docs: add warning to DefaultEmitter

1 files changed, 16 insertions, 0 deletions

diff --git a/src/emitter.rs b/src/emitter.rs
index 90aa4db..69e9d45 100644
--- a/src/emitter.rs
+++ b/src/emitter.rs
@@ -160,6 +160,22 @@ pub trait Emitter<O> {
 }
 
 /// The default implementation of [`Emitter`], used to produce tokens.
+///
+/// # Warning
+///
+/// * Using the DefaultEmitter without calling [`Tokenizer::set_state`]
+///   results in wrong state transitions:
+///
+///   ```
+///   # use html5tokenizer::{DefaultEmitter, Tokenizer, Token};
+///   let emitter = DefaultEmitter::default();
+///   let html = "<script><b>";
+///   let mut tokens = Tokenizer::new(html, emitter).flatten();
+///   assert!(matches!(tokens.next().unwrap(), Token::StartTag(tag) if tag.name == "script"));
+///   assert!(matches!(tokens.next().unwrap(), Token::StartTag(tag) if tag.name == "b"));
+///   ```
+///
+/// [`Tokenizer::set_state`]: crate::Tokenizer::set_state
 pub struct DefaultEmitter<O = NoopOffset> {
     current_characters: String,
     current_token: Option<Token<O>>,