diff --git a/fine/src/main.rs b/fine/src/main.rs index fe40cff2..62c9b484 100644 --- a/fine/src/main.rs +++ b/fine/src/main.rs @@ -18,7 +18,7 @@ pub fn process_file(file: &str) { // This is... probably wrong, I don't know, what am I doing? for t in tree.trees() { - let _ = semantics.type_of(t, false); + let _ = semantics.type_of(t); } // OK now there might be errors. diff --git a/fine/src/semantics.rs b/fine/src/semantics.rs index f32eb2c3..7d087afd 100644 --- a/fine/src/semantics.rs +++ b/fine/src/semantics.rs @@ -90,6 +90,7 @@ impl Type { (Type::String, Type::String) => true, (Type::Bool, Type::Bool) => true, (Type::Unreachable, Type::Unreachable) => true, + (Type::Nothing, Type::Nothing) => true, // Avoid introducing more errors (Type::Error, _) => true, @@ -126,7 +127,7 @@ pub struct Semantics<'a> { syntax_tree: &'a SyntaxTree<'a>, lines: &'a Lines, errors: RefCell>, - types: RefCell>, + types: RefCell>, } impl<'a> Semantics<'a> { @@ -209,29 +210,27 @@ impl<'a> Semantics<'a> { } } - pub fn type_of(&self, t: TreeRef, value_required: bool) -> Option { - if let Some(existing) = self.types.borrow().get(&(t, value_required)) { + pub fn type_of(&self, t: TreeRef) -> Option { + if let Some(existing) = self.types.borrow().get(&t) { return Some(existing.clone()); } let tree = &self.syntax_tree[t]; let result = match tree.kind { TreeKind::Error => Some(Type::Error), - TreeKind::UnaryExpression => self.type_of_unary(tree, value_required), - TreeKind::BinaryExpression => self.type_of_binary(tree, value_required), - TreeKind::TypeExpression => self.type_of_type_expr(tree, value_required), - TreeKind::Block => self.type_of_block(tree, value_required), + TreeKind::UnaryExpression => self.type_of_unary(tree), + TreeKind::BinaryExpression => self.type_of_binary(tree), + TreeKind::TypeExpression => self.type_of_type_expr(tree), + TreeKind::Block => self.type_of_block(tree), TreeKind::LiteralExpression => self.type_of_literal(tree), - TreeKind::GroupingExpression => self.type_of_grouping(tree, value_required), - TreeKind::ConditionalExpression => self.type_of_conditional(tree, value_required), + TreeKind::GroupingExpression => self.type_of_grouping(tree), + TreeKind::ConditionalExpression => self.type_of_conditional(tree), TreeKind::CallExpression => self.type_of_call(tree), TreeKind::Argument => self.type_of_argument(tree), TreeKind::LetStatement => Some(Type::Nothing), TreeKind::ReturnStatement => Some(Type::Unreachable), - TreeKind::ExpressionStatement => { - self.type_of_expression_statement(tree, value_required) - } + TreeKind::ExpressionStatement => self.type_of_expression_statement(tree), TreeKind::Identifier => self.type_of_identifier(tree), _ => return None, }; @@ -239,20 +238,18 @@ impl<'a> Semantics<'a> { // NOTE: These return `None` if they encounter some problem. let result = result.unwrap_or(Type::Error); - self.types - .borrow_mut() - .insert((t, value_required), result.clone()); + self.types.borrow_mut().insert(t, result.clone()); Some(result) } - fn type_of_unary(&self, tree: &Tree, value_required: bool) -> Option { + fn type_of_unary(&self, tree: &Tree) -> Option { assert_eq!(tree.kind, TreeKind::UnaryExpression); let op = tree.nth_token(0)?; let expr = tree.nth_tree(1)?; let argument_type = self - .type_of(expr, value_required) + .type_of(expr) .expect("Our argument should be an expression"); match (op.kind, argument_type) { @@ -286,14 +283,14 @@ impl<'a> Semantics<'a> { } } - fn type_of_binary(&self, tree: &Tree, value_required: bool) -> Option { + fn type_of_binary(&self, tree: &Tree) -> Option { assert_eq!(tree.kind, TreeKind::BinaryExpression); let lhs = self - .type_of(tree.nth_tree(0)?, value_required) + .type_of(tree.nth_tree(0)?) .expect("must be an expression"); let op = tree.nth_token(1)?; let rhs = self - .type_of(tree.nth_tree(2)?, value_required) + .type_of(tree.nth_tree(2)?) .expect("must be an expression"); match (op.kind, lhs, rhs) { @@ -338,12 +335,12 @@ impl<'a> Semantics<'a> { } } - fn type_of_type_expr(&self, tree: &Tree, _value_required: bool) -> Option { + fn type_of_type_expr(&self, tree: &Tree) -> Option { assert_eq!(tree.kind, TreeKind::TypeExpression); Some(Type::Error) } - fn type_of_block(&self, tree: &Tree, value_required: bool) -> Option { + fn type_of_block(&self, tree: &Tree) -> Option { assert_eq!(tree.kind, TreeKind::Block); if tree.children.len() < 2 { @@ -363,7 +360,7 @@ impl<'a> Semantics<'a> { let mut is_unreachable = false; for i in 1..last_index { is_unreachable = self - .type_of(tree.nth_tree(i)?, false) + .type_of(tree.nth_tree(i)?) .map(|t| matches!(t, Type::Unreachable)) .unwrap_or(false) || is_unreachable; @@ -374,7 +371,7 @@ impl<'a> Semantics<'a> { // (And explicitly not Error, which is what returning None // would yield.) let last_type = self - .type_of(tree.nth_tree(last_index)?, value_required) + .type_of(tree.nth_tree(last_index)?) .unwrap_or(Type::Nothing); // If anything in this block generated an "Unreachable" then the @@ -399,34 +396,29 @@ impl<'a> Semantics<'a> { Some(pig) } - fn type_of_grouping(&self, tree: &Tree, value_required: bool) -> Option { + fn type_of_grouping(&self, tree: &Tree) -> Option { assert_eq!