feat: store paren positions on argument list

src/cli/tokenize.rs

@@ -1,7 +1,10 @@
 use serde::Serialize;
 
 use crate::{
-    error_handling::MistiError, lexic::{get_tokens, token::Token}, semantic, syntax::build_ast
+    error_handling::MistiError,
+    lexic::{get_tokens, token::Token},
+    semantic,
+    syntax::build_ast,
 };
 use std::io::{self, BufRead};
 
@@ -35,11 +38,9 @@ pub fn tokenize_command(_options: Vec<String>) -> Result<(), ()> {
         Ok(tokens) => {
             let ast_result = build_ast(&tokens);
             match ast_result {
-                Ok(ast) => {
-                    match semantic::check_semantics(&ast) {
+                Ok(ast) => match semantic::check_semantics(&ast) {
                     Ok(()) => TokenizeResult::Ok(tokens),
-                        Err(error) => TokenizeResult::SyntaxOnly(tokens, error)
-                    }
+                    Err(error) => TokenizeResult::SyntaxOnly(tokens, error),
                 },
                 Err(error) => TokenizeResult::TokensOnly(tokens, error),
             }

src/codegen/mod.rs

@@ -8,8 +8,3 @@ pub trait Transpilable {
     /// Transforms this struct into PHP
     fn transpile(&self) -> String;
 }
-
-/// Transforms an AST to its representation in PHP
-pub fn codegen<'a>(ast: &'a impl Transpilable) -> String {
-    ast.transpile()
-}

src/file/mod.rs

@@ -1,8 +1,9 @@
 use colored::*;
 use std::{fs, path::Path};
 
-use crate::lexic::token::Token;
-use crate::{codegen, error_handling::PrintableError, lexic, syntax};
+use crate::codegen::Transpilable;
+use crate::php_ast::transformers::PHPTransformable;
+use crate::{error_handling::PrintableError, lexic, syntax};
 
 pub fn compile_file(input: &String) -> Result<(), ()> {
     let input_path = Path::new(input);
@@ -58,49 +59,50 @@ pub fn compile_file(input: &String) -> Result<(), ()> {
     }
 }
 
-/// THP source code goes in, PHP code or an error comes out
+/// Full pipeline from THP source code to PHP output
 fn compile(input: &String) -> Result<String, String> {
-    let tokens = lexic::get_tokens(input);
-
-    let tokens = match tokens {
-        Ok(tokens) => tokens,
+    //
+    // Lexical analysis
+    //
+    let tokens = match lexic::get_tokens(input) {
+        Ok(t) => t,
         Err(error) => {
             let chars: Vec<char> = input.chars().into_iter().collect();
-            return Err(format!(
-                "{}:\n{}",
-                "syntax error".on_red(),
-                error.get_error_str(&chars)
-            ));
+            return Err(error.get_error_str(&chars));
         }
     };
 
-    build_ast(input, tokens)
-}
-
-/// Executes Syntax analysis, and for now, Semantic analysis and Code generation.
-///
-/// Prints the generated code in stdin
-fn build_ast(input: &String, tokens: Vec<Token>) -> Result<String, String> {
-    let ast = syntax::build_ast(&tokens);
-
-    let ast = match ast {
+    //
+    // Syntax analysis
+    //
+    let ast = match syntax::build_ast(&tokens) {
         Ok(ast) => ast,
         Err(reason) => {
             let chars: Vec<char> = input.chars().into_iter().collect();
-            let error = format!("{}: {}", "error".on_red(), reason.get_error_str(&chars));
-            return Err(error);
+            return Err(reason.get_error_str(&chars));
         }
     };
 
-    match crate::semantic::check_semantics(&ast) {
+    //
+    // Semantic analysis
+    //
+    let res1 = crate::semantic::check_semantics(&ast);
+    match res1 {
         Ok(_) => {}
         Err(reason) => {
             let chars: Vec<char> = input.chars().into_iter().collect();
             let error = format!("{}: {}", "error".on_red(), reason.get_error_str(&chars));
             return Err(error);
         }
-    };
-
-    Err("Code generation disabled: rewriting into PHP AST".into())
-    // Ok(codegen::codegen(&ast))
+    }
+
+    //
+    // Intermediate representation (THP -> PHP ast)
+    //
+    let php_ast = ast.into_php_ast();
+
+    //
+    // Codegen
+    //
+    Ok(php_ast.transpile())
 }

