100 lines
3.0 KiB
Rust
100 lines
3.0 KiB
Rust
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use std::collections::HashMap;
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use crate::{
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backend::environment::EnvironmentStack,
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common::{
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ast::{AstNode, Expr, Stmt},
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lox_result::{LoxError, LoxResult},
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},
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frontend::source_registry::SourceSlice,
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middleend::visit_ast::{walk_expr, walk_stmt, Visitor},
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};
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struct Resolver {
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scopes: EnvironmentStack<bool>,
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locals: HashMap<SourceSlice, usize>,
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}
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impl Resolver {
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pub fn new() -> Self {
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Resolver {
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scopes: EnvironmentStack::new(),
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locals: HashMap::new(),
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}
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}
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fn declare(&mut self, name: &String) {
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if self.scopes.is_empty() {
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return;
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}
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let _ = self.scopes.set(name.clone(), false);
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}
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fn define(&mut self, name: &String) {
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if self.scopes.is_empty() {
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return;
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}
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let _ = self.scopes.set(name.clone(), true);
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}
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fn resolve_local(&mut self, name: &String) {
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let depth = self.scopes.depth();
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for i in (0..depth).rev() {
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if self.scopes.scope_contains(i, name) {
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self.locals.insert(, i);
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}
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}
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}
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}
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impl Visitor for Resolver {
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fn visit_stmt(&mut self, stmt: &AstNode<Stmt>) -> LoxResult<()> {
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match &stmt.node {
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Stmt::VarDeclaration { name, .. } => {
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self.declare(name);
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// `walk_stmt` resolves the initializer (if present).
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walk_stmt(self, stmt)?;
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self.define(name);
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Ok(())
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}
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Stmt::VarAssigment { name, .. } => {
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match self.scopes.get(name) {
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Ok(true) => (),
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Ok(false) => {
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return Err(LoxError::RuntimeError {
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source_slice: SourceSlice::default(),
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message: "Cant read local variable in it own lintilizer".to_string(),
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})
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}
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Err(err) => return Err(err),
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}
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// `walk_stmt` resolves the assigned value.
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walk_stmt(self, stmt)
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}
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Stmt::Block { .. } => {
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self.scopes.push_new_scope();
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walk_stmt(self, stmt)?;
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self.scopes.pop_scope();
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Ok(())
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}
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// Expression, Print, Return, If, While, For: default traversal.
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_ => walk_stmt(self, stmt),
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}
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}
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fn visit_expr(&mut self, expr: &AstNode<Expr>) -> LoxResult<()> {
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match &expr.node {
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Expr::Identifier { name, .. } => {
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if !self.scopes.is_empty() && self.scopes.get(name).is_ok() {
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return Err(LoxError::ParseError {
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source_slice: SourceSlice::default(),
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message: "Cant read local varialbe in it own initializer".to_string(),
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});
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}
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Ok(())
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}
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_ => walk_expr(self, expr),
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}
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}
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}
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