Merge pull request #2 from Rafael-Sapienza/feat/polymorphism_and_func_as_param

Feat/polymorphism and func as param

Author: Rafael-Sapienza

src/environment/environment.rs

@@ -1,13 +1,15 @@
+use crate::ir::ast::FuncSignature;
 use crate::ir::ast::Function;
 use crate::ir::ast::Name;
 use crate::ir::ast::ValueConstructor;
 use std::collections::HashMap;
 use std::collections::LinkedList;
+use std::fmt::Debug;
 
 #[derive(Clone)]
 pub struct Scope<A> {
     pub variables: HashMap<Name, (bool, A)>,
-    pub functions: HashMap<Name, Function>,
+    pub functions: HashMap<FuncSignature, Function>,
     pub adts: HashMap<Name, Vec<ValueConstructor>>,
 }
 
@@ -26,7 +28,8 @@ impl<A: Clone> Scope<A> {
     }
 
     fn map_function(&mut self, function: Function) -> () {
-        self.functions.insert(function.name.clone(), function);
+        let func_signature = FuncSignature::from_func(&function);
+        self.functions.insert(func_signature, function);
         return ();
     }
 
@@ -41,8 +44,18 @@ impl<A: Clone> Scope<A> {
             .map(|(mutable, value)| (*mutable, value.clone()))
     }
 
-    fn lookup_function(&self, name: &Name) -> Option<&Function> {
-        self.functions.get(name)
+    fn lookup_function(&self, func_signature: &FuncSignature) -> Option<&Function> {
+        self.functions.get(func_signature)
+    }
+
+    fn lookup_function_by_name(&self, name: &Name) -> Option<&Function> {
+        self.functions.iter().find_map(|(signature, function)| {
+            if &signature.name == name {
+                Some(function)
+            } else {
+                None
+            }
+        })
     }
 
     fn lookup_adt(&self, name: &Name) -> Option<&Vec<ValueConstructor>> {
@@ -51,30 +64,34 @@ impl<A: Clone> Scope<A> {
 }
 
 #[derive(Clone)]
-pub struct Environment<A> {
-    pub current_func: String,
+pub struct Environment<A: Clone + Debug> {
+    pub current_func: FuncSignature,
     pub globals: Scope<A>,
     pub stack: LinkedList<Scope<A>>,
 }
 
-impl<A: Clone> Environment<A> {
+impl<A: Clone + Debug> Environment<A> {
     pub fn new() -> Environment<A> {
         Environment {
-            current_func: String::new(),
+            current_func: FuncSignature::new(),
             globals: Scope::new(),
             stack: LinkedList::new(),
         }
     }
 
-    pub fn get_current_func(&self) -> String {
+    pub fn get_current_func(&self) -> FuncSignature {
         return self.current_func.clone();
     }
 
-    pub fn set_current_func(&mut self, func_name: &str) {
-        self.current_func = func_name.to_string();
+    pub fn get_current_scope(&self) -> &Scope<A> {
+        self.stack.front().unwrap_or(&self.globals)
+    }
+
+    pub fn set_current_func(&mut self, func_signature: &FuncSignature) {
+        self.current_func = func_signature.clone();
     }
 
-    pub fn set_global_functions(&mut self, global_functions: HashMap<Name, Function>) {
+    pub fn set_global_functions(&mut self, global_functions: HashMap<FuncSignature, Function>) {
         self.globals.functions = global_functions;
     }
 
@@ -108,13 +125,31 @@ impl<A: Clone> Environment<A> {
         self.globals.lookup_var(var)
     }
 
-    pub fn lookup_function(&self, name: &Name) -> Option<&Function> {
+    pub fn lookup_function(&self, func_signature: &FuncSignature) -> Option<&Function> {
         for scope in self.stack.iter() {
-            if let Some(func) = scope.lookup_function(name) {
+            if let Some(func) = scope.lookup_function(func_signature) {
                 return Some(func);
             }
         }
-        self.globals.lookup_function(name)
+        self.globals.lookup_function(func_signature)
+    }
+
+    pub fn lookup_var_or_func(&self, name: &Name) -> Option<FuncOrVar<A>> {
+        for scope in self.stack.iter() {
+            if let Some(value) = scope.lookup_var(name) {
+                return Some(FuncOrVar::Var(value));
+            }
+            if let Some(func) = scope.lookup_function_by_name(name) {
+                return Some(FuncOrVar::Func(func.clone()));
+            }
+        }
+        if let Some(value) = self.globals.lookup_var(name) {
+            return Some(FuncOrVar::Var(value));
+        }
+        if let Some(func) = self.globals.lookup_function_by_name(name) {
+            return Some(FuncOrVar::Func(func.clone()));
+        }
+        return None;
     }
 
