feat: unified and context diff syntax highlighting

src/components/EditorTextArea.tsx

@@ -17,7 +17,8 @@ import themes, { Theme } from '../style/themes';
 
 import type { editor } from 'monaco-editor';
 import { ResetFunction } from './Editor';
-import { logLanguage } from '../util/log-language';
+import { logLanguage } from '../util/languages/log';
+import { diffLanguage } from '../util/languages/diff';
 
 import * as monaco from 'monaco-editor';
 import { loader } from '@monaco-editor/react';
@@ -68,6 +69,8 @@ export default function EditorTextArea({
 
     monaco.languages.register({ id: 'log' });
     monaco.languages.setMonarchTokensProvider('log', logLanguage);
+    monaco.languages.register({ id: 'diff' });
+    monaco.languages.setMonarchTokensProvider('diff', diffLanguage);
 
     monaco.languages.typescript.typescriptDefaults.setDiagnosticsOptions({
       noSemanticValidation: true,

src/style/themes.ts

@@ -64,6 +64,9 @@ const themes: Themes = {
         logWarning: '#d29922', // yellow.3
         logDate: '#33B3AE', // teal.3
         logException: '#f8e3a1', // yellow.0
+        diffMeta: '#33B3AE', // teal.3
+        diffAddition: '#3fb950', // green.3
+        diffDeletion: '#f85149', // red.4
       },
     }),
   },
@@ -100,6 +103,9 @@ const themes: Themes = {
         logWarning: '#d4a72c', // yellow.3
         logDate: '#136061', // teal.6
         logException: '#7d4e00', // yellow.6
+        diffMeta: '#136061', // teal.6
+        diffAddition: '#2da44e', // green.4
+        diffDeletion: '#cf222e', // red.5
       },
     }),
   },
@@ -114,12 +120,15 @@ const themes: Themes = {
       color: '#586e75',
       backgroundColor: '#44475a',
     },
-    editor: addLogColors(dracula as editor.IStandaloneThemeData, {
-      info: '#50FA7B', // green
-      error: '#FF5555', // red
-      warning: '#FFB86C', // orange
-      date: '#BD93F9', // purple
-      exception: '#F1FA8C', // yellow
+    editor: addExtraColors(dracula as editor.IStandaloneThemeData, {
+      logInfo: '#50FA7B', // green
+      logError: '#FF5555', // red
+      logWarning: '#FFB86C', // orange
+      logDate: '#BD93F9', // purple
+      logException: '#F1FA8C', // yellow
+      diffMeta: '#BD93F9', // purple
+      diffAddition: '#50FA7B', // green
+      diffDeletion: '#FF5555', // red
     }),
   },
   'monokai': {
@@ -133,12 +142,15 @@ const themes: Themes = {
       color: '#49483E',
       backgroundColor: '#3E3D32',
     },
-    editor: addLogColors(monokai as editor.IStandaloneThemeData, {
-      info: '#a6e22e', // green
-      error: '#f92672', // red
-      warning: '#fd971f', // orange
-      date: '#AB9DF2', // purple
-      exception: '#F1FA8C', // yellow
+    editor: addExtraColors(monokai as editor.IStandaloneThemeData, {
+      logInfo: '#a6e22e', // green
+      logError: '#f92672', // red
+      logWarning: '#fd971f', // orange
+      logDate: '#AB9DF2', // purple
+      logException: '#F1FA8C', // yellow
+      diffMeta: '#AB9DF2', // purple
+      diffAddition: '#a6e22e', // green
+      diffDeletion: '#f92672', // red
     }),
   },
   'solarized': {
@@ -152,12 +164,15 @@ const themes: Themes = {
       color: '#93a1a1', // base1
       backgroundColor: '#073642', // base02
     },
-    editor: addLogColors(solarizedDark as editor.IStandaloneThemeData, {
-      info: '#268bd2', // blue
-      error: '#dc322f', // red
-      warning: '#b58900', // yellow
-      date: '#2aa198', // cyan
-      exception: '#859900', // green
+    editor: addExtraColors(solarizedDark as editor.IStandaloneThemeData, {
+      logInfo: '#268bd2', // blue
+      logError: '#dc322f', // red
+      logWarning: '#b58900', // yellow
+      logDate: '#2aa198', // cyan
+      logException: '#859900', // green
+      diffMeta: '#2aa198', // cyan
+      diffAddition: '#859900', // green
+      diffDeletion: '#dc322f', // red
     }),
   },
   'solarized-light': {
@@ -171,18 +186,32 @@ const themes: Themes = {
       color: '#586e75', // base01
       backgroundColor: '#eee8d5', // base2
     },
-    editor: addLogColors(solarizedLight as editor.IStandaloneThemeData, {
-      info: '#268bd2', // blue
-      error: '#dc322f', // red
-      warning: '#b58900', // yellow
-      date: '#2aa198', // cyan
-      exception: '#859900', // green
+    editor: addExtraColors(solarizedLight as editor.IStandaloneThemeData, {
+      logInfo: '#268bd2', // blue
+      logError: '#dc322f', // red
+      logWarning: '#b58900', // yellow
+      logDate: '#2aa198', // cyan
+      logException: '#859900', // green
+      diffMeta: '#2aa198', // cyan
+      diffAddition: '#859900', // green
+      diffDeletion: '#dc322f', // red
     }),
   },
 };
 
 export default themes;
 
