[D] Add bracket fold rules and reenable indentation folding (sublimeh…

…q#3879)

* [D] Add syntax based fold rules for brackets

Fixes sublimehq#3878

Thus commit scopes sections in brackets `meta.brackets` and adds
corresponding fold rules to enable scope based folding.

Note: Meta scopes are required to ensure subsequent brackets (e.g.: [[`)
are correctly tokenized individually.

* [D] Reenable indentation folding

Required to allow folding of code sections not covered by scope based folding.

D/D.sublime-syntax

@@ -815,11 +815,13 @@ contexts:
     - match: '(?=\S)'
       pop: true
   basic-type2-after-brackets:
+    - meta_scope: meta.brackets.d
     - match: '\]'
       scope: punctuation.section.brackets.end.d
       pop: true
     - include: not-whitespace-illegal-pop
   basic-type2-after-parens:
+    - meta_scope: meta.parens.d
     - match: '\)'
       scope: punctuation.section.parens.end.d
       pop: true
@@ -1111,11 +1113,13 @@ contexts:
     - match: '(?=\S)'
       set: [value-list-after, value-after]
   first-value-bracket-after:
+    - meta_scope: meta.brackets.d
     - match: '\]'
       scope: punctuation.section.brackets.end.d
       set: first-value-after
     - include: not-whitespace-illegal-pop
   first-value-parens-after:
+    - meta_scope: meta.parens.d
     - match: '\)'
       scope: punctuation.section.parens.end.d
       set: first-value-after
@@ -1496,6 +1500,7 @@ contexts:
       set: value-after
     - include: not-whitespace-illegal-pop
   value-bracket-after:
+    - meta_scope: meta.brackets.d
     - match: '\]'
       scope: punctuation.section.brackets.end.d
       set: value-after

D/Fold.tmPreferences

@@ -6,7 +6,7 @@
     <key>settings</key>
     <dict>
         <key>indentationFoldingEnabled</key>
-        <false/>
+        <true/>
         <key>foldScopes</key>
         <array>
             <dict>
@@ -15,6 +15,14 @@
                 <key>end</key>
                 <string>punctuation.section.block.end</string>
             </dict>
+            <dict>
+                <key>begin</key>
+                <string>punctuation.section.brackets.begin</string>
+                <key>end</key>
+                <string>punctuation.section.brackets.end</string>
+                <key>excludeTrailingNewlines</key>
+                <false/>
+            </dict>
         </array>
     </dict>
 </dict>

D/tests/syntax_test_d.d

@@ -579,6 +579,7 @@ extern(1)
 //          ^ keyword.operator.assignment.d
 //            ^^^^^ storage.modifier.d
 //                  ^^^ storage.type.d
+//                     ^^^^^^^^ meta.brackets.d
 //                     ^ punctuation.section.brackets.begin.d
 //                      ^^^^^^ support.type.builtin-alias.d
 //                            ^ punctuation.section.brackets.end.d
@@ -598,6 +599,7 @@ extern(1)
 //^^^^^ keyword.control.alias.d
 //      ^^^^^ storage.modifier.d
 //            ^^^ storage.type.d
+//               ^^^^^^^^ meta.brackets.d
 //               ^ punctuation.section.brackets.begin.d
 //                ^^^^^^ support.type.builtin-alias.d
 //                      ^ punctuation.section.brackets.end.d
@@ -648,6 +650,7 @@ extern(1)
 //     ^ punctuation.terminator.d
   foo[string] b = 123;
 //^^^ storage.type.d
+//   ^^^^^^^^ meta.brackets.d
 //   ^ punctuation.section.brackets.begin.d
 //    ^^^^^^ support.type.builtin-alias.d
 //          ^ punctuation.section.brackets.end.d
@@ -667,6 +670,7 @@ extern(1)
 //                   ^ punctuation.terminator.d
   foo[BAR] baz;
 //^^^ storage.type.d
+//   ^^^^^ meta.brackets.d
 //   ^ punctuation.section.brackets.begin.d
 //    ^^^ variable.other.d
 //       ^ punctuation.section.brackets.end.d
@@ -995,6 +999,7 @@ extern(1)
 //^^^^ keyword.declaration.enum.d
 //     ^ punctuation.separator.mapping.d
 //       ^^^ storage.type.d
+//          ^^^^^^^^ meta.brackets.d
 //          ^ punctuation.section.brackets.begin.d
 //           ^^^^^^ support.type.builtin-alias.d
 //                 ^ punctuation.section.brackets.end.d
@@ -1277,6 +1282,7 @@ extern(1)
 
   int[string] foo() {}
 //^^^ storage.type.d
+//   ^^^^^^^^ meta.brackets.d
 //   ^ punctuation.section.brackets.begin.d
 //    ^^^^^^ support.type.builtin-alias.d
 //          ^ punctuation.section.brackets.end.d
@@ -2289,6 +2295,7 @@ extern(1)
 //               ^^^^^ string.quoted.double.d
 //                    ^ punctuation.section.parens.end.d
 //                      ^^^^^^ support.type.builtin-alias.d
+//                            ^^^^ meta.brackets.d
 //                            ^ punctuation.section.brackets.begin.d
 //                             ^^ meta.number.integer.decimal.d
 //                               ^ punctuation.section.brackets.end.d
@@ -2320,6 +2327,7 @@ extern(1)
 //          ^ meta.number.integer.decimal.d
 //           ^ punctuation.section.parens.end.d
 //             ^^^^^^ support.type.builtin-alias.d
+//                   ^^^^ meta.brackets.d
 //                   ^ punctuation.section.brackets.begin.d
 //                    ^^ meta.number.integer.decimal.d
 //                      ^ punctuation.section.brackets.end.d
@@ -2430,6 +2438,7 @@ extern(1)
 //           ^^^ variable.other.d
 //               ^ keyword.operator.arithmetic.d
 //                ^^^ variable.other.d
+//                   ^^^^^^^^^^ meta.brackets.d
 //                   ^ punctuation.section.brackets.begin.d
 //                    ^^^ variable.other.d
 //                       ^ keyword.operator.arithmetic.d
@@ -3156,6 +3165,7 @@ extern(1)
 
   void[int**]* foo;
 //^^^^ storage.type.d
+//    ^^^^^^^ meta.brackets.d
 //    ^ punctuation.section.brackets.begin.d
 //     ^^^ storage.type.d
 //        ^^ keyword.operator.pointer.d
@@ -3180,6 +3190,7 @@ extern(1)
 //             ^ punctuation.section.block.end.d
   a[b] * c;
 //^ meta.path.d variable.other.d
+// ^^^ meta.brackets.d
 // ^ punctuation.section.brackets.begin.d
 //  ^ meta.path.d variable.other.d
 //   ^ punctuation.section.brackets.end.d