     pub fn lookup_adt(&self, name: &Name) -> Option<&Vec<ValueConstructor>> {
@@ -160,20 +195,29 @@ impl<A: Clone> Environment<A> {
     }
 
     // The type checker ensures that each function is defined only once
-    pub fn get_all_functions(&self) -> HashMap<Name, Function> {
+    pub fn get_all_functions(&self) -> HashMap<FuncSignature, Function> {
         let mut all_functions = HashMap::new();
-        for (name, func) in &self.globals.functions {
-            all_functions.insert(name.clone(), func.clone());
+        for (func_signature, func) in &self.globals.functions {
+            all_functions.insert(func_signature.clone(), func.clone());
         }
-        for scope in self.stack.iter() {
-            for (name, func) in &scope.functions {
-                all_functions.insert(name.clone(), func.clone());
+        // It is necessary to traverse the scope stack from bottom to top
+        // so that functions defined in inner scopes can shadow those
+        // defined in outer scopes.
+        for scope in self.stack.iter().rev() {
+            for (func_signature, func) in &scope.functions {
+                all_functions.insert(func_signature.clone(), func.clone());
             }
         }
         all_functions
     }
 }
 
+pub enum FuncOrVar<A: Clone + Debug> {
+    Func(Function),
+    Var((bool, A)),
+}
+
+/*
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -245,3 +289,4 @@ mod tests {
         assert!(env.lookup_function(&"local".to_string()).is_none()); // local gone
     }
 }
+*/

src/interpreter/expression_eval.rs

@@ -1,6 +1,8 @@
 use super::statement_execute::Computation;
-use crate::environment::environment::{Environment, Scope};
+use crate::environment::environment::{Environment, FuncOrVar};
 use crate::ir::ast::{Expression, Name};
+use crate::ir::ast::{FuncSignature, Type};
+use crate::type_checker::check_expr;
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum ExpressionResult {
@@ -383,51 +385,102 @@ pub fn eval_lookup(
 
 // Function call
 pub fn eval_function_call(
-    name: Name,
+    func_name: Name,
     args: Vec<Expression>,
     env: &Environment<Expression>,
 ) -> Result<ExpressionResult, String> {
-    match env.lookup_function(&name) {
-        Some(function_definition) => {
-            let mut new_env = Environment::new();
-
-            if args.len() != function_definition.params.len() {
-                return Err(format!(
-                    "[Runtime Error] Invalid number of arguments for '{}'.",
-                    name
-                ));
+    let mut actual_arg_values = Vec::new();
+    let mut actual_arg_types = Vec::new();
+    for arg in args.iter() {
+        match arg {
+            Expression::Var(name) => match env.lookup_var_or_func(name) {
+                Some(FuncOrVar::Var((_, _var_exp))) => match eval_lookup(name.to_string(), env)? {
+                    ExpressionResult::Propagate(expr) => {
+                        return Ok(ExpressionResult::Propagate(expr));
+                    }
+                    ExpressionResult::Value(expr) => {
+                        actual_arg_values.push(expr);
+                    }
+                },
+                Some(FuncOrVar::Func(func)) => {
+                    actual_arg_values.push(Expression::Lambda(func));
+                }
+                None => return Err(format!("Identifier '{}' was never declared", name)),
+            },
+            Expression::Lambda(func) => {
+                actual_arg_values.push(Expression::Lambda(func.clone()));
             }
+            _ => match eval(arg.clone(), env)? {
+                ExpressionResult::Value(expr) => {
+                    actual_arg_values.push(expr);
+                }
+                ExpressionResult::Propagate(expr) => {
+                    return Ok(ExpressionResult::Propagate(expr));
+                }
+            },
+        }
+    }
+    for value in &actual_arg_values {
+        actual_arg_types.push(check_expr(value.clone(), &Environment::<Type>::new())?);
+    }
 
