Check for function & binding duplication in the global scope

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## TODO
 
+- Formally define the top level constructs
 - Implement AST transformation before codegen:
     Create a new AST to represent PHP source code
     and a THP ast -> PHP ast process, so that the
@@ -32,9 +33,9 @@
 - [x] Minimal symbol table
 - [x] Check duplicate function declarations
 - [x] Improve REPL/File compilation code
-- [ ] Typecheck bindings
-- [x] Typecheck functions
-- [ ] Transform simple THP expression into PHP statements
+- [x] Check binding duplication in it's scope
+- [x] Check function duplication in it's scope
+- [x] Transform simple THP expression into PHP statements
 
 ## v0.0.9
 

src/codegen/binding.rs

@@ -6,22 +6,27 @@ impl Transpilable for Binding<'_> {
     fn transpile(&self) -> String {
         let expression_str = self.expression.transpile();
 
-        format!("${} = {}", self.identifier, expression_str)
+        format!("${} = {}", self.identifier.value, expression_str)
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::syntax::ast::{var_binding::Binding, Expression};
+    use crate::{lexic::token::{Token, TokenType}, syntax::ast::{var_binding::Binding, Expression}};
 
     #[test]
     fn binding_should_transpile() {
         let id = String::from("identifier");
+        let id_token = Token {
+            token_type: TokenType::Identifier,
+            value: id,
+            position: 0,
+        };
         let value = String::from("322");
         let binding = Binding {
             datatype: None,
-            identifier: Box::new(id),
+            identifier: &id_token,
             expression: Expression::Number(&value),
             is_mutable: false,
         };

src/codegen/module_ast.rs

@@ -18,15 +18,20 @@ impl Transpilable for ModuleAST<'_> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::syntax::ast::{var_binding::Binding, Expression, TopLevelDeclaration};
+    use crate::{lexic::token::{Token, TokenType}, syntax::ast::{var_binding::Binding, Expression, TopLevelDeclaration}};
 
     #[test]
     fn module_ast_should_transpile() {
         let id = String::from("identifier");
+        let id_token = Token {
+            token_type: TokenType::Identifier,
+            value: id,
+            position: 0,
+        };
         let value = String::from("322");
         let binding = Binding {
             datatype: None,
-            identifier: Box::new(id),
+            identifier: &id_token,
             expression: Expression::Number(&value),
             is_mutable: false,
         };

src/semantic/impls.rs

@@ -4,7 +4,7 @@ use crate::{
     syntax::ast::{ModuleAST, TopLevelDeclaration},
 };
 
-use super::symbol_table::SymbolTable;
+use super::symbol_table::{SymbolEntry, SymbolTable};
 
 pub trait SemanticCheck {
     fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError>;
@@ -24,18 +24,46 @@ impl SemanticCheck for ModuleAST<'_> {
 impl SemanticCheck for TopLevelDeclaration<'_> {
     fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError> {
         match self {
-            TopLevelDeclaration::Binding(_) => {
+            TopLevelDeclaration::Binding(binding) => {
+                let binding_name = &binding.identifier.value;
+
+                if scope.test(binding_name) {
                     let error = SemanticError {
-                    error_start: 0,
-                    error_end: 0,
-                    reason: "Binding typechecking: Not implemented".into(),
+                        error_start: binding.identifier.position,
+                        error_end: binding.identifier.get_end_position(),
+                        reason: format!(
+                            "Duplicated function: A function with name {} was already defined",
+                            binding_name
+                        ),
                     };
 
-                Err(MistiError::Semantic(error))
+                    return Err(MistiError::Semantic(error));
+                }
+
+                let datatype = match binding.datatype {
+                    Some(t) => t,
+                    None => {
+                        let error = SemanticError {
+                            error_start: binding.identifier.position,
+                            error_end: binding.identifier.get_end_position(),
+                            reason: format!(
+                                "The variable `{}` didn't define a datatype. Datatype inference is not implemented.",
+                                binding_name
+                            ),
+                        };
+    
+                        return Err(MistiError::Semantic(error));
+                    }
+                };
+
+                scope.insert(binding_name.clone(), SymbolEntry::new_variable(datatype.value.clone()));
+
+                Ok(())
             }
             TopLevelDeclaration::FunctionDeclaration(function) => {
                 let function_name = function.identifier.value.clone();
 
+                // Check that the function is not already defined
                 if scope.test(&function_name) {
                     let error = SemanticError {
                         error_start: function.identifier.position,
@@ -49,10 +77,7 @@ impl SemanticCheck for TopLevelDeclaration<'_> {
                     return Err(MistiError::Semantic(error));
                 }
 
-                scope.insert(
-                    function_name,
-                    super::symbol_table::SymbolEntry::Function(vec![], "Unit".into()),
-                );
+                scope.insert(function_name, SymbolEntry::new_function(vec![], "Unit".into()));
 
                 Ok(())
             }

src/syntax/ast/var_binding.rs

@@ -1,9 +1,11 @@
+use crate::lexic::token::Token;
+
 use super::Expression;
 
 #[derive(Debug)]
 pub struct Binding<'a> {
-    pub datatype: Option<String>,
-    pub identifier: Box<String>,
+    pub datatype: Option<&'a Token>,
+    pub identifier: &'a Token,
     pub expression: Expression<'a>,
     pub is_mutable: bool,
 }

src/syntax/binding.rs

@@ -97,7 +97,7 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Binding,
 
     let binding = Binding {
         datatype: None,
-        identifier: Box::new(identifier.value.clone()),
+        identifier: &identifier,
         expression,
         is_mutable,
     };
@@ -117,7 +117,7 @@ mod tests {
             panic!()
         };
 
-        assert_eq!("identifier", format!("{}", binding.identifier));
+        assert_eq!("identifier", format!("{}", binding.identifier.value));
     }
 
     #[test]