src/php_ast/transformers/expression.rs

@@ -13,15 +13,15 @@ impl<'a> PHPTransformable<'a> for Expression<'_> {
     fn into_php_ast(&'a self) -> Self::Item {
         match self {
             Expression::String(value) => {
-                let expr = PhpPrimaryExpression::StringLiteral(value);
+                let expr = PhpPrimaryExpression::StringLiteral(&value.value);
                 PhpExpression::Assignment(PhpAssignmentExpression::Primary(expr))
             }
             Expression::Int(value) => {
-                let expr = PhpPrimaryExpression::IntegerLiteral(value);
+                let expr = PhpPrimaryExpression::IntegerLiteral(&value.value);
                 PhpExpression::Assignment(PhpAssignmentExpression::Primary(expr))
             }
             Expression::Float(value) => {
-                let expr = PhpPrimaryExpression::FloatingLiteral(value);
+                let expr = PhpPrimaryExpression::FloatingLiteral(&value.value);
                 PhpExpression::Assignment(PhpAssignmentExpression::Primary(expr))
             }
             _ => todo!("transformation for expression: {:?}", self),
@@ -32,6 +32,7 @@ impl<'a> PHPTransformable<'a> for Expression<'_> {
 #[cfg(test)]
 mod tests {
     use crate::{
+        lexic::token::Token,
         php_ast::{
             transformers::PHPTransformable, PhpAssignmentExpression, PhpExpression,
             PhpPrimaryExpression,
@@ -41,8 +42,8 @@ mod tests {
 
     #[test]
     fn should_transform_string() {
-        let value = String::from("Hello");
-        let input = Expression::String(&value);
+        let t = Token::new_string("Hello".into(), 0);
+        let input = Expression::String(&t);
         let output = input.into_php_ast();
 
         match output {
@@ -57,8 +58,8 @@ mod tests {
 
     #[test]
     fn should_transform_int() {
-        let value = String::from("322");
-        let input = Expression::Int(&value);
+        let binding = Token::new_int(String::from("322"), 0);
+        let input = Expression::Int(&binding);
         let output = input.into_php_ast();
 
         match output {
@@ -73,8 +74,8 @@ mod tests {
 
     #[test]
     fn should_transform_float() {
-        let value = String::from("322.644");
-        let input = Expression::Float(&value);
+        let t = Token::new_float("322.644".into(), 0);
+        let input = Expression::Float(&t);
         let output = input.into_php_ast();
 
         match output {

src/php_ast/transformers/module_ast.rs

@@ -25,7 +25,7 @@ impl<'a> PHPTransformable<'a> for ModuleAST<'_> {
                             // TODO: This definitely needs refactoring
                             let function_expr: &Expression = &*fc.function;
                             match function_expr {
-                                Expression::Identifier(id) if *id == "print" => {
+                                Expression::Identifier(id) if id.value == "print" => {
                                     // transform to print() expression
                                     // no parameters supported
 
@@ -37,7 +37,7 @@ impl<'a> PHPTransformable<'a> for ModuleAST<'_> {
                                         match e {
                                             Expression::String(v) => {
                                                 expressions.push(
-                                                    PhpExpression::Assignment(PhpAssignmentExpression::Primary(PhpPrimaryExpression::StringLiteral(v)))
+                                                    PhpExpression::Assignment(PhpAssignmentExpression::Primary(PhpPrimaryExpression::StringLiteral(&v.value)))
                                                 )
                                             },
                                             _ => todo!("Non string expressions not supported")
@@ -54,21 +54,21 @@ impl<'a> PHPTransformable<'a> for ModuleAST<'_> {
                         Expression::Int(value) => {
                             php_statements.push(PhpStatement::PhpExpressionStatement(
                                 PhpExpression::Assignment(PhpAssignmentExpression::Primary(
-                                    PhpPrimaryExpression::IntegerLiteral(value),
+                                    PhpPrimaryExpression::IntegerLiteral(&value.value),
                                 )),
                             ));
                         }
                         Expression::Float(value) => {
                             php_statements.push(PhpStatement::PhpExpressionStatement(
                                 PhpExpression::Assignment(PhpAssignmentExpression::Primary(
-                                    PhpPrimaryExpression::FloatingLiteral(value),
+                                    PhpPrimaryExpression::FloatingLiteral(&value.value),
                                 )),
                             ));
                         }
                         Expression::String(value) => {
                             php_statements.push(PhpStatement::PhpExpressionStatement(
                                 PhpExpression::Assignment(PhpAssignmentExpression::Primary(
-                                    PhpPrimaryExpression::StringLiteral(value),
+                                    PhpPrimaryExpression::StringLiteral(&value.value),
                                 )),
                             ));
                         }

