656 lines
22 KiB
Rust
656 lines
22 KiB
Rust
//! Tools for analyzing an abstract syntax tree and catching errors before running the virtual
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//! machine.
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//!
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//! This module provides two anlysis options:
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//! - `analyze` convenience function, which takes a string input
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//! - `Analyzer` struct, which borrows an abstract syntax tree and a context
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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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ast::{
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AbstractSyntaxTree, BlockExpression, CallExpression, ElseExpression, FieldAccessExpression,
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IfExpression, LetStatement, ListExpression, ListIndexExpression, LoopExpression,
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MapExpression, Node, OperatorExpression, RangeExpression, Span, Statement,
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StructDefinition, StructExpression, TupleAccessExpression,
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},
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parse, Context, DustError, Expression, Identifier, StructType, 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 context = Context::new();
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let mut analyzer = Analyzer::new(&abstract_tree, &context);
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analyzer
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.analyze()
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.map_err(|analysis_error| DustError::AnalysisError {
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analysis_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 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 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<(), AnalysisError> {
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for statement in &self.abstract_tree.statements {
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self.analyze_statement(statement)?;
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}
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Ok(())
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}
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fn analyze_statement(&mut self, statement: &Statement) -> Result<(), AnalysisError> {
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match statement {
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Statement::Expression(expression) => self.analyze_expression(expression)?,
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Statement::ExpressionNullified(expression_node) => {
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self.analyze_expression(&expression_node.inner)?;
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}
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Statement::Let(let_statement) => match &let_statement.inner {
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LetStatement::Let { identifier, value }
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| LetStatement::LetMut { identifier, value } => {
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let r#type = value.return_type(self.context);
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if let Some(r#type) = r#type {
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self.context.set_variable_type(
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identifier.inner.clone(),
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r#type,
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identifier.position,
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);
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} else {
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return Err(AnalysisError::ExpectedValueFromExpression {
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expression: value.clone(),
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found_type: r#type,
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});
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}
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self.analyze_expression(value)?;
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}
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LetStatement::LetType { .. } => todo!(),
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LetStatement::LetMutType { .. } => todo!(),
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},
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Statement::StructDefinition(struct_definition) => match &struct_definition.inner {
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StructDefinition::Unit { name } => self.context.set_constructor_type(
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name.inner.clone(),
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StructType::Unit {
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name: name.inner.clone(),
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},
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name.position,
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),
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StructDefinition::Tuple { name, items } => {
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let fields = items.iter().map(|item| item.inner.clone()).collect();
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self.context.set_constructor_type(
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name.inner.clone(),
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StructType::Tuple {
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name: name.inner.clone(),
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fields,
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},
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name.position,
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);
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}
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StructDefinition::Fields { name, fields } => {
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let fields = fields
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.iter()
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.map(|(identifier, r#type)| {
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(identifier.inner.clone(), r#type.inner.clone())
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})
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.collect();
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self.context.set_constructor_type(
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name.inner.clone(),
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StructType::Fields {
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name: name.inner.clone(),
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fields,
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},
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name.position,
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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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fn analyze_expression(&mut self, expression: &Expression) -> Result<(), AnalysisError> {
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match expression {
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Expression::Block(block_expression) => self.analyze_block(&block_expression.inner)?,
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Expression::Call(call_expression) => {
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let CallExpression { invoker, arguments } = call_expression.inner.as_ref();
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self.analyze_expression(invoker)?;
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for argument in arguments {
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self.analyze_expression(argument)?;
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}
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}
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Expression::FieldAccess(field_access_expression) => {
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let FieldAccessExpression { container, field } =
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field_access_expression.inner.as_ref();
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self.context
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.update_last_position(&field.inner, field.position);
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self.analyze_expression(container)?;
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}
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Expression::Grouped(expression) => {
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self.analyze_expression(expression.inner.as_ref())?;
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}
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Expression::Identifier(identifier) => {
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self.context
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.update_last_position(&identifier.inner, identifier.position);
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}
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Expression::If(if_expression) => self.analyze_if(&if_expression.inner)?,
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Expression::List(list_expression) => match list_expression.inner.as_ref() {
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ListExpression::AutoFill {
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repeat_operand,
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length_operand,
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} => {
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self.analyze_expression(repeat_operand)?;
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self.analyze_expression(length_operand)?;
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}
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ListExpression::Ordered(expressions) => {
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for expression in expressions {
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self.analyze_expression(expression)?;
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}
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}
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},
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Expression::ListIndex(list_index_expression) => {
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let ListIndexExpression { list, index } = list_index_expression.inner.as_ref();
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self.analyze_expression(list)?;
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self.analyze_expression(index)?;
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}
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Expression::Literal(_) => {
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// Literals don't need to be analyzed
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}
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Expression::Loop(loop_expression) => match loop_expression.inner.as_ref() {
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LoopExpression::Infinite { block } => self.analyze_block(&block.inner)?,
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LoopExpression::While { condition, block } => {
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self.analyze_expression(condition)?;
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self.analyze_block(&block.inner)?;
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}
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LoopExpression::For {
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iterator, block, ..
