1 files changed, 54 insertions, 0 deletions
diff --git a/src/construct/partial_bom.rs b/src/construct/partial_bom.rs
new file mode 100644
index 0000000..be8d6c8
--- /dev/null
+++ b/src/construct/partial_bom.rs
@@ -0,0 +1,54 @@
+//! To do.
+
+use crate::token::Token;
+use crate::tokenizer::{State, Tokenizer};
+
+/// Before a BOM.
+///
+/// ```text
+/// > | 0xEF 0xBB 0xBF
+///     ^^^^
+/// ```
+pub fn start(tokenizer: &mut Tokenizer) -> State {
+    match tokenizer.current {
+        Some(0xEF) => {
+            tokenizer.enter(Token::ByteOrderMark);
+            tokenizer.consume();
+            State::Fn(Box::new(cont))
+        }
+        _ => State::Nok,
+    }
+}
+
+/// Second byte in BOM.
+///
+/// ```text
+/// > | 0xEF 0xBB 0xBF
+///          ^^^^
+/// ```
+fn cont(tokenizer: &mut Tokenizer) -> State {
+    match tokenizer.current {
+        Some(0xBB) => {
+            tokenizer.consume();
+            State::Fn(Box::new(end))
+        }
+        _ => State::Nok,
+    }
+}
+
+/// Last byte in BOM.
+///
+/// ```text
+/// > | 0xEF 0xBB 0xBF
+///               ^^^^
+/// ```
+fn end(tokenizer: &mut Tokenizer) -> State {
+    match tokenizer.current {
+        Some(0xBF) => {
+            tokenizer.consume();
+            tokenizer.exit(Token::ByteOrderMark);
+            State::Ok
+        }
+        _ => State::Nok,
+    }
+}