perspective 2.0.0

////////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2018, the Perspective Authors.
//
// This file is part of the Perspective library, distributed under the terms
// of the Apache License 2.0.  The full license can be found in the LICENSE
// file.

use yew::prelude::*;

use crate::js::PerspectiveValidationError;

/// Because ExprTK reports errors in column/row coordinates and visually needs
/// to be applied to an entire token rather than a single character, we need
/// fairly obnoxious counter logic to figure out how to generate the resulting
/// syntax-highlighted HTML. The `Counter<'a>` struct encpsulates this logic,
/// generating a `NodeRef` to any autocomplete-able `<span>` tokens, as well
/// as other convenient data for HTML rendering, and can be called incrementally
/// while iterating tokens after parsing.
pub struct Cursor<'a> {
    row: usize,
    col: usize,
    index: u32,
    pub err: &'a Option<PerspectiveValidationError>,
    pub txt: &'a str,
    pub noderef: NodeRef,
    pub auto: Option<String>,
}

impl<'a> Cursor<'a> {
    pub fn new(err: &'a Option<PerspectiveValidationError>) -> Self {
        Self {
            row: 1,
            col: 0,
            index: 0,
            err,
            txt: "",
            auto: None,
            noderef: NodeRef::default(),
        }
    }

    /// Is the cursor currently overlapping a token with an error?
    pub const fn is_error(&self) -> bool {
        if let Some(err) = &self.err {
            err.line + 1 == self.row as i32
                && err.column >= self.col as i32
                && err.column < (self.col + self.txt.len()) as i32
        } else {
            false
        }
    }

    /// Is the cursor currently overlapping an  autocomplete-able token?
    pub const fn is_autocomplete(&self, position: u32) -> bool {
        position > self.index && position <= self.index + self.txt.len() as u32
    }

    /// TODO this is alot of type backage for what could just be `num_rows()`.
    pub fn map_rows<T, F: Fn(usize) -> T>(self, f: F) -> impl Iterator<Item = T> {
        (0..self.row).map(f)
    }

    /// Increment the counter column by `size` characters.
    pub fn increment_column(&mut self, size: usize) {
        self.col += size;
        self.index += size as u32;
    }

    /// Increment to the next line, typewriter-style.
    pub fn increment_line(&mut self) {
        self.row += 1;
        self.col = 0;
        self.index += 1;
    }
}