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use crate::error::{Error, ErrorType, Located, Position};
use crate::tokens::Token;
pub struct Lexer {
pub text: String,
pub symbols: Vec<String>,
pub keywords: Vec<String>,
pub idx: usize,
pub ln: usize,
pub col: usize,
}
impl Lexer {
pub fn new(text: String) -> Self {
Self {
text,
symbols: vec![],
keywords: vec![],
idx: 0,
ln: 0,
col: 0,
}
}
pub fn pos(&self) -> Position {
Position {
idx: self.idx..self.idx + 1,
ln: self.ln..self.ln + 1,
col: self.col..self.col + 1,
}
}
pub fn advance(&mut self) {
self.idx += 1;
if self.text.get(self.idx..self.idx + 1) == Some("\n") {
self.ln += 1;
self.col = 0;
} else {
self.col += 1;
}
}
pub fn get(&self) -> Option<char> {
self.text
.get(self.idx..self.idx + 1)
.and_then(|s| s.chars().next())
}
pub fn next_char(&mut self) -> Option<char> {
let c = self.get();
self.advance();
c
}
pub fn has_symbols(&self) -> bool {
!self.symbols.is_empty()
}
pub fn symbols(mut self, symbols: &[&str]) -> Self {
self.symbols = symbols.iter().map(|symbol| symbol.to_string()).collect();
self
}
pub fn keywords(mut self, keywords: &[&str]) -> Self {
self.keywords = keywords.iter().map(|symbol| symbol.to_string()).collect();
self
}
pub fn lex(&mut self) -> Result<Vec<Located<Token>>, Error> {
let mut tokens = vec![];
while let Some(c) = self.get() {
let mut pos = self.pos();
match c {
' ' | '\t' | '\r' | '\n' => {
self.advance();
}
'0'..='9' => {
let mut num = self.next_char().unwrap().to_string();
while let Some('0'..='9') = self.get() {
pos.extend(&self.pos());
num.push(self.next_char().unwrap());
}
if let Some('.') = self.get() {
pos.extend(&self.pos());
num.push(self.next_char().unwrap());
while let Some('0'..='9') = self.get() {
num.push(self.next_char().unwrap());
pos.extend(&self.pos());
}
tokens.push(Located::new(Token::Float(num.parse().unwrap()), pos));
} else {
tokens.push(Located::new(Token::Int(num.parse().unwrap()), pos));
}
}
'a'..='z' | 'A'..='Z' | '_' => {
let mut ident = self.next_char().unwrap().to_string();
while let Some('a'..='z') | Some('A'..='Z') | Some('_') | Some('0'..='9') =
self.get()
{
pos.extend(&self.pos());
ident.push(self.next_char().unwrap());
}
tokens.push(Located::new(
if self.keywords.contains(&ident) {
Token::Keyword(ident)
} else {
Token::Ident(ident)
},
pos,
));
}
'\'' => {
self.advance();
let mut c = self.next_char().unwrap();
if c == '\\' {
c = match self.next_char().unwrap() {
'n' => '\n',
't' => '\t',
'r' => '\r',
'\\' => '\\',
'\'' => '\'',
_ => return Err(Error::new(ErrorType::BadChar(c), pos)),
}
}
pos.extend(&self.pos());
if self.next_char().unwrap() != '\'' {
return Err(Error::new(ErrorType::BadChar(c), pos));
}
tokens.push(Located::new(Token::Char(c), pos));
}
'"' => {
self.advance();
let mut string = String::new();
while let Some(c) = self.get() {
if c == '"' {
break;
}
let c = self.next_char().unwrap();
if c == '\\' {
let c = match self.next_char().unwrap() {
'n' => '\n',
't' => '\t',
'r' => '\r',
'\\' => '\\',
'"' => '"',
_ => return Err(Error::new(ErrorType::BadChar(c), pos)),
};
string.push(c);
} else {
string.push(c);
}
}
if let Some('"') = self.get() {
pos.extend(&self.pos());
self.advance();
tokens.push(Located::new(Token::String(string), pos));
} else {
return Err(Error::new(ErrorType::UnclosedString, pos));
}
}
_ => {
if self.has_symbols() {
let mut symbol = self.next_char().unwrap().to_string();
while self.get().is_some() {
let matches = self
.symbols
.iter()
.filter(|s| *s == &symbol || s.starts_with(&symbol))
.count();
if matches == 0 {
symbol.pop();
break;
} else if matches == 1 {
break;
} else {
symbol.push(self.next_char().unwrap());
pos.extend(&self.pos());
}
}
if self.symbols.iter().any(|s| s == &symbol) {
if symbol.len() == 1 {
tokens.push(Located::new(
Token::Symbol(symbol.chars().next().unwrap()),
pos,
));
} else {
tokens.push(Located::new(Token::LongSymbol(symbol), pos));
}
} else {
return Err(Error::new(ErrorType::InvalidSymbol(symbol), pos));
}
} else {
let c = self.next_char().unwrap();
tokens.push(Located::new(Token::Symbol(c), pos));
}
}
}
}
Ok(tokens)
}
}