ReplaceInputStream (wip)

[nikiroo-utils.git] / src / be / nikiroo / utils / ReplaceInputStream.java

diff --git a/src/be/nikiroo/utils/ReplaceInputStream.java b/src/be/nikiroo/utils/ReplaceInputStream.java
new file mode 100644 (file)
index 0000000..5ce9ef3
--- /dev/null
+++ b/src/be/nikiroo/utils/ReplaceInputStream.java
@@ -0,0 +1,68 @@
+package be.nikiroo.utils;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UnsupportedEncodingException;
+
+public class ReplaceInputStream extends BufferedInputStream {
+       private byte[] from;
+       private byte[] to;
+
+       private byte[] source;
+       private int spos;
+       private int slen;
+
+       public ReplaceInputStream(InputStream in, String from, String to) {
+               this(in, bytes(from), bytes(to));
+       }
+
+       public ReplaceInputStream(InputStream in, byte[] from, byte[] to) {
+               super(in);
+               this.from = from;
+               this.to = to;
+
+               source = new byte[4096];
+               spos = 0;
+               slen = 0;
+       }
+
+       @Override
+       protected int read(InputStream in, byte[] buffer) throws IOException {
+               if (buffer.length < to.length) {
+                       throw new IOException(
+                                       "Underlaying buffer is too small to contain the replace String");
+               }
+
+               if (spos >= slen) {
+                       spos = 0;
+                       slen = in.read(source);
+               }
+
+               // Note: very simple, not efficient implementation, sorry.
+               int count = 0;
+               int i = spos;
+               while (i < slen && count < buffer.length - to.length) {
+                       if (from.length > 0 && startsWith(from, source, spos)) {
+                               System.arraycopy(to, 0, buffer, spos, to.length);
+                               count += to.length;
+                               i += to.length;
+                               spos += to.length;
+                       } else {
+                               buffer[count++] = source[i++];
+                               spos++;
+                       }
+               }
+
+               return count;
+       }
+
+       static private byte[] bytes(String str) {
+               try {
+                       return str.getBytes("UTF-8");
+               } catch (UnsupportedEncodingException e) {
+                       // All conforming JVM must support UTF-8
+                       e.printStackTrace();
+                       return null;
+               }
+       }
+}