allow syntax highlighting in diffs

scm-ui/ui-components/src/repos/Diff.stories.tsx

@@ -7,8 +7,9 @@ import simpleDiff from "../__resources__/Diff.simple";
 import hunksDiff from "../__resources__/Diff.hunks";
 import binaryDiff from "../__resources__/Diff.binary";
 import Button from "../buttons/Button";
-import { DiffEventContext } from "./DiffTypes";
+import { DiffEventContext, File } from "./DiffTypes";
 import Toast from "../toast/Toast";
+import { getPath } from "./diffs";
 
 const diffFiles = parser.parse(simpleDiff);
 
@@ -57,4 +58,16 @@ storiesOf("Diff", module)
   .add("Binaries", () => {
     const binaryDiffFiles = parser.parse(binaryDiff);
     return <Diff diff={binaryDiffFiles} />;
+  })
+  .add("SyntaxHighlighting", () => {
+    const filesWithLanguage = diffFiles.map((file: File) => {
+      const ext = getPath(file).split(".")[1];
+      if (ext === "tsx") {
+        file.language = "typescript";
+      } else {
+        file.language = ext;
+      }
+      return file;
+    });
+    return <Diff diff={filesWithLanguage} />;
   });

scm-ui/ui-components/src/repos/DiffFile.tsx

@@ -3,11 +3,12 @@ import { withTranslation, WithTranslation } from "react-i18next";
 import classNames from "classnames";
 import styled from "styled-components";
 // @ts-ignore
-import { Diff as DiffComponent, getChangeKey, Hunk, Decoration } from "react-diff-view";
+import { getChangeKey, Hunk, Decoration } from "react-diff-view";
 import { Button, ButtonGroup } from "../buttons";
 import Tag from "../Tag";
 import Icon from "../Icon";
 import { ChangeEvent, Change, File, Hunk as HunkType, DiffObjectProps } from "./DiffTypes";
+import TokenizedDiffView from "./TokenizedDiffView";
 
 const EMPTY_ANNOTATION_FACTORY = {};
 
@@ -57,33 +58,6 @@ const ChangeTypeTag = styled(Tag)`
   margin-left: 0.75rem;
 `;
 
-const ModifiedDiffComponent = styled(DiffComponent)`
-  /* align line numbers */
-  & .diff-gutter {
-    text-align: right;
-  }
-  /* column sizing */
-  > colgroup .diff-gutter-col {
-    width: 3.25rem;
-  }
-  /* prevent following content from moving down */
-  > .diff-gutter:empty:hover::after {
-    font-size: 0.7rem;
-  }
-  /* smaller font size for code */
-  & .diff-line {
-    font-size: 0.75rem;
-  }
-  /* comment padding for sidebyside view */
-  &.split .diff-widget-content .is-indented-line {
-    padding-left: 3.25rem;
-  }
-  /* comment padding for combined view */
-  &.unified .diff-widget-content .is-indented-line {
-    padding-left: 6.5rem;
-  }
-`;
-
 class DiffFile extends React.Component<Props, State> {
   static defaultProps: Partial<Props> = {
     defaultCollapse: false,
@@ -264,9 +238,9 @@ class DiffFile extends React.Component<Props, State> {
       body = (
         <div className="panel-block is-paddingless">
           {fileAnnotations}
-          <ModifiedDiffComponent className={viewType} viewType={viewType} hunks={file.hunks} diffType={file.type}>
+          <TokenizedDiffView className={viewType} viewType={viewType} file={file}>
             {(hunks: HunkType[]) => this.concat(hunks.map(this.renderHunk))}
-          </ModifiedDiffComponent>
+          </TokenizedDiffView>
         </div>
       );
     }

scm-ui/ui-components/src/repos/DiffTypes.ts

@@ -18,6 +18,7 @@ export type File = {
   oldPath: string;
   oldRevision?: string;
   type: FileChangeType;
+  language?: string;
   // TODO does this property exists?
   isBinary?: boolean;
 };

scm-ui/ui-components/src/repos/Tokenize.worker.ts

@@ -0,0 +1,29 @@
+/* eslint-disable no-restricted-globals */
+// @ts-ignore we have no types for react-diff-view
+import { tokenize } from "react-diff-view";
+import refractor from "./refractorAdapter";
+
+self.addEventListener("message", ({ data: { id, payload } }) => {
+  const { hunks, language } = payload;
+  const options = {
+    highlight: language !== "text",
+    language: language,
+    refractor
+  };
+  try {
+    const tokens = tokenize(hunks, options);
+    const payload = {
+      success: true,
+      tokens: tokens
+    };
+    // @ts-ignore seems to use wrong typing
+    self.postMessage({ id, payload });
+  } catch (ex) {
+    const payload = {
+      success: false,
+      reason: ex.message
+    };
+    // @ts-ignore seems to use wrong typing
+    self.postMessage({ id, payload });
+  }
+});

scm-ui/ui-components/src/repos/TokenizedDiffView.tsx

@@ -0,0 +1,62 @@
+import React, { FC } from "react";
+import styled from "styled-components";
+// @ts-ignore we have no typings for react-diff-view
+import { Diff, useTokenizeWorker } from "react-diff-view";
+// @ts-ignore we use webpack worker-loader to load the web worker
+import TokenizeWorker from "./Tokenize.worker";
+import { File } from "./DiffTypes";
+
+// styling for the diff tokens
+// this must be aligned with th style, which is used in the SyntaxHighlighter component
+import "highlight.js/styles/arduino-light.css";
+
+const DiffView = styled(Diff)`
+  /* align line numbers */
+  & .diff-gutter {
+    text-align: right;
+  }
+  /* column sizing */
+  > colgroup .diff-gutter-col {
+    width: 3.25rem;
+  }
+  /* prevent following content from moving down */
+  > .diff-gutter:empty:hover::after {
+    font-size: 0.7rem;
+  }
+  /* smaller font size for code */
+  & .diff-line {
+    font-size: 0.75rem;
+  }
+  /* comment padding for sidebyside view */
+  &.split .diff-widget-content .is-indented-line {
+    padding-left: 3.25rem;
+  }
+  /* comment padding for combined view */
+  &.unified .diff-widget-content .is-indented-line {
+    padding-left: 6.5rem;
+  }
+`;
+
+// WebWorker which creates tokens for syntax highlighting
+const tokenize = new TokenizeWorker();
+
+type Props = {
+  file: File;
+  viewType: "split" | "unified";
+  className?: string;
+};
+
+const TokenizedDiffView: FC<Props> = ({ file, viewType, className, children }) => {
+  const { tokens } = useTokenizeWorker(tokenize, {
+    hunks: file.hunks,
+    language: file.language || "text"
+  });
+
+  return (
+    <DiffView className={className} viewType={viewType} tokens={tokens} hunks={file.hunks} diffType={file.type}>
+      {children}
+    </DiffView>
+  );
+};
+
+export default TokenizedDiffView;

scm-ui/ui-components/src/repos/refractorAdapter.ts

@@ -0,0 +1,14 @@
+import lowlight from "lowlight";
+
+// adapter to let lowlight look like refractor
+// this is required because react-diff-view does only support refractor,
+// but we want same highlighting as in the source code browser.
+
+const refractorAdapter = {
+  ...lowlight,
+  highlight: (value: string, language: string) => {
+    return lowlight.highlight(language, value).value;
+  }
+};
+
+export default refractorAdapter;