618 lines
20 KiB
Rust
618 lines
20 KiB
Rust
//! Tools for analyzing an abstract syntax tree and catch errors before running the virtual
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//! machine.
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//!
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//! This module provides to anlysis options, both of which borrow an abstract syntax tree and a
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//! hash map of variables:
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//! - `analyze` convenience function
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//! - `Analyzer` struct
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use std::{
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error::Error,
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fmt::{self, Display, Formatter},
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};
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use crate::{
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abstract_tree::BinaryOperator, parse, AbstractSyntaxTree, Context, DustError, Node, Span,
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Statement, Type,
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};
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/// Analyzes the abstract syntax tree for errors.
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///
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/// # Examples
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/// ```
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/// # use std::collections::HashMap;
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/// # use dust_lang::*;
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/// let input = "x = 1 + false";
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/// let result = analyze(input);
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///
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/// assert!(result.is_err());
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/// ```
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pub fn analyze(source: &str) -> Result<(), DustError> {
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let abstract_tree = parse(source)?;
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let mut context = Context::new();
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let mut analyzer = Analyzer::new(&abstract_tree, &mut context);
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analyzer
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.analyze()
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.map_err(|analyzer_error| DustError::AnalyzerError {
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analyzer_error,
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source,
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})
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}
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/// Static analyzer that checks for potential runtime errors.
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///
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/// # Examples
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/// ```
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/// # use std::collections::HashMap;
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/// # use dust_lang::*;
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/// let input = "x = 1 + false";
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/// let abstract_tree = parse(input).unwrap();
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/// let mut context = Context::new();
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/// let mut analyzer = Analyzer::new(&abstract_tree, &mut context);
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/// let result = analyzer.analyze();
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///
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/// assert!(result.is_err());
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pub struct Analyzer<'a> {
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abstract_tree: &'a AbstractSyntaxTree,
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context: &'a mut Context,
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}
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impl<'a> Analyzer<'a> {
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pub fn new(abstract_tree: &'a AbstractSyntaxTree, context: &'a mut Context) -> Self {
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Self {
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abstract_tree,
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context,
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}
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}
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pub fn analyze(&mut self) -> Result<(), AnalyzerError> {
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for node in &self.abstract_tree.nodes {
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self.analyze_node(node)?;
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}
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Ok(())
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}
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fn analyze_node(&mut self, node: &Node<Statement>) -> Result<(), AnalyzerError> {
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match &node.inner {
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Statement::BinaryOperation {
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left,
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operator,
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right,
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} => {
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if let BinaryOperator::Assign = operator.inner {
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if let Statement::Identifier(identifier) = &left.inner {
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self.analyze_node(right)?;
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let right_type = right.inner.expected_type(self.context);
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self.context.set_type(
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identifier.clone(),
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right_type.ok_or(AnalyzerError::ExpectedValue {
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actual: right.as_ref().clone(),
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})?,
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);
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return Ok(());
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}
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}
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self.analyze_node(left)?;
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self.analyze_node(right)?;
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let left_type = left.inner.expected_type(self.context);
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let right_type = right.inner.expected_type(self.context);
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if let BinaryOperator::Add
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| BinaryOperator::Subtract
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| BinaryOperator::Multiply
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| BinaryOperator::Divide
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| BinaryOperator::Greater
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| BinaryOperator::GreaterOrEqual
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| BinaryOperator::Less
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| BinaryOperator::LessOrEqual = operator.inner
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{
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if let Some(expected_type) = left_type {
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if let Some(actual_type) = right_type {
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expected_type.check(&actual_type).map_err(|conflict| {
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AnalyzerError::TypeConflict {
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actual_statement: right.as_ref().clone(),
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actual_type: conflict.actual,
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expected: conflict.expected,
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}
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})?;
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} else {
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return Err(AnalyzerError::ExpectedValue {
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actual: right.as_ref().clone(),
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});
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}
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}
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}
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}
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Statement::Block(statements) => {
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for statement in statements {
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self.analyze_node(statement)?;
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}
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}
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Statement::BuiltInFunctionCall {
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function,
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value_arguments,
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..
