106 lines
3.1 KiB
Rust
106 lines
3.1 KiB
Rust
use crate::tokens::Token;
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use std::sync::Arc;
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pub struct Lexer {
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/// GLSL source
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pub input: Vec<char>,
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/// Position in source
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pub position: usize,
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/// [`char`] under position
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pub current_char: Option<char>,
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}
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#[macro_export]
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macro_rules! lex {
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($source:expr) => {{
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$crate::lexer::Lexer::get_tokens(&mut $crate::Lexer::new($source))
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}};
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}
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impl Lexer {
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pub fn new(input: &str) -> Self {
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let mut lexer = Lexer {
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input: input.chars().collect(),
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position: 0,
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current_char: None,
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};
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lexer.current_char = if lexer.position < lexer.input.len() {
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Some(lexer.input[lexer.position])
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} else {
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None
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};
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lexer
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}
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pub fn advance(&mut self) {
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self.position += 1;
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self.current_char = if self.position < self.input.len() {
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Some(self.input[self.position])
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} else {
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None
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};
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}
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/// Peeks the next char in the source without incrementing `self.position`.
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pub fn peek(&self) -> Option<char> {
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if self.position + 1 < self.input.len() {
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Some(self.input[self.position + 1])
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} else {
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None
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}
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}
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/// Parses the source given the [`Lexer`] upon initialization and returns a vector of [`Token`].
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/// # Example:
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/// ```
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/// use glsl_lexer::*;
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/// let source = r#"
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/// #version 440
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/// uniform float time;
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/// void main() {
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/// gl_FragColor = vec4(1.0, 0.5, 0.2, 1.0);
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/// }
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/// "#;
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/// let mut lexer = glsl_lexer::Lexer::new(&source);
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/// let tokens = lexer.get_tokens();
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/// dbg!("{}", tokens);
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///```
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// We are using Arc<[Token]> as return type for cheaper cloning of the returned value
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pub fn get_tokens(&mut self) -> Arc<[Token]> {
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let mut tokens: Vec<Token> = Vec::new();
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while let Some(c) = self.current_char {
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if c.is_whitespace() {
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self.consume_whitespace();
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tokens.push(Token::Whitespace);
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} else if c.is_alphabetic() || c == '_' {
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tokens.push(self.consume_identifier_or_keyword());
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} else if c.is_ascii_digit() {
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tokens.push(self.consume_number());
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} else if c == '/' && self.peek() == Some('/') {
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tokens.push(self.consume_comment());
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} else {
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match c {
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// TODO Implement operands like +=
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'+' | '-' | '*' | '/' | '%' | '&' | '|' | '^' | '!' | '=' | '<' | '>' | '?' => {
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tokens.push(self.consume_operator());
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}
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'{' | '}' | '(' | ')' | '#' | ',' | ';' => {
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tokens.push(self.consume_symbol());
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}
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'.' => {
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tokens.push(self.consume_number());
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}
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_ => {
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tokens.push(self.consume_unknown());
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}
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}
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}
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}
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tokens.into()
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}
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}
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