perspective 2.0.0

A data visualization and analytics component, especially well-suited for large and/or streaming datasets.
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////////////////////////////////////////////////////////////////////////////////
//
// 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::exprtk::{Cursor, Token};

/// Highlight a token if the cursor overlaps an error.  This is not a
/// `Component` because of the the lifetimes associated with `Cursor<'a>` etc.
/// This makes the performance assumption that naively re-rendering is faster
/// than allocating this data on the heap (plus a few copies), since virtually
/// any update to the `CodeEditor` component will be an update to the parsed
/// text.
///
/// TODO Validate this assumption with actual data.
pub fn highlight<'a>(cursor: &mut Cursor<'a>, token: Token<'a>, position: u32) -> Html {
    cursor.txt = token.content();
    let is_auto = cursor.is_autocomplete(position);
    let is_break = matches!(token, Token::Break(_));
    let is_overlap = cursor.is_error();
    let result = match (is_auto, is_overlap, is_break) {
        (true, true, false) => html! {
            <span
                ref={ cursor.noderef.clone() }
                class="error_highlight">
                { token }
            </span>
        },
        (false, true, false) => html! {
            <span class="error_highlight">
                { token }
            </span>
        },
        (true, false, false) => html! {
            <span ref={ cursor.noderef.clone() }>
                { token }
            </span>
        },
        _ => html! { token },
    };

    if is_auto && matches!(token, Token::Symbol(_)) {
        cursor.auto = Some(token.content().to_owned());
    }

    if matches!(token, Token::Break(_)) {
        cursor.increment_line();
    } else {
        cursor.increment_column(token.content().len());
    }

    result
}