implement huffman encoding

jetty-hpack/src/main/java/org/eclipse/jetty/hpack/Huffman.java

@@ -344,6 +344,8 @@ public class Huffman
 
     static public String decode(ByteBuffer buf) throws IOException 
     {
+        // TODO offer a version that does a direct lookup of compressed strings to known values
+        
         StringBuilder out = new StringBuilder(buf.remaining()*2);
         int node = 0;
         int current = 0;
@@ -391,4 +393,38 @@ public class Huffman
 
         return out.toString();
     }
+    
+
+    static public void encode(ByteBuffer buf,String s) throws IOException 
+    {
+        long current = 0;
+        int n = 0;
+
+        int len = s.length();
+        for (int i=0;i<len;i++)
+        {
+            char c=s.charAt(i);
+            if (c>=128)
+                throw new IllegalArgumentException();
+            int code = CODES[c][0];
+            int bits = CODES[c][1];
+
+            current <<= bits;
+            current |= code;
+            n += bits;
+
+            while (n >= 8) 
+            {
+                n -= 8;
+                buf.put((byte)(current >> n));
+            }
+        }
+
+        if (n > 0) 
+        {
+          current <<= (8 - n);
+          current |= (0xFF >>> n); 
+          buf.put((byte)current);
+        }
+    }
 }

jetty-hpack/src/main/java/org/eclipse/jetty/hpack/NBitInteger.java

@@ -114,7 +114,7 @@ public class NBitInteger
         }
     }
 
-    public static int dencode5(ByteBuffer buf)
+    public static int decode5(ByteBuffer buf)
     {
         int nbits = 0xFF >>> (8 - 5);
 
@@ -135,7 +135,7 @@ public class NBitInteger
         return i;
     }
 
-    public static int dencode8(ByteBuffer buf)
+    public static int decode8(ByteBuffer buf)
     {
         int nbits = 0xFF >>> (8 - 8);
 

jetty-hpack/src/test/java/org/eclipse/jetty/hpack/HuffmanTest.java

@@ -21,12 +21,12 @@ package org.eclipse.jetty.hpack;
 import java.nio.ByteBuffer;
 
 import org.junit.Assert;
+import org.eclipse.jetty.util.BufferUtil;
 import org.eclipse.jetty.util.TypeUtil;
 import org.junit.Test;
 
 public class HuffmanTest
 {
-
     String[][] tests =
         {
             {"D.4.1","e7cf9bebe89b6fb16fa9b6ff","www.example.com"},
@@ -49,6 +49,21 @@ public class HuffmanTest
             String decoded=Huffman.decode(ByteBuffer.wrap(encoded));
             Assert.assertEquals(test[0],test[2],decoded);
         }
+    }
+    
+    @Test
+    public void testEncode() throws Exception
+    {
+        for (String[] test:tests)
+        {
+            ByteBuffer buf = BufferUtil.allocate(1024);
+            int pos=BufferUtil.flipToFill(buf);
+            Huffman.encode(buf,test[2]);
+            BufferUtil.flipToFlush(buf,pos);
+            String encoded=TypeUtil.toHexString(BufferUtil.toArray(buf)).toLowerCase();
+            Assert.assertEquals(test[0],test[1],encoded);
+        }
         
     }
+    
 }

jetty-hpack/src/test/java/org/eclipse/jetty/hpack/NBitIntegerTest.java

@@ -50,7 +50,7 @@ public class NBitIntegerTest
         ByteBuffer buf = ByteBuffer.wrap(TypeUtil.fromHexString("77EaFF"));
         buf.position(2);
         
-        Assert.assertEquals(10,NBitInteger.dencode5(buf));
+        Assert.assertEquals(10,NBitInteger.decode5(buf));
     }
     
 
@@ -76,7 +76,7 @@ public class NBitIntegerTest
         ByteBuffer buf = ByteBuffer.wrap(TypeUtil.fromHexString("881f9a0aff"));
         buf.position(2);
         
-        Assert.assertEquals(1337,NBitInteger.dencode5(buf));
+        Assert.assertEquals(1337,NBitInteger.decode5(buf));
     }
     
     
@@ -103,7 +103,7 @@ public class NBitIntegerTest
         ByteBuffer buf = ByteBuffer.wrap(TypeUtil.fromHexString("882aFf"));
         buf.position(1);
         
-        Assert.assertEquals(42,NBitInteger.dencode8(buf));
+        Assert.assertEquals(42,NBitInteger.decode8(buf));
     }