yyyi_ru/mtgott/src/charclasses.rs

use std::ops::RangeBounds;

pub fn is_lnspace(ch: char) -> bool {
    ch == '\t' || ch == ' ' || ch == '\r'
}

pub fn is_whitespace(ch: char) -> bool {
    is_lnspace(ch) || ch == '\n'
}

pub fn is_digit(ch: char) -> bool {
    ('0'..='9').contains(&ch)
}

pub fn is_normal_word_constituent(ch: char) -> bool {
    ('0'..='9').contains(&ch) || ('a'..='z').contains(&ch) || ('A'..='Z').contains(&ch)
    || "-_+/|&~!^*".contains(ch)
}

pub fn is_normal_word(s: &str) -> bool {
    s.chars().all( is_normal_word_constituent)
}

pub fn escape_for_html(s: &str) -> String {
    s.replace("&", "&amd;").replace("<", "&lt;").replace(">", "&gt;")
        .replace("'", "&#39;").replace("\"", "&quot;")
}

pub fn is_special_name(s: &str) -> bool {
    s.chars().any(|ch| "+'/|&~!^%*".contains(ch)) || s.ends_with("-") || s == "this"
}