Initial tree-sitter grammar for Dgraph DQL

Skeleton grammar supporting blocks, comments, strings, numbers,
and identifiers. Full DQL keyword support planned for Phase 2.

grammar.js

@@ -0,0 +1,46 @@
+/// <reference types="tree-sitter-cli/dsl" />
+// @ts-check
+
+module.exports = grammar({
+  name: "dql",
+
+  extras: ($) => [/\s/, $.comment],
+
+  rules: {
+    source_file: ($) => repeat($._definition),
+
+    _definition: ($) => choice($.block, $.identifier, $.string, $.number),
+
+    block: ($) =>
+      prec(1, seq(
+        optional(field("name", $.identifier)),
+        "{",
+        repeat($._definition),
+        "}"
+      )),
+
+    comment: ($) => token(seq("#", /.*/)),
+
+    string: ($) =>
+      token(
+        seq(
+          '"',
+          repeat(
+            choice(
+              /[^"\\]/,
+              seq("\\", /./),
+            )
+          ),
+          '"'
+        )
+      ),
+
+    number: ($) => token(choice(/\d+\.\d+/, /\d+/)),
+
+    identifier: ($) => token(choice(
+      seq("@", /[a-zA-Z_][a-zA-Z0-9_.:]*/),
+      seq("$", /[a-zA-Z_][a-zA-Z0-9_]*/),
+      /[a-zA-Z_][a-zA-Z0-9_.:]*/,
+    )),
+  },
+});