Move the sexp parser into the parser crate.

We need to parse sexp for diary sexp.

src/parser/mod.rs

@@ -21,6 +21,7 @@ mod parser_with_context;
 mod plain_list;
 mod plain_text;
 mod property_drawer;
+pub mod sexp;
 mod source;
 mod table;
 mod util;

src/parser/sexp.rs

@@ -0,0 +1,212 @@
+use crate::error::Res;
+use std::collections::HashMap;
+
+use nom::branch::alt;
+use nom::bytes::complete::escaped;
+use nom::bytes::complete::tag;
+use nom::bytes::complete::take_till1;
+use nom::character::complete::multispace0;
+use nom::character::complete::multispace1;
+use nom::character::complete::one_of;
+use nom::combinator::map;
+use nom::combinator::not;
+use nom::combinator::opt;
+use nom::combinator::peek;
+use nom::multi::separated_list1;
+use nom::sequence::delimited;
+use nom::sequence::preceded;
+use nom::sequence::tuple;
+
+#[derive(Debug)]
+pub enum Token<'s> {
+    Atom(&'s str),
+    List(Vec<Token<'s>>),
+    TextWithProperties(TextWithProperties<'s>),
+}
+
+#[derive(Debug)]
+pub struct TextWithProperties<'s> {
+    #[allow(dead_code)]
+    text: &'s str,
+    #[allow(dead_code)]
+    properties: Vec<Token<'s>>,
+}
+
+impl<'s> Token<'s> {
+    pub fn as_list<'p>(&'p self) -> Result<&'p Vec<Token<'s>>, Box<dyn std::error::Error>> {
+        Ok(match self {
+            Token::List(children) => Ok(children),
+            _ => Err("wrong token type"),
+        }?)
+    }
+
+    pub fn as_atom<'p>(&'p self) -> Result<&'s str, Box<dyn std::error::Error>> {
+        Ok(match self {
+            Token::Atom(body) => Ok(*body),
+            _ => Err("wrong token type"),
+        }?)
+    }
+
+    pub fn as_map<'p>(
+        &'p self,
+    ) -> Result<HashMap<&'s str, &'p Token<'s>>, Box<dyn std::error::Error>> {
+        let mut hashmap = HashMap::new();
+
+        let children = self.as_list()?;
+        if children.len() % 2 != 0 {
+            return Err("Expecting an even number of children".into());
+        }
+        let mut key: Option<&str> = None;
+        for child in children.iter() {
+            match key {
+                None => {
+                    key = Some(child.as_atom()?);
+                }
+                Some(key_val) => {
+                    key = None;
+                    hashmap.insert(key_val, child);
+                }
+            };
+        }
+
+        Ok(hashmap)
+    }
+}
+
+#[tracing::instrument(ret, level = "debug")]
+pub fn sexp<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
+    let (remaining, _) = multispace0(input)?;
+    let (remaining, tkn) = token(remaining)?;
+    let (remaining, _) = multispace0(remaining)?;
+    Ok((remaining, tkn))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn token<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
+    alt((list, atom))(input)
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn list<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
+    let (remaining, _) = tag("(")(input)?;
+    let (remaining, children) = delimited(
+        multispace0,
+        separated_list1(multispace1, token),
+        multispace0,
+    )(remaining)?;
+    let (remaining, _) = tag(")")(remaining)?;
+    Ok((remaining, Token::List(children)))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn atom<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
+    not(peek(tag(")")))(input)?;
+    alt((text_with_properties, quoted_atom, unquoted_atom))(input)
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn unquoted_atom<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
+    let (remaining, body) = take_till1(|c| match c {
+        ' ' | '\t' | '\r' | '\n' | ')' => true,
+        _ => false,
+    })(input)?;
+    Ok((remaining, Token::Atom(body)))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn quoted_atom<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
+    let (remaining, _) = tag(r#"""#)(input)?;
+    let (remaining, _) = escaped(
+        take_till1(|c| match c {
+            '\\' | '"' | ')' => true,
+            _ => false,
+        }),
+        '\\',
+        one_of(r#""n"#),
+    )(remaining)?;
+    let (remaining, _) = tag(r#"""#)(remaining)?;
+    let source = get_consumed(input, remaining);
+    Ok((remaining, Token::Atom(source)))
+}
+
+fn text_with_properties<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
+    let (remaining, _) = tag("#(")(input)?;
+    let (remaining, (text, props)) = delimited(
+        multispace0,
+        tuple((
+            map(quoted_atom, |atom| match atom {
+                Token::Atom(body) => body,
+                _ => unreachable!(),
+            }),
+            preceded(multispace1, opt(separated_list1(multispace1, token))),
+        )),
+        multispace0,
+    )(remaining)?;
+    let (remaining, _) = tag(")")(remaining)?;
+    Ok((
+        remaining,
+        Token::TextWithProperties(TextWithProperties {
+            text,
+            properties: props.unwrap_or(Vec::new()),
+        }),
+    ))
+}
+
+/// Get a slice of the string that was consumed in a parser using the original input to the parser and the remaining input after the parser.
+fn get_consumed<'s>(input: &'s str, remaining: &'s str) -> &'s str {
+    assert!(is_slice_of(input, remaining));
+    let source = {
+        let offset = remaining.as_ptr() as usize - input.as_ptr() as usize;
+        &input[..offset]
+    };
+    source
+}
+
+/// Check if the child string slice is a slice of the parent string slice.
+fn is_slice_of(parent: &str, child: &str) -> bool {
+    let parent_start = parent.as_ptr() as usize;
+    let parent_end = parent_start + parent.len();
+    let child_start = child.as_ptr() as usize;
+    let child_end = child_start + child.len();
+    child_start >= parent_start && child_end <= parent_end
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn simple() {
+        let input = "  (foo bar baz )  ";
+        let (remaining, parsed) = sexp(input).expect("Parse the input");
+        assert_eq!(remaining, "");
+        assert!(match parsed {
+            Token::Atom(_) => false,
+            Token::List(_) => true,
+            Token::TextWithProperties(_) => false,
+        });
+    }
+
+    #[test]
+    fn quoted() {
+        let input = r#"  ("foo" bar baz )  "#;
+        let (remaining, parsed) = sexp(input).expect("Parse the input");
+        assert_eq!(remaining, "");
+        assert!(match parsed {
+            Token::Atom(_) => false,
+            Token::List(_) => true,
+            Token::TextWithProperties(_) => false,
+        });
+        let children = match parsed {
+            Token::List(children) => children,
+            _ => panic!("Should be a list."),
+        };
+        assert_eq!(
+            match children.first() {
+                Some(Token::Atom(body)) => *body,
+                _ => panic!("First child should be an atom."),
+            },
+            r#""foo""#
+        )
+    }
+}