Interpreter - Split into multiple modules
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81b5f27f0a
commit
bf6e150085
3 changed files with 206 additions and 201 deletions
181
src/interpreter/interpretable.rs
Normal file
181
src/interpreter/interpretable.rs
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@ -0,0 +1,181 @@
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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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tokens::{Token, TokenType},
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};
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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) -> Result<Value, InterpreterError>;
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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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match ast.interprete() {
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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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None
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}
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}
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}
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/* ----------------------------- *
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* INTERPRETER FOR PROGRAM NODES *
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* ----------------------------- */
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impl Interpretable for ast::ProgramNode {
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fn interprete(&self) -> Result<Value, InterpreterError> {
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for stmt in self.0.iter() {
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stmt.interprete()?;
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}
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Ok(Value::Nil)
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}
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}
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/* ------------------------------- *
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* INTERPRETER FOR STATEMENT NODES *
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* ------------------------------- */
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impl Interpretable for ast::StmtNode {
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fn interprete(&self) -> Result<Value, InterpreterError> {
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match self {
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ast::StmtNode::Expression(expr) => expr.interprete(),
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ast::StmtNode::Print(expr) => {
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let value = expr.interprete()?;
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let output = match value {
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Value::Nil => String::from("nil"),
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Value::Boolean(true) => String::from("true"),
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Value::Boolean(false) => String::from("false"),
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Value::Number(n) => n.to_string(),
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Value::String(s) => s,
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};
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println!("{}", output);
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Ok(Value::Nil)
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}
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}
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}
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}
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/* -------------------------------- *
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* INTERPRETER FOR EXPRESSION NODES *
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* -------------------------------- */
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impl Interpretable for ast::ExprNode {
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fn interprete(&self) -> Result<Value, InterpreterError> {
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match self {
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ast::ExprNode::Binary {
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left,
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operator,
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right,
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} => self.on_binary(left, operator, right),
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ast::ExprNode::Unary { operator, right } => self.on_unary(operator, right),
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ast::ExprNode::Grouping { expression } => expression.interprete(),
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ast::ExprNode::Litteral { value } => self.on_litteral(value),
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}
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}
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}
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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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left: &ast::ExprNode,
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operator: &Token,
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right: &ast::ExprNode,
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) -> Result<Value, InterpreterError> {
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let left_value = left.interprete()?;
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let right_value = right.interprete()?;
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match operator.token_type {
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TokenType::Plus => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Number(a + b)),
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(Value::String(a), Value::String(b)) => Ok(Value::String(a + &b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Minus => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Number(a - b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Star => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Number(a * b)),
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(Value::String(a), Value::Number(b)) => Ok(Value::String(a.repeat(b as usize))),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Slash => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => {
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if b == 0. {
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Err(InterpreterError::new(operator, "division by zero"))
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} else {
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Ok(Value::Number(a / b))
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}
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}
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Greater => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a > b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::GreaterEqual => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a >= b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Less => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a < b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::LessEqual => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a <= b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Equal => Ok(Value::Boolean(left_value == right_value)),
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TokenType::BangEqual => Ok(Value::Boolean(left_value != right_value)),
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_ => panic!(
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"Unsupported token type for binary operator (token {:?})",
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operator
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),
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}
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}
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/// Evaluate an unary operator.
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fn on_unary(&self, operator: &Token, right: &ast::ExprNode) -> Result<Value, InterpreterError> {
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let right_value = right.interprete()?;
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match operator.token_type {
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TokenType::Minus => {
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if let Value::Number(n) = right_value {
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Ok(Value::Number(-n))
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} else {
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Err(InterpreterError::new(operator, "number expected"))
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}
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}
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TokenType::Bang => Ok(Value::Boolean(!right_value.is_truthy())),
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_ => panic!(
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"Unsupported token type for unary operator (token {:?})",
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operator
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),
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}
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}
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/// Evaluate a litteral.
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fn on_litteral(&self, value: &Token) -> Result<Value, InterpreterError> {
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match &value.token_type {
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TokenType::Nil => Ok(Value::Nil),
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TokenType::True => Ok(Value::Boolean(true)),
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TokenType::False => Ok(Value::Boolean(false)),
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TokenType::Number(n) => Ok(Value::Number(*n)),
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TokenType::String(s) => Ok(Value::String(s.clone())),
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_ => panic!("Unsupported token type for litteral (token {:?})", value),
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}
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}
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}
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@ -1,202 +1,5 @@
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use crate::{
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ast,
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errors::{ErrorHandler, InterpreterError},
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tokens::{Token, TokenType},
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};
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mod interpretable;
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mod value;
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/// A value being handled by the interpreter.
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#[derive(Debug, Clone, PartialEq)]
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pub enum Value {
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Nil,
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Boolean(bool),
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String(String),
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Number(f64),
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}
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impl Value {
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/// Check whether a value is truthy or not.
