//! Utilities for working with ASCII characters.

/// Determine if a character is a valid ASCII character for float grammar.

#[inline(always)]

pub const fn is_valid_ascii(c: u8) -> bool {

    // Below 0x20 is mostly control characters, with no representation.

    // 0x7F is a control character, DEL, so don't include it.

    // We also want the few visual characters below 0x20:

    //  0x09 - Horizontal Tab

    //  0x0A - Newline

    //  0x0B - Vertical Tab (Deprecated)

    //  0x0C - Form Feed (Deprecated)

    //  0x0D - Carriage Return

    (c >= 0x09 && c <= 0x0d) || (c >= 0x20 && c < 0x7F)

}

/// Determine if a slice is all valid ASCII characters for float grammar.

#[inline(always)]

pub const fn is_valid_ascii_slice(slc: &[u8]) -> bool {

    let mut index = 0;

    while index < slc.len() {

        if !is_valid_ascii(slc[index]) {

            return false;

        }

        index += 1;

    }

    true

}

/// Determine if a character is a valid ASCII letter.

#[inline(always)]

pub const fn is_valid_letter(c: u8) -> bool {

    (c >= 0x41 && c <= 0x5a) || (c >= 0x61 && c <= 0x7a)

}

/// Determine if a slice is all valid ASCII letters.

#[inline(always)]

pub const fn is_valid_letter_slice(slc: &[u8]) -> bool {

    let mut index = 0;

    while index < slc.len() {

        if !is_valid_letter(slc[index]) {

            return false;

        }

        index += 1;

    }

    true

}