehind[1] = second most recent
+    private char[] lookBehind = new char[] { OUT_OF_BOUNDS, OUT_OF_BOUNDS }; 
+  
+    CharIndexedReader(Reader reader, int index) {
+	if (reader instanceof BufferedReader) {
+	    br = (BufferedReader) reader; 
+	} else {
+	    br = new BufferedReader(reader,BUFFER_INCREMENT);
+	}
+	next();
+	if (index > 0) move(index);
+    }
+    
+    private boolean next() {
+	lookBehind[1] = lookBehind[0];
+	lookBehind[0] = cached;
+
+	if (end == 1) {
+	    cached = OUT_OF_BOUNDS;
+	    return false;
+	}
+	end--; // closer to end
+	
+	try {
+	    if (index != -1) {
+		br.reset();
+	    }
+	    int i = br.read();
+	    br.mark(bufsize);
+	    if (i == -1) {
+		end = 1;
+		cached = OUT_OF_BOUNDS;
+		return false;
+	    }
+
+	    // convert the byte read into a char
+	    cached = (char) i;
+	    index = 1;
+	} catch (IOException e) { 
+	    e.printStackTrace();
+	    cached = OUT_OF_BOUNDS;
+	    return false; 
+	}
+	return true;
+    }
+    
+    public char charAt(int index) {
+	if (index == 0) {
+	    return cached;
+	} else if (index >= end) {
+	    return OUT_OF_BOUNDS;
+	} else if (index >= bufsize) {
+	    // Allocate more space in the buffer.
+	    try {
+		while (bufsize <= index) bufsize += BUFFER_INCREMENT;
+		br.reset();
+		br.mark(bufsize);
+		br.skip(index-1);
+	    } catch (IOException e) { }
+	} else if (this.index != index) {
+	    try {
+		br.reset();
+		br.skip(index-1);
+	    } catch (IOException e) { }
+	} else if (index == -1) {
+	    return lookBehind[0];
+	} else if (index == -2) {
+	    return lookBehind[1];
+	} else if (index < -2) {
+	    return OUT_OF_BOUNDS;
+	}
+
+	char ch = OUT_OF_BOUNDS;
+	
+	try {
+	    int i = br.read();
+	    this.index = index+1; // this.index is index of next pos relative to charAt(0)
+	    if (i == -1) {
+		// set flag that next should fail next time?
+		end = index;
+		return ch;
+	    }
+	    ch = (char) i;
+	} catch (IOException ie) { }
+	
+	return ch;
+    }
+    
+    public boolean move(int index) {
+	// move read position [index] clicks from 'charAt(0)'
+	boolean retval = true;
+	while (retval && (index-- > 0)) retval = next();
+	return retval;
+    }
+    
+    public boolean isValid() {
+	return (cached != OUT_OF_BOUNDS);
+    }
+}