src/php_ast/transformers/statement.rs

@@ -58,8 +58,9 @@ mod tests {
             value: "name".into(),
             position: 0,
         };
-        let expr_value = String::from("Hello");
-        let expression = Expression::String(&expr_value);
+
+        let t = Token::new_string("Hello".into(), 0);
+        let expression = Expression::String(&t);
         let binding = Statement::Binding(VariableBinding {
             datatype: None,
             identifier: &identifier_token,

src/semantic/checks/expression.rs

@@ -0,0 +1,223 @@
+use crate::{
+    error_handling::{semantic_error::SemanticError, MistiError},
+    semantic::{
+        impls::SemanticCheck,
+        symbol_table::SymbolTable,
+        types::{Type, Typed},
+    },
+    syntax::ast::{Expression, Positionable},
+};
+
+impl SemanticCheck for Expression<'_> {
+    fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError> {
+        match self {
+            Expression::FunctionCall(f) => {
+                let fun = &*f.function;
+                let arguments = &*f.arguments.arguments;
+
+                let function_datatype = fun.get_type(scope)?;
+                match function_datatype {
+                    Type::Function(parameters, _return_type) => {
+                        // Check parameters length
+                        if parameters.len() != arguments.len() {
+                            let (error_start, error_end) = f.arguments.get_position();
+
+                            return Err(MistiError::Semantic(SemanticError {
+                                error_start,
+                                error_end,
+                                reason: format!(
+                                    "Expected {} arguments, got {}",
+                                    parameters.len(),
+                                    arguments.len(),
+                                ),
+                            }));
+                        }
+
+                        // Check that each argument matches the required datatype
+                        for i in 0..parameters.len() {
+                            let parameter = &parameters[i];
+                            let argument = &arguments[i];
+
+                            let argument_datatype = argument.get_type(scope)?;
+                            if !argument_datatype.is_value(parameter) {
+                                // The argument and the parameter have diferent types
+                                let (error_start, error_end) = argument.get_position();
+                                return Err(MistiError::Semantic(SemanticError {
+                                    // TODO: fix
+                                    error_start,
+                                    error_end,
+                                    reason: format!(
+                                        "Expected a {}, got {:?}",
+                                        parameter, argument_datatype
+                                    ),
+                                }));
+                            }
+                        }
+                    }
+                    _ => {
+                        let (error_start, error_end) = fun.get_position();
+                        return Err(MistiError::Semantic(SemanticError {
+                            error_start,
+                            error_end,
+                            reason: format!(
+                                "Expected a function type, got {:?}",
+                                function_datatype
+                            ),
+                        }));
+                    }
+                }
+            }
+            Expression::Int(_) => {}
+            Expression::Float(_) => {}
+            Expression::String(_) => {}
+            Expression::Boolean(_) => {}
+            _ => todo!("Check semantics for expression other than function call and primitive"),
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        error_handling::MistiError,
+        lexic::token::Token,
+        semantic::{impls::SemanticCheck, std::populate, symbol_table::SymbolTable},
+        syntax::ast::{
+            functions::{ArgumentsList, FunctionCall},
+            Expression,
+        },
+    };
+
+    #[test]
+    fn should_error_on_undefined_symbol() {
+        // source code: `print()`
+        let expr_token = Token::new_identifier("print".into(), 0);
+        let expr_function = Expression::Identifier(&expr_token);
+        let arguments = ArgumentsList {
+            arguments: vec![],
+            paren_open_pos: 5,
+            paren_close_pos: 7,
+        };
+
+        let expr = Expression::FunctionCall(FunctionCall {
+            function: Box::new(expr_function),
+            arguments: Box::new(arguments),
+        });
+
+        let scope = SymbolTable::new();
+
+        let output = expr.check_semantics(&scope);
+        match output {
+            Ok(_) => panic!("Expected an error"),
+            Err(MistiError::Semantic(err)) => {
+                assert_eq!(err.reason, "Cannot find `print` in this scope.");
+                assert_eq!(err.error_start, 0);
+                assert_eq!(err.error_end, 5);
+            }
+            Err(e) => panic!("Expected a Semantic error, got {:?}", e),
+        }
+    }
+
+    #[test]
+    fn should_error_on_invalid_function_argument() {
+        // source code: `print(322)`
+        let mut scope = SymbolTable::new();
+        populate(&mut scope);
+
+        let expr_token = Token::new_identifier("print".into(), 0);
+        let expr_function = Expression::Identifier(&expr_token);
+
+        let arg_t = Token::new_int(String::from("322"), 6);
+        let arg_1 = Expression::Int(&arg_t);
+        let arguments = ArgumentsList {
+            arguments: vec![arg_1],
+            paren_open_pos: 5,
+            paren_close_pos: 10,
+        };
+
+        let expr = Expression::FunctionCall(FunctionCall {
+            function: Box::new(expr_function),
+            arguments: Box::new(arguments),
+        });
+
+        match expr.check_semantics(&scope) {
+            Ok(_) => panic!("Expected semantic error, got ok"),
+            Err(MistiError::Semantic(e)) => {
+                assert_eq!(e.reason, "Expected a String, got Value(\"Int\")");
+                assert_eq!(e.error_start, 6);
+                assert_eq!(e.error_end, 9);
+            }
+            Err(e) => panic!("Expected semantic error, got {:?}", e),
+        }
+    }
+
+    #[test]
+    fn should_error_on_invalid_function_argument_count() {
+        // source code: `print()`
+        let mut scope = SymbolTable::new();
+        populate(&mut scope);
+
+        let expr_token = Token::new_identifier("print".into(), 0);
+        let expr_function = Expression::Identifier(&expr_token);
+
+        let arguments = ArgumentsList {
+            arguments: vec![],
+            paren_open_pos: 5,
+            paren_close_pos: 7,
+        };
+
+        let expr = Expression::FunctionCall(FunctionCall {
+            function: Box::new(expr_function),
+            arguments: Box::new(arguments),
+        });
+
+        match expr.check_semantics(&scope) {
+            Ok(_) => panic!("Expected semantic error, got ok"),
+            Err(MistiError::Semantic(e)) => {
+                assert_eq!(e.reason, "Expected 1 arguments, got 0");
+                assert_eq!(e.error_start, 5);
+                assert_eq!(e.error_end, 7);
+            }
+            Err(e) => panic!("Expected semantic error, got {:?}", e),
+        }
+    }
+
+    #[test]
+    fn should_error_on_invalid_function_argument_2() {
+        // source code: `print(322, 644)`
+        let mut scope = SymbolTable::new();
+        populate(&mut scope);
+
+        let expr_token = Token::new_identifier("print".into(), 0);
+        let expr_function = Expression::Identifier(&expr_token);
+
+        let arg_t = Token::new_int(String::from("322"), 6);
+        let arg_1 = Expression::Int(&arg_t);
+
+        let arg_t_2 = Token::new_int(String::from("644"), 11);
+        let arg_2 = Expression::Int(&arg_t_2);
+
+        let arguments = ArgumentsList {
+            arguments: vec![arg_1, arg_2],
+            paren_open_pos: 5,
+            paren_close_pos: 15,
+        };
+
+        let expr = Expression::FunctionCall(FunctionCall {
+            function: Box::new(expr_function),
+            arguments: Box::new(arguments),
+        });
+
+        match expr.check_semantics(&scope) {
+            Ok(_) => panic!("Expected semantic error, got ok"),
+            Err(MistiError::Semantic(e)) => {
+                assert_eq!(e.reason, "Expected 1 arguments, got 2");
+                assert_eq!(e.error_start, 5);
+                assert_eq!(e.error_end, 15);
+            }
+            Err(e) => panic!("Expected semantic error, got {:?}", e),
+        }
+    }
+}

