2003/06/28 06:54:18

[org.ibex.core.git] / src / gnu / regexp / CharIndexedInputStream.java

diff --git a/src/gnu/regexp/CharIndexedInputStream.java b/src/gnu/regexp/CharIndexedInputStream.java
new file mode 100644 (file)
index 0000000..d972ea3
--- /dev/null
+++ b/src/gnu/regexp/CharIndexedInputStream.java
@@ -0,0 +1,131 @@
+/*
+ *  gnu/regexp/CharIndexedReader.java
+ *  Copyright (C) 1998-2001 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.InputStream;
+import java.io.BufferedInputStream;
+import java.io.IOException;
+
+// TODO: move(x) shouldn't rely on calling next() x times
+
+class CharIndexedInputStream implements CharIndexed {
+    private static final int BUFFER_INCREMENT = 1024;
+    private static final int UNKNOWN = Integer.MAX_VALUE; // value for end
+    
+    private BufferedInputStream 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 }; 
+    
+    CharIndexedInputStream(InputStream str, int index) {
+       if (str instanceof BufferedInputStream) br = (BufferedInputStream) str;
+       else br = new BufferedInputStream(str,BUFFER_INCREMENT);
+       next();
+       if (index > 0) move(index);
+    }
+    
+    private boolean next() {
+       if (end == 1) 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;
+           }
+           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 == -1) {
+           return lookBehind[0];
+       } else if (index == -2) {
+           return lookBehind[1];
+       } else if (index < -2) {
+           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) { }
+       }
+       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);
+    }
+}
+