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#[derive(Debug, Clone, PartialEq)]
enum TokenType {
Lparen,
Rparen,
Lbrace,
Rbrace,
Lbracket,
Rbracket,
Colon,
Identifier(String),
Eof,
}
#[derive(Debug, Clone, Copy)]
struct Blame {
line: usize,
char: usize,
}
#[derive(Debug)]
struct Token {
token: TokenType,
blame: Blame,
}
struct Lexer;
impl Lexer {
pub fn analyze(program: &str) -> Vec<Token> {
let mut tokens: Vec<Token> = program
.lines()
.enumerate()
.flat_map(|(line, text)| Self::lex_line(line, text))
.collect();
tokens.push(Token {
token: TokenType::Eof,
blame: Blame {
line: tokens.len(),
char: 0,
},
});
tokens
}
fn lex_line(line: usize, text: &str) -> Vec<Token> {
let mut tokens = Vec::new();
let mut ident_start: Option<usize> = None;
let flush = |tokens: &mut Vec<Token>, ident_start: &mut Option<usize>, end: usize| {
if let Some(start) = ident_start.take() {
if end > start {
tokens.push(Token {
token: TokenType::Identifier(text[start..end].to_string()),
blame: Blame { line, char: start },
});
}
}
};
for (i, c) in text.char_indices() {
let singlechar = match c {
'(' => Some(TokenType::Lparen),
')' => Some(TokenType::Rparen),
'[' => Some(TokenType::Lbracket),
']' => Some(TokenType::Rbracket),
'{' => Some(TokenType::Lbrace),
'}' => Some(TokenType::Rbrace),
':' => Some(TokenType::Colon),
_ => None,
};
if c == ' ' || c == '\t' {
flush(&mut tokens, &mut ident_start, i);
continue;
}
if let Some(tt) = singlechar {
flush(&mut tokens, &mut ident_start, i);
tokens.push(Token {
token: tt,
blame: Blame { line, char: i },
});
continue;
}
if ident_start.is_none() {
ident_start = Some(i);
}
}
flush(&mut tokens, &mut ident_start, text.len());
tokens
}
}
enum Atomic {
Unit,
Bool,
Int,
}
enum SimpleType {
Arrow((Box<SimpleType>, Box<SimpleType>)),
Atom(Atomic),
}
type Identifier = String;
struct Binding {
name: Identifier,
arg_type: Option<SimpleType>,
}
enum ASTNode {
Abstraction {
binding: Binding,
body: Box<ASTNode>,
},
Application((Box<ASTNode>, Box<ASTNode>)),
Identifier(Identifier),
}
pub enum StepResult<T> {
Terminal(T),
Continue,
}
pub trait Steppable<T> {
fn small_step(&mut self) -> StepResult<T>;
}
pub struct Environment<'a, T> {
parent_scope: Option<&'a Environment<'a, T>>,
capture: Identifier,
substitution: &'a T,
}
impl<T> Environment<'_, T> {
fn add<'a>(&'a self, identifier: Identifier, substitution: &'a T) -> Environment<'a, T> {
return Environment {
parent_scope: Some(&self),
capture: identifier,
substitution: substitution,
};
}
fn get<'a>(&'a self, identifier: Identifier) -> Option<&'a T> {
if *identifier == *(self.capture) {
return Some(self.substitution);
}
return match self.parent_scope {
Some(scope) => (*scope).get(identifier),
None => None,
};
}
fn root<'a>(identifier: Identifier, substitution: &'a T) -> Environment<'a, T> {
return Environment {
parent_scope: None,
capture: identifier,
substitution: substitution,
};
}
}
fn main() {
println!("Hello, world!");
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_env() {
let ident = Identifier::from("ident");
let ident2 = Identifier::from("ident2");
let val: i32 = 1;
let val2: i32 = 2;
let val3: i32 = 3;
let env = Environment::root(ident.clone(), &val);
assert_eq!(env.get(ident.clone()), Some(&val));
let env2 = env.add(ident2.clone(), &val2);
assert_eq!(env2.get(ident.clone()), Some(&val2));
let env3 = env2.add(ident.clone(), &val3);
assert_eq!(env3.get(ident2.clone()), Some(&val2));
assert_eq!(env3.get(ident.clone()), Some(&val3));
assert_eq!(env.get(ident.clone()), Some(&val));
}
}
|