src/semantic/checks/mod.rs

@@ -1,3 +1,4 @@
 pub mod binding;
+pub mod expression;
 pub mod function_declaration;
 pub mod top_level_declaration;

src/semantic/checks/top_level_declaration.rs

@@ -29,72 +29,3 @@ impl SemanticCheck for Statement<'_> {
         }
     }
 }
-
-// TODO: Move to its own file when it grows
-impl SemanticCheck for Expression<'_> {
-    fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError> {
-        match self {
-            Expression::FunctionCall(f) => {
-                let fun = &*f.function;
-                let arguments = &*f.arguments.arguments;
-
-                let function_datatype = fun.get_type(scope)?;
-                match function_datatype {
-                    Type::Function(parameters, _return_type) => {
-                        // Check parameters length
-                        if parameters.len() != arguments.len() {
-                            return Err(MistiError::Semantic(SemanticError {
-                                // TODO: fix
-                                error_start: 0,
-                                error_end: 1,
-                                reason: format!(
-                                    "Expected {} arguments, found {}",
-                                    parameters.len(),
-                                    arguments.len(),
-                                ),
-                            }));
-                        }
-
-                        // Check that each argument matches the required datatype
-                        for i in 0..parameters.len() {
-                            let parameter = &parameters[i];
-                            let argument = &arguments[i];
-
-                            let argument_datatype = argument.get_type(scope)?;
-                            if !argument_datatype.is_value(parameter) {
-                                // The argument and the parameter have diferent types
-                                return Err(MistiError::Semantic(SemanticError {
-                                    // TODO: fix
-                                    error_start: 0,
-                                    error_end: 1,
-                                    reason: format!(
-                                        "Expected datatype {}, got {:?}",
-                                        parameter, argument
-                                    ),
-                                }));
-                            }
-                        }
-                    }
-                    _ => {
-                        return Err(MistiError::Semantic(SemanticError {
-                            // TODO: fix
-                            error_start: 0,
-                            error_end: 1,
-                            reason: format!(
-                                "Expected a function type, got {:?}",
-                                function_datatype
-                            ),
-                        }));
-                    }
-                }
-            }
-            Expression::Int(_) => {}
-            Expression::Float(_) => {}
-            Expression::String(_) => {}
-            Expression::Boolean(_) => {}
-            _ => todo!("Check semantics for expression other than function call and primitive"),
-        }
-
-        Ok(())
-    }
-}

