fix(prettier): remove dependency on diff-match-patch, fixing incorrect formatting in some cases

Author: djcsdy

package.json

@@ -29,7 +29,6 @@
   },
   "dependencies": {
     "@softwareventures/array": "4.1.3",
-    "diff-match-patch": "1.0.5",
     "execa": "5.1.1",
     "find-up": "5.0.0",
     "glob": "7.2.0",
@@ -47,7 +46,6 @@
     "@softwareventures/prettier-config": "2.0.0",
     "@softwareventures/semantic-release-config": "2.0.0",
     "@softwareventures/tsconfig": "5.1.0",
-    "@types/diff-match-patch": "1.0.32",
     "@types/find-up": "2.1.1",
     "@types/glob": "7.2.0",
     "@types/jest": "27.0.3",

src/precise-formatters/prettier.ts

@@ -1,14 +1,11 @@
 import * as fs from "fs";
-import {diff_match_patch as DiffMatchPatch} from "diff-match-patch";
 import ignore from "ignore";
 import {extname, join} from "path";
 import {Options as PrettierOptions, getSupportInfo, format, resolveConfig, check} from "prettier";
 
 import {PreciseFormatter} from "../precise-formatter";
 import {CharacterRange} from "../utils";
 
-const dmp = new DiffMatchPatch();
-
 let PRETTIER_SUPPORTED_FILE_EXTENSIONS: string[] = [];
 getSupportInfo().languages.forEach(language => {
     PRETTIER_SUPPORTED_FILE_EXTENSIONS = [
@@ -67,20 +64,14 @@ export const preciseFormatterPrettier: PreciseFormatter<PrettierOptions> = {
         config: PrettierOptions | null,
         characterRanges: CharacterRange[]
     ): string {
-        let patches: any = [];
-        characterRanges.forEach(characterRange => {
-            const diffs = dmp.diff_main(
-                fileContents,
-                format(fileContents, {
-                    ...config,
-                    rangeStart: characterRange.rangeStart,
-                    rangeEnd: characterRange.rangeEnd
-                })
-            );
-            patches = [...patches, ...dmp.patch_make(fileContents, diffs)];
-        });
-        const [formattedContents] = dmp.patch_apply(patches, fileContents);
-        return formattedContents;
+        // Start from the last character range and work backwards so that
+        // we don't have to update character ranges to account for the changes
+        // we've already made.
+        return characterRanges.reduceRight(
+            (fileContents, {rangeStart, rangeEnd}) =>
+                format(fileContents, {...config, rangeStart, rangeEnd}),
+            fileContents
+        );
     },
     /**
      * Generate a predicate function which will return true if the filename

yarn.lock

@@ -973,11 +973,6 @@
   dependencies:
     "@babel/types" "^7.3.0"
 
-"@types/diff-match-patch@1.0.32":
-  version "1.0.32"
-  resolved "https://registry.yarnpkg.com/@types/diff-match-patch/-/diff-match-patch-1.0.32.tgz#d9c3b8c914aa8229485351db4865328337a3d09f"
-  integrity sha512-bPYT5ECFiblzsVzyURaNhljBH2Gh1t9LowgUwciMrNAhFewLkHT2H0Mto07Y4/3KCOGZHRQll3CTtQZ0X11D/A==
-
 "@types/find-up@2.1.1":
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/@types/find-up/-/find-up-2.1.1.tgz#1cd2d240f1ad1f48d32346074724dc3107248a11"
@@ -2149,11 +2144,6 @@ dezalgo@^1.0.0:
     asap "^2.0.0"
     wrappy "1"
 
-diff-match-patch@1.0.5:
-  version "1.0.5"
-  resolved "https://registry.yarnpkg.com/diff-match-patch/-/diff-match-patch-1.0.5.tgz#abb584d5f10cd1196dfc55aa03701592ae3f7b37"
-  integrity sha512-IayShXAgj/QMXgB0IWmKx+rOPuGMhqm5w6jvFxmVenXKIzRqTAAsbBPT3kWQeGANj3jGgvcvv4yK6SxqYmikgw==
-
 diff-sequences@^27.4.0:
   version "27.4.0"
   resolved "https://registry.yarnpkg.com/diff-sequences/-/diff-sequences-27.4.0.tgz#d783920ad8d06ec718a060d00196dfef25b132a5"