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} => {
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let value_parameters = function.value_parameters();
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if let Some(arguments) = value_arguments {
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for argument in arguments {
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self.analyze_node(argument)?;
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}
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if arguments.len() != value_parameters.len() {
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return Err(AnalyzerError::ExpectedValueArgumentCount {
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expected: value_parameters.len(),
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actual: arguments.len(),
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position: node.position,
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});
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}
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for ((_identifier, parameter_type), argument) in
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value_parameters.iter().zip(arguments)
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{
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let argument_type_option = argument.inner.expected_type(self.context);
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if let Some(argument_type) = argument_type_option {
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parameter_type.check(&argument_type).map_err(|conflict| {
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AnalyzerError::TypeConflict {
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actual_statement: argument.clone(),
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actual_type: conflict.actual,
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expected: parameter_type.clone(),
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}
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})?;
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} else {
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return Err(AnalyzerError::ExpectedValue {
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actual: argument.clone(),
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});
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}
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}
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if arguments.is_empty() && !value_parameters.is_empty() {
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return Err(AnalyzerError::ExpectedValueArgumentCount {
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expected: value_parameters.len(),
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actual: 0,
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position: node.position,
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});
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}
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} else if !value_parameters.is_empty() {
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return Err(AnalyzerError::ExpectedValueArgumentCount {
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expected: value_parameters.len(),
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actual: 0,
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position: node.position,
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});
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}
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}
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Statement::Constant(_) => {}
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Statement::FunctionCall {
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function,
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value_arguments,
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..
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} => {
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self.analyze_node(function)?;
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if let Some(arguments) = value_arguments {
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for argument in arguments {
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self.analyze_node(argument)?;
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}
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}
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}
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Statement::Identifier(identifier) => {
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let exists = self.context.add_allowed_use(identifier);
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if !exists {
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return Err(AnalyzerError::UndefinedVariable {
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identifier: node.clone(),
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});
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}
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}
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Statement::If { condition, body } => {
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self.analyze_node(condition)?;
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if let Some(Type::Boolean) = condition.inner.expected_type(self.context) {
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// Condition is valid
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} else {
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return Err(AnalyzerError::ExpectedBoolean {
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actual: condition.as_ref().clone(),
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});
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}
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self.analyze_node(body)?;
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}
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Statement::IfElse {
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condition,
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if_body,
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else_body,
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} => {
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self.analyze_node(condition)?;
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if let Some(Type::Boolean) = condition.inner.expected_type(self.context) {
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// Condition is valid
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} else {
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return Err(AnalyzerError::ExpectedBoolean {
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actual: condition.as_ref().clone(),
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});
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}
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self.analyze_node(if_body)?;
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self.analyze_node(else_body)?;
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}
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Statement::IfElseIf {
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condition,
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if_body,
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else_ifs,
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} => {
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self.analyze_node(condition)?;
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if let Some(Type::Boolean) = condition.inner.expected_type(self.context) {
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// Condition is valid
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} else {
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return Err(AnalyzerError::ExpectedBoolean {
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actual: condition.as_ref().clone(),
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});
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}
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self.analyze_node(if_body)?;
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for (condition, body) in else_ifs {
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self.analyze_node(condition)?;
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if let Some(Type::Boolean) = condition.inner.expected_type(self.context) {
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// Condition is valid
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} else {
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return Err(AnalyzerError::ExpectedBoolean {
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actual: condition.clone(),
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});
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}
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self.analyze_node(body)?;
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}
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}
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Statement::IfElseIfElse {
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condition,
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if_body,
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else_ifs,
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else_body,
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} => {
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self.analyze_node(condition)?;
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if let Some(Type::Boolean) = condition.inner.expected_type(self.context) {
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// Condition is valid
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} else {
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return Err(AnalyzerError::ExpectedBoolean {
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actual: condition.as_ref().clone(),
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});
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}
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self.analyze_node(if_body)?;
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for (condition, body) in else_ifs {
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self.analyze_node(condition)?;
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if let Some(Type::Boolean) = condition.inner.expected_type(self.context) {
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// Condition is valid
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} else {
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return Err(AnalyzerError::ExpectedBoolean {
