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|
use std::fmt;
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum LexicalError {
}
impl fmt::Display for LexicalError {
// This trait requires `fmt` with this exact signature.
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("{}")
}
}
pub type Spanned<Token, Loc, LexicalError>
= Result<(Loc, Token, Loc), LexicalError>;
// The type of the parser's input.
//
// The parser iterators over tuples consisting of the token's starting
// position, the token itself, and the token's ending position.
pub(crate) type LexerItem<Token, Loc, LexicalError>
= Spanned<Token, Loc, LexicalError>;
/// The components of an OpenPGP Message.
#[derive(Debug, Clone, PartialEq)]
#[allow(clippy::upper_case_acronyms)]
pub enum Token {
PIPE,
STAR,
PLUS,
QUESTION,
LPAREN,
RPAREN,
DOT,
CARET,
DOLLAR,
BACKSLASH,
LBRACKET,
RBRACKET,
DASH,
OTHER(char),
}
assert_send_and_sync!(Token);
impl fmt::Display for Token {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(&format!("{:?}", self)[..])
}
}
impl From<Token> for String {
fn from(t: Token) -> String {
use self::Token::*;
match t {
PIPE => '|'.to_string(),
STAR => '*'.to_string(),
PLUS => '+'.to_string(),
QUESTION => '?'.to_string(),
LPAREN => '('.to_string(),
RPAREN => ')'.to_string(),
DOT => '.'.to_string(),
CARET => '^'.to_string(),
DOLLAR => '$'.to_string(),
BACKSLASH => '\\'.to_string(),
LBRACKET => '['.to_string(),
RBRACKET => ']'.to_string(),
DASH => '-'.to_string(),
OTHER(c) => c.to_string(),
}
}
}
impl Token {
pub fn to_char(&self) -> char {
use self::Token::*;
match self {
PIPE => '|',
STAR => '*',
PLUS => '+',
QUESTION => '?',
LPAREN => '(',
RPAREN => ')',
DOT => '.',
CARET => '^',
DOLLAR => '$',
BACKSLASH => '\\',
LBRACKET => '[',
RBRACKET => ']',
DASH => '-',
OTHER(c) => *c,
}
}
}
pub(crate) struct Lexer<'input> {
offset: usize,
input: &'input str,
}
impl<'input> Lexer<'input> {
pub fn new(input: &'input str) -> Self {
Lexer { offset: 0, input }
}
}
impl<'input> Iterator for Lexer<'input> {
type Item = LexerItem<Token, usize, LexicalError>;
fn next(&mut self) -> Option<Self::Item> {
use self::Token::*;
tracer!(super::TRACE, "regex::Lexer::next");
// Returns the length of the first character in s in bytes.
// If s is empty, returns 0.
fn char_bytes(s: &str) -> usize {
if let Some(c) = s.chars().next() {
c.len_utf8()
} else {
0
}
}
let one = |input: &'input str| -> Option<Token> {
let c = input.chars().next()?;
Some(match c {
'|' => PIPE,
'*' => STAR,
'+' => PLUS,
'?' => QUESTION,
'(' => LPAREN,
')' => RPAREN,
'.' => DOT,
'^' => CARET,
'$' => DOLLAR,
'\\' => BACKSLASH,
'[' => LBRACKET,
']' => RBRACKET,
'-' => DASH,
_ => OTHER(c),
})
};
let l = char_bytes(self.input);
let t = match one(self.input) {
Some(t) => t,
None => return None,
};
self.input = &self.input[l..];
let start = self.offset;
let end = start + l;
self.offset += l;
t!("Returning token at offset {}: '{:?}'",
start, t);
Some(Ok((start, t, end)))
}
}
impl<'input> From<&'input str> for Lexer<'input> {
fn from(i: &'input str) -> Lexer<'input> {
Lexer::new(i)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn lexer() {
fn lex(s: &str, expected: &[Token]) {
let tokens: Vec<Token> = Lexer::new(s)
.map(|t| t.unwrap().1)
.collect();
assert_eq!(&tokens[..], expected,
"{}", s);
}
use Token::*;
lex("|", &[ PIPE ]);
lex("*", &[ STAR ]);
lex("+", &[ PLUS ]);
lex("?", &[ QUESTION ]);
lex("(", &[ LPAREN ]);
lex(")", &[ RPAREN ]);
lex(".", &[ DOT ]);
lex("^", &[ CARET ]);
lex("$", &[ DOLLAR ]);
lex("\\", &[ BACKSLASH ]);
lex("[", &[ LBRACKET ]);
lex("]", &[ RBRACKET ]);
lex("-", &[ DASH ]);
lex("a", &[ OTHER('a') ]);
lex("aa", &[ OTHER('a'), OTHER('a') ]);
lex("foo", &[
|
