fix: add tests to the function declaration parser

src/syntax/ast/mod.rs

@@ -89,7 +89,7 @@ pub struct ParamsList<'a> {
 
 impl Positionable for ParamsList<'_> {
     fn get_position(&self) -> (usize, usize) {
-        todo!()
+        (self.start, self.end)
     }
 }
 

src/syntax/functions/params_list.rs

@@ -4,7 +4,10 @@ use crate::{
         ErrorContainer, ErrorLabel,
     },
     lexic::token::{Token, TokenType},
-    syntax::{utils::parse_token_type, ParsingError, ParsingResult},
+    syntax::{
+        utils::{parse_token_type, Tokenizer},
+        ParsingError, ParsingResult,
+    },
 };
 
 use super::super::{
@@ -93,14 +96,15 @@ pub fn parse_params_list(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Param
                     start: opening_paren.position,
                     end: opening_paren.get_end_position(),
                 };
+                let label_2_pos = tokens.code_position_from_idx(current_pos);
                 let label_2 = ErrorLabel {
                     message: String::from("The code ends here without closing the parameter list"),
-                    start: current_pos,
+                    start: label_2_pos,
-                    end: current_pos + 1,
+                    end: label_2_pos + 1,
                 };
                 let econtainer = ErrorContainer {
                     error_code: SYNTAX_INCOMPLETE_PARAMETER_LIST,
-                    error_offset: current_pos,
+                    error_offset: tokens.code_position_from_idx(current_pos),
                     labels: vec![label_1, label_2],
                     note: None,
                     help: None,
@@ -172,7 +176,7 @@ fn parse_param_definition(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Para
                 };
                 let econtainer = ErrorContainer {
                     error_code: SYNTAX_INVALID_PARAMETER_DECLARATION,
-                    error_offset: datatype_token.position,
+                    error_offset: datatype_token.get_end_position(),
                     labels: vec![label],
                     note: None,
                     help: None,
@@ -290,4 +294,126 @@ mod tests {
         assert_eq!(second_param.datatype, "String");
         assert_eq!(second_param.identifier, "y");
     }
+
+    #[test]
+    fn should_fail_on_incomplete_params_list() {
+        let tokens = get_tokens(&String::from("   (   ")).unwrap();
+        let result = parse_params_list(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INCOMPLETE_PARAMETER_LIST, err.error_code);
+                assert_eq!(err.error_offset, 4);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "The parameter list starts here");
+                assert_eq!(label.start, 3);
+                assert_eq!(label.end, 4);
+
+                let label = &err.labels[1];
+                assert_eq!(
+                    label.message,
+                    "The code ends here without closing the parameter list"
+                );
+                assert_eq!(label.start, 4);
+                assert_eq!(label.end, 5);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_invalid_params_closing() {
+        let tokens = get_tokens(&String::from("   (   &")).unwrap();
+        let result = parse_params_list(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INCOMPLETE_PARAMETER_LIST, err.error_code);
+                assert_eq!(err.error_offset, 7);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "The parameter list starts here");
+                assert_eq!(label.start, 3);
+                assert_eq!(label.end, 4);
+
+                let label = &err.labels[1];
+                assert_eq!(label.message, "Expected a closing paren `)` here");
+                assert_eq!(label.start, 7);
+                assert_eq!(label.end, 8);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_invalid_params_closing_2() {
+        let tokens = get_tokens(&String::from("   (   Int i &")).unwrap();
+        let result = parse_params_list(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INCOMPLETE_PARAMETER_LIST, err.error_code);
+                assert_eq!(err.error_offset, 13);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "The parameter list starts here");
+                assert_eq!(label.start, 3);
+                assert_eq!(label.end, 4);
+
+                let label = &err.labels[1];
+                assert_eq!(label.message, "Expected a closing paren `)` here");
+                assert_eq!(label.start, 13);
+                assert_eq!(label.end, 14);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+}
+
+#[cfg(test)]
+mod params_tests {
+    use super::*;
+    use crate::lexic::get_tokens;
+
+    #[test]
+    fn should_fail_on_missing_identifier() {
+        let tokens = get_tokens(&String::from("  Int ")).unwrap();
+        let result = parse_param_definition(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INVALID_PARAMETER_DECLARATION, err.error_code);
+                assert_eq!(err.error_offset, 5);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "Expected an identifier after this datatype");
+                assert_eq!(label.start, 2);
+                assert_eq!(label.end, 5);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_wrong_identifier() {
+        let tokens = get_tokens(&String::from("  Int 322")).unwrap();
+        let result = parse_param_definition(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INVALID_PARAMETER_DECLARATION, err.error_code);
+                assert_eq!(err.error_offset, 6);
+
+                let label = &err.labels[0];
+                assert_eq!(
+                    label.message,
+                    "Expected an identifier here, found this instead"
+                );
+                assert_eq!(label.start, 6);
+                assert_eq!(label.end, 9);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
 }

src/syntax/parsers/block.rs

@@ -4,7 +4,7 @@ use crate::{
     syntax::{
         ast::{Block, BlockMember, Expression, Statement},
         parseable::{Parseable, ParsingError, ParsingResult},
-        utils::parse_token_type,
+        utils::{parse_token_type, Tokenizer},
     },
 };
 
