From 4c06c8554c35887f8f5147783953b2b7e7c2327f Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Wed, 8 Jun 2022 15:52:16 +0200
Subject: .

---
 src/construct/character_escape.rs | 69 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 src/construct/character_escape.rs

(limited to 'src/construct/character_escape.rs')

diff --git a/src/construct/character_escape.rs b/src/construct/character_escape.rs
new file mode 100644
index 0000000..5ea995e
--- /dev/null
+++ b/src/construct/character_escape.rs
@@ -0,0 +1,69 @@
+//! Character escapes are a construct that occurs in the string and text
+//! content types.
+//!
+//! They’re formed with the following BNF:
+//!
+//! ```bnf
+//! character_escape ::= '\\' ascii_punctuation
+//! ```
+//!
+//! Like much of markdown, there are no “invalid” character escapes: just a
+//! slash, or a slash followed by anything other than an ASCII punctuation
+//! character, is exactly that: just a slash.
+//! To escape (most) arbitrary characters, use a
+//! [character reference][] instead
+//! (as in, `&amp;`, `&#123;`, or say `&#x9;`).
+//! It is also possible to escape a line ending in text with a similar
+//! construct: a backslash followed by a line ending (that is part of the
+//! construct instead of ending it).
+//!
+//! ## References
+//!
+//! *   [`character-escape.js` in `micromark`](https://github.com/micromark/micromark/blob/main/packages/micromark-core-commonmark/dev/lib/character-escape.js)
+//! *   [*§ 2.4 Backslash escapes* in `CommonMark`](https://spec.commonmark.org/0.30/#backslash-escapes)
+//!
+//! [character reference]: crate::construct::character_reference
+//!
+//! <!-- To do: link `hard_break_escape`, `string`, `text` -->
+
+use crate::tokenizer::{Code, State, StateFnResult, TokenType, Tokenizer};
+
+/// Start of a character escape.
+///
+/// ```markdown
+/// a|\*b
+/// a|\b
+/// a|\ b
+/// ```
+pub fn start(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
+    match code {
+        Code::Char('\\') => {
+            tokenizer.enter(TokenType::CharacterEscape);
+            tokenizer.enter(TokenType::CharacterEscapeMarker);
+            tokenizer.consume(code);
+            tokenizer.exit(TokenType::CharacterEscapeMarker);
+            (State::Fn(Box::new(inside)), None)
+        }
+        _ => (State::Nok, None),
+    }
+}
+
+/// Inside a character escape, after `\`.
+///
+/// ```markdown
+/// a\|*b
+/// a\|b
+/// a\| b
+/// ```
+fn inside(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
+    match code {
+        Code::Char(char) if char.is_ascii_punctuation() => {
+            tokenizer.enter(TokenType::CharacterEscapeValue);
+            tokenizer.consume(code);
+            tokenizer.exit(TokenType::CharacterEscapeValue);
+            tokenizer.exit(TokenType::CharacterEscape);
+            (State::Ok, None)
+        }
+        _ => (State::Nok, None),
+    }
+}
-- 
cgit