enh(bash) add arithmetic support

CHANGES.md

@@ -17,6 +17,7 @@ Core Changes:
 
 Language Improvements:
 
+- enh(bash) Add arithmetic expression support (#) [Josh Goebel][]
 - enh(clojure) Add support for global definitions name (#2347) [Alexandre Grison][]
 - enh(fortran) Support Fortran 77 style comments (#2416) [Josh Goebel][]
 - (csharp) add support for `@identifier` style identifiers (#2414) [Josh Goebel][]

src/languages/bash.js

@@ -36,6 +36,15 @@ export default function(hljs) {
     className: 'string',
     begin: /'/, end: /'/
   };
+  const ARITHEMETIC = {
+    begin: /\$\(\(/,
+    end: /\)\)/,
+    contains: [
+      { begin: /\d+#[0-9a-f]+/, className: "number" },
+      hljs.NUMBER_MODE,
+      VAR
+    ]
+  };
 
   return {
     name: 'Bash',
@@ -79,6 +88,7 @@ export default function(hljs) {
         contains: [hljs.inherit(hljs.TITLE_MODE, {begin: /\w[\w\d_]*/})],
         relevance: 0
       },
+      ARITHEMETIC,
       hljs.HASH_COMMENT_MODE,
       QUOTE_STRING,
       ESCAPED_QUOTE,

test/markup/bash/arithmetic.expect.txt

@@ -0,0 +1,8 @@
+<span class="hljs-built_in">echo</span> $(( <span class="hljs-number">16#deadbeef</span> / <span class="hljs-number">1003</span> ))
+
+yumi=deadbeef
+<span class="hljs-built_in">echo</span> $(( <span class="hljs-number">16</span>#<span class="hljs-variable">$yumi</span> / <span class="hljs-number">1003</span> ))
+
+B=20
+yumi=deadbeef
+<span class="hljs-built_in">echo</span> $(( <span class="hljs-variable">$B</span>#<span class="hljs-variable">$yumi</span> / <span class="hljs-number">1003</span> ))

test/markup/bash/arithmetic.txt

@@ -0,0 +1,8 @@
+echo $(( 16#deadbeef / 1003 ))
+
+yumi=deadbeef
+echo $(( 16#$yumi / 1003 ))
+
+B=20
+yumi=deadbeef
+echo $(( $B#$yumi / 1003 ))