5 files changed, 189 insertions, 2 deletions
diff --git a/src/main/java/io/trygvis/btree/Bits.java b/src/main/java/io/trygvis/btree/Bits.java
new file mode 100644
index 0000000..c38e865
--- /dev/null
+++ b/src/main/java/io/trygvis/btree/Bits.java
@@ -0,0 +1,11 @@
+package io.trygvis.btree;
+
+public class Bits {
+    public static byte[] toBytes(int i) {
+        return new byte[]{(byte) (i >> 24), (byte) (i >> 16), (byte) (i >> 8), (byte) i};
+    }
+
+    public static int intFromBytes(byte[] bytes) {
+        return (bytes[0] << 24) + (bytes[1] << 16) + (bytes[2] << 8) + bytes[2];
+    }
+}
diff --git a/src/main/java/io/trygvis/btree/BtreeFile.java b/src/main/java/io/trygvis/btree/BtreeFile.java
new file mode 100644
index 0000000..7300b5e
--- /dev/null
+++ b/src/main/java/io/trygvis/btree/BtreeFile.java
@@ -0,0 +1,63 @@
+package io.trygvis.btree;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Iterator;
+
+public class BtreeFile implements Closeable {
+    private final HeapFile heap;
+    private final int keySize;
+    private final int itemsPerPage;
+
+    public BtreeFile(HeapFile heap, int keySize) throws IOException {
+        this.heap = heap;
+        this.keySize = keySize;
+        itemsPerPage = heap.PAGE_SIZE / keySize;
+
+        // Make sure we always have a page #0.
+        if (heap.pageCount() == 0) {
+            HeapPage root = heap.blankPage();
+            heap.writePage(root);
+        }
+    }
+
+    public void add(byte[] key, byte[] value) throws IOException {
+        HeapPage page = heap.loadPage(0);
+
+        ByteBuffer k = ByteBuffer.wrap(key);
+        ByteBuffer current;
+        ByteBuffer smaller;
+
+        Iterator<ByteBuffer> it = page.items().iterator();
+
+        int position = 0;
+
+        while(it.hasNext()) {
+            current = it.next();
+
+            int diff = k.compareTo(current);
+
+            if(diff < 0) {
+                break;
+            }
+        }
+
+//        page.prepend();
+    }
+
+    @Override
+    public void close() throws IOException {
+        heap.close();
+    }
+
+    public static class BtreeItem {
+        private final byte[] from;
+        private final int page;
+
+        public BtreeItem(byte[] from, int page) {
+            this.from = from;
+            this.page = page;
+        }
+    }
+}
diff --git a/src/main/java/io/trygvis/btree/BtreeMap.java b/src/main/java/io/trygvis/btree/BtreeMap.java
new file mode 100644
index 0000000..06c348f
--- /dev/null
+++ b/src/main/java/io/trygvis/btree/BtreeMap.java
@@ -0,0 +1,97 @@
+package io.trygvis.btree;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Set;
+
+public class BtreeMap<K, V> implements Map<K, V>, Closeable {
+
+    public static interface Serializer<A> {
+        byte[] toBytes(A a);
+
+        A fromBytes(byte[] bytes);
+    }
+
+    private final BtreeFile tree;
+    private final Serializer<K> kSerializer;
+    private final Serializer<V> vSerializer;
+
+    public BtreeMap(BtreeFile tree, Serializer<K> kSerializer, Serializer<V> vSerializer) {
+        this.tree = tree;
+        this.kSerializer = kSerializer;
+        this.vSerializer = vSerializer;
+    }
+
+    @Override
+    public void close() throws IOException {
+        tree.close();
+    }
+
+    @Override
+    public int size() {
+        return 0;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return size() == 0;
+    }
+
+    @Override
+    public boolean containsKey(Object key) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean containsValue(Object value) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V get(Object key) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V put(K key, V value) {
+        try {
+            tree.add(kSerializer.toBytes(key), vSerializer.toBytes(value));
+
+            return null;
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    public V remove(Object key) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void putAll(Map<? extends K, ? extends V> m) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Set<K> keySet() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Collection<V> values() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Set<Entry<K, V>> entrySet() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/src/main/java/io/trygvis/btree/HeapFile.java b/src/main/java/io/trygvis/btree/HeapFile.java
index 6bd0451..83b2f48 100644
--- a/src/main/java/io/trygvis/btree/HeapFile.java
+++ b/src/main/java/io/trygvis/btree/HeapFile.java
@@ -11,7 +11,7 @@ import static io.trygvis.btree.HeapPage.blankHeapPage;
 import static java.nio.ByteBuffer.allocateDirect;
 
 public class HeapFile implements Closeable {
-    private final int PAGE_SIZE;
+    public final int PAGE_SIZE;
 
     private final RandomAccessFile file;
     private final FileChannel channel;
diff --git a/src/main/java/io/trygvis/btree/HeapPage.java b/src/main/java/io/trygvis/btree/HeapPage.java
index a931260..32ba0ef 100644
--- a/src/main/java/io/trygvis/btree/HeapPage.java
+++ b/src/main/java/io/trygvis/btree/HeapPage.java
@@ -53,11 +53,27 @@ public class HeapPage {
         bytes.putInt(FREE_POSITION_INDEX, freePosition);
     }
 
+    public void prepend(byte[] item) {
+        int bytesFree = bytesFree();
+        int bytesRequested = item.length;
+
+        if (bytesRequested > bytesFree) {
+            throw new PageOverflowException(bytesFree, bytesRequested);
+        }
+
+        byte[] array = bytes.array();
+        int offset = bytes.arrayOffset();
+
+        System.arraycopy(array, offset, array, offset + bytesRequested, bytesRequested);
+
+        freePosition -= itemSize;
+    }
+
     public int bytesFree() {
         return freePosition - headerSize;
     }
 
-    public Iterable<ByteBuffer> bufferIterator() {
+    public Iterable<ByteBuffer> items() {
         return new Iterable<ByteBuffer>() {
             @Override
             public Iterator<ByteBuffer> iterator() {