error when reserved function name is used for a user defined function

src/compiler/ast_pass.rs

@@ -18,6 +18,7 @@ use crate::value::Value;
 use crate::{DATE_FORMAT_TIMEZONE, Expr, Stmt, SymbolTable};
 use log::debug;
 use std::collections::HashMap;
+use crate::builtins::globals::GLOBAL_FUNCTIONS;
 
 pub fn compile(
     path: Option<&str>,
@@ -235,6 +236,9 @@ impl AstCompiler {
 
     fn function_declaration(&mut self, symbol_table: &mut SymbolTable) -> Stmt {
         let name_token = self.consume(&Identifier, Expected("function name."))?;
+        if GLOBAL_FUNCTIONS.contains_key(name_token.lexeme.as_str()) {
+            return Err(self.raise(CompilerError::ReservedFunctionName(name_token.lexeme.clone())))
+        }
         self.consume(&LeftParen, Expected("'(' after function name."))?;
         let mut parameters = vec![];
         while !self.check(&RightParen) {

src/compiler/compiler_tests.rs

@@ -1,7 +1,7 @@
 #[cfg(test)]
 mod tests {
     use crate::compiler::{compile, run};
-    use crate::errors::CompilerError::IllegalArgumentsException;
+    use crate::errors::CompilerError::{IllegalArgumentsException, ReservedFunctionName};
     use crate::errors::CompilerErrorAtLine;
     use crate::errors::RuntimeError::{IllegalArgumentException, IndexOutOfBounds};
     use crate::errors::TipiLangError::{Compiler, Runtime};
@@ -417,6 +417,12 @@ sum
         assert!(DateTime::parse_from_str(&date_time_string, DATE_FORMAT_TIMEZONE).is_ok());
     }
 
+    #[test]
+    fn global_fns_are_not_allowed() {
+        let value = run(r#"fn now():"#);
+        assert_eq!(value, Err(Compiler(CompilerErrorAtLine { error: ReservedFunctionName("now".to_string()), line: 1 })));
+    }
+
     // #[test]
     // fn package() {
     //     assert_eq!(run(r#"a.b.c()"#), Ok(Value::U32(48)));

src/compiler/mod.rs

@@ -46,10 +46,10 @@ pub fn map_underlying() -> fn(std::io::Error) -> TipiLangError {
 
 
 pub fn compile(src: &str) -> Result<HashMap<String, AsmChunk>, TipiLangError> {
-    let tokens = compiler::scan_pass::scan(src)?;
+    let tokens = scan_pass::scan(src)?;
     let mut asm_registry = HashMap::new();
     let mut symbol_table = HashMap::new();
-    let ast = compiler::ast_pass::compile(None, tokens, &mut symbol_table)?;
+    let ast = ast_pass::compile(None, tokens, &mut symbol_table)?;
     symbol_builder::build("", &ast, &mut symbol_table);
     assembly_pass::compile(None, &ast, &symbol_table, &mut asm_registry)?;
     Ok(asm_registry)
@@ -57,9 +57,9 @@ pub fn compile(src: &str) -> Result<HashMap<String, AsmChunk>, TipiLangError> {
 
 #[cfg(test)]
 pub(crate) fn run(src: &str) -> Result<crate::value::Value, TipiLangError> {
-    let tokens = compiler::scan_pass::scan(src)?;
+    let tokens = scan_pass::scan(src)?;
     let mut symbol_table = HashMap::new();
-    let ast = compiler::ast_pass::compile(None, tokens, &mut symbol_table)?;
+    let ast = ast_pass::compile(None, tokens, &mut symbol_table)?;
     symbol_builder::build("", &ast, &mut symbol_table);
     let mut asm_registry = HashMap::new();
     assembly_pass::compile(None, &ast, &symbol_table, &mut asm_registry)?;

src/errors.rs

@@ -14,14 +14,14 @@ pub enum TipiLangError {
 }
 
 #[derive(Error, Debug, PartialEq)]
-pub struct CompilerErrorAtLine{
+pub struct CompilerErrorAtLine {
     pub error: CompilerError,
-    pub line: usize
+    pub line: usize,
 }
 
 impl CompilerErrorAtLine {
-    pub(crate) fn raise(error:CompilerError, line: usize) -> Self{
+    pub(crate) fn raise(error: CompilerError, line: usize) -> Self {
-        Self {error, line}
+        Self { error, line }
     }
 }
 
@@ -70,7 +70,9 @@ pub enum CompilerError {
     #[error("Illegal argument: '{0}' cannot be indexed")]
     IllegalTypeToIndex(String),
     #[error("The number of of arguments for {0} is not correct. Should be {1}, got {2}")]
-    IllegalArgumentsException(String,usize,usize),
+    IllegalArgumentsException(String, usize, usize),
+    #[error("Function name {0} is a global function and cannot be used here.")]
+    ReservedFunctionName(String),
 }
 
 #[derive(Error, Debug, PartialEq)]
@@ -84,7 +86,7 @@ pub enum RuntimeError {
     #[error("Function {0} not found")]
     FunctionNotFound(String),
     #[error("The number of of arguments for {0} is not correct. Should be {1}, got {2}")]
-    IllegalArgumentsException(String,usize,usize),
+    IllegalArgumentsException(String, usize, usize),
     #[error("{0}")]
     IllegalArgumentException(String),
     #[error("Expected {0}")]