Add DTD language support (helix-editor#6644)

- Added syntax highlighting for the DTD subset of the XML spec.
- Included .dtd and .ent as common file extensions

book/src/generated/lang-support.md

@@ -28,6 +28,7 @@
 | diff | ✓ |  |  |  |
 | dockerfile | ✓ |  |  | `docker-langserver` |
 | dot | ✓ |  |  | `dot-language-server` |
+| dtd | ✓ |  |  |  |
 | edoc | ✓ |  |  |  |
 | eex | ✓ |  |  |  |
 | ejs | ✓ |  |  |  |

languages.toml

@@ -2099,6 +2099,26 @@ roots = []
 name = "xml"
 source = { git = "https://github.com/RenjiSann/tree-sitter-xml", rev = "48a7c2b6fb9d515577e115e6788937e837815651" }
 
+
+[[language]]
+name = "dtd"
+scope = "source.dtd"
+injection-regex = "dtd"
+file-types = ["dtd", "ent"]
+indent = {tab-width = 2, unit = "  "}
+roots = []
+
+[language.auto-pairs]
+'(' = ')'
+'[' = ']'
+'"' = '"'
+"'" = "'"
+'<' = '>'
+
+[[grammar]]
+name = "dtd"
+source = { git = "https://github.com/KMikeeU/tree-sitter-dtd", rev = "6116becb02a6b8e9588ef73d300a9ba4622e156f"}
+
 [[language]]
 name = "wit"
 scope = "source.wit"

runtime/queries/dtd/highlights.scm

@@ -0,0 +1,39 @@
+; highlights.scm
+
+(comment) @comment
+
+[
+    "ELEMENT"
+    "ATTLIST"
+] @keyword
+
+[
+    "#REQUIRED"
+    "#IMPLIED"
+    "#FIXED"
+    "#PCDATA"
+] @keyword.directive
+
+[
+    "EMPTY"
+    "ANY"
+    "SYSTEM"
+    "PUBLIC"
+] @constant
+
+(element_name) @module
+
+
+(attribute_name) @attribute
+
+(system_literal) @string
+(pubid_literal) @string
+(attribute_value) @string
+
+[
+    ">"
+    "</"
+    "<?"
+    "?>"
+    "<!"
+] @punctuation.bracket

runtime/queries/dtd/injections.scm

@@ -0,0 +1,2 @@
+((comment) @injection.content
+ (#set! injection.language "comment"))