From 55b0e59213e751884b579bb22b228d1b51717606 Mon Sep 17 00:00:00 2001
From: CosmicHorror <LovecraftianHorror@pm.me>
Date: Sun, 29 Jan 2023 12:27:19 -0700
Subject: [PATCH] Rust: Attempt to lex constant idents (#741)

---
 lexers/embedded/rust.xml                   |  3 +
 lexers/testdata/rust/const_idents.actual   | 10 +++
 lexers/testdata/rust/const_idents.expected | 74 ++++++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 lexers/testdata/rust/const_idents.actual
 create mode 100644 lexers/testdata/rust/const_idents.expected

diff --git a/lexers/embedded/rust.xml b/lexers/embedded/rust.xml
index 1ee1413c8..2ae11b419 100644
--- a/lexers/embedded/rust.xml
+++ b/lexers/embedded/rust.xml
@@ -294,6 +294,9 @@
       <rule pattern="[+\-*/%&amp;|&lt;&gt;^!~@=:?]">
         <token type="Operator"/>
       </rule>
+      <rule pattern="\b(r#)?_?([A-Z][A-Z0-9_]*){2,}\b">
+        <token type="NameConstant"/>
+      </rule>
       <rule pattern="(r#)?[a-zA-Z_]\w*">
         <token type="Name"/>
       </rule>
diff --git a/lexers/testdata/rust/const_idents.actual b/lexers/testdata/rust/const_idents.actual
new file mode 100644
index 000000000..119d4bbae
--- /dev/null
+++ b/lexers/testdata/rust/const_idents.actual
@@ -0,0 +1,10 @@
+const IM_A_CONST: () = ();
+
+fn main() {
+    dbg!(IM_A_CONST);
+}
+
+// None of this should be considered const
+fn foo<T0, T1, U>(_: (T0, T1, U)) {
+    let _: std::collections::BTreeSet<()> = todo!();
+}
diff --git a/lexers/testdata/rust/const_idents.expected b/lexers/testdata/rust/const_idents.expected
new file mode 100644
index 000000000..7808d45a5
--- /dev/null
+++ b/lexers/testdata/rust/const_idents.expected
@@ -0,0 +1,74 @@
+[
+  {"type":"Keyword","value":"const"},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"NameConstant","value":"IM_A_CONST"},
+  {"type":"Text","value":": "},
+  {"type":"Punctuation","value":"()"},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Operator","value":"="},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Punctuation","value":"();"},
+  {"type":"TextWhitespace","value":"\n\n"},
+  {"type":"Keyword","value":"fn"},
+  {"type":"Text","value":" "},
+  {"type":"NameFunction","value":"main"},
+  {"type":"Punctuation","value":"()"},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Punctuation","value":"{"},
+  {"type":"TextWhitespace","value":"\n    "},
+  {"type":"NameFunctionMagic","value":"dbg!"},
+  {"type":"Punctuation","value":"("},
+  {"type":"NameConstant","value":"IM_A_CONST"},
+  {"type":"Punctuation","value":");"},
+  {"type":"TextWhitespace","value":"\n"},
+  {"type":"Punctuation","value":"}"},
+  {"type":"TextWhitespace","value":"\n\n"},
+  {"type":"CommentSingle","value":"// None of this should be considered const\n"},
+  {"type":"Keyword","value":"fn"},
+  {"type":"Text","value":" "},
+  {"type":"NameFunction","value":"foo"},
+  {"type":"Operator","value":"\u003c"},
+  {"type":"Name","value":"T0"},
+  {"type":"Punctuation","value":","},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Name","value":"T1"},
+  {"type":"Punctuation","value":","},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Name","value":"U"},
+  {"type":"Operator","value":"\u003e"},
+  {"type":"Punctuation","value":"("},
+  {"type":"Name","value":"_"},
+  {"type":"Text","value":": "},
+  {"type":"Punctuation","value":"("},
+  {"type":"Name","value":"T0"},
+  {"type":"Punctuation","value":","},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Name","value":"T1"},
+  {"type":"Punctuation","value":","},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Name","value":"U"},
+  {"type":"Punctuation","value":"))"},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Punctuation","value":"{"},
+  {"type":"TextWhitespace","value":"\n    "},
+  {"type":"KeywordDeclaration","value":"let"},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Name","value":"_"},
+  {"type":"Text","value":": "},
+  {"type":"NameClass","value":"std"},
+  {"type":"Text","value":"::"},
+  {"type":"Name","value":"collections"},
+  {"type":"Text","value":"::"},
+  {"type":"Name","value":"BTreeSet"},
+  {"type":"Operator","value":"\u003c"},
+  {"type":"Punctuation","value":"()"},
+  {"type":"Operator","value":"\u003e"},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"Operator","value":"="},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"NameFunctionMagic","value":"todo!"},
+  {"type":"Punctuation","value":"();"},
+  {"type":"TextWhitespace","value":"\n"},
+  {"type":"Punctuation","value":"}"},
+  {"type":"TextWhitespace","value":"\n"}
+]