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} => {
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self.analyze_expression(iterator)?;
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self.analyze_block(&block.inner)?;
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}
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},
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Expression::Map(map_expression) => {
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let MapExpression { pairs } = map_expression.inner.as_ref();
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for (_, expression) in pairs {
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self.analyze_expression(expression)?;
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}
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}
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Expression::Operator(operator_expression) => match operator_expression.inner.as_ref() {
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OperatorExpression::Assignment { assignee, value } => {
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self.analyze_expression(assignee)?;
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self.analyze_expression(value)?;
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}
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OperatorExpression::Comparison { left, right, .. } => {
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self.analyze_expression(left)?;
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self.analyze_expression(right)?;
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}
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OperatorExpression::CompoundAssignment {
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assignee, modifier, ..
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} => {
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self.analyze_expression(assignee)?;
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self.analyze_expression(modifier)?;
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let expected_type = assignee.return_type(self.context);
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let actual_type = modifier.return_type(self.context);
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if expected_type.is_none() {
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return Err(AnalysisError::ExpectedValueFromExpression {
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expression: assignee.clone(),
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found_type: expected_type,
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});
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}
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if actual_type.is_none() {
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return Err(AnalysisError::ExpectedValueFromExpression {
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expression: modifier.clone(),
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found_type: actual_type,
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});
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}
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if let (Some(expected_type), Some(actual_type)) = (expected_type, actual_type) {
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expected_type.check(&actual_type).map_err(|_| {
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AnalysisError::TypeConflict {
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actual_expression: modifier.clone(),
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actual_type,
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expected: expected_type,
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}
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})?;
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}
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}
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OperatorExpression::ErrorPropagation(_) => todo!(),
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OperatorExpression::Negation(expression) => {
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self.analyze_expression(expression)?;
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}
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OperatorExpression::Not(expression) => {
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self.analyze_expression(expression)?;
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}
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OperatorExpression::Math { left, right, .. } => {
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self.analyze_expression(left)?;
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self.analyze_expression(right)?;
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}
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OperatorExpression::Logic { left, right, .. } => {
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self.analyze_expression(left)?;
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self.analyze_expression(right)?;
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}
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},
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Expression::Range(range_expression) => match range_expression.inner.as_ref() {
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RangeExpression::Exclusive { start, end } => {
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self.analyze_expression(start)?;
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self.analyze_expression(end)?;
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}
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RangeExpression::Inclusive { start, end } => {
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self.analyze_expression(start)?;
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self.analyze_expression(end)?;
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}
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},
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Expression::Struct(struct_expression) => match struct_expression.inner.as_ref() {
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StructExpression::Fields { name, fields } => {
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self.context
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.update_last_position(&name.inner, name.position);
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for (_, expression) in fields {
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self.analyze_expression(expression)?;
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}
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}
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},
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Expression::TupleAccess(tuple_access) => {
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let TupleAccessExpression { tuple, .. } = tuple_access.inner.as_ref();
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self.analyze_expression(tuple)?;
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}
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}
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Ok(())
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}
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fn analyze_block(&mut self, block_expression: &BlockExpression) -> Result<(), AnalysisError> {
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match block_expression {
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BlockExpression::Async(statements) => {
