add translated string support

grammar.js

@@ -30,6 +30,9 @@ function spaced(separator, keyword, ...args) {
   return seq(separator, keyword, ...args);
 }
 
+/** Django's string constant, which takes any escape but a line break. */
+const STRING = /"(?:[^"\\]|\\[^\n])*"|'(?:[^'\\]|\\[^\n])*'/;
+
 const django = grammar({
   name: "django",
   extras: ($) => [/[ \t]/],
@@ -72,12 +75,20 @@ const django = grammar({
     filter_expression: ($) =>
       seq($.filter, repeat(seq(token.immediate("|"), $.filter))),
     value: ($) => choice($.literal, $.variable_attribute),
-    literal: ($) => seq(choice($.number, $.string), $._after_literal),
+    literal: ($) =>
+      seq(choice($.number, $.string, $.translated_string), $._after_literal),
     // digits, with single underscores allowed between them, as Python's
     // int() and float() accept ("1_000") and Django's Variable relies on
     number: ($) =>
       /[-+]?(?:[0-9](?:_?[0-9])*(?:\.(?:[0-9](?:_?[0-9])*)?)?|\.[0-9](?:_?[0-9])*)(?:[eE][0-9](?:_?[0-9])*)?/,
-    string: ($) => /"(?:[^"\\]|\\[^\n])*"|'(?:[^'\\]|\\[^\n])*'/,
+    string: ($) => STRING,
+    /**
+     * A string to translate at render time. Django matches "_(" and ")" as
+     * part of the constant itself, so nothing may come between them and the
+     * string: "_( 'a' )" is a syntax error there, not a translated literal.
+     */
+    translated_string: ($) =>
+      seq("_(", alias(token.immediate(STRING), $.string), token.immediate(")")),
     attribute: ($) => /[a-zA-Z0-9][a-zA-Z0-9_]*(?:\.[a-zA-Z0-9][a-zA-Z0-9_]*)*/,
     variable_attribute: ($) =>
       seq($.identifier, optional(seq(token.immediate("."), $.attribute))),

queries/highlights.scm

@@ -34,6 +34,8 @@ variable: (identifier) @variable.parameter
     ("}}")
     ("#}")
     ("%}")
+    ("_(")
+    (")")
     (",")] @punctuation
 
 (number) @number

src/grammar.json

@@ -127,6 +127,10 @@
             {
               "type": "SYMBOL",
               "name": "string"
+            },
+            {
+              "type": "SYMBOL",
+              "name": "translated_string"
             }
           ]
         },
@@ -144,6 +148,34 @@
       "type": "PATTERN",
       "value": "\"(?:[^\"\\\\]|\\\\[^\\n])*\"|'(?:[^'\\\\]|\\\\[^\\n])*'"
     },
+    "translated_string": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "_("
+        },
+        {
+          "type": "ALIAS",
+          "content": {
+            "type": "IMMEDIATE_TOKEN",
+            "content": {
+              "type": "PATTERN",
+              "value": "\"(?:[^\"\\\\]|\\\\[^\\n])*\"|'(?:[^'\\\\]|\\\\[^\\n])*'"
+            }
+          },
+          "named": true,
+          "value": "string"
+        },
+        {
+          "type": "IMMEDIATE_TOKEN",
+          "content": {
+            "type": "STRING",
+            "value": ")"
+          }
+        }
+      ]
+    },
     "attribute": {
       "type": "PATTERN",
       "value": "[a-zA-Z0-9][a-zA-Z0-9_]*(?:\\.[a-zA-Z0-9][a-zA-Z0-9_]*)*"

src/node-types.json

@@ -657,6 +657,10 @@
         {
           "type": "string",
           "named": true
+        },
+        {
+          "type": "translated_string",
+          "named": true
         }
       ]
     }
@@ -1018,6 +1022,21 @@
       ]
     }
   },
+  {
+    "type": "translated_string",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": false,
+      "required": true,
+      "types": [
+        {
+          "type": "string",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "url_block",
     "named": true,
@@ -1230,6 +1249,10 @@
     "type": "%}",
     "named": false
   },
+  {
+    "type": ")",
+    "named": false
+  },
   {
     "type": ",",
     "named": false
@@ -1262,6 +1285,10 @@
     "type": ">=",
     "named": false
   },
+  {
+    "type": "_(",
+    "named": false
+  },
   {
     "type": "add:",
     "named": false

test/corpus/template_variable.txt

@@ -274,3 +274,52 @@ Template Variable Attribute Beginning With Underscore
 
 (ERROR)
 
+==================
+Template Variable Translated String
+==================
+
+{{ _("Hello") }}
+
+---
+
+(template
+  (content)
+  (template_variable
+    (filtered_value
+      (value
+        (literal
+          (translated_string
+            (string))))))
+  (content))
+
+==================
+Template Variable Translated String With Filter
+==================
+
+{{ _('Hello')|upper }}
+
+---
+
+(template
+  (content)
+  (template_variable
+    (filtered_value
+      (value
+        (literal
+          (translated_string
+            (string))))
+      (filter_expression
+        (filter))))
+  (content))
+
+==================
+Template Variable Translated String With Spaces
+:error
+==================
+
+{{ _( "Hello" ) }}
+
+---
+
+(ERROR)
+