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use super::node_type::*;
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/// Try to infer types of variables
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///
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/// TODO: Global symbol table is passed around randomly.
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/// This could probably be cleaned up.
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pub(super) fn infer(program: &mut Program) -> Result<(), String> {
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let table = &program.get_symbol_table();
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// TODO: Fix aweful nesting
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for func in &mut program.func {
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if let Statement::Block(statements, _) = &mut func.body {
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for statement in statements {
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match statement {
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Statement::Declare(var, expr) => {
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if let None = &var.ty {
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if let Some(e) = expr {
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var.ty = infer_expression(&e, table);
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#[cfg(debug_assertions)]
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if let None = var.ty {
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println!("Type of {} could not be infered: {:?}", &var.name, e);
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}
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}
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}
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}
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_ => {}
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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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/// Function table is needed to infer possible function calls
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fn infer_expression(expr: &Expression, table: &SymbolTable) -> Option<Type> {
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match expr {
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Expression::Int(_) => Some(Type::Int),
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Expression::Bool(_) => Some(Type::Bool),
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Expression::Str(_) => Some(Type::Str),
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Expression::FunctionCall(name, _) => infer_function_call(name, table),
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Expression::Array(els) => infer_array(els, table),
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_ => None,
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}
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}
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fn infer_array(elements: &Vec<Expression>, table: &SymbolTable) -> Option<Type> {
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let types: Vec<Option<Type>> = elements
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.iter()
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.map(|el| infer_expression(el, table))
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.collect();
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// TODO: This approach only relies on the first element.
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// It will not catch that types are possibly inconsistent.
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match types.first().and_then(|ty| ty.to_owned()) {
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Some(ty) => Some(Type::Array(Box::new(ty))),
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None => None,
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}
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}
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fn infer_function_call(name: &str, table: &SymbolTable) -> Option<Type> {
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match table.get(name) {
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Some(t) => t.to_owned(),
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None => None,
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}
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}
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