MMM: Janky outer flanking rules implementation

magnetar_mmm_parser/src/lib.rs

@@ -6,8 +6,8 @@ use nom::character::complete::{
     alpha1, alphanumeric1, anychar, char as one_char, line_ending, not_line_ending, one_of,
     satisfy, space1, tab,
 };
-use nom::combinator::{eof, fail, map, not, opt, recognize};
-use nom::error::{ErrorKind, ParseError};
+use nom::combinator::{eof, fail, map, not, opt, peek, recognize};
+use nom::error::ErrorKind;
 use nom::multi::{many0, many0_count, many1, many1_count, many_till, separated_list1};
 use nom::sequence::tuple;
 use nom::{IResult, Offset, Parser, Slice};
@@ -273,8 +273,11 @@ fn collect_char_sequence(
 }
 
 #[inline]
-fn alpha1_unicode(input: Span) -> IResult<Span, Span> {
-    recognize(many1_count(satisfy(char::is_alphanumeric)))(input)
+fn space1_unicode(input: Span) -> IResult<Span, Span> {
+    recognize(many1_count(tuple((
+        not(line_ending),
+        satisfy(char::is_whitespace),
+    ))))(input)
 }
 
 #[inline]
@@ -770,6 +773,14 @@ impl Context {
                 }
             }
 
+            if let FlankingRule::Strict = opening_rule {
+                let (input, pre) =
+                    opt(recognize(tuple((alphanumeric1_unicode, &opening_tag))))(input)?;
+                if let Some(pre_text) = pre {
+                    return Ok((input, Token::PlainText(pre_text.into_fragment().into())));
+                }
+            }
+
             let begin = input;
             let (post_open, _) = opening_tag(input)?;
 
@@ -832,8 +843,12 @@ impl Context {
                     true
                 };
 
-            // TODO: Unfinished flanking rules
-            let correct_flanking = correct_left_flanking && correct_right_flanking;
+            let (input, alphanum) = opt(peek(alphanumeric1_unicode))(input)?;
+            let correct_right_outer =
+                alphanum.is_none() || !matches!(closing_rule, FlankingRule::Strict);
+
+            let correct_flanking =
+                correct_left_flanking && correct_right_flanking && correct_right_outer;
 
             if !correct_flanking {
                 return Ok((
@@ -1293,7 +1308,12 @@ impl Context {
     }
 
     fn tag_hashtag<'a>(&self, input: Span<'a>) -> IResult<Span<'a>, Token> {
-        // TODO: Skip when preceded by alphanumerics
+        let (input, maybe_preceded) =
+            opt(recognize(tuple((alphanumeric1_unicode, tag("#")))))(input)?;
+
+        if let Some(preceded) = maybe_preceded {
+            return Ok((input, Token::PlainText(preceded.into_fragment().into())));
+        }
 
         let (input, _) = tag("#")(input)?;
 
@@ -1347,8 +1367,8 @@ impl Context {
                 tag("）"),
             ))),
             recognize(tuple((
-                not(space1),
-                not_line_ending,
+                not(space1_unicode),
+                not(line_ending),
                 not(one_of(".,:;!?#?/[]【】()「」（）<>")),
                 anychar,
             ))),
@@ -1501,6 +1521,20 @@ mod test {
             Token::PlainText("* italic *".into())
         );
 
+        assert_eq!(
+            parse_full("snake_case_variable"),
+            Token::PlainText("snake_case_variable".into())
+        );
+
+        assert_eq!(
+            parse_full("intra*word*italic"),
+            Token::Sequence(vec![
+                Token::PlainText("intra".into()),
+                Token::Italic(Box::new(Token::PlainText("word".into()))),
+                Token::PlainText("italic".into())
+            ])
+        );
+
         assert_eq!(
             parse_full(r#"_ italic *"#),
             Token::PlainText("_ italic *".into())
@@ -1699,6 +1733,20 @@ text</center>"#
             ])
         );
 
+        assert_eq!(
+            parse_full("test #hashtag tail"),
+            Token::Sequence(vec![
+                Token::PlainText("test ".into()),
+                Token::Hashtag("hashtag".into()),
+                Token::PlainText(" tail".into())
+            ])
+        );
+
+        assert_eq!(
+            parse_full("not#hashtag tail"),
+            Token::PlainText("not#hashtag tail".into())
+        );
+
         assert_eq!(
             parse_full("<https://example.com>"),
             Token::UrlNoEmbed("https://example.com".into())