From b184d1ccfcd1d13c364aff7c82f795030472b4a0 Mon Sep 17 00:00:00 2001
From: Ian Cottrell <iancottrell@google.com>
Date: Fri, 5 Apr 2019 12:16:45 -0400
Subject: [PATCH] internal/lsp: change diff Op.Content to be the unjoined
 strings

This also means we don't need the J2 becasue it is implied by len(Content)

Change-Id: I04e2cbaa3e1faa1e3add22ec2d478821b9062419
Reviewed-on: https://go-review.googlesource.com/c/tools/+/170878
Run-TryBot: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
---
 internal/lsp/diff/diff.go      | 15 +++++----------
 internal/lsp/diff/diff_test.go | 16 ++++++++--------
 internal/lsp/source/format.go  |  2 +-
 3 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/internal/lsp/diff/diff.go b/internal/lsp/diff/diff.go
index 573190b0..5e06ec41 100644
--- a/internal/lsp/diff/diff.go
+++ b/internal/lsp/diff/diff.go
@@ -5,19 +5,15 @@
 // Package diff implements the Myers diff algorithm.
 package diff
 
-import (
-	"strings"
-)
-
 // Sources:
 // https://blog.jcoglan.com/2017/02/17/the-myers-diff-algorithm-part-3/
 // https://www.codeproject.com/Articles/42279/%2FArticles%2F42279%2FInvestigating-Myers-diff-algorithm-Part-1-of-2
 
 type Op struct {
 	Kind    OpKind
-	Content string
-	I1, I2  int // indices of the line in a
-	J1, J2  int // indices of the line in b
+	Content []string // content from b
+	I1, I2  int      // indices of the line in a
+	J1      int      // indices of the line in b, J2 implied by len(Content)
 }
 
 type OpKind int
@@ -53,7 +49,7 @@ func ApplyEdits(a []string, operations []*Op) []string {
 		}
 		switch op.Kind {
 		case Equal, Insert:
-			b = append(b, op.Content)
+			b = append(b, op.Content...)
 		}
 		prevI2 = op.I2
 	}
@@ -82,9 +78,8 @@ func Operations(a, b []string) []*Op {
 			return
 		}
 		op.I2 = i2
-		op.J2 = j2
 		if op.Kind == Insert {
-			op.Content = strings.Join(b[op.J1:op.J2], "")
+			op.Content = b[op.J1:j2]
 		}
 		solution[i] = op
 		i++
diff --git a/internal/lsp/diff/diff_test.go b/internal/lsp/diff/diff_test.go
index 9a615e3b..966511fe 100644
--- a/internal/lsp/diff/diff_test.go
+++ b/internal/lsp/diff/diff_test.go
@@ -19,20 +19,20 @@ func TestDiff(t *testing.T) {
 			a: []string{"A", "B", "C", "A", "B", "B", "A"},
 			b: []string{"C", "B", "A", "B", "A", "C"},
 			operations: []*Op{
-				&Op{Kind: Delete, I1: 0, I2: 1, J1: 0, J2: 0},
-				&Op{Kind: Delete, I1: 1, I2: 2, J1: 0, J2: 0},
-				&Op{Kind: Insert, Content: "B", I1: 3, I2: 3, J1: 1, J2: 2},
-				&Op{Kind: Delete, I1: 5, I2: 6, J1: 4, J2: 4},
-				&Op{Kind: Insert, Content: "C", I1: 7, I2: 7, J1: 5, J2: 6},
+				&Op{Kind: Delete, I1: 0, I2: 1, J1: 0},
+				&Op{Kind: Delete, I1: 1, I2: 2, J1: 0},
+				&Op{Kind: Insert, Content: []string{"B"}, I1: 3, I2: 3, J1: 1},
+				&Op{Kind: Delete, I1: 5, I2: 6, J1: 4},
+				&Op{Kind: Insert, Content: []string{"C"}, I1: 7, I2: 7, J1: 5},
 			},
 		},
 		{
 			a: []string{"A", "B"},
 			b: []string{"A", "C", ""},
 			operations: []*Op{
-				&Op{Kind: Delete, I1: 1, I2: 2, J1: 1, J2: 1},
-				&Op{Kind: Insert, Content: "C", I1: 2, I2: 2, J1: 1, J2: 2},
-				&Op{Kind: Insert, Content: "", I1: 2, I2: 2, J1: 2, J2: 3},
+				&Op{Kind: Delete, I1: 1, I2: 2, J1: 1},
+				&Op{Kind: Insert, Content: []string{"C"}, I1: 2, I2: 2, J1: 1},
+				&Op{Kind: Insert, Content: []string{""}, I1: 2, I2: 2, J1: 2},
 			},
 		},
 	} {
diff --git a/internal/lsp/source/format.go b/internal/lsp/source/format.go
index cda09168..bdcf64af 100644
--- a/internal/lsp/source/format.go
+++ b/internal/lsp/source/format.go
@@ -75,7 +75,7 @@ func computeTextEdits(ctx context.Context, file File, formatted string) (edits [
 			edits = append(edits, TextEdit{Span: s})
 		case diff.Insert:
 			// Insert: formatted[j1:j2] is inserted at unformatted[i1:i1].
-			edits = append(edits, TextEdit{Span: s, NewText: op.Content})
+			edits = append(edits, TextEdit{Span: s, NewText: strings.Join(op.Content, "")})
 		}
 	}
 	return edits