Support interpolated string syntax highlighting

Fix #496

Author: WebFreak001

syntaxes/d.json

@@ -2325,6 +2325,15 @@
         },
         {
           "include": "#token-string"
+        },
+        {
+          "include": "#ies-string"
+        },
+        {
+          "include": "#ies-wysiwyg-string"
+        },
+        {
+          "include": "#ies-token-string"
         }
       ]
     },
@@ -2356,6 +2365,26 @@
         }
       ]
     },
+    "ies-wysiwyg-string": {
+      "patterns": [
+        {
+          "begin": "i`",
+          "end": "`[cwd]?",
+          "name": "string.ies-wysiwyg-string.d",
+          "patterns": [
+            {
+              "include": "#interpolation-escape"
+            },
+            {
+              "include": "#interpolation-sequence"
+            },
+            {
+              "include": "#wysiwyg-characters"
+            }
+          ]
+        }
+      ]
+    },
     "double-quoted-string": {
       "patterns": [
         {
@@ -2370,6 +2399,26 @@
         }
       ]
     },
+    "ies-string": {
+      "patterns": [
+        {
+          "begin": "i\"",
+          "end": "\"[cwd]?",
+          "name": "string.ies-string.d",
+          "patterns": [
+            {
+              "include": "#interpolation-escape"
+            },
+            {
+              "include": "#interpolation-sequence"
+            },
+            {
+              "include": "#double-quoted-characters"
+            }
+          ]
+        }
+      ]
+    },
     "hex-string": {
       "patterns": [
         {
@@ -2415,6 +2464,28 @@
         }
       ]
     },
+    "ies-token-string": {
+      "begin": "iq\\{",
+      "end": "\\}[cdw]?",
+      "beginCaptures": {
+        "0": {
+          "name": "string.quoted.token.d"
+        }
+      },
+      "endCaptures": {
+        "0": {
+          "name": "string.quoted.token.d"
+        }
+      },
+      "patterns": [
+        {
+          "include": "#interpolation-sequence"
+        },
+        {
+          "include": "#token-string-content"
+        }
+      ]
+    },
     "token-string": {
       "begin": "q\\{",
       "end": "\\}[cdw]?",
@@ -2476,6 +2547,30 @@
         }
       ]
     },
+    "interpolation-escape": {
+      "match": "\\\\\\$",
+      "name": "constant.character.escape-sequence.d"
+    },
+    "interpolation-sequence": {
+      "begin": "\\$\\(",
+      "end": "\\)",
+      "name": "meta.interpolation.expression.d",
+      "beginCaptures": {
+        "0": {
+          "name": "punctuation.definition.template-expression.begin.d"
+        }
+      },
+      "endCaptures": {
+        "0": {
+          "name": "punctuation.definition.template-expression.end.d"
+        }
+      },
+      "patterns": [
+        {
+          "include": "#expression"
+        }
+      ]
+    },
     "delimited-string-braces": {
       "patterns": [
         {

syntaxes/d.yml

@@ -1091,6 +1091,9 @@ repository:
     - include: '#delimited-string'
     - include: '#double-quoted-string'
     - include: '#token-string'
+    - include: '#ies-string'
+    - include: '#ies-wysiwyg-string'
+    - include: '#ies-token-string'
   wysiwyg-string:
     patterns:
     - begin: r\"
@@ -1105,13 +1108,31 @@ repository:
       name: string.alternate-wysiwyg-string.d
       patterns:
       - include: '#wysiwyg-characters'
+  ies-wysiwyg-string:
+    patterns:
+    - begin: 'i`'
+      end: '`[cwd]?'
+      name: string.ies-wysiwyg-string.d
+      patterns:
+      - include: '#interpolation-escape'
+      - include: '#interpolation-sequence'
+      - include: '#wysiwyg-characters'
   double-quoted-string:
     patterns:
     - begin: '"'
       end: '"[cwd]?'
       name: string.double-quoted-string.d
       patterns:
       - include: '#double-quoted-characters'
+  ies-string:
+    patterns:
+    - begin: 'i"'
+      end: '"[cwd]?'
+      name: string.ies-string.d
+      patterns:
+      - include: '#interpolation-escape'
+      - include: '#interpolation-sequence'
+      - include: '#double-quoted-characters'
   hex-string:
     patterns:
     - begin: x"
@@ -1136,6 +1157,18 @@ repository:
     - include: '#delimited-string-parens'
     - include: '#delimited-string-angle-brackets'
     - include: '#delimited-string-braces'
+  ies-token-string:
+    begin: iq\{
+    end: \}[cdw]?
+    beginCaptures:
+      0:
+        name: string.quoted.token.d
+    endCaptures:
+      0:
+        name: string.quoted.token.d
+    patterns:
+    - include: '#interpolation-sequence'
+    - include: '#token-string-content'
   token-string:
     begin: q\{
     end: \}[cdw]?
@@ -1168,6 +1201,21 @@ repository:
       name: constant.character.angle-brackets.d
       patterns:
       - include: '#wysiwyg-characters'
+  interpolation-escape:
+    match: \\\$
+    name: constant.character.escape-sequence.d
+  interpolation-sequence:
+    begin: \$\(
+    end: \)
+    name: meta.interpolation.expression.d
+    beginCaptures:
+      0:
+        name: punctuation.definition.template-expression.begin.d
+    endCaptures:
+      0:
+        name: punctuation.definition.template-expression.end.d
+    patterns:
+    - include: '#expression'
   delimited-string-braces:
     patterns:
     - begin: \{