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//! Utilities for working with ASCII characters.
/// Determine if a character is a valid ASCII character for float grammar.
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.
/// Modified to be used in a const fn, since for loops and iter don't work.
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.
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.
/// Modified to be used in a const fn, since for loops and iter don't work.
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
}