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actual: condition.clone(),
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});
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}
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self.analyze_node(body)?;
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}
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self.analyze_node(else_body)?;
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}
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Statement::List(statements) => {
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for statement in statements {
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self.analyze_node(statement)?;
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}
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}
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Statement::Map(properties) => {
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for (_key, value_node) in properties {
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self.analyze_node(value_node)?;
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}
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}
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Statement::Nil(node) => {
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self.analyze_node(node)?;
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}
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Statement::PropertyAccess(left, right) => {
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self.analyze_node(left)?;
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if let Statement::Identifier(_) = right.inner {
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// Do not expect a value for property accessors
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} else {
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self.analyze_node(right)?;
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}
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if let Some(Type::List { .. }) = left.inner.expected_type(self.context) {
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if let Some(Type::Integer) = right.inner.expected_type(self.context) {
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// Allow indexing lists with integers
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} else {
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return Err(AnalyzerError::ExpectedInteger {
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actual: right.as_ref().clone(),
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});
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}
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}
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if let Some(Type::Map { .. }) = left.inner.expected_type(self.context) {
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if let Some(Type::String) = right.inner.expected_type(self.context) {
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// Allow indexing maps with strings
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} else if let Statement::Identifier(_) = right.inner {
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// Allow indexing maps with identifiers
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} else {
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return Err(AnalyzerError::ExpectedIdentifierOrString {
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actual: right.as_ref().clone(),
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});
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}
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}
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}
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Statement::While { condition, body } => {
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self.analyze_node(condition)?;
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self.analyze_node(body)?;
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if let Some(Type::Boolean) = condition.inner.expected_type(self.context) {
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} else {
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return Err(AnalyzerError::ExpectedBoolean {
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actual: condition.as_ref().clone(),
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});
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}
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}
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}
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Ok(())
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}
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}
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#[derive(Clone, Debug, PartialEq)]
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pub enum AnalyzerError {
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ExpectedBoolean {
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actual: Node<Statement>,
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},
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ExpectedIdentifier {
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actual: Node<Statement>,
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},
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ExpectedIdentifierOrString {
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actual: Node<Statement>,
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},
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ExpectedInteger {
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actual: Node<Statement>,
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},
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ExpectedValue {
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actual: Node<Statement>,
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},
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ExpectedValueArgumentCount {
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expected: usize,
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actual: usize,
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position: Span,
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},
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TypeConflict {
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actual_statement: Node<Statement>,
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actual_type: Type,
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expected: Type,
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},
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UndefinedVariable {
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identifier: Node<Statement>,
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},
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UnexpectedIdentifier {
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identifier: Node<Statement>,
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},
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UnexectedString {
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actual: Node<Statement>,
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},
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}
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impl AnalyzerError {
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pub fn position(&self) -> Span {
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match self {
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AnalyzerError::ExpectedBoolean { actual, .. } => actual.position,
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AnalyzerError::ExpectedIdentifier { actual, .. } => actual.position,
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AnalyzerError::ExpectedIdentifierOrString { actual } => actual.position,
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AnalyzerError::ExpectedInteger { actual, .. } => actual.position,
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AnalyzerError::ExpectedValue { actual } => actual.position,
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AnalyzerError::ExpectedValueArgumentCount { position, .. } => *position,
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AnalyzerError::TypeConflict {
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actual_statement, ..
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} => actual_statement.position,
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AnalyzerError::UndefinedVariable { identifier } => identifier.position,
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AnalyzerError::UnexpectedIdentifier { identifier } => identifier.position,
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AnalyzerError::UnexectedString { actual } => actual.position,
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}
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}
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}
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impl Error for AnalyzerError {}
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impl Display for AnalyzerError {
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fn fmt(&self, f: &mut Formatter) -> fmt::Result {
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match self {
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AnalyzerError::ExpectedBoolean { actual, .. } => {
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write!(f, "Expected boolean, found {}", actual)
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}
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AnalyzerError::ExpectedIdentifier { actual, .. } => {
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write!(f, "Expected identifier, found {}", actual)
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}
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AnalyzerError::ExpectedIdentifierOrString { actual } => {
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write!(f, "Expected identifier or string, found {}", actual)
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}
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AnalyzerError::ExpectedInteger { actual, .. } => {
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write!(f, "Expected integer, found {}", actual)
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}
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AnalyzerError::ExpectedValue { actual, .. } => {
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write!(f, "Expected value, found {}", actual)
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}
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AnalyzerError::ExpectedValueArgumentCount {
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expected, actual, ..
