79 lines
2.3 KiB
Rust
79 lines
2.3 KiB
Rust
use crate::{
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callable::{Callable, CallingError},
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environment::Environment,
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instance::Instance,
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interpreter::Interpreter,
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statement::Statement,
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token::Token,
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value::Value,
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};
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use core::fmt::Debug;
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use std::{cell::RefCell, fmt::Display, rc::Rc};
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/// A Lox function with name, parameters, body, and closure environment.
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#[derive(Debug, Clone)]
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pub struct Function {
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pub name: Token,
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pub is_initializer: bool,
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pub params: Vec<Token>,
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pub body: Vec<Statement>,
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pub closure: Rc<RefCell<Environment>>,
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}
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impl Display for Function {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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write!(f, "{}", self.name.lexeme)
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}
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}
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impl PartialEq for Function {
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fn eq(&self, other: &Self) -> bool {
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self.name == other.name && self.params == other.params && self.body == other.body
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}
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}
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impl Callable for Function {
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fn name(&self) -> String {
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self.name.lexeme.clone()
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}
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fn arity(&self) -> usize {
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self.params.len()
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}
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fn call(&self, interpreter: &mut Interpreter, args: Vec<Value>) -> Result<Value, CallingError> {
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let mut env = Environment::with_enclosing(self.closure.clone());
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for (i, param) in self.params.iter().enumerate() {
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let arg = args
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.get(i)
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.ok_or(CallingError::ArgumentMismatch(
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self.params.len(),
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args.len(),
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))?
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.clone();
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env.define(param.lexeme.clone(), arg);
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}
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Ok(interpreter
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.block(&self.body, env)
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.map_err(|e| CallingError::CallInterpretationFailed(e.to_string()))?
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.unwrap_or(Value::Nil))
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}
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}
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impl Function {
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/// Bind a method to an instance, creating a new function with "this" defined in its environment.
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/// This allows methods to access the instance they belong to.
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pub fn bind(&self, instance: Rc<RefCell<Instance>>) -> Self {
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let mut env = Environment::with_enclosing(self.closure.clone());
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env.define("this".to_string(), Value::Instance(instance));
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Self {
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name: self.name.clone(),
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is_initializer: self.is_initializer,
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params: self.params.clone(),
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body: self.body.clone(),
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closure: Rc::new(RefCell::new(env)),
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}
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}
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}
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