@@ -80,15 +80,21 @@ impl<'a> Parseable<'a> for Block<'a> {
                     return Err(ParsingError::Err(econtainer));
                 }
                 Err(ParsingError::Unmatched) => {
-                    let label = ErrorLabel {
+                    let label_1 = ErrorLabel {
-                        message: String::from("Expected a closing brace `}` here"),
+                        message: String::from("The block starts here"),
-                        start: current_pos,
+                        start: opening_brace.position,
-                        end: current_pos + 1,
+                        end: opening_brace.get_end_position(),
+                    };
+                    let label_2_pos = tokens.code_position_from_idx(current_pos);
+                    let label_2 = ErrorLabel {
+                        message: String::from("The code ends here without closing the block"),
+                        start: label_2_pos,
+                        end: label_2_pos + 1,
                     };
                     let econtainer = ErrorContainer {
                         error_code: SYNTAX_INCOMPLETE_BLOCK,
-                        error_offset: current_pos,
+                        error_offset: tokens.code_position_from_idx(current_pos),
-                        labels: vec![label],
+                        labels: vec![label_1, label_2],
                         note: None,
                         help: None,
                     };

src/syntax/parsers/function_declaration.rs

@@ -7,7 +7,7 @@ use crate::{
         ast::{Block, FunctionDeclaration, Positionable},
         functions::params_list::parse_params_list,
         parseable::{Parseable, ParsingError, ParsingResult},
-        utils::{parse_token_type, try_operator},
+        utils::{parse_token_type, try_operator, Tokenizer},
     },
 };
 
@@ -184,13 +184,13 @@ impl<'a> Parseable<'a> for FunctionDeclaration<'a> {
                     }
                 };
                 let label = ErrorLabel {
-                    message: String::from("Expected a block here, after the function declaration"),
+                    message: String::from("Expected a block after this parameter list"),
                     start: error_start,
                     end: error_end,
                 };
                 let econtainer = ErrorContainer {
                     error_code: SYNTAX_INVALID_FUNCTION_DECLARATION,
-                    error_offset: error_start,
+                    error_offset: tokens.code_position_from_idx(current_pos),
                     labels: vec![label],
                     note: None,
                     help: None,
@@ -215,7 +215,12 @@ impl<'a> Parseable<'a> for FunctionDeclaration<'a> {
 
 #[cfg(test)]
 mod tests {
-    use crate::{error_handling::error_messages::SYNTAX_INCOMPLETE_BLOCK, lexic::get_tokens};
+    use crate::{
+        error_handling::error_messages::{
+            SYNTAX_INCOMPLETE_BLOCK, SYNTAX_INCOMPLETE_PARAMETER_LIST,
+        },
+        lexic::get_tokens,
+    };
 
     use super::*;
 
@@ -230,98 +235,125 @@ mod tests {
     }
 
     #[test]
-    fn should_not_parse_fun_without_identifier() {
+    fn should_fail_on_incomplete_1() {
-        let tokens = get_tokens(&String::from("fun = 20")).unwrap();
-        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
-
-        match fun_decl {
-            Err(ParsingError::Err(err)) => {
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
-                assert_eq!(err.error_offset, 4);
-            }
-            _ => panic!("Expected an error: {:?}", fun_decl),
-        }
-
         let tokens = get_tokens(&String::from("fun ")).unwrap();
         let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+
         match fun_decl {
             Err(ParsingError::Err(err)) => {
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
                 assert_eq!(err.error_offset, 0);
+                assert_eq!(SYNTAX_INVALID_FUNCTION_DECLARATION, err.error_code);
+                let first_label = &err.labels[0];
+                assert_eq!(first_label.start, 0);
+                assert_eq!(first_label.end, 3);
+                assert_eq!(
+                    first_label.message,
+                    "Expected an identifier after this `fun` keyword",
+                );
             }
-            _ => panic!("Expected an error: {:?}", fun_decl),
+            _ => panic!("Expected a ParsingErr"),
         }
     }
 
