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go/src/infra/libs/gitiles/commit_diff.go

Index: go/src/infra/libs/gitiles/commit_diff.go
diff --git a/go/src/infra/libs/gitiles/commit_diff.go b/go/src/infra/libs/gitiles/commit_diff.go
new file mode 100644
index 0000000000000000000000000000000000000000..87b17b0094a812e96d6309004d5f30c0bf9f2c5a
--- /dev/null
+++ b/go/src/infra/libs/gitiles/commit_diff.go
@@ -0,0 +1,66 @@
+package gitiles
+
+import "strings"
+
+import "infra/libs/git"
+
+// CommitDiffResult contains a git.TreeDiff, or an error.
+type CommitDiffResult struct {
+	Err  error
+	Diff git.TreeDiff
+}
+
+type TextCommitDiffResult struct {
+	Err  error
+	Diff []string
+}
+
+// GetCommitDiff returns the CommitDiffResult from the given committish.
+func (g *Gitiles) GetCommitDiff(committish string) CommitDiffResult {
+	rslt := <-g.JSON(jsonCommitDiff{}, "+", committish)
+	if rslt.Err != nil {
+		return CommitDiffResult{Err: rslt.Err}
+	}
+	diff := *rslt.DataPtr.(*jsonCommitDiff)
+	return diff.ToResult()
+}
+
+func (g *Gitiles) GetTextCommitDiff(id git.ObjectID) TextCommitDiffResult {
+	rslt := <-g.Text("+", id.String()+"^!")
+	if rslt.Err != nil {
+		return TextCommitDiffResult{Err: rslt.Err}
+	}
+	return TextCommitDiffResult{Diff: strings.Split(string(rslt.Data), "\n")}
+}
+
+// private
+
+type jsonCommitDiff struct {
+	TreeDiff []struct {
+		Type    string   `json:"type"`
+		OldID   string   `json:"old_id"`
+		OldMode git.Mode `json:"old_mode"`
+		OldPath string   `json:"old_path"`
+		NewID   string   `json:"new_id"`
+		NewMode git.Mode `json:"new_mode"`
+		NewPath string   `json:"new_path"`
+	} `json:"tree_diff"`
+}
+
+func (c *jsonCommitDiff) ToResult() CommitDiffResult {
+	td := make(git.TreeDiff, 0, len(c.TreeDiff))
+	for _, ent := range c.TreeDiff {
+		td = append(td, git.TreeDiffEntry{
+			Action: strings.ToUpper(ent.Type[:1]),
+			Old: git.TreeDiffEntryHalf{
+				Child: *git.NewEmptyChild(ent.OldMode, git.MakeObjectID(ent.OldID)),
+				Name:  ent.OldPath,
+			},
+			New: git.TreeDiffEntryHalf{
+				Child: *git.NewEmptyChild(ent.NewMode, git.MakeObjectID(ent.NewID)),
+				Name:  ent.NewPath,
+			},
+		})
+	}
+	return CommitDiffResult{Diff: td}
+}