add modes.MATCH_NOTHING_RE

CHANGES.md

@@ -8,8 +8,15 @@ Language grammar improvements:
 
 - enh(swift) Improved highlighting for operator and precedencegroup declarations. (#2938) [Steven Van Impe][]
 
+Parser:
+
+- add `modes.MATCH_NOTHING_RE` that will never match
+  - This can be used with `end` to hold a mode open (it must then be ended with
+    `endsParent` in one of it's children modes) [Josh Goebel][]
+
 [Michael Newton]: https://github.com/miken32
 [Steven Van Impe]: https://github.com/svanimpe/
+[Josh Goebel]: https://github.com/joshgoebel
 
 
 ## Version 10.5.0

src/languages/swift.js

@@ -416,11 +416,8 @@ export default function(hljs) {
   // https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID380
   const OPERATOR_DECLARATION = {
     beginKeywords: 'operator',
+    end: hljs.MATCH_NOTHING_RE,
     contains: [
-      {
-        match: /\s+/,
-        relevance: 0
-      },
       {
         className: 'title',
         match: Swift.operator,
@@ -433,11 +430,8 @@ export default function(hljs) {
   // https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID550
   const PRECEDENCEGROUP = {
     beginKeywords: 'precedencegroup',
+    end: hljs.MATCH_NOTHING_RE,
     contains: [
-      {
-        match: /\s+/,
-        relevance: 0
-      },
       {
         className: 'title',
         match: Swift.typeIdentifier,

src/lib/modes.js

@@ -2,6 +2,7 @@ import { inherit } from './utils.js';
 import * as regex from './regex.js';
 
 // Common regexps
+export const MATCH_NOTHING_RE = /\b\B/;
 export const IDENT_RE = '[a-zA-Z]\\w*';
 export const UNDERSCORE_IDENT_RE = '[a-zA-Z_]\\w*';
 export const NUMBER_RE = '\\b\\d+(\\.\\d+)?';

types/index.d.ts

@@ -58,6 +58,7 @@ interface ModesAPI {
     // built in regex
     IDENT_RE: string
     UNDERSCORE_IDENT_RE: string
+    MATCH_NOTHING_RE: string
     NUMBER_RE: string
     C_NUMBER_RE: string
     BINARY_NUMBER_RE: string