src/semantic/types/expression.rs

@@ -16,13 +16,13 @@ impl Typed for Expression<'_> {
             Expression::Boolean(_) => Ok(Type::Value("Bool".into())),
             Expression::Identifier(identifier) => {
                 // Attempt to get the datatype of the identifier in the current scope
-                let datatype = match scope.get_type(identifier) {
+                let datatype = match scope.get_type(&identifier.value) {
                     Some(x) => x,
                     None => {
                         return Err(MistiError::Semantic(SemanticError {
-                            error_start: 0,
-                            error_end: 1,
-                            reason: format!("The identifier {} does not exist.", identifier),
+                            error_start: identifier.position,
+                            error_end: identifier.get_end_position(),
+                            reason: format!("Cannot find `{}` in this scope.", identifier.value),
                         }))
                     }
                 };
@@ -35,17 +35,26 @@ impl Typed for Expression<'_> {
                 // for this to work with any arbitrary expression.
                 // for now it justs expects an identifier
 
+                // TODO: Should this check that the type signature is correct?
+                // or is this done elsewhere?
+
                 match &*f.function {
                     Expression::Identifier(id) => {
-                        match scope.get_type(id) {
-                            Some(t) => Ok(t),
+                        match scope.get_type(&id.value) {
+                            Some(Type::Function(_, return_type)) => {
+                                // Return the return type of the function,
+                                // not the function itself
+                                Ok(Type::Value(return_type))
+                            }
+                            Some(_) => Err(MistiError::Semantic(SemanticError {
+                                error_start: id.position,
+                                error_end: id.get_end_position(),
+                                reason: format!("Expected `{}` to be a function", &id.value),
+                            })),
                             None => Err(MistiError::Semantic(SemanticError {
-                                // TODO: Actually find the start and end position
-                                // this requires the token to be stored, rather than
-                                // just the string value
-                                error_start: 0,
-                                error_end: 1,
-                                reason: format!("Type not found for symbol {}", id),
+                                error_start: id.position,
+                                error_end: id.get_end_position(),
+                                reason: format!("Cannot find `{}` in this scope.", id.value),
                             })),
                         }
                     }
@@ -114,3 +123,143 @@ impl Typed for Expression<'_> {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        error_handling::MistiError,
+        lexic::token::Token,
+        semantic::{
+            std::populate,
+            symbol_table::SymbolTable,
+            types::{Type, Typed},
+        },
+        syntax::ast::{
+            functions::{ArgumentsList, FunctionCall},
+            Expression,
+        },
+    };
+
+    #[test]
+    fn should_get_global_print_type() {
+        let mut scope = SymbolTable::new();
+        populate(&mut scope);
+
+        let identifier_token = Token::new_identifier("print".into(), 0);
+        let expr = Expression::Identifier(&identifier_token);
+
+        match expr.get_type(&scope) {
+            Ok(Type::Function(params, return_type)) => {
+                assert_eq!(params.len(), 1);
+                assert_eq!(params[0], "String");
+                assert_eq!(return_type, "Void");
+            }
+            Ok(t) => panic!("Expected a Function, got {:?}", t),
+            Err(e) => panic!("Expected Ok, got Err: {:?}", e),
+        }
+    }
+
+    #[test]
+    fn should_error_on_invalid_identifier() {
+        let identifier_token = Token::new_identifier("print".into(), 0);
+        let expr = Expression::Identifier(&identifier_token);
