Enable call in function-call style.

RELEASES.md

@@ -4,6 +4,11 @@ Rhai Release Notes
 Version 0.18.0
 ==============
 
+New features
+------------
+
+* `call` can now be called function-call style for function pointers - this is to handle builds with `no_object`.
+* Disallow many keywords as variables, such as `print`, `eval`, `call`, `this` etc.
 
 
 Version 0.17.0

doc/src/language/fn-ptr.md

@@ -6,7 +6,7 @@ Function Pointers
 It is possible to store a _function pointer_ in a variable just like a normal value.
 In fact, internally a function pointer simply stores the _name_ of the function as a string.
 
-Call a function pointer using the `call` method, which needs to be called in method-call style.
+Call a function pointer using the `call` method.
 
 
 Built-in methods
@@ -40,7 +40,7 @@ func.call(1) == 42;         // call a function pointer with the 'call' method
 
 foo(1) == 42;               // <- the above de-sugars to this
 
-call(func, 1);              //<- error: 'call (Fn, i64)' is not a registered function
+call(func, 1);              // normal function call style also works for 'call'
 
 let len = Fn("len");        // 'Fn' also works with registered native Rust functions
 

src/engine.rs

@@ -944,7 +944,7 @@ impl Engine {
     }
 
     // Has a system function an override?
-    fn has_override(&self, lib: &Module, (hash_fn, hash_script): (u64, u64)) -> bool {
+    fn has_override(&self, lib: &Module, hash_fn: u64, hash_script: u64) -> bool {
         // NOTE: We skip script functions for global_module and packages, and native functions for lib
 
         // First check script-defined functions
@@ -986,13 +986,15 @@ impl Engine {
 
         match fn_name {
             // type_of
-            KEYWORD_TYPE_OF if args.len() == 1 && !self.has_override(lib, hashes) => Ok((
+            KEYWORD_TYPE_OF if args.len() == 1 && !self.has_override(lib, hashes.0, hashes.1) => {
-                self.map_type_name(args[0].type_name()).to_string().into(),
+                Ok((
-                false,
+                    self.map_type_name(args[0].type_name()).to_string().into(),
-            )),
+                    false,
+                ))
+            }
 
             // Fn
-            KEYWORD_FN_PTR if args.len() == 1 && !self.has_override(lib, hashes) => {
+            KEYWORD_FN_PTR if args.len() == 1 && !self.has_override(lib, hashes.0, hashes.1) => {
                 Err(Box::new(EvalAltResult::ErrorRuntime(
                     "'Fn' should not be called in method style. Try Fn(...);".into(),
                     Position::none(),
@@ -1000,7 +1002,7 @@ impl Engine {
             }
 
             // eval - reaching this point it must be a method-style call
-            KEYWORD_EVAL if args.len() == 1 && !self.has_override(lib, hashes) => {
+            KEYWORD_EVAL if args.len() == 1 && !self.has_override(lib, hashes.0, hashes.1) => {
                 Err(Box::new(EvalAltResult::ErrorRuntime(
                     "'eval' should not be called in method style. Try eval(...);".into(),
                     Position::none(),
@@ -1926,7 +1928,7 @@ impl Engine {
                     let hash_fn =
                         calc_fn_hash(empty(), name, 1, once(TypeId::of::<ImmutableString>()));
 
-                    if !self.has_override(lib, (hash_fn, *hash)) {
+                    if !self.has_override(lib, hash_fn, *hash) {
                         // Fn - only in function call style
                         let expr = args_expr.get(0);
                         let arg_value =
@@ -1952,7 +1954,7 @@ impl Engine {
                     let hash_fn =
                         calc_fn_hash(empty(), name, 1, once(TypeId::of::<ImmutableString>()));
 
-                    if !self.has_override(lib, (hash_fn, *hash)) {
+                    if !self.has_override(lib, hash_fn, *hash) {
                         // eval - only in function call style
                         let prev_len = scope.len();
                         let expr = args_expr.get(0);
@@ -1972,6 +1974,36 @@ impl Engine {
                     }
                 }
 
