change package for Streams to nikiroo.utils.streams

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

diff --git a/src/be/nikiroo/utils/streams/ReplaceInputStream.java b/src/be/nikiroo/utils/streams/ReplaceInputStream.java
new file mode 100644 (file)
index 0000000..5eac0b4
--- /dev/null
+++ b/src/be/nikiroo/utils/streams/ReplaceInputStream.java
@@ -0,0 +1,101 @@
+package be.nikiroo.utils.streams;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UnsupportedEncodingException;
+
+/**
+ * This {@link InputStream} will replace some of its content by replacing it
+ * with something else.
+ * 
+ * @author niki
+ */
+public class ReplaceInputStream extends BufferedInputStream {
+       private byte[] from;
+       private byte[] to;
+
+       private byte[] source;
+       private int spos;
+       private int slen;
+
+       /**
+        * Create a {@link ReplaceInputStream} that will replace <tt>from</tt> with
+        * <tt>to</tt>.
+        * 
+        * @param in
+        *            the under-laying {@link InputStream}
+        * @param from
+        *            the {@link String} to replace
+        * @param to
+        *            the {@link String} to replace with
+        */
+       public ReplaceInputStream(InputStream in, String from, String to) {
+               this(in, bytes(from), bytes(to));
+       }
+
+       /**
+        * Create a {@link ReplaceInputStream} that will replace <tt>from</tt> with
+        * <tt>to</tt>.
+        * 
+        * @param in
+        *            the under-laying {@link InputStream}
+        * @param from
+        *            the value to replace
+        * @param to
+        *            the value to replace with
+        */
+       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 || source.length < to.length * 2) {
+                       throw new IOException(
+                                       "An underlaying buffer is too small for this replace value");
+               }
+
+               if (spos >= slen) {
+                       spos = 0;
+                       slen = in.read(source);
+               }
+
+               // Note: very simple, not efficient implementation, sorry.
+               int count = 0;
+               while (spos < slen && count < buffer.length - to.length) {
+                       if (from.length > 0 && startsWith(from, source, spos, slen)) {
+                               System.arraycopy(to, 0, buffer, spos, to.length);
+                               count += to.length;
+                               spos += from.length;
+                       } else {
+                               buffer[count++] = source[spos++];
+                       }
+               }
+
+               return count;
+       }
+
+       /**
+        * Return the bytes array representation of the given {@link String} in
+        * UTF-8.
+        * 
+        * @param str
+        *            the string to transform into bytes
+        * @return the content in bytes
+        */
+       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;
+               }
+       }
+}