[gtksourceview/gnome-3-18] Add highlighting for ES6 Template Strings

[Paolo Borelli <pborelli src gnome org>]

commit 4ecd0e6c08a3ddfe3ad8e7328cff9f924326b68f
Author: Tobias Schönberg <tobias47n9e gmail com>
Date:   Sun Jan 31 14:42:04 2016 +0100

    Add highlighting for ES6 Template Strings
    
    Template strings are part of ES6 and are currently not
    highlighted as strings. This patch adds a context that
    gives template strings the same color as single-quoted
    and double-quoted strings. The brackets of the template
    expressions are given the color of functions. The
    expressions themselves are highlighted as functions
    too.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=758024
    Fixes #758024

 data/language-specs/javascript.lang |   12 ++++++++++++
 tests/syntax-highlighting/file.js   |   12 ++++++++++++
 2 files changed, 24 insertions(+), 0 deletions(-)
---
diff --git a/data/language-specs/javascript.lang b/data/language-specs/javascript.lang
index 4ac3406..c9cdc88 100644
--- a/data/language-specs/javascript.lang
+++ b/data/language-specs/javascript.lang
@@ -309,6 +309,17 @@
       <keyword>static</keyword>
     </context>
 
+    <context id="template-string" style-ref="string">
+      <start>`</start>
+      <end>`</end>
+      <include>
+        <context id="template-expression" style-ref="function">
+          <start>\$\{</start>
+          <end>\}</end>
+        </context>
+      </include>
+    </context>
+
     <!--main context-->
     <context id="js" class="no-spell-check">
       <include>
@@ -317,6 +328,7 @@
         <context ref="def:c-like-close-comment-outside-comment"/>
         <context ref="def:string" style-ref="string"/>
         <context ref="def:single-quoted-string" style-ref="string"/>
+        <context ref="template-string"/>
         <context ref="def:float"/>
         <context ref="def:decimal"/>
         <context ref="def:octal"/>
diff --git a/tests/syntax-highlighting/file.js b/tests/syntax-highlighting/file.js
index 4480c4e..78cf4ef 100644
--- a/tests/syntax-highlighting/file.js
+++ b/tests/syntax-highlighting/file.js
@@ -13,3 +13,15 @@ var matches = /abc/.exec('Alphabet ... that should contain abc, right?');
 a = [thing / thing, thing / thing];
 x = a /b/ c / d;
 
+// Template strings
+// ----------------
+// Template strings are delimited by back-ticks (grave accent) and
+// can span multiple lines. They allow for expressions that inside
+// of a dollar-sign plus curly-bracket construct (${...}).
+
+console.log(`The sum of 2 and 2 is ${2 + 2}`);
+
+let y = 8;
+let my_string = `This is a multiline
+string that also contains
+a template ${y + (4.1 - 2.2)}`;