     #[test]
-    fn should_not_parse_fun_without_parens() {
+    fn should_fail_on_invalid_identifier() {
+        let tokens = get_tokens(&String::from("fun 322")).unwrap();
+        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+
+        match fun_decl {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(err.error_offset, 4);
+                assert_eq!(SYNTAX_INVALID_FUNCTION_DECLARATION, err.error_code);
+                let first_label = &err.labels[0];
+                assert_eq!(first_label.start, 4);
+                assert_eq!(first_label.end, 7);
+                assert_eq!(first_label.message, "Expected an identifier here",);
+            }
+            _ => panic!("Expected a ParsingErr"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_missing_params_list() {
+        let tokens = get_tokens(&String::from("fun id")).unwrap();
+        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+
+        match fun_decl {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(err.error_offset, 6);
+                assert_eq!(SYNTAX_INVALID_FUNCTION_DECLARATION, err.error_code);
+                let first_label = &err.labels[0];
+                assert_eq!(first_label.start, 4);
+                assert_eq!(first_label.end, 6);
+                assert_eq!(
+                    first_label.message,
+                    "Expected a parameter list after this identifier",
+                );
+            }
+            _ => panic!("Expected a ParsingErr"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_invalid_params_list() {
         let tokens = get_tokens(&String::from("fun id =")).unwrap();
         let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
 
         match fun_decl {
             Err(ParsingError::Err(err)) => {
                 assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
-                assert_eq!(err.error_offset, 7);
+                assert_eq!(err.error_offset, 8);
-            }
-            _ => panic!("Expected an error: {:?}", fun_decl),
-        }
 
-        let tokens = get_tokens(&String::from("fun id")).unwrap();
+                let label = &err.labels[0];
-        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+                assert_eq!(label.start, 7);
-        match fun_decl {
+                assert_eq!(label.end, 8);
-            Err(ParsingError::Err(err)) => {
+                assert_eq!(label.message, "Expected a parameter list here");
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
-                assert_eq!(err.error_offset, 4);
             }
-            _ => panic!("Expected an error: {:?}", fun_decl),
+            _ => panic!("Expected an error, got {:?}", fun_decl),
         }
     }
 
     #[test]
-    fn should_not_parse_fun_without_closing_paren() {
+    fn should_fail_on_incomplete_params_list() {
-        let tokens = get_tokens(&String::from("fun id(=")).unwrap();
-        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
-
-        match fun_decl {
-            Err(ParsingError::Err(err)) => {
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
-                assert_eq!(err.error_offset, 7);
-            }
-            _ => panic!("Expected an error: {:?}", fun_decl),
-        }
-
         let tokens = get_tokens(&String::from("fun id(")).unwrap();
         let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+
         match fun_decl {
             Err(ParsingError::Err(err)) => {
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
+                assert_eq!(err.error_code, SYNTAX_INCOMPLETE_PARAMETER_LIST);
-                assert_eq!(err.error_offset, 6);
+                assert_eq!(err.error_offset, 7);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "The parameter list starts here");
+                assert_eq!(label.start, 6);
+                assert_eq!(label.end, 7);
+
+                let label = &err.labels[1];
+                assert_eq!(
+                    label.message,
+                    "The code ends here without closing the parameter list"
+                );
+                assert_eq!(label.start, 7);
+                assert_eq!(label.end, 8);
             }
             _ => panic!("Expected an error: {:?}", fun_decl),
         }
     }
 
     #[test]
-    fn should_not_parse_fun_when_missing_id() {
+    fn should_fail_on_missing_body() {
-        let tokens = get_tokens(&String::from("fun")).unwrap();
+        let tokens = get_tokens(&String::from("fun id() ")).unwrap();
         let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
 
         match fun_decl {
             Err(ParsingError::Err(err)) => {
                 assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
-                assert_eq!(err.error_offset, 0);
+                assert_eq!(err.error_offset, 8);
-            }
-            _ => panic!("Expected an error: {:?}", fun_decl),
-        }
 
-        let tokens = get_tokens(&String::from("fun\n")).unwrap();
+                let label = &err.labels[0];
-        println!("{:?}", tokens);
+                assert_eq!(label.message, "Expected a block after this parameter list");
-        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+                assert_eq!(label.start, 6);
-
+                assert_eq!(label.end, 8);
-        match fun_decl {
-            Err(ParsingError::Err(err)) => {
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
-                assert_eq!(err.error_offset, 0);
             }
             _ => panic!("Expected an error: {:?}", fun_decl),
         }
@@ -336,16 +368,14 @@ mod tests {
             Err(ParsingError::Err(err)) => {
                 assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
                 assert_eq!(err.error_offset, 9);
-            }
-            _ => panic!("Expected an error: {:?}", fun_decl),
-        }
 