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for statement in statements {
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self.analyze_statement(statement)?;
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}
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}
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BlockExpression::Sync(statements) => {
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for statement in statements {
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self.analyze_statement(statement)?;
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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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fn analyze_if(&mut self, if_expression: &IfExpression) -> Result<(), AnalysisError> {
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match if_expression {
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IfExpression::If {
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condition,
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if_block,
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} => {
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self.analyze_expression(condition)?;
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self.analyze_block(&if_block.inner)?;
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}
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IfExpression::IfElse {
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condition,
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if_block,
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r#else,
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} => {
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self.analyze_expression(condition)?;
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self.analyze_block(&if_block.inner)?;
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match r#else {
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ElseExpression::Block(block_expression) => {
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self.analyze_block(&block_expression.inner)?;
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}
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ElseExpression::If(if_expression) => {
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self.analyze_if(&if_expression.inner)?;
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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 AnalysisError {
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ExpectedBoolean {
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actual: Statement,
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},
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ExpectedIdentifier {
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actual: Statement,
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},
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ExpectedIdentifierOrString {
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actual: Statement,
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},
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ExpectedIntegerOrRange {
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actual: Statement,
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},
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ExpectedList {
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actual: Statement,
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},
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ExpectedMap {
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actual: Statement,
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},
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ExpectedValueFromStatement {
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actual: Statement,
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},
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ExpectedValueFromExpression {
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expression: Expression,
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found_type: Option<Type>,
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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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IndexOutOfBounds {
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list: Statement,
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index: Statement,
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index_value: usize,
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length: usize,
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},
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TypeConflict {
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actual_expression: Expression,
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actual_type: Type,
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expected: Type,
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},
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UndefinedField {
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identifier: Statement,
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statement: Statement,
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},
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UndefinedType {
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identifier: Node<Identifier>,
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},
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UnexpectedIdentifier {
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identifier: Node<Identifier>,
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},
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UnexectedString {
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actual: Statement,
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},
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UndefinedVariable {
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identifier: Node<Identifier>,
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},
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}
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impl AnalysisError {
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pub fn position(&self) -> Span {
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match self {
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AnalysisError::ExpectedBoolean { actual } => actual.position(),
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AnalysisError::ExpectedIdentifier { actual } => actual.position(),
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AnalysisError::ExpectedIdentifierOrString { actual } => actual.position(),
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AnalysisError::ExpectedIntegerOrRange { actual } => actual.position(),
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AnalysisError::ExpectedList { actual } => actual.position(),
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AnalysisError::ExpectedMap { actual } => actual.position(),
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AnalysisError::ExpectedValueFromExpression { expression, .. } => expression.position(),
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AnalysisError::ExpectedValueFromStatement { actual } => actual.position(),
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AnalysisError::ExpectedValueArgumentCount { position, .. } => *position,
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AnalysisError::IndexOutOfBounds { index, .. } => index.position(),
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AnalysisError::TypeConflict {
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actual_expression, ..
