ajson 0.3.1

JSON Parser for Rust - Get JSON values quickly
Documentation 
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use std::{fmt, str};

use crate::{element, util};

pub struct SubSelector<'a> {
    pub name: &'a [u8],
    pub path: &'a [u8],
}

impl<'a> SubSelector<'a> {
    pub fn new(name: &'a [u8], path: &'a [u8]) -> SubSelector<'a> {
        SubSelector { name, path }
    }
}

impl<'a> fmt::Debug for SubSelector<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "<sel")?;
        write!(f, " name=`{}`", str::from_utf8(self.name).unwrap())?;
        write!(f, " path=`{}`", str::from_utf8(self.path).unwrap())?;
        write!(f, ">")
    }
}

fn last_of_name(v: &[u8]) -> &[u8] {
    // for mut i in (0..v.len()).rev() {
    //     match v[i] {
    //         b'\\' => i -= 1,
    //         b'.' => return &v[i + 1..],
    //         _ => (),
    //     }
    // }

    if v.is_empty() {
        return v;
    }

    let mut i = v.len() - 1;
    loop {
        match v[i] {
            b'\\' => i -= 1,
            b'.' => return &v[i + 1..],
            _ => (),
        }
        if i == 0 {
            break;
        }
        i -= 1;
    }

    v
}

pub fn parse_selectors(v: &[u8]) -> (Vec<SubSelector>, usize, bool) {
    let mut i = 0;
    let mut depth = 0;
    let mut start = 0;
    let mut colon = 0;
    let mut sels = Vec::new();

    macro_rules! push_sel {
        () => {{
            if start < i {
                let sel = if colon == 0 {
                    let key = last_of_name(&v[start..i]);
                    SubSelector::new(key, &v[start..i])
                } else {
                    let key = util::trim_u8(&v[start..colon], b'"');
                    SubSelector::new(key, &v[colon + 1..i])
                };
                sels.push(sel);
            }
        }};
    }

    while i < v.len() {
        let &b = unsafe { v.get_unchecked(i) };

        match b {
            b'\\' => {
                i += 1;
            }
            b'"' => {
                let input = unsafe { std::str::from_utf8_unchecked(v.get_unchecked(i..)) };
                let (a, _) = element::string(input).unwrap();
                i += a.len();

                continue;
            }
            b':' => {
                if depth == 1 {
                    colon = i;
                }
            }
            b',' => {
                if depth == 1 {
                    push_sel!();
                    colon = 0;
                    start = i;
                }
            }
            b'[' | b'(' | b'{' => {
                depth += 1;
                if depth == 1 {
                    start = i + 1;
                }
            }

            b']' | b')' | b'}' => {
                depth -= 1;
                if depth == 0 {
                    push_sel!();
                    let length = i;
                    return (sels, length, true);
                }
            }
            _ => (),
        }

        i += 1;
    }

    (vec![], 0, false)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_selectors_from_utf8() {
        #![allow(unused_variables)]
        let path = r#"{name.first,age,murphys:friends.#(last="Murphy")#.first}"#;
        let (sels, length, ok) = parse_selectors(path.as_bytes());

        let path = r#"[name,a]"#;
        let (sels, length, ok) = parse_selectors(path.as_bytes());
    }
}