Interpreter - Nested environments
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parent
d9e3ef2623
commit
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1 changed files with 26 additions and 16 deletions
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@ -1,24 +1,24 @@
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use std::{cell::RefCell, rc::Rc};
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use crate::{
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ast,
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errors::{ErrorHandler, InterpreterError},
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interpreter::Value,
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interpreter::{Environment, EnvironmentRef, Value},
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tokens::{Token, TokenType},
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};
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use super::Environment;
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/// A result returned by some part of the interpreter.
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pub type InterpreterResult = Result<Value, InterpreterError>;
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/// An Interpretable can be evaluated and will return a value.
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pub trait Interpretable {
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fn interprete(&self, environment: &mut Environment) -> InterpreterResult;
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fn interprete(&self, environment: &EnvironmentRef) -> InterpreterResult;
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}
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/// Evaluate an interpretable, returning its value.
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pub fn evaluate(err_hdl: &mut ErrorHandler, ast: &dyn Interpretable) -> Option<Value> {
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let mut env = Environment::default();
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match ast.interprete(&mut env) {
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let env = Rc::new(RefCell::new(Environment::default()));
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match ast.interprete(&env) {
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Ok(v) => Some(v),
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Err(e) => {
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e.report(err_hdl);
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@ -32,7 +32,7 @@ pub fn evaluate(err_hdl: &mut ErrorHandler, ast: &dyn Interpretable) -> Option<V
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* ----------------------------- */
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impl Interpretable for ast::ProgramNode {
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fn interprete(&self, environment: &mut Environment) -> InterpreterResult {
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fn interprete(&self, environment: &EnvironmentRef) -> InterpreterResult {
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for stmt in self.0.iter() {
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stmt.interprete(environment)?;
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}
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@ -45,18 +45,19 @@ impl Interpretable for ast::ProgramNode {
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* ------------------------------- */
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impl Interpretable for ast::StmtNode {
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fn interprete(&self, environment: &mut Environment) -> InterpreterResult {
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fn interprete(&self, environment: &EnvironmentRef) -> InterpreterResult {
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match self {
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ast::StmtNode::Expression(expr) => expr.interprete(environment),
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ast::StmtNode::Print(expr) => self.on_print(environment, expr),
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ast::StmtNode::VarDecl(name, expr) => self.on_var_decl(environment, name, expr),
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ast::StmtNode::Block(statements) => self.on_block(environment, statements),
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}
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}
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}
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impl ast::StmtNode {
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/// Handle the `print` statement.
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fn on_print(&self, environment: &mut Environment, expr: &ast::ExprNode) -> InterpreterResult {
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fn on_print(&self, environment: &EnvironmentRef, expr: &ast::ExprNode) -> InterpreterResult {
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let value = expr.interprete(environment)?;
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let output = match value {
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Value::Nil => String::from("nil"),
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@ -72,7 +73,7 @@ impl ast::StmtNode {
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/// Handle a variable declaration.
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fn on_var_decl(
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&self,
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environment: &mut Environment,
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environment: &EnvironmentRef,
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name: &Token,
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initializer: &Option<ast::ExprNode>,
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) -> InterpreterResult {
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@ -80,7 +81,16 @@ impl ast::StmtNode {
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Some(expr) => expr.interprete(environment)?,
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None => Value::Nil,
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};
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environment.define(name.lexeme.clone(), value);
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environment.borrow_mut().define(name.lexeme.clone(), value);
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Ok(Value::Nil)
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}
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/// Execute the contents of a block.
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fn on_block(&self, environment: &EnvironmentRef, stmts: &Vec<Box<ast::StmtNode>>) -> InterpreterResult {
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let child = Environment::create_child(environment);
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for stmt in stmts.iter() {
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stmt.interprete(&child)?;
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}
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Ok(Value::Nil)
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}
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}
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@ -90,11 +100,11 @@ impl ast::StmtNode {
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* -------------------------------- */
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impl Interpretable for ast::ExprNode {
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fn interprete(&self, environment: &mut Environment) -> InterpreterResult {
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fn interprete(&self, environment: &EnvironmentRef) -> InterpreterResult {
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match self {
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ast::ExprNode::Assignment{ name, value} => {
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let value = value.interprete(environment)?;
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environment.assign(name, value)
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environment.borrow_mut().assign(name, value)
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}
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ast::ExprNode::Binary {
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left,
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@ -104,7 +114,7 @@ impl Interpretable for ast::ExprNode {
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ast::ExprNode::Unary { operator, right } => self.on_unary(environment, operator, right),
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ast::ExprNode::Grouping { expression } => expression.interprete(environment),
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ast::ExprNode::Litteral { value } => self.on_litteral(value),
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ast::ExprNode::Variable { name } => environment.get(name),
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ast::ExprNode::Variable { name } => environment.borrow().get(name),
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}
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}
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}
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@ -113,7 +123,7 @@ impl ast::ExprNode {
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/// Evaluate a binary operator.
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fn on_binary(
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&self,
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environment: &mut Environment,
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environment: &EnvironmentRef,
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left: &ast::ExprNode,
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operator: &Token,
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right: &ast::ExprNode,
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@ -182,7 +192,7 @@ impl ast::ExprNode {
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/// Evaluate an unary operator.
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fn on_unary(
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&self,
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environment: &mut Environment,
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environment: &EnvironmentRef,
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operator: &Token,
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right: &ast::ExprNode,
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) -> InterpreterResult {
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