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} => write!(f, "Expected {} value arguments, found {}", expected, actual),
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AnalyzerError::TypeConflict {
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actual_statement,
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actual_type,
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expected,
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} => {
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write!(
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f,
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"Expected type {}, found {}, which has type {}",
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expected, actual_statement, actual_type
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)
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}
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AnalyzerError::UndefinedVariable { identifier } => {
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write!(f, "Undefined variable {}", identifier)
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}
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AnalyzerError::UnexpectedIdentifier { identifier, .. } => {
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write!(f, "Unexpected identifier {}", identifier)
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}
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AnalyzerError::UnexectedString { actual, .. } => {
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write!(f, "Unexpected string {}", actual)
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}
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::{Identifier, Value};
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use super::*;
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#[test]
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fn malformed_list_index() {
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let source = "[1, 2, 3].foo";
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assert_eq!(
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analyze(source),
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Err(DustError::AnalyzerError {
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analyzer_error: AnalyzerError::ExpectedInteger {
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actual: Node::new(Statement::Identifier(Identifier::new("foo")), (10, 13)),
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},
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source
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})
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);
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}
|
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|
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#[test]
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fn malformed_property_access() {
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let source = "{ x = 1 }.0";
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assert_eq!(
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analyze(source),
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Err(DustError::AnalyzerError {
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analyzer_error: AnalyzerError::ExpectedIdentifierOrString {
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actual: Node::new(Statement::Constant(Value::integer(0)), (10, 11)),
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},
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source
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})
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);
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}
|
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|
|
#[test]
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fn length_no_arguments() {
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let source = "length()";
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|
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assert_eq!(
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analyze(source),
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Err(DustError::AnalyzerError {
|
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analyzer_error: AnalyzerError::ExpectedValueArgumentCount {
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expected: 1,
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actual: 0,
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position: (0, 6)
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},
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source
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})
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);
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}
|
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|
|
#[test]
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|
fn float_plus_integer() {
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let source = "42.0 + 2";
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|
|
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assert_eq!(
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analyze(source),
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Err(DustError::AnalyzerError {
|
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analyzer_error: AnalyzerError::TypeConflict {
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actual_statement: Node::new(Statement::Constant(Value::integer(2)), (7, 8)),
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actual_type: Type::Integer,
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expected: Type::Float,
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},
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source
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})
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)
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}
|
|
|
|
#[test]
|
|
fn integer_plus_boolean() {
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let source = "42 + true";
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assert_eq!(
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analyze(source),
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Err(DustError::AnalyzerError {
|
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analyzer_error: AnalyzerError::TypeConflict {
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actual_statement: Node::new(Statement::Constant(Value::boolean(true)), (5, 9)),
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actual_type: Type::Boolean,
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expected: Type::Integer,
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},
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source
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})
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)
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}
|
|
|
|
#[test]
|
|
fn is_even_expects_number() {
|
|
let source = "is_even('hello')";
|
|
|
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assert_eq!(
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analyze(source),
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Err(DustError::AnalyzerError {
|
|
analyzer_error: AnalyzerError::TypeConflict {
|
|
actual_statement: Node::new(
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Statement::Constant(Value::string("hello")),
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(8, 15)
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),
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actual_type: Type::String,
|
|
expected: Type::Number,
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},
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source
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})
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);
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}
|
|
|
|
#[test]
|
|
fn is_odd_expects_number() {
|
|
let source = "is_odd('hello')";
|
|
|
|
assert_eq!(
|
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analyze(source),
|
|
Err(DustError::AnalyzerError {
|
|
analyzer_error: AnalyzerError::TypeConflict {
|
|
actual_statement: Node::new(
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Statement::Constant(Value::string("hello")),
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(7, 14)
|
|
),
|
|
actual_type: Type::String,
|
|
expected: Type::Number,
|
|
},
|
|
source
|
|
})
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn undefined_variable() {
|
|
let source = "foo";
|
|
|
|
assert_eq!(
|
|
analyze(source),
|
|
Err(DustError::AnalyzerError {
|
|
analyzer_error: AnalyzerError::UndefinedVariable {
|
|
identifier: Node::new(Statement::Identifier(Identifier::new("foo")), (0, 3)),
|
|
},
|
|
source
|
|
})
|
|
);
|
|
}
|
|
}
|