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1 files changed, 120 insertions, 0 deletions

diff --git a/src/content/string.rs b/src/content/string.rs
new file mode 100644
index 0000000..a8a81b2
--- /dev/null
+++ b/src/content/string.rs
@@ -0,0 +1,120 @@
+//! The string content type.
+//!
+//! **String** is a limited **text** like content type which only allows
+//! character escapes and character references.
+//! It exists in things such as identifiers (media references, definitions),
+//! titles, URLs, code (fenced) info and meta parts.
+//!
+//! The constructs found in strin are:
+//!
+//! *   [Character escape][crate::construct::character_escape]
+//! *   [Character reference][crate::construct::character_reference]
+
+use crate::construct::{
+    character_escape::start as character_escape, character_reference::start as character_reference,
+};
+use crate::tokenizer::{Code, Event, State, StateFnResult, TokenType, Tokenizer};
+
+/// Turn `codes` as the string content type into events.
+// To do: remove this `allow` when all the content types are glued together.
+#[allow(dead_code)]
+pub fn string(codes: Vec<Code>) -> Vec<Event> {
+    let mut tokenizer = Tokenizer::new();
+    let (state, remainder) = tokenizer.feed(codes, Box::new(before), true);
+
+    if let Some(ref x) = remainder {
+        if !x.is_empty() {
+            unreachable!("expected no final remainder {:?}", x);
+        }
+    }
+
+    match state {
+        State::Ok => {}
+        _ => unreachable!("expected final state to be `State::Ok`"),
+    }
+
+    tokenizer.events
+}
+
+/// Before string.
+///
+/// First we assume character reference.
+///
+/// ```markdown
+/// |&amp;
+/// |\&
+/// |qwe
+/// ```
+fn before(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
+    match code {
+        Code::None => (State::Ok, None),
+        _ => tokenizer.attempt(character_reference, |ok| {
+            Box::new(if ok {
+                before
+            } else {
+                before_not_character_reference
+            })
+        })(tokenizer, code),
+    }
+}
+
+/// Before string, not at a character reference.
+///
+/// Assume character escape.
+///
+/// ```markdown
+/// |\&
+/// |qwe
+/// ```
+fn before_not_character_reference(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
+    match code {
+        Code::None => (State::Ok, None),
+        _ => tokenizer.attempt(character_escape, |ok| {
+            Box::new(if ok {
+                before
+            } else {
+                before_not_character_escape
+            })
+        })(tokenizer, code),
+    }
+}
+
+/// Before string, not at a character reference or character escape.
+///
+/// We’re at data.
+///
+/// ```markdown
+/// |qwe
+/// ```
+fn before_not_character_escape(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
+    if let Code::None = code {
+        (State::Ok, None)
+    } else {
+        tokenizer.enter(TokenType::Data);
+        tokenizer.consume(code);
+        (State::Fn(Box::new(in_data)), None)
+    }
+}
+
+/// In data.
+///
+/// ```markdown
+/// q|w|e
+/// ```
+fn in_data(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
+    match code {
+        Code::None => {
+            tokenizer.exit(TokenType::Data);
+            (State::Ok, None)
+        }
+        // To do: somehow get these markers from constructs.
+        Code::Char('&' | '\\') => {
+            tokenizer.exit(TokenType::Data);
+            before(tokenizer, code)
+        }
+        _ => {
+            tokenizer.consume(code);
+            (State::Fn(Box::new(in_data)), None)
+        }
+    }
+}