refactor md parser, TODO: parse_str

cracked_md/src/parse_trait.rs

@@ -0,0 +1,111 @@
+/*
+
+use crate::MdParseError;
+
+pub type Pattern<T> = Vec<PatternToken<T>>;
+
+pub enum PatternToken<T> {
+    Once(T),
+    Optional(T),
+    AtLeastOnce(T),
+    NTimes(T),
+}
+
+/// panics: on invalid pattern
+pub fn char_pattern(s: &str) -> Pattern<char> {
+    let mut s_chars = s.chars().peekable();
+    let mut pat: Pattern<char> = Vec::new();
+    while let Some(token) = s_chars.next() {
+        pat.push(if let Some(&next) = s_chars.peek() {
+            match next {
+                '?' => {
+                    s_chars.next().unwrap();
+                    PatternToken::Optional(token)
+                }
+                '+' => {
+                    s_chars.next().unwrap();
+                    PatternToken::AtLeastOnce(token)
+                }
+                '*' => {
+                    s_chars.next().unwrap();
+                    PatternToken::NTimes(token)
+                }
+                _ => PatternToken::Once(token),
+            }
+        } else {
+            PatternToken::Once(token)
+        });
+    }
+    pat
+}
+
+pub trait ParsePattern: Iterator + Clone {
+    fn parse<T>(&mut self, expect: Pattern<T>) -> Result<Vec<Self::Item>, MdParseError>
+    where
+        T: PartialEq<<Self as Iterator>::Item>,
+    {
+        let mut consumed = Vec::new();
+        let mut cloned = self.clone();
+
+        for pat_token in expect {
+            match pat_token {
+                PatternToken::Once(c) => {
+                    if !cloned.next().map(|v| c == v).unwrap_or(false) {
+                        return None;
+                    }
+                }
+                PatternToken::Optional(c) => if cloned.peek().map(|v| c == *v).unwrap_or(false) {},
+            }
+        }
+
+        *self = cloned;
+
+        Some(consumed)
+    }
+}
+*/
+
+pub trait Parse: Iterator {
+    fn follows(&mut self, token: char) -> bool;
+
+    fn parse_token(&mut self, token: char) -> bool {
+        if self.follows(token) {
+            let _ = self.next();
+            true
+        } else {
+            false
+        }
+    }
+
+    fn parse_str(&mut self, _tokens: &str) -> bool {
+        todo!()
+    }
+}
+
+impl Parse for std::iter::Peekable<std::str::Chars<'_>> {
+    fn follows(&mut self, token: char) -> bool {
+        self.peek().map(|c| c == &token).unwrap_or(false)
+    }
+}
+
+impl Parse for std::iter::Peekable<std::iter::Enumerate<std::str::Chars<'_>>> {
+    fn follows(&mut self, token: char) -> bool {
+        self.peekable()
+            .peek()
+            .map(|&(_i, c)| c == token)
+            .unwrap_or(false)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn chars_parse_follows_double() {
+        let mut c = "abc".chars().peekable();
+
+        assert!(c.follows('a'));
+        assert!(c.follows('a'));
+    }
+}