(tree.kind, TreeKind::GroupingExpression); let expr = tree.nth_tree(1)?; Some( - self.type_of(expr, value_required) + self.type_of(expr) .expect("the thing in the parenthesis must have some type"), ) } - fn type_of_conditional(&self, tree: &Tree, value_required: bool) -> Option { + fn type_of_conditional(&self, tree: &Tree) -> Option { assert_eq!(tree.kind, TreeKind::ConditionalExpression); let cond_tree = tree.nth_tree(1)?; - let cond_type = self.type_of(cond_tree, true).expect("must be expression"); - let then_type = self - .type_of(tree.nth_tree(2)?, value_required) - .expect("must be expression"); + let cond_type = self.type_of(cond_tree).expect("must be expression"); + let then_type = self.type_of(tree.nth_tree(2)?).expect("must be expression"); let has_else = tree .nth_token(3) .map(|t| t.kind == TokenKind::Else) .unwrap_or(false); let else_type = if has_else { - Some( - self.type_of(tree.nth_tree(4)?, value_required) - .expect("must be expression"), - ) + Some(self.type_of(tree.nth_tree(4)?).expect("must be expression")) } else { None }; @@ -440,23 +432,14 @@ impl<'a> Semantics<'a> { match (then_type, else_type) { (Type::Error, _) => Some(Type::Error), (_, Some(Type::Error)) => Some(Type::Error), - (_, None) if value_required => { - self.report_error_tree( - tree, - "this conditional expression needs an else arm to produce a value", - ); - Some(Type::Error) - } - (then_type, Some(else_type)) if value_required => { - if else_type.compatible_with(&Type::Unreachable) { - // Doesn't matter if the value is required; the else branch - // will never generate a value for us so let's ignore it. - Some(then_type) - } else if then_type.compatible_with(&Type::Unreachable) { - // Or the then branch is unreachable, same thing with else - // then. - Some(else_type) - } else if !then_type.compatible_with(&else_type) { + + (Type::Unreachable, None) => Some(Type::Unreachable), + (Type::Unreachable, Some(t)) => Some(t), + (t, Some(Type::Unreachable)) => Some(t), + + (then_type, else_type) => { + let else_type = else_type.unwrap_or(Type::Nothing); + if !then_type.compatible_with(&else_type) { self.report_error_tree( tree, format!("the type of the `then` branch ({then_type}) must match the type of the `else` branch ({else_type})"), @@ -466,10 +449,6 @@ impl<'a> Semantics<'a> { Some(then_type) } } - (_, _) => { - assert!(!value_required); - Some(Type::Unreachable) - } } } } @@ -484,22 +463,20 @@ impl<'a> Semantics<'a> { Some(Type::Error) } - fn type_of_expression_statement(&self, tree: &Tree, value_required: bool) -> Option { + fn type_of_expression_statement(&self, tree: &Tree) -> Option { assert_eq!(tree.kind, TreeKind::ExpressionStatement); let last_is_semicolon = tree .nth_token(tree.children.len() - 1) .map(|t| t.kind == TokenKind::Semicolon) .unwrap_or(false); - let expression_type = self - .type_of(tree.nth_tree(0)?, value_required && !last_is_semicolon) - .expect("must be expression"); + let expression_type = self.type_of(tree.nth_tree(0)?).expect("must be expression"); Some(match expression_type { - Type::Error => Type::Error, Type::Unreachable => Type::Unreachable, _ => { // A semicolon at the end of an expression statement discards - // the value, leaving us with nothing. + // the value, leaving us with nothing. (Even if the + // expression otherwise generated a type error!) if last_is_semicolon { Type::Nothing } else { diff --git a/fine/tests/example_tests.rs b/fine/tests/example_tests.rs index ba991106..d2bd33b2 100644 --- a/fine/tests/example_tests.rs +++ b/fine/tests/example_tests.rs @@ -150,7 +150,7 @@ fn assert_type_at( None => semantic_panic!(&semantics, "Unable to find the subtee at position {pos}"), }; - let tree_type = semantics.type_of(tree_ref, true); + let tree_type = semantics.type_of(tree_ref); let actual = format!("{}", tree_type.unwrap_or(Type::Error)); semantic_assert_eq!( &semantics, @@ -173,7 +173,7 @@ fn assert_type_error_at( None => semantic_panic!(&semantics, "Unable to find the subtee at position {pos}"), }; - let tree_type = semantics.type_of(tree_ref, true); + let tree_type = semantics.type_of(tree_ref); semantic_assert!( &semantics, matches!(tree_type, Some(Type::Error)), diff --git a/fine/tests/expression/errors/if_requires_else.fine b/fine/tests/expression/errors/if_requires_else.fine index f258ee5a..274fcb10 100644 --- a/fine/tests/expression/errors/if_requires_else.fine +++ b/fine/tests/expression/errors/if_requires_else.fine @@ -1,2 +1,2 @@ if (if false { true }) { 32 } else { 23 } -// type-error: 4 this conditional expression needs an else arm to produce a value +// type-error: 4 the type of the `then` branch (bool) must match the type of the `else` branch (())