+        let scope = SymbolTable::new();
+
+        let expr_type = expr.get_type(&scope);
+        match expr_type {
+            Ok(_) => panic!("Expected an error"),
+            Err(MistiError::Semantic(err)) => {
+                assert_eq!(err.error_start, 0);
+                assert_eq!(err.error_end, 5);
+                assert_eq!(err.reason, "Cannot find `print` in this scope.");
+            }
+            Err(e) => panic!("Expected a semantic error, got {:?}", e),
+        }
+    }
+
+    #[test]
+    fn should_get_type_from_function_call() {
+        let mut scope = SymbolTable::new();
+        populate(&mut scope);
+
+        let id_token = Token::new_identifier("print".into(), 0);
+        let fn_expr = Expression::Identifier(&id_token);
+
+        let args = ArgumentsList {
+            arguments: vec![],
+            paren_open_pos: 5,
+            paren_close_pos: 7,
+        };
+
+        let fn_call = Expression::FunctionCall(FunctionCall {
+            function: Box::new(fn_expr),
+            arguments: Box::new(args),
+        });
+
+        match fn_call.get_type(&scope) {
+            Ok(Type::Value(v)) => assert_eq!(v, "Void"),
+            Ok(v) => panic!("Expected a value, got {:?}", v),
+            Err(e) => panic!("Expected a value, got Err {:?}", e),
+        }
+    }
+
+    #[test]
+    fn should_fail_if_a_function_is_expected() {
+        let scope = SymbolTable::new();
+        // Add `print` as a Int
+        scope.insert("print".into(), Type::Value("Int".into()));
+
+        let id_token = Token::new_identifier("print".into(), 0);
+        let fn_expr = Expression::Identifier(&id_token);
+
+        let args = ArgumentsList {
+            arguments: vec![],
+            paren_open_pos: 5,
+            paren_close_pos: 7,
+        };
+
+        let fn_call = Expression::FunctionCall(FunctionCall {
+            function: Box::new(fn_expr),
+            arguments: Box::new(args),
+        });
+
+        match fn_call.get_type(&scope) {
+            Ok(v) => panic!("Expected an error, got {:?}", v),
+            Err(MistiError::Semantic(e)) => {
+                assert_eq!(e.error_start, 0);
+                assert_eq!(e.error_end, 5);
+                assert_eq!(e.reason, "Expected `print` to be a function");
+            }
+            Err(e) => panic!("Expected a semantic error, got {:?}", e),
+        }
+    }
+
+    #[test]
+    fn should_fail_if_a_function_is_not_defined() {
+        let scope = SymbolTable::new();
+
+        let id_token = Token::new_identifier("print".into(), 0);
+        let fn_expr = Expression::Identifier(&id_token);
+
+        let args = ArgumentsList {
+            arguments: vec![],
+            paren_open_pos: 5,
+            paren_close_pos: 7,
+        };
+
+        let fn_call = Expression::FunctionCall(FunctionCall {
+            function: Box::new(fn_expr),
+            arguments: Box::new(args),
+        });
+
+        match fn_call.get_type(&scope) {
+            Ok(v) => panic!("Expected an error, got {:?}", v),
+            Err(MistiError::Semantic(e)) => {
+                assert_eq!(e.error_start, 0);
+                assert_eq!(e.error_end, 5);
+                assert_eq!(e.reason, "Cannot find `print` in this scope.");
+            }
+            Err(e) => panic!("Expected a semantic error, got {:?}", e),
+        }
+    }
+}

src/syntax/ast/functions.rs

@@ -1,4 +1,4 @@
-use super::Expression;
+use super::{Expression, Positionable};
 
 #[derive(Debug)]
 pub struct FunctionCall<'a> {
@@ -9,4 +9,13 @@ pub struct FunctionCall<'a> {
 #[derive(Debug)]
 pub struct ArgumentsList<'a> {
     pub arguments: Vec<Expression<'a>>,
+    pub paren_open_pos: usize,
+    /// This is after the paren is closed
+    pub paren_close_pos: usize,
+}
+
+impl Positionable for ArgumentsList<'_> {
+    fn get_position(&self) -> (usize, usize) {
+        (self.paren_open_pos, self.paren_close_pos)
+    }
 }

src/syntax/ast/mod.rs

@@ -6,6 +6,12 @@ use var_binding::VariableBinding;
 pub mod functions;
 pub mod var_binding;
 
+/// Trait that allows nodes to inform
+/// on where they start and end on the source code
+pub trait Positionable {
+    fn get_position(&self) -> (usize, usize);
+}
+
 /// The AST for a whole THP file
 #[derive(Debug)]
 pub struct ModuleAST<'a> {
@@ -60,12 +66,29 @@ pub struct Parameter<'a> {
 
