Fix error messages to display the value instead of token type

src/cli/ast/mod.rs

@@ -173,7 +173,7 @@ mod tests {
         ];
         let result = generate(tokens);
         assert!(result[0].is_err());
-        let expected = vec![Err("Error at line 1, column 0: Unexpected token type: Into".to_string())];
+        let expected = vec![Err("Error at line 1, column 0: Unexpected value: INTO".to_string())];
         assert_eq!(expected, result);
     }
 
@@ -242,7 +242,7 @@ mod tests {
         assert!(result[0].is_err());
         assert!(result[1].is_ok());
         let expected = vec![
-            Err("Error at line 1, column 0: Unexpected token type: SemiColon".to_string()),
+            Err("Error at line 1, column 0: Unexpected value: ;".to_string()),
             Ok(SqlStatement::InsertInto(InsertIntoStatement {
 
                 table_name: "users".to_string(),

src/cli/ast/parser.rs

@@ -49,8 +49,8 @@ impl<'a> Parser<'a> {
         if self.current < self.tokens.len() {
             let token = &self.tokens[self.current];
             return format!(
-                "Error at line {:?}, column {:?}: Unexpected token type: {:?}",
-                token.line_num, token.col_num, token.token_type
+                "Error at line {:?}, column {:?}: Unexpected value: {}",
+                token.line_num, token.col_num, token.value.to_string()
             );
         } else {
             return "Error at end of input.".to_string();
@@ -101,7 +101,7 @@ mod tests {
         let tokens = vec![token(TokenTypes::Insert, "INSERT", 15, 3)];
         let parser = Parser::new(tokens);
         let result = parser.format_error();
-        assert_eq!(result, "Error at line 3, column 15: Unexpected token type: Insert");
+        assert_eq!(result, "Error at line 3, column 15: Unexpected value: INSERT");
     }
 
     pub struct MockStatementBuilder;
@@ -196,7 +196,7 @@ mod tests {
         let mut parser = Parser::new(tokens);
         let builder : &dyn StatementBuilder = &MockStatementBuilder;
         let result = parser.next_statement(builder);
-        let expected = Some(Err("Error at line 1, column 1: Unexpected token type: Identifier".to_string()));
+        let expected = Some(Err("Error at line 1, column 1: Unexpected value: users".to_string()));
         assert_eq!(result, expected);
     }
 }

src/cli/ast/select_statement.rs

@@ -1,4 +1,4 @@
-use crate::cli::{ast::{parser::Parser, SqlStatement, SelectStatement, SelectStatementColumns, Operator, common::token_to_value, common::tokens_to_identifier_list, common::expect_token_type, WhereClause, OrderByClause, OrderByDirection, LimitClause}, tokenizer::token::TokenTypes};
+use crate::{cli::{ast::{common::{expect_token_type, token_to_value, tokens_to_identifier_list}, parser::Parser, LimitClause, Operator, OrderByClause, OrderByDirection, SelectStatement, SelectStatementColumns, SqlStatement, WhereClause}, tokenizer::token::TokenTypes}, db::table::Value};
 
 pub fn build(parser: &mut Parser) -> Result<SqlStatement, String> {
     parser.advance()?;
@@ -138,6 +138,11 @@ fn get_limit(parser: &mut Parser) -> Result<Option<LimitClause>, String> {
 
     expect_token_type(parser, TokenTypes::IntLiteral)?;
     let offset = token_to_value(parser)?;
+    if let Value::Integer(offset) = offset {
+        if offset < 0 {
+            return Err(parser.format_error());
+        }
+    };
     parser.advance()?;
 
     return Ok(Some(LimitClause {
@@ -165,6 +170,7 @@ mod tests {
 
     #[test]
     fn select_statement_with_all_tokens_is_generated_correctly() {
+        // SELECT * FROM users;
         let tokens = vec![
             token(TokenTypes::Select, "SELECT"),
             token(TokenTypes::Asterisk, "*"),
@@ -187,6 +193,7 @@ mod tests {
 
     #[test]
     fn select_statement_with_a_single_column_is_generated_correctly() {
+        // SELECT id FROM guests;
         let tokens = vec![
             token(TokenTypes::Select, "SELECT"),
             token(TokenTypes::Identifier, "id"),
@@ -211,6 +218,7 @@ mod tests {
 
     #[test]
     fn select_statement_with_multiple_columns_is_generated_correctly() {
+        // SELECT id, name FROM users;
         let tokens = vec![
             token(TokenTypes::Select, "SELECT"),
             token(TokenTypes::Identifier, "id"),
@@ -238,6 +246,7 @@ mod tests {
 
     #[test]
     fn select_statement_with_all_clauses_is_generated_correctly() {
+        // SELECT id FROM guests WHERE id = 1 ORDER BY id ASC, name DESC, age ASC LIMIT 10 OFFSET 5;
         let tokens = vec![
             token(TokenTypes::Select, "SELECT"),
             token(TokenTypes::Identifier, "id"),
@@ -299,6 +308,7 @@ mod tests {
 
     #[test]
     fn select_statement_with_limit_clause_no_offset_is_generated_correctly() {
+        // SELECT id FROM guests WHERE id > 1 LIMIT 10;
         let tokens = vec![
             token(TokenTypes::Select, "SELECT"),
             token(TokenTypes::Identifier, "id"),
@@ -333,4 +343,24 @@ mod tests {
             }),
         }));
     }
+
+    #[test]
+    fn select_statement_with_limit_clause_with_negative_offset_is_generated_correctly() {
+        // SELECT id FROM guests LIMIT 10 OFFSET -5;
+        let tokens = vec![
+            token(TokenTypes::Select, "SELECT"),
+            token(TokenTypes::Identifier, "id"),
+            token(TokenTypes::From, "FROM"),
+            token(TokenTypes::Identifier, "guests"),
+            token(TokenTypes::Limit, "LIMIT"),
+            token(TokenTypes::IntLiteral, "10"),
+            token(TokenTypes::Offset, "OFFSET"),
+            token(TokenTypes::IntLiteral, "-5"),
+            token(TokenTypes::SemiColon, ";"),
+        ];
+        let mut parser = Parser::new(tokens);
+        let result = build(&mut parser);
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err(), "Error at line 1, column 0: Unexpected value: -5");
+    }
 }