+interface ExtraColors {
+  logInfo: Color;
+  logError: Color;
+  logWarning: Color;
+  logDate: Color;
+  logException: Color;
+  diffMeta: Color;
+  diffAddition: Color;
+  diffDeletion: Color;
+}
+
 interface MonacoThemeProps {
   base: 'vs' | 'vs-dark';
   colors: {
@@ -198,12 +227,7 @@ interface MonacoThemeProps {
     keyword: Color;
     type: Color;
     variable: Color;
-    logInfo: Color;
-    logError: Color;
-    logWarning: Color;
-    logDate: Color;
-    logException: Color;
-  };
+  } & ExtraColors;
 }
 
 export function makeMonacoTheme(
@@ -246,6 +270,9 @@ export function makeMonacoTheme(
       { token: 'warning.log', foreground: colors.logWarning },
       { token: 'date.log', foreground: colors.logDate },
       { token: 'exception.log', foreground: colors.logException },
+      { token: 'meta.diff', foreground: colors.diffMeta },
+      { token: 'addition.diff', foreground: colors.diffAddition },
+      { token: 'deletion.diff', foreground: colors.diffDeletion },
     ],
     colors: {
       'editor.background': `#${colors.background}`,
@@ -254,28 +281,23 @@ export function makeMonacoTheme(
   };
 }
 
-interface LogColors {
-  info: Color;
-  error: Color;
-  warning: Color;
-  date: Color;
-  exception: Color;
-}
-
-export function addLogColors(
+export function addExtraColors(
   theme: editor.IStandaloneThemeData,
-  logColors: LogColors
+  extraColors: ExtraColors
 ): editor.IStandaloneThemeData {
   const colors = Object.fromEntries(
-    Object.entries(logColors).map(([key, color]) => [key, color.substring(1)])
-  ) as Record<keyof LogColors, string>;
+    Object.entries(extraColors).map(([key, color]) => [key, color.substring(1)])
+  ) as Record<keyof ExtraColors, string>;
   theme.rules.push(
     ...[
-      { token: 'info.log', foreground: colors.info },
-      { token: 'error.log', foreground: colors.error, fontStyle: 'bold' },
-      { token: 'warning.log', foreground: colors.warning },
-      { token: 'date.log', foreground: colors.date },
-      { token: 'exception.log', foreground: colors.exception },
+      { token: 'info.log', foreground: colors.logInfo },
+      { token: 'error.log', foreground: colors.logError, fontStyle: 'bold' },
+      { token: 'warning.log', foreground: colors.logWarning },
+      { token: 'date.log', foreground: colors.logDate },
+      { token: 'exception.log', foreground: colors.logException },
+      { token: 'meta.diff', foreground: colors.diffMeta },
+      { token: 'addition.diff', foreground: colors.diffAddition },
+      { token: 'deletion.diff', foreground: colors.diffDeletion },
     ]
   );
   return theme;

src/util/highlighting.ts

@@ -17,10 +17,10 @@ export const languages = {
     'go',
     'lua',
     'swift',
-    'c'
+    'c',
   ],
   web: ['html', 'css', 'scss', 'php', 'graphql'],
-  misc: ['dockerfile', 'markdown', 'proto'],
+  misc: ['diff', 'dockerfile', 'markdown', 'proto'],
 };
 
 export const languageIds = Object.values(languages).flat(1);

src/util/languages/diff.ts

@@ -0,0 +1,30 @@
+import { languages } from 'monaco-editor';
+
+export const diffLanguage: languages.IMonarchLanguage = {
+  defaultToken: '',
+  tokenizer: {
+    root: [
+      // Meta lines (e.g., @@ -1,2 +3,4 @@)
+      [/@@@ +-\d+,\d+ +\+\d+,\d+ +@@@/, 'meta'],
+      [/^\*\*\* +\d+,\d+ +\*\*\*\*$/, 'meta'],
+      [/^--- +\d+,\d+ +----$/, 'meta'],
+
+      // Comments
+      [/Index: .*/, 'comment'],
+      [/^index.*/, 'comment'],
+      [/={3,}/, 'comment'],
+      [/^-{3}.*/, 'comment'],
+      [/^\*{3} .*/, 'comment'],
+      [/^\+{3}.*/, 'comment'],
+      [/^diff --git.*/, 'comment'],
+      [/^\*{15}$/, 'comment'],
+
+      // Additions
+      [/^\+.*/, 'addition'],
+      [/^!.*/, 'addition'],
+
+      // Deletions
+      [/^-.*/, 'deletion'],
+    ],
+  },
+};