 #[derive(Debug)]
 pub enum Expression<'a> {
-    Int(&'a String),
-    Float(&'a String),
-    String(&'a String),
-    Boolean(bool),
-    Identifier(&'a String),
+    Int(&'a Token),
+    Float(&'a Token),
+    String(&'a Token),
+    Boolean(&'a Token),
+    Identifier(&'a Token),
     FunctionCall(FunctionCall<'a>),
     UnaryOperator(&'a String, Box<Expression<'a>>),
     BinaryOperator(Box<Expression<'a>>, Box<Expression<'a>>, &'a String),
 }
+
+impl Positionable for Expression<'_> {
+    /// Returns the absolute start and end position
+    /// of this expression
+    fn get_position(&self) -> (usize, usize) {
+        match self {
+            Expression::Identifier(id) => (id.position, id.get_end_position()),
+            Expression::Int(id) => (id.position, id.get_end_position()),
+            Expression::Float(id) => (id.position, id.get_end_position()),
+            Expression::String(id) => (id.position, id.get_end_position()),
+            Expression::Boolean(id) => (id.position, id.get_end_position()),
+            Expression::FunctionCall(_) => (0, 1),
+            Expression::UnaryOperator(_, _) => (0, 1),
+            Expression::BinaryOperator(_, _, _) => (0, 1),
+        }
+    }
+}

src/syntax/functions/arguments_list.rs

@@ -53,7 +53,7 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<Argume
     }
 
     // Parse closing paren
-    let (_closing_paren, next_pos) =
+    let (closing_paren, next_pos) =
         match parse_token_type(tokens, current_pos, TokenType::RightParen) {
             Ok((t, next)) => (t, next),
             Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
@@ -74,7 +74,14 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<Argume
         };
     current_pos = next_pos;
 
-    Ok((ArgumentsList { arguments }, current_pos))
+    Ok((
+        ArgumentsList {
+            arguments,
+            paren_open_pos: opening_paren.position,
+            paren_close_pos: closing_paren.get_end_position(),
+        },
+        current_pos,
+    ))
 }
 
 #[cfg(test)]

src/syntax/parsers/expression/comparison.rs

@@ -62,8 +62,8 @@ mod tests {
                 Expression::BinaryOperator(exp1, exp2, op) => {
                     match (*exp1, *exp2) {
                         (Expression::Identifier(id1), Expression::Identifier(id2)) => {
-                            assert_eq!("a", id1);
-                            assert_eq!("b", id2);
+                            assert_eq!("a", id1.value);
+                            assert_eq!("b", id2.value);
                         }
                         _ => panic!("Expected 2 identifiers"),
                     }

src/syntax/parsers/expression/equality.rs

@@ -61,8 +61,8 @@ mod tests {
                 Expression::BinaryOperator(exp1, exp2, op) => {
                     match (*exp1, *exp2) {
                         (Expression::Identifier(id1), Expression::Identifier(id2)) => {
-                            assert_eq!("a", id1);
-                            assert_eq!("b", id2);
+                            assert_eq!("a", id1.value);
+                            assert_eq!("b", id2.value);
                         }
                         _ => panic!("Expected 2 identifiers"),
                     }

src/syntax/parsers/expression/factor.rs

@@ -65,8 +65,8 @@ mod tests {
                 Expression::BinaryOperator(exp1, exp2, op) => {
                     match (*exp1, *exp2) {
                         (Expression::Identifier(id1), Expression::Identifier(id2)) => {
-                            assert_eq!("a", id1);
-                            assert_eq!("b", id2);
+                            assert_eq!("a", id1.value);
+                            assert_eq!("b", id2.value);
                         }
                         _ => panic!("Expected 2 identifiers"),
                     }

src/syntax/parsers/expression/primary.rs

@@ -13,13 +13,13 @@ use crate::{
 pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     match tokens.get_significant(pos) {
         Some((token, token_pos)) => match token.token_type {
-            TokenType::Int => Ok((Expression::Int(&token.value), token_pos + 1)),
-            TokenType::Float => Ok((Expression::Float(&token.value), token_pos + 1)),
-            TokenType::String => Ok((Expression::String(&token.value), token_pos + 1)),
+            TokenType::Int => Ok((Expression::Int(&token), token_pos + 1)),
+            TokenType::Float => Ok((Expression::Float(&token), token_pos + 1)),
+            TokenType::String => Ok((Expression::String(&token), token_pos + 1)),
             TokenType::Identifier if token.value == "true" || token.value == "false" => {
-                Ok((Expression::Boolean(token.value == "true"), token_pos + 1))
+                Ok((Expression::Boolean(&token), token_pos + 1))
             }
-            TokenType::Identifier => Ok((Expression::Identifier(&token.value), token_pos + 1)),
+            TokenType::Identifier => Ok((Expression::Identifier(&token), token_pos + 1)),
             TokenType::LeftParen => parse_parenthesized_expression(tokens, token_pos),
             _ => Err(ParsingError::Unmatched),
         },
@@ -53,7 +53,7 @@ mod tests {
 
