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//! Lexes some types of literals. It's a isolated
//! module because it requires a lot of code to
//! parse some specific things like escaped characters
//! inside of strings.
use kind_span::Range;
use crate::diagnostic::{EncodeSequence, SyntaxDiagnostic};
use crate::lexer::tokens::Token;
use crate::Lexer;
impl<'a> Lexer<'a> {
/// Lex a sequence of digits of the base @base@ with
/// maximum length of @size@ and turns it into a char.
fn lex_char_encoded(
&mut self,
start: usize,
size: usize,
base: u32,
err: EncodeSequence,
) -> Result<char, SyntaxDiagnostic> {
let string = self.next_chars(size);
let to_chr = string.and_then(|x| u32::from_str_radix(x, base).ok());
if let Some(chr) = to_chr.and_then(char::from_u32) {
return Ok(chr);
}
Err(SyntaxDiagnostic::InvalidEscapeSequence(
err,
self.mk_range(start),
))
}
/// Turns a escaped char into a normal char.
fn lex_escaped_char(&mut self, start: usize) -> Result<char, SyntaxDiagnostic> {
match self.peekable.peek() {
None => Err(SyntaxDiagnostic::UnfinishedString(
self.mk_one_column_range(start),
)),
Some(&x) => {
self.next_char();
match x {
'\'' => Ok('\''),
'\"' => Ok('\"'),
'n' => Ok('\n'),
'r' => Ok('\r'),
't' => Ok('\t'),
'0' => Ok('\0'),
'\\' => Ok('\\'),
'x' => self.lex_char_encoded(start, 2, 16, EncodeSequence::Hexa),
'u' => self.lex_char_encoded(start, 4, 16, EncodeSequence::Unicode),
other => Ok(other),
}
}
}
}
/// Lexes a number of base @base@, figuring out it's type
/// Lexes 0 if not at a digit position
fn lex_num_and_type_with_base(
&mut self,
num_start: usize,
base: u32,
err: EncodeSequence,
) -> (Token, Range) {
let num = self.accumulate_while(&|x| x.is_digit(base) || x == '_');
let num = if num.is_empty() { "0" } else { num };
let num = num.to_string();
let type_start = self.span();
let make_num_err = |x: &Self| {
(
Token::Error(Box::new(SyntaxDiagnostic::InvalidNumberRepresentation(
err,
x.mk_range(num_start),
))),
x.mk_range(num_start),
)
};
match self.peekable.peek() {
Some('n' | 'N') => {
self.next_char();
if let Ok(res) = u128::from_str_radix(&num.replace('_', ""), base) {
(Token::Nat(res), self.mk_range(num_start))
} else {
make_num_err(self)
}
}
Some('U' | 'u') => {
self.next_char();
let type_ = self.accumulate_while(&|x| x.is_ascii_digit());
match type_ {
"60" => {
if let Ok(res) = u64::from_str_radix(&num.replace('_', ""), base) {
(Token::Num60(res), self.mk_range(num_start))
} else {
make_num_err(self)
}
}
"120" => {
if let Ok(res) = u128::from_str_radix(&num.replace('_', ""), base) {
(Token::Num120(res), self.mk_range(num_start))
} else {
make_num_err(self)
}
}
_ => (
Token::Error(Box::new(SyntaxDiagnostic::InvalidNumberType(
format!("u{}", type_),
self.mk_range(type_start),
))),
self.mk_range(type_start),
),
}
}
Some(_) | None => {
if let Ok(res) = u64::from_str_radix(&num.replace('_', ""), base) {
(Token::Num60(res), self.mk_range(num_start))
} else {
make_num_err(self)
}
}
}
}
/// Lex numbers with decimal, hexadecimal, binary or octal.
pub fn lex_number(&mut self) -> (Token, Range) {
let start = self.span();
match self.peekable.peek() {
None => (Token::Eof, self.mk_range(start)),
Some('0') => {
self.next_char();
match self.peekable.peek() {
Some('x' | 'X') => {
self.next_char();
self.lex_num_and_type_with_base(start, 16, EncodeSequence::Hexa)
}
Some('o' | 'O') => {
self.next_char();
self.lex_num_and_type_with_base(start, 8, EncodeSequence::Octal)
}
Some('b' | 'B') => {
self.next_char();
self.lex_num_and_type_with_base(start, 2, EncodeSequence::Binary)
}
Some('0'..='9' | _) | None => {
self.lex_num_and_type_with_base(start, 10, EncodeSequence::Decimal)
}
}
}
Some('0'..='9' | _) => {
self.lex_num_and_type_with_base(start, 10, EncodeSequence::Decimal)
}
}
}
pub fn lex_char(&mut self) -> Result<char, SyntaxDiagnostic> {
let start = self.span();
if let Some(&x) = self.peekable.peek() {
let chr_start = self.span();
match x {
'\\' => {
self.next_char();
match self.lex_escaped_char(chr_start) {
Ok(x) => Ok(x),
Err(t) => Err(t),
}
}
x => {
self.next_char();
Ok(x)
}
}
} else {
Err(SyntaxDiagnostic::UnfinishedChar(self.mk_range(start)))
}
}
/// Lexes a string that starts with '"' and ends with the
/// same char. each string item can contain a escaped char
/// and if the esaped char is not well-formed then it will
/// acummulate the error until the end of the string.
/// TODO: Accumulate multiple encoding errors?
pub fn lex_string(&mut self) -> (Token, Range) {
let start = self.span();
self.next_char();
let mut string = String::new();
let mut error: Option<(Token, Range)> = None;
while let Some(&x) = self.peekable.peek() {
let chr_start = self.span();
match x {
'\"' => break,
'\\' => {
self.next_char();
match self.lex_escaped_char(chr_start) {
Ok(x) => string.push(x),
Err(t) => {
self.accumulate_while(&|x| x != '"');
error = Some((Token::Error(Box::new(t)), self.mk_range(start)));
}
}
continue;
}
x => string.push(x),
}
// FIXME: Not sure if it causes a bug!
self.next_char();
}
match (self.next_char(), error) {
(_, Some(err)) => err,
(Some('"'), _) => (Token::Str(string), self.mk_range(start)),
_ => (
Token::Error(Box::new(SyntaxDiagnostic::UnfinishedString(
self.mk_one_column_range(start),
))),
self.mk_range(start),
),
}
}
}