92 lines
2.7 KiB
Rust
92 lines
2.7 KiB
Rust
use super::error::ParserError;
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use super::token::{CharCursor, Keyword, Symbol, Token, TokenInstance};
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use super::FilePos;
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pub struct TokenCursor<'a> {
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cursor: CharCursor<'a>,
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next: Option<TokenInstance>,
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next_pos: FilePos,
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prev_end: FilePos,
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}
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impl<'a> TokenCursor<'a> {
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pub fn next(&mut self) -> Option<TokenInstance> {
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self.prev_end = self.cursor.prev_pos();
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self.next_pos = self.cursor.next_pos();
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std::mem::replace(&mut self.next, TokenInstance::parse(&mut self.cursor))
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}
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pub fn expect_next(&mut self) -> Result<TokenInstance, ParserError> {
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self.peek().ok_or(ParserError::unexpected_end())?;
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Ok(self.next().unwrap())
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}
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pub fn expect_token(&mut self, t: Token) -> Result<(), ParserError> {
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let next = self.expect_next()?;
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if t == next.token {
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Ok(())
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} else {
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Err(ParserError::unexpected_token(&next, &format!("{t:?}")))
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}
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}
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pub fn expect_sym(&mut self, symbol: Symbol) -> Result<(), ParserError> {
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self.expect_token(Token::Symbol(symbol))
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}
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pub fn seek_sym(&mut self, symbol: Symbol) {
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while self
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.next()
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.is_some_and(|n| n.token != Token::Symbol(symbol))
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{}
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}
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pub fn seek_syms(&mut self, syms: &[Symbol]) {
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while self
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.peek()
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.is_some_and(|n| !syms.iter().any(|s| n.is_symbol(*s)))
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{
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self.next();
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}
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}
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pub fn seek(&mut self, f: impl Fn(&TokenInstance) -> bool) -> Option<&TokenInstance> {
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loop {
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if f(self.peek()?) {
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return self.peek();
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}
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self.next();
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}
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}
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pub fn expect_kw(&mut self, kw: Keyword) -> Result<(), ParserError> {
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self.expect_token(Token::Keyword(kw))
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}
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pub fn peek(&self) -> Option<&TokenInstance> {
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self.next.as_ref()
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}
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pub fn expect_peek(&mut self) -> Result<&TokenInstance, ParserError> {
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self.peek().ok_or(ParserError::unexpected_end())
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}
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pub fn chars(&mut self) -> &mut CharCursor<'a> {
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&mut self.cursor
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}
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pub fn prev_end(&self) -> FilePos {
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self.prev_end
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}
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pub fn next_pos(&self) -> FilePos {
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self.next_pos
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}
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}
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impl<'a> From<&'a str> for TokenCursor<'a> {
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fn from(string: &'a str) -> Self {
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Self::from(CharCursor::from(string))
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}
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}
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impl<'a> From<CharCursor<'a>> for TokenCursor<'a> {
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fn from(mut cursor: CharCursor<'a>) -> Self {
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let cur = TokenInstance::parse(&mut cursor);
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Self {
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cursor,
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next: cur,
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next_pos: FilePos::start(),
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prev_end: FilePos::start(),
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}
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}
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}
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