         match expression {
             Ok((Expression::Int(value), _)) => {
-                assert_eq!("40", format!("{}", value))
+                assert_eq!("40", format!("{}", value.value))
             }
             _ => panic!(),
         }
@@ -66,7 +66,7 @@ mod tests {
 
         match expression {
             Ok((Expression::String(value), _)) => {
-                assert_eq!("Hello", format!("{}", value))
+                assert_eq!("Hello", format!("{}", value.value))
             }
             _ => panic!(),
         }
@@ -78,7 +78,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            Ok((Expression::Boolean(value), _)) => assert!(value),
+            Ok((Expression::Boolean(value), _)) => assert_eq!(value.value, "true"),
             _ => panic!(),
         }
     }
@@ -90,7 +90,7 @@ mod tests {
 
         match expression {
             Ok((Expression::Identifier(value), _)) => {
-                assert_eq!("someIdentifier", format!("{}", value))
+                assert_eq!("someIdentifier", format!("{}", value.value))
             }
             _ => panic!(),
         }
@@ -103,7 +103,7 @@ mod tests {
 
         match expression {
             Ok((Expression::Identifier(value), _)) => {
-                assert_eq!("identifier", format!("{}", value))
+                assert_eq!("identifier", format!("{}", value.value))
             }
             _ => panic!(),
         }

src/syntax/parsers/expression/term.rs

@@ -66,8 +66,8 @@ mod tests {
                 Expression::BinaryOperator(exp1, exp2, op) => {
                     match (*exp1, *exp2) {
                         (Expression::Identifier(id1), Expression::Identifier(id2)) => {
-                            assert_eq!("a", id1);
-                            assert_eq!("b", id2);
+                            assert_eq!("a", id1.value);
+                            assert_eq!("b", id2.value);
                         }
                         _ => panic!("Expected 2 identifiers"),
                     }

src/syntax/parsers/expression/unary.rs

@@ -38,7 +38,7 @@ mod tests {
 
         match expression {
             Ok((Expression::Identifier(value), _)) => {
-                assert_eq!("identifier", format!("{}", value))
+                assert_eq!("identifier", format!("{}", value.value))
             }
             _ => panic!(),
         }
@@ -54,7 +54,7 @@ mod tests {
                 match (operator, *expression) {
                     (op, Expression::Int(value)) => {
                         assert_eq!(*op, "-");
-                        assert_eq!(*value, "10");
+                        assert_eq!(value.value, "10");
                     }
                     _ => panic!("unexpected values"),
                 }

src/syntax/utils.rs

@@ -11,13 +11,15 @@ impl Tokenizer for Vec<Token> {
     fn get_significant<'a>(&'a self, index: usize) -> Option<(&'a Token, usize)> {
         let mut current_pos = index;
 
-        // Ignore all whitespace and newlines
+        // Ignore all whitespace, newlines and comments
         loop {
             match self.get(current_pos) {
                 Some(token) => {
                     if token.token_type == TokenType::INDENT
                         || token.token_type == TokenType::DEDENT
                         || token.token_type == TokenType::NewLine
+                        || token.token_type == TokenType::Comment
+                        || token.token_type == TokenType::MultilineComment
                     {
                         current_pos += 1;
                     } else {
@@ -44,7 +46,7 @@ pub fn try_operator(tokens: &Vec<Token>, pos: usize, operator: String) -> Parsin
 
 /// Expects the token at `pos` to be of type `token_type`, and returns the token and the next position.
 ///
-/// Ignores all whitespace and newlines.
+/// Ignores all whitespace, newlines and comments.
 ///
 /// Only returns: Ok, Unmatched, Mismatched
 pub fn parse_token_type(
@@ -59,6 +61,8 @@ pub fn parse_token_type(
         if t.token_type == TokenType::INDENT
             || t.token_type == TokenType::DEDENT
             || t.token_type == TokenType::NewLine
+            || t.token_type == TokenType::Comment
+            || t.token_type == TokenType::MultilineComment
         {
             current_pos += 1;
         } else {