add readme and diff.Interface example with different input types

Author: mb0

README.md

@@ -0,0 +1,32 @@
+diff
+====
+
+A difference algorithm package for go.
+
+The algorithm is described by Eugene Myers in
+["An O(ND) Difference Algorithm and its Variations"](http://www.xmailserver.org/diff2.pdf).
+
+Example
+-------
+You can use diff.Ints and diff.Runes
+
+    d := &diff.Runes{[]rune("sögen"), []rune("mögen")}
+    d.Diff() // returns []Changes{{0,0,1,1}}
+
+or you can implement diff.Interface and use diff.Diff(data)
+
+    type MixedInput struct {
+    	A []int
+    	B []string
+    }
+    func (m *MixedInput) N() int {
+    	return len(m.A)
+    }
+    func (m *MixedInput) M() int {
+    	return len(m.B)
+    }
+    func (m *MixedInput) Equal(a, b int) bool {
+    	return m.A[a] == len(m.B[b])
+    }
+
+Documentation at http://go.pkgdoc.org/github.com/mb0/diff

example_test.go

@@ -0,0 +1,43 @@
+// Copyright 2009 Martin Schnabel. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package diff_test
+
+import (
+	"fmt"
+	"github.com/mb0/diff"
+)
+
+var names = map[string]int {
+	"one": 1,
+	"two": 2,
+	"three": 3,
+}
+
+// Diff on inputs with different representations
+type MixedInput struct {
+	A []int
+	B []string
+}
+
+func (m *MixedInput) N() int {
+	return len(m.A)
+}
+func (m *MixedInput) M() int {
+	return len(m.B)
+}
+func (m *MixedInput) Equal(a, b int) bool {
+	return m.A[a] == names[m.B[b]]
+}
+
+func ExampleInterface() {
+	m := &MixedInput{
+		[]int{1, 2, 3, 1, 2, 2, 1},
+		[]string{"three", "two", "one", "two", "one", "three"},
+	}
+	changes := diff.Diff(m)
+	for _, c := range changes {
+		fmt.Println("change at", c.A, c.B)
+	}
+}