Improves diffing

src/vs/editor/common/diff/algorithms/joinSequenceDiffs.ts

@@ -149,6 +149,29 @@ export function removeRandomMatches(sequence1: LinesSliceCharSequence, sequence2
 		diffs = result;
 	} while (counter++ < 10 && shouldRepeat);
 
+	// Remove short suffixes/prefixes
+	for (let i = 0; i < diffs.length; i++) {
+		const cur = diffs[i];
+
+		let range1 = cur.seq1Range;
+		let range2 = cur.seq2Range;
+
+		const fullRange1 = sequence1.extendToFullLines(cur.seq1Range);
+		const prefix = sequence1.getText(new OffsetRange(fullRange1.start, cur.seq1Range.start));
+		if (prefix.length > 0 && prefix.trim().length <= 3 && cur.seq1Range.length + cur.seq2Range.length > 100) {
+			range1 = cur.seq1Range.deltaStart(-prefix.length);
+			range2 = cur.seq2Range.deltaStart(-prefix.length);
+		}
+
+		const suffix = sequence1.getText(new OffsetRange(cur.seq1Range.endExclusive, fullRange1.endExclusive));
+		if (suffix.length > 0 && (suffix.trim().length <= 3 && cur.seq1Range.length + cur.seq2Range.length > 150)) {
+			range1 = range1.deltaEnd(suffix.length);
+			range2 = range2.deltaEnd(suffix.length);
+		}
+
+		diffs[i] = new SequenceDiff(range1, range2);
+	}
+
 	return diffs;
 }
 

src/vs/editor/test/node/diffing/fixtures/class-replacement/advanced.expected.diff.json

@@ -13,8 +13,8 @@
 			"modifiedRange": "[29,37)",
 			"innerChanges": [
 				{
-					"originalRange": "[29,1 -> 60,48]",
-					"modifiedRange": "[29,1 -> 36,66]"
+					"originalRange": "[29,1 -> 61,1]",
+					"modifiedRange": "[29,1 -> 37,1]"
 				}
 			]
 		},

src/vs/editor/test/node/diffing/fixtures/method-splitting/advanced.expected.diff.json

@@ -13,8 +13,8 @@
 			"modifiedRange": "[6,11)",
 			"innerChanges": [
 				{
-					"originalRange": "[6,2 -> 11,49]",
-					"modifiedRange": "[6,2 -> 6,91]"
+					"originalRange": "[6,1 -> 11,49]",
+					"modifiedRange": "[6,1 -> 6,91]"
 				},
 				{
 					"originalRange": "[12,76 -> 12,76]",

src/vs/editor/test/node/diffing/fixtures/noise-1/advanced.expected.diff.json

@@ -21,8 +21,8 @@
 					"modifiedRange": "[53,6 -> 53,45]"
 				},
 				{
-					"originalRange": "[52,77 -> 55,53]",
-					"modifiedRange": "[53,98 -> 65,66]"
+					"originalRange": "[52,77 -> 56,1]",
+					"modifiedRange": "[53,98 -> 66,1]"
 				}
 			]
 		}

src/vs/editor/test/node/diffing/fixtures/ts-class/advanced.expected.diff.json

@@ -47,8 +47,8 @@
 			"modifiedRange": "[8,12)",
 			"innerChanges": [
 				{
-					"originalRange": "[11,10 -> 20,25]",
-					"modifiedRange": "[8,10 -> 11,51]"
+					"originalRange": "[11,10 -> 21,1]",
+					"modifiedRange": "[8,10 -> 12,1]"
 				}
 			]
 		},

src/vs/editor/test/node/diffing/fixtures/ts-confusing-2/advanced.expected.diff.json

@@ -43,8 +43,8 @@
 			"modifiedRange": "[14,18)",
 			"innerChanges": [
 				{
-					"originalRange": "[14,120 -> 14,211]",
-					"modifiedRange": "[14,120 -> 17,1]"
+					"originalRange": "[14,120 -> 15,1]",
+					"modifiedRange": "[14,120 -> 18,1]"
 				}
 			]
 		},
@@ -65,8 +65,8 @@
 					"modifiedRange": "[21,18 -> 21,43]"
 				},
 				{
-					"originalRange": "[17,71 -> 23,4]",
-					"modifiedRange": "[21,74 -> 21,81]"
+					"originalRange": "[17,71 -> 24,1]",
+					"modifiedRange": "[21,74 -> 22,1]"
 				}
 			]
 		},
@@ -93,8 +93,8 @@
 			"modifiedRange": "[26,38)",
 			"innerChanges": [
 				{
-					"originalRange": "[28,1 -> 30,31]",
-					"modifiedRange": "[26,1 -> 37,9]"
+					"originalRange": "[28,1 -> 31,1]",
+					"modifiedRange": "[26,1 -> 38,1]"
 				}
 			]
 		}

src/vs/editor/test/node/diffing/fixtures/ts-example1/advanced.expected.diff.json

@@ -27,8 +27,8 @@
 			"modifiedRange": "[17,80)",
 			"innerChanges": [
 				{
-					"originalRange": "[13,10 -> 14,43]",
-					"modifiedRange": "[17,10 -> 79,2]"
+					"originalRange": "[13,10 -> 15,1]",
+					"modifiedRange": "[17,10 -> 80,1]"
 				}
 			]
 		}

src/vs/editor/test/node/diffing/fixtures/ts-too-much-minimization/advanced.expected.diff.json

@@ -13,8 +13,8 @@
 			"modifiedRange": "[9,15)",
 			"innerChanges": [
 				{
-					"originalRange": "[9,124 -> 9,124]",
-					"modifiedRange": "[9,124 -> 14,143]"
+					"originalRange": "[9,124 -> 10,1]",
+					"modifiedRange": "[9,124 -> 15,1]"
 				}
 			]
 		}

src/vs/editor/test/node/diffing/fixtures/ws-alignment/advanced.expected.diff.json

@@ -23,8 +23,8 @@
 			"modifiedRange": "[7,18)",
 			"innerChanges": [
 				{
-					"originalRange": "[7,5 -> 12,17]",
-					"modifiedRange": "[7,5 -> 16,7]"
+					"originalRange": "[7,1 -> 13,1]",
+					"modifiedRange": "[7,1 -> 17,1]"
 				},
 				{
 					"originalRange": "[13,6 -> 13,11]",