Add module/function docs to language utils

1 files changed, 10 insertions, 0 deletions

diff --git a/src/util/language.rs b/src/util/language.rs
index c9bd1ea..c0f9c0d 100644
--- a/src/util/language.rs
+++ b/src/util/language.rs
@@ -1,11 +1,20 @@
+//! Language detection for Markdown code fences.
+
 use std::path::Path;
 
+/// Detects a Markdown code-fence language tag from a filename and file contents.
+///
+/// Extension-based detection is tried first. If the extension is unknown, the
+/// first line is inspected for a shebang.
+///
+/// Returns an empty string when no language is detected.
 pub fn detect_language(filename: &Path, contents: &str) -> &'static str {
     detect_from_extension(filename)
         .or_else(|| detect_from_shebang(contents))
         .unwrap_or("")
 }
 
+/// Detects a language tag from the file extension.
 fn detect_from_extension(filename: &Path) -> Option<&'static str> {
     let ext = filename
         .extension()
@@ -24,6 +33,7 @@ fn detect_from_extension(filename: &Path) -> Option<&'static str> {
     }
 }
 
+/// Detects a language tag from a shebang on the first line.
 fn detect_from_shebang(contents: &str) -> Option<&'static str> {
     if let Some(first_line) = contents.lines().next()
         && first_line.starts_with("#!")