-        let tokens = get_tokens(&String::from("fun id()")).unwrap();
+                let label = &err.labels[0];
-        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+                assert_eq!(
-        match fun_decl {
+                    label.message,
-            Err(ParsingError::Err(err)) => {
+                    "Expected a block here, after the function declaration"
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
+                );
-                assert_eq!(err.error_offset, 4);
+                assert_eq!(label.start, 9);
+                assert_eq!(label.end, 10);
             }
             _ => panic!("Expected an error: {:?}", fun_decl),
         }
@@ -359,18 +389,20 @@ mod tests {
         match fun_decl {
             Err(ParsingError::Err(err)) => {
                 assert_eq!(err.error_code, SYNTAX_INCOMPLETE_BLOCK);
-                assert_eq!(err.error_offset, 9);
+                assert_eq!(err.error_offset, 10);
-            }
-            _ => panic!("Expected an error: {:?}", fun_decl),
-        }
 
-        let tokens = get_tokens(&String::from("fun id() {")).unwrap();
+                let label = &err.labels[0];
-        let fun_decl = FunctionDeclaration::try_parse(&tokens, 0);
+                assert_eq!(label.message, "The block starts here");
+                assert_eq!(label.start, 9);
+                assert_eq!(label.end, 10);
 
-        match fun_decl {
+                let label = &err.labels[1];
-            Err(ParsingError::Err(err)) => {
+                assert_eq!(
-                assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
+                    label.message,
-                assert_eq!(err.error_offset, 9);
+                    "The code ends here without closing the block"
+                );
+                assert_eq!(label.start, 10);
+                assert_eq!(label.end, 11);
             }
             _ => panic!("Expected an error: {:?}", fun_decl),
         }
@@ -405,7 +437,12 @@ mod tests {
         match fun_decl {
             Err(ParsingError::Err(err)) => {
                 assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
-                assert_eq!(err.error_offset, 9);
+                assert_eq!(err.error_offset, 12);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "Expected a Datatype here");
+                assert_eq!(label.start, 12);
+                assert_eq!(label.end, 13);
             }
             _ => panic!("Expected an error: {:?}", fun_decl),
         }
@@ -420,6 +457,14 @@ mod tests {
             Err(ParsingError::Err(err)) => {
                 assert_eq!(err.error_code, SYNTAX_INVALID_FUNCTION_DECLARATION);
                 assert_eq!(err.error_offset, 9);
+
+                let label = &err.labels[0];
+                assert_eq!(
+                    label.message,
+                    "Expected a Datatype after this arrow `->` operator"
+                );
+                assert_eq!(label.start, 9);
+                assert_eq!(label.end, 11);
             }
             _ => panic!("Expected an error: {:?}", fun_decl),
         }

src/syntax/parsers/module.rs

@@ -19,7 +19,7 @@ impl<'a> Parseable<'a> for ModuleAST<'a> {
     /// As this function parses the whole file, it ignores `current_pos` and
     /// always starts from token 0.
     ///
-    /// Its grammar is defined it the spec, at the webpage
+    /// Its grammar is defined at the spec, at the webpage
     fn try_parse(tokens: &'a Vec<Token>, _current_pos: usize) -> ParsingResult<'a, Self::Item> {
         let mut productions = Vec::<ModuleMembers>::new();
         let tokens_len = tokens.len();

src/syntax/utils.rs

@@ -4,6 +4,7 @@ use super::{ParsingError, ParsingResult};
 
 pub trait Tokenizer {
     fn get_significant<'a>(&'a self, index: usize) -> Option<(&'a Token, usize)>;
+    fn code_position_from_idx(&self, idx: usize) -> usize;
 }
 
 impl Tokenizer for Vec<Token> {
@@ -30,6 +31,30 @@ impl Tokenizer for Vec<Token> {
             }
         }
     }
+
+    /// Returns the position in the code from the token idx.
+    ///
+    /// If the token at `idx` exists, returns `tokens[idx].position`.
+    ///
+    /// Otherwise returns `tokens[idx - 1].get_end_position()`
+    fn code_position_from_idx(&self, idx: usize) -> usize {
+        // try to get the token at idx
+        match self.get(idx) {
+            Some(t) if t.token_type == TokenType::EOF => {
+                // If idx points at EOF, return the end position of the previous token
+                // This shouldnt fail
+                self[idx - 1].get_end_position()
+            }
+            Some(t) => t.position,
+            None => {
+                // this should never happen.
+                // the token stream always ends with an EOF token,
+                // and the parser should never be able to go
+                // to a position after that EOF token
+                unreachable!("Compiler error: Tried to get an out of bound token. This means that somewhere a token beyond EOF was requested.")
+            }
+        }
+    }
 }
 
 /// Expects the token at `pos` to be an operator of value `operator`. Doesn't ignore whitespace or newlines