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|
//! Utilities to deal with character codes.
use crate::constant::TAB_SIZE;
use crate::tokenizer::Code;
/// Turn a string into codes.
pub fn parse(value: &str) -> Vec<Code> {
// Note: It’ll grow a bit bigger with each `Code::VirtualSpace`, smaller
// with `Code::CarriageReturnLineFeed`.
let mut codes = Vec::with_capacity(value.len());
let mut at_start = true;
let mut at_carriage_return = false;
let mut column = 1;
for char in value.chars() {
if at_start {
at_start = false;
if char == '\u{feff}' {
// Ignore.
continue;
}
}
// Send a CRLF.
if at_carriage_return && '\n' == char {
at_carriage_return = false;
codes.push(Code::CarriageReturnLineFeed);
} else {
// Send the previous CR: we’re not at a next `\n`.
if at_carriage_return {
at_carriage_return = false;
codes.push(Code::Char('\r'));
}
match char {
// Send a replacement character.
'\0' => {
column += 1;
codes.push(Code::Char(char::REPLACEMENT_CHARACTER));
}
// Send a tab and virtual spaces.
'\t' => {
let remainder = column % TAB_SIZE;
let mut virtual_spaces = if remainder == 0 {
0
} else {
TAB_SIZE - remainder
};
codes.push(Code::Char(char));
column += 1;
while virtual_spaces > 0 {
codes.push(Code::VirtualSpace);
column += 1;
virtual_spaces -= 1;
}
}
// Send an LF.
'\n' => {
column = 1;
codes.push(Code::Char(char));
}
// Don’t send anything yet.
'\r' => {
column = 1;
at_carriage_return = true;
}
// Send the char.
_ => {
column += 1;
codes.push(Code::Char(char));
}
}
};
}
// Send the last CR: we’re not at a next `\n`.
if at_carriage_return {
codes.push(Code::Char('\r'));
}
codes
}
/// Serialize codes, optionally expanding tabs.
pub fn serialize(codes: &[Code], expand_tabs: bool) -> String {
let mut at_tab = false;
// Note: It’ll grow a bit smaller with each
// `Code::Char('\t') | Code::VirtualSpace` if `expand_tabs` is false,
// and bigger with `Code::CarriageReturnLineFeed`,
let mut value = String::with_capacity(codes.len());
for code in codes {
let mut at_tab_next = false;
match code {
Code::CarriageReturnLineFeed => {
value.push_str("\r\n");
}
Code::Char(char) if *char == '\n' || *char == '\r' => {
value.push(*char);
}
Code::Char(char) if *char == '\t' => {
at_tab_next = true;
value.push(if expand_tabs { ' ' } else { *char });
}
Code::VirtualSpace => {
if !expand_tabs && at_tab {
continue;
}
value.push(' ');
}
Code::Char(char) => {
value.push(*char);
}
Code::None => {
unreachable!("unexpected EOF code in codes");
}
}
at_tab = at_tab_next;
}
value
}
|
