unicode-matching 0.6.7

Rust library crate to match Unicode open/close brackets
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!run:echo "#![doc = include_str!(\"../README.md\")]"

use gstring::{GString, GStringTrait, Grapheme};

use std::collections::BTreeMap;

!run:../bin/matching.pl
/// Trait to provide the [`FindMatching::find_matching`] method
pub trait FindMatching {
    /**
    Find the index of the matching open or close grapheme for the grapheme at `position`, given the
    matching `closing` and `opening` brackets

    If the grapheme at `position` is not an opening or closing grapheme, `position` is greater or
    equal to the length of `self`, or the algorithm fails to find the matching grapheme (e.g.
    matching graphemes are unbalanced), the given `position` is returned.
    */
    fn find_matching(
        &self,
        position: usize,
        closing: &BTreeMap<&str, &str>,
        opening: &BTreeMap<&str, &str>,
    ) -> usize;
}

impl FindMatching for str {
    /**
    Find the index of the matching open or close grapheme for the grapheme at `position`, given the
    matching `closing` and `opening` brackets

    If the grapheme at `position` is not an opening or closing grapheme, `position` is greater or
    equal to the length of `self`, or the algorithm fails to find the matching grapheme (e.g.
    matching graphemes are unbalanced), the given `position` is returned.
    */
    fn find_matching(&self,
        position: usize,
        closing: &BTreeMap<&str, &str>,
        opening: &BTreeMap<&str, &str>,
    ) -> usize {
        self.gstring().find_matching(position, closing, opening)
    }
}

impl FindMatching for GString {
    /**
    Find the index of the matching open or close grapheme for the grapheme at `position`, given the
    matching `closing` and `opening` brackets

    If the grapheme at `position` is not an opening or closing grapheme, `position` is greater or
    equal to the length of `self`, or the algorithm fails to find the matching grapheme (e.g.
    matching graphemes are unbalanced), the given `position` is returned.
    */
    fn find_matching(&self,
        position: usize,
        closing: &BTreeMap<&str, &str>,
        opening: &BTreeMap<&str, &str>,
    ) -> usize {
        let v = self.graphemes();

        if position >= v.len() {
            return position;
        }

        let close = closing.get(&v[position].as_str());
        let open = opening.get(&v[position].as_str());

        if close.is_none() && open.is_none() {
            return position;
        }

        let mut stack: Vec<(usize, &Grapheme)> = vec![];
        for (i, g) in v.iter().enumerate() {
            if let Some(open) = opening.get(&g.as_str()) {
                // g is a close
                if let Some(prev) = stack.pop() {
                    // There is a previous open
                    if prev.1 == open {
                        // This close matches the previous open

                        if prev.0 == position {
                            // Return this close's position if the open is at the position
                            return i;
                        } else if i == position {
                            // Return the previous open's position if this close is at the position
                            return prev.0;
                        }
                    } else if closing.contains_key(&g.as_str()) {
                        // This close doesn't match the previous open but is also an open
                        stack.push(prev);
                        stack.push((i, g));
                    } else {
                        // This close doesn't match the previous open and is not an open
                        // So it's a mismatched close and should just return the position
                        return position;
                    }
                } else if closing.contains_key(&g.as_str()) {
                    // There is no previous open and is an open
                    stack.push((i, g));
                }
            } else if closing.contains_key(&g.as_str()) {
                // g is an open
                stack.push((i, g));
            }
        }

        position
    }
}