-            // new_env.push(); <- Removed the push; parameters are now mapped directly to the global scope
-            //In this new environment, external functions and actual parameters are regarded as globally accessible
-            //This is justified, since their visibility extends across the entire function body
-            new_env.set_current_func(&name);
+    let func_signature = FuncSignature {
+        name: func_name.clone(),
+        argument_types: actual_arg_types.clone(),
+    };
+    match env.lookup_function(&func_signature).cloned() {
+        Some(func) => {
+
+            let mut new_env = Environment::new();
+
+            new_env.set_current_func(&func_signature);
             // Functions from the outer environment must be propagated to new_env to ensure access to external functions within the function body.
             // This also allows the function to reference itself, which enables recursion
             new_env.set_global_functions(env.get_all_functions());
 
-            for (formal, actual) in function_definition.params.iter().zip(args.iter()) {
-                let value = match eval(actual.clone(), env)? {
-                    ExpressionResult::Value(expr) => expr,
-                    ExpressionResult::Propagate(expr) => {
-                        return Ok(ExpressionResult::Propagate(expr))
+            for (formal_arg, value) in func.params.iter().zip(actual_arg_values.iter()) {
+                match formal_arg.argument_type {
+                    Type::TFunction(..) => {
+                        match value {
+                            Expression::Lambda(arg_func) => {
+                                let mut inner_func = arg_func.clone();
+                                inner_func.name = formal_arg.argument_name.clone();
+                                new_env.map_function(inner_func);
+                            }
+                            //This will never happen, but I need to cover all cases, otherwise it won't compile
+                            _ => {
+                                return Err(format!(
+                                    "[Runtime Error] Function {:?} expected another function as argument, but received a non functional argument",
+                                    func_signature
+                                ));
+                            }
+                        }
+                    }
+                    _ => {
+                        new_env.map_variable(
+                            formal_arg.argument_name.clone(),
+                            false,
+                            value.clone(),
+                        );
                     }
-                };
-                new_env.map_variable(formal.argument_name.clone(), false, value);
+                }
             }
 
             // Execute the body of the function.
-            match super::statement_execute::execute(
-                *function_definition.body.as_ref().unwrap().clone(), //Push occurs here, because function body is a Statement::Block
-                &new_env,
-            ) {
+            match super::statement_execute::execute(*func.body.as_ref().unwrap().clone(), &new_env)
+            {
                 Ok(Computation::Continue(_)) => Err("Function did not return a value".to_string()),
-                Ok(Computation::Return(value, _)) => Ok(ExpressionResult::Value(value)),
+                Ok(Computation::Return(value, _final_env)) => {
+                    Ok(ExpressionResult::Value(value))
+                }
                 Ok(Computation::PropagateError(value, _)) => Ok(ExpressionResult::Propagate(value)),
                 Err(e) => Err(e),
             }
         }
-        _ => Err(format!("Function {} not found", name)),
+
+        _ => {
+            Err(format!("Function '{}' not found", func_signature))
+        }
     }
 }
 

src/interpreter/statement_execute.rs

@@ -59,14 +59,23 @@ pub fn execute(stmt: Statement, env: &Environment<Expression>) -> Result<Computa
         }
 
         Statement::Assignment(name, exp) => {
-            let value = match eval(*exp, &new_env)? {
-                ExpressionResult::Value(expr) => expr,
-                ExpressionResult::Propagate(expr) => {
-                    return Ok(Computation::PropagateError(expr, new_env))
+            match *exp {
+                Expression::Lambda(mut func) => {
+                    func.name = name;
+                    new_env.map_function(func);
+                    return Ok(Computation::Continue(new_env));
                 }
-            };
-            new_env.map_variable(name, true, value);
-            Ok(Computation::Continue(new_env))
+                _ => {
+                    let value = match eval(*exp, &mut new_env)? {
+                        ExpressionResult::Value(expr) => expr,
+                        ExpressionResult::Propagate(expr) => {
+                            return Ok(Computation::PropagateError(expr, new_env));
+                        }
+                    };
+                    new_env.map_variable(name, true,value);
+                    return Ok(Computation::Continue(new_env));
+                }
+            }
         }
 
         Statement::IfThenElse(cond, stmt_then, stmt_else) => {