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} => actual_expression.position(),
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AnalysisError::UndefinedField { identifier, .. } => identifier.position(),
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AnalysisError::UndefinedType { identifier } => identifier.position,
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AnalysisError::UndefinedVariable { identifier } => identifier.position,
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AnalysisError::UnexpectedIdentifier { identifier } => identifier.position,
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AnalysisError::UnexectedString { actual } => actual.position(),
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}
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}
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}
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impl Error for AnalysisError {}
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impl Display for AnalysisError {
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fn fmt(&self, f: &mut Formatter) -> fmt::Result {
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match self {
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AnalysisError::ExpectedBoolean { actual, .. } => {
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write!(f, "Expected boolean, found {}", actual)
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}
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AnalysisError::ExpectedIdentifier { actual, .. } => {
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write!(f, "Expected identifier, found {}", actual)
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}
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AnalysisError::ExpectedIdentifierOrString { actual } => {
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write!(f, "Expected identifier or string, found {}", actual)
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}
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AnalysisError::ExpectedIntegerOrRange { actual, .. } => {
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write!(f, "Expected integer or range, found {}", actual)
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}
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AnalysisError::ExpectedList { actual } => write!(f, "Expected list, found {}", actual),
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AnalysisError::ExpectedMap { actual } => write!(f, "Expected map, found {}", actual),
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AnalysisError::ExpectedValueFromExpression {
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expression,
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found_type,
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} => {
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write!(
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f,
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"Expected {} to produce a value, found {:?}",
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expression, found_type
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)
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}
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AnalysisError::ExpectedValueFromStatement { actual, .. } => {
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write!(f, "Expected statement to produce a value, found {}", actual)
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}
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AnalysisError::ExpectedValueArgumentCount {
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expected, actual, ..
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} => write!(f, "Expected {} value arguments, found {}", expected, actual),
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AnalysisError::IndexOutOfBounds {
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list,
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index_value,
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length,
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..
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} => write!(
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f,
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"Index {} out of bounds for list {} with length {}",
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index_value, list, length
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),
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AnalysisError::TypeConflict {
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actual_expression: 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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AnalysisError::UndefinedField {
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identifier,
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statement: map,
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} => {
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write!(f, "Undefined field {} in map {}", identifier, map)
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}
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AnalysisError::UndefinedType { identifier } => {
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write!(f, "Undefined type {}", identifier)
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}
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AnalysisError::UndefinedVariable { identifier } => {
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write!(f, "Undefined variable {}", identifier)
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}
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AnalysisError::UnexpectedIdentifier { identifier, .. } => {
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write!(f, "Unexpected identifier {}", identifier)
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}
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AnalysisError::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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|
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use super::*;
|
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|
|
#[test]
|
|
fn add_assign_wrong_type() {
|
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let source = "
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let mut a = 1;
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a += 1.0
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";
|
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|
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assert_eq!(
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analyze(source),
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Err(DustError::AnalysisError {
|
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analysis_error: AnalysisError::TypeConflict {
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actual_expression: Expression::literal(1.0, (45, 48)),
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actual_type: Type::Float,
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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 subtract_assign_wrong_type() {
|
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let source = "
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a = 1
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a -= 1.0
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";
|
|
|
|
assert_eq!(
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analyze(source),
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Err(DustError::AnalysisError {
|
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analysis_error: AnalysisError::TypeConflict {
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actual_expression: Expression::literal(1.0, (45, 48)),
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actual_type: Type::Float,
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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 tuple_struct_with_wrong_field_types() {
|
|
let source = "
|
|
struct Foo(int, float)
|
|
Foo(1, 2)
|
|
";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn constant_list_index_out_of_bounds() {
|
|
let source = "[1, 2, 3][3]";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn nonexistant_field_identifier() {
|
|
let source = "{ x = 1 }.y";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn nonexistant_field_string() {
|
|
let source = "{ x = 1 }.'y'";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn malformed_list_index() {
|
|
let source = "[1, 2, 3]['foo']";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn malformed_field_access() {
|
|
let source = "{ x = 1 }.0";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn length_no_arguments() {
|
|
let source = "length()";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn float_plus_integer() {
|
|
let source = "42.0 + 2";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn integer_plus_boolean() {
|
|
let source = "42 + true";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn is_even_expects_number() {
|
|
let source = "is_even('hello')";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn is_odd_expects_number() {
|
|
let source = "is_odd('hello')";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
|
|
#[test]
|
|
fn undefined_variable() {
|
|
let source = "foo";
|
|
|
|
assert_eq!(analyze(source), todo!());
|
|
}
|
|
}
|