add Compare
diff --git a/pretty/.gitignore b/pretty/.gitignore
index 9938b36..fa9a735 100644
--- a/pretty/.gitignore
+++ b/pretty/.gitignore
@@ -2,3 +2,4 @@
*.bench
*.golden
*.txt
+*.prof
diff --git a/pretty/doc.go b/pretty/doc.go
index 1734256..ecd7041 100644
--- a/pretty/doc.go
+++ b/pretty/doc.go
@@ -10,4 +10,5 @@
// - Catch cycles
// - Compare function
// - Logging helpers
+// - Change Options to Config
package pretty
diff --git a/pretty/reflect.go b/pretty/reflect.go
index bc0e8ec..dbedb7f 100644
--- a/pretty/reflect.go
+++ b/pretty/reflect.go
@@ -80,15 +80,3 @@
return rawVal(val.String())
}
-
-// Print writes the default representation of the given values to standard output.
-func Print(vals ...interface{}) {
- DefaultOptions.Print(vals...)
-}
-
-// Print writes the configured presentation of the given values to standard output.
-func (o *Options) Print(vals ...interface{}) {
- for _, val := range vals {
- fmt.Println(Reflect(val, o))
- }
-}
diff --git a/pretty/util.go b/pretty/util.go
new file mode 100644
index 0000000..ee3bacc
--- /dev/null
+++ b/pretty/util.go
@@ -0,0 +1,126 @@
+package pretty
+
+import (
+ "bytes"
+ "fmt"
+ "strings"
+)
+
+// Print writes the default representation of the given values to standard output.
+func Print(vals ...interface{}) {
+ DefaultOptions.Print(vals...)
+}
+
+// Print writes the configured presentation of the given values to standard output.
+func (o *Options) Print(vals ...interface{}) {
+ for _, val := range vals {
+ fmt.Println(Reflect(val, o))
+ }
+}
+
+func Compare(got, want interface{}) string {
+ diffOpt := &Options{Diffable: true}
+ gotLines := strings.Split(Reflect(got, diffOpt), "\n")
+ wantLines := strings.Split(Reflect(want, diffOpt), "\n")
+
+ chunks := diff(gotLines, wantLines)
+ return diffString(chunks)
+}
+
+type chunk struct {
+ add []string
+ del []string
+ eq []string
+}
+
+// Diff uses an O(D(N+M)) shortest-edit-script algorithm
+// to compute the difference between A and B.
+//
+// algorithm: http://www.xmailserver.org/diff2.pdf
+func diff(A, B []string) []chunk {
+ N, M := len(A), len(B)
+ MAX := N + M
+ V := make([]int, 2*MAX+1)
+ Vs := make([][]int, 0, 8)
+
+ var D int
+dLoop:
+ for D = 0; D <= MAX; D++ {
+ for k := -D; k <= D; k += 2 {
+ var x int
+ if k == -D || (k != D && V[MAX+k-1] < V[MAX+k+1]) {
+ x = V[MAX+k+1]
+ } else {
+ x = V[MAX+k-1] + 1
+ }
+ y := x - k
+ for x < N && y < M && A[x] == B[y] {
+ x++
+ y++
+ }
+ V[MAX+k] = x
+ if x >= N && y >= M {
+ Vs = append(Vs, append(make([]int, 0, len(V)), V...))
+ break dLoop
+ }
+ }
+ Vs = append(Vs, append(make([]int, 0, len(V)), V...))
+ }
+ fmt.Println(D, N-M)
+ for _, V := range Vs {
+ fmt.Println(V[:MAX-1], V[MAX:MAX+1], V[MAX+1:])
+ }
+ if D == 0 {
+ return nil
+ }
+ chunks := make([]chunk, D+1)
+
+ x, y := N, M
+ for d := D; d > 0; d-- {
+ V := Vs[d]
+ k := x - y
+ insert := k == -d || (k != d && V[MAX+k-1] < V[MAX+k+1])
+
+ x1 := V[MAX+k]
+ var x0, xM, kk int
+ if insert {
+ kk = k + 1
+ x0 = V[MAX+kk]
+ xM = x0
+ } else {
+ kk = k - 1
+ x0 = V[MAX+kk]
+ xM = x0 + 1
+ }
+ y0 := x0 - kk
+
+ var c chunk
+ if insert {
+ c.add = B[y0:][:1]
+ } else {
+ c.del = A[x0:][:1]
+ }
+ c.eq = A[xM:][:x1-xM]
+
+ x, y = x0, y0
+ chunks[d] = c
+ }
+ chunks[0].eq = A[:x]
+ return chunks
+}
+
+func diffString(chunks []chunk) string {
+ buf := new(bytes.Buffer)
+ for _, c := range chunks {
+ for _, line := range c.del {
+ fmt.Fprintf(buf, "-%s\n", line)
+ }
+ for _, line := range c.add {
+ fmt.Fprintf(buf, "+%s\n", line)
+ }
+ for _, line := range c.eq {
+ fmt.Fprintf(buf, " %s\n", line)
+ }
+ }
+ return buf.String()
+}
diff --git a/pretty/util_test.go b/pretty/util_test.go
new file mode 100644
index 0000000..499449a
--- /dev/null
+++ b/pretty/util_test.go
@@ -0,0 +1,59 @@
+package pretty
+
+import (
+ "testing"
+)
+
+func TestDiff(t *testing.T) {
+ type example struct {
+ name string
+ age int
+ friends []string
+ }
+
+ tests := []struct {
+ desc string
+ got, want interface{}
+ diff string
+ }{
+ {
+ desc: "basic struct",
+ got: example{
+ name: "Zaphd",
+ age: 42,
+ friends: []string{
+ "Ford Prefect",
+ "Trillian",
+ "Marvin",
+ },
+ },
+ want: example{
+ name: "Zaphod",
+ age: 42,
+ friends: []string{
+ "Ford Prefect",
+ "Trillian",
+ },
+ },
+ diff: ` {
+- name: "Zaphd",
++ name: "Zaphod",
+ age: 42,
+ friends: [
+ "Ford Prefect",
+ "Trillian",
+- "Marvin",
+ ],
+ }
+`,
+ },
+ }
+
+ for _, test := range tests {
+ if got, want := Compare(test.got, test.want), test.diff; got != want {
+ t.Errorf("%s:", test.desc)
+ t.Errorf(" got: %q", got)
+ t.Errorf(" want: %q", want)
+ }
+ }
+}