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pub fn is_truthy(&self) -> bool {
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if self == &Value::Nil {
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false
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} else if let Value::Boolean(b) = self {
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*b
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} else {
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true
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}
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}
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}
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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) -> Result<Value, InterpreterError>;
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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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match ast.interprete() {
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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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None
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}
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}
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}
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/* ----------------------------- *
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* INTERPRETER FOR PROGRAM NODES *
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* ----------------------------- */
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impl Interpretable for ast::ProgramNode {
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fn interprete(&self) -> Result<Value, InterpreterError> {
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for stmt in self.0.iter() {
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stmt.interprete()?;
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}
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Ok(Value::Nil)
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}
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}
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/* ------------------------------- *
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* INTERPRETER FOR STATEMENT NODES *
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* ------------------------------- */
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impl Interpretable for ast::StmtNode {
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fn interprete(&self) -> Result<Value, InterpreterError> {
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match self {
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ast::StmtNode::Expression(expr) => expr.interprete(),
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ast::StmtNode::Print(expr) => {
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let value = expr.interprete()?;
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let output = match value {
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Value::Nil => String::from("nil"),
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Value::Boolean(true) => String::from("true"),
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Value::Boolean(false) => String::from("false"),
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Value::Number(n) => n.to_string(),
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Value::String(s) => s,
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};
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println!("{}", output);
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Ok(Value::Nil)
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}
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}
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}
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}
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/* -------------------------------- *
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* INTERPRETER FOR EXPRESSION NODES *
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* -------------------------------- */
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impl Interpretable for ast::ExprNode {
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fn interprete(&self) -> Result<Value, InterpreterError> {
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match self {
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ast::ExprNode::Binary {
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left,
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operator,
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right,
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} => self.on_binary(left, operator, right),
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ast::ExprNode::Unary { operator, right } => self.on_unary(operator, right),
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ast::ExprNode::Grouping { expression } => expression.interprete(),
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ast::ExprNode::Litteral { value } => self.on_litteral(value),
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}
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}
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}
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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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left: &ast::ExprNode,
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operator: &Token,
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right: &ast::ExprNode,
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) -> Result<Value, InterpreterError> {
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let left_value = left.interprete()?;
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let right_value = right.interprete()?;
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match operator.token_type {
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TokenType::Plus => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Number(a + b)),
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(Value::String(a), Value::String(b)) => Ok(Value::String(a + &b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Minus => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Number(a - b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Star => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Number(a * b)),
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(Value::String(a), Value::Number(b)) => Ok(Value::String(a.repeat(b as usize))),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Slash => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => {
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if b == 0. {
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Err(InterpreterError::new(operator, "division by zero"))
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} else {
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Ok(Value::Number(a / b))
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}
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}
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Greater => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a > b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::GreaterEqual => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a >= b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Less => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a < b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::LessEqual => match (left_value, right_value) {
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(Value::Number(a), Value::Number(b)) => Ok(Value::Boolean(a <= b)),
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_ => Err(InterpreterError::new(operator, "type error")),
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},
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TokenType::Equal => Ok(Value::Boolean(left_value == right_value)),
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TokenType::BangEqual => Ok(Value::Boolean(left_value != right_value)),
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_ => panic!(
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"Unsupported token type for binary operator (token {:?})",
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operator
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),
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}
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}
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/// Evaluate an unary operator.
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fn on_unary(&self, operator: &Token, right: &ast::ExprNode) -> Result<Value, InterpreterError> {
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let right_value = right.interprete()?;
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match operator.token_type {
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TokenType::Minus => {
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if let Value::Number(n) = right_value {
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Ok(Value::Number(-n))
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} else {
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Err(InterpreterError::new(operator, "number expected"))
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}
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}
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TokenType::Bang => Ok(Value::Boolean(!right_value.is_truthy())),
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_ => panic!(
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"Unsupported token type for unary operator (token {:?})",
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operator
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),
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}
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}
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/// Evaluate a litteral.
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fn on_litteral(&self, value: &Token) -> Result<Value, InterpreterError> {
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match &value.token_type {
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TokenType::Nil => Ok(Value::Nil),
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TokenType::True => Ok(Value::Boolean(true)),
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TokenType::False => Ok(Value::Boolean(false)),
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TokenType::Number(n) => Ok(Value::Number(*n)),
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TokenType::String(s) => Ok(Value::String(s.clone())),
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_ => panic!("Unsupported token type for litteral (token {:?})", value),
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}
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}
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}
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pub use interpretable::*;
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pub use value::*;
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21
src/interpreter/value.rs
Normal file
21
src/interpreter/value.rs
Normal file
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@ -0,0 +1,21 @@
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/// A value being handled by the interpreter.
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#[derive(Debug, Clone, PartialEq)]
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pub enum Value {
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Nil,
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Boolean(bool),
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String(String),
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Number(f64),
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}
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impl Value {
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/// Check whether a value is truthy or not.
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pub fn is_truthy(&self) -> bool {
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if self == &Value::Nil {
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false
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} else if let Value::Boolean(b) = self {
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*b
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} else {
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true
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}
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}
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}
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