From 052b3a62a354ba1e9e2141bb73f5c6878043d65f Mon Sep 17 00:00:00 2001
From: Wilfred Hughes <me@wilfred.me.uk>
Date: Tue, 30 Jan 2024 21:22:12 -0800
Subject: [PATCH] Use XML file headers as language detection hints

Fixes #630
---
 CHANGELOG.md                |  2 ++
 src/parse/guess_language.rs | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b34b838b8f..9dac3f9b4e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@
 
 Added support for Objective-C and VHDL.
 
+Files starting with `<?xml` are now parsed as XML.
+
 ### Display
 
 The default display width for tabs has changed to 4.
diff --git a/src/parse/guess_language.rs b/src/parse/guess_language.rs
index 98db844e88..89f7bf88de 100644
--- a/src/parse/guess_language.rs
+++ b/src/parse/guess_language.rs
@@ -416,6 +416,10 @@ fn looks_like_objc(path: &Path, src: &str) -> bool {
     false
 }
 
+fn looks_like_xml(src: &str) -> bool {
+    src.starts_with("<?xml")
+}
+
 pub(crate) fn guess(
     path: &Path,
     src: &str,
@@ -458,6 +462,10 @@ pub(crate) fn guess(
         return Some(lang);
     }
 
+    if looks_like_xml(src) {
+        return Some(Language::Xml);
+    }
+
     None
 }
 
@@ -651,6 +659,12 @@ mod tests {
         assert_eq!(guess(path, "# -*-python-*-", &[]), Some(Python));
     }
 
+    #[test]
+    fn test_guess_by_xml_header() {
+        let path = Path::new("foo");
+        assert_eq!(guess(path, "<?xml version=\"1.0\" encoding=\"utf-8\"?>", &[]), Some(Xml));
+    }
+
     #[test]
     fn test_guess_unknown() {
         let path = Path::new("jfkdlsjfkdsljfkdsljf");