+                // Handle call() - Redirect function call
+                let redirected;
+                let mut name = name.as_ref();
+                let mut args_expr = args_expr.as_ref();
+                let mut hash = *hash;
+
+                if name == KEYWORD_FN_PTR_CALL
+                    && args_expr.len() >= 1
+                    && !self.has_override(lib, 0, hash)
+                {
+                    let expr = args_expr.get(0).unwrap();
+                    let fn_ptr = self.eval_expr(scope, mods, state, lib, this_ptr, expr, level)?;
+
+                    if fn_ptr.is::<FnPtr>() {
+                        // Redirect function name
+                        redirected = Some(fn_ptr.cast::<FnPtr>().take_fn_name());
+                        name = redirected.as_ref().unwrap();
+                        // Skip the first argument
+                        args_expr = &args_expr.as_ref()[1..];
+                        // Recalculate hash
+                        hash = calc_fn_hash(empty(), name, args_expr.len(), empty());
+                    } else {
+                        return Err(Box::new(EvalAltResult::ErrorMismatchOutputType(
+                            self.map_type_name(type_name::<FnPtr>()).into(),
+                            fn_ptr.type_name().into(),
+                            expr.position(),
+                        )));
+                    }
+                }
+
                 // Normal function call - except for Fn and eval (handled above)
                 let mut arg_values: StaticVec<Dynamic>;
                 let mut args: StaticVec<_>;
@@ -1983,7 +2015,7 @@ impl Engine {
                 } else {
                     // See if the first argument is a variable, if so, convert to method-call style
                     // in order to leverage potential &mut first argument and avoid cloning the value
-                    match args_expr.get(0) {
+                    match args_expr.get(0).unwrap() {
                         // func(x, ...) -> x.func(...)
                         lhs @ Expr::Variable(_) => {
                             arg_values = args_expr
@@ -2020,7 +2052,7 @@ impl Engine {
 
                 let args = args.as_mut();
                 self.exec_fn_call(
-                    state, lib, name, *native, *hash, args, is_ref, false, def_val, level,
+                    state, lib, name, *native, hash, args, is_ref, false, def_val, level,
                 )
                 .map(|(v, _)| v)
                 .map_err(|err| err.new_position(*pos))

src/parser.rs

@@ -7,7 +7,7 @@ use crate::error::{LexError, ParseError, ParseErrorType};
 use crate::module::{Module, ModuleRef};
 use crate::optimize::{optimize_into_ast, OptimizationLevel};
 use crate::scope::{EntryType as ScopeEntryType, Scope};
-use crate::token::{Position, Token, TokenStream};
+use crate::token::{is_valid_identifier, Position, Token, TokenStream};
 use crate::utils::{StaticVec, StraightHasherBuilder};
 
 #[cfg(feature = "internals")]
@@ -440,6 +440,8 @@ struct ParseSettings {
     pos: Position,
     /// Is the construct being parsed located at global level?
     is_global: bool,
+    /// Is the construct being parsed located at function definition level?
+    is_function_scope: bool,
     /// Is the current position inside a loop?
     is_breakable: bool,
     /// Is anonymous function allowed?
@@ -1460,6 +1462,21 @@ fn parse_primary(
             let index = state.find_var(&s);
             Expr::Variable(Box::new(((s, settings.pos), None, 0, index)))
         }
+        // Function call is allowed to have reserved keyword
+        Token::Reserved(s) if s != KEYWORD_THIS && input.peek().unwrap().0 == Token::LeftParen => {
+            Expr::Variable(Box::new(((s, settings.pos), None, 0, None)))
+        }
+        // Access to `this` as a variable is OK
+        Token::Reserved(s) if s == KEYWORD_THIS && input.peek().unwrap().0 != Token::LeftParen => {
+            if !settings.is_function_scope {
+                return Err(
+                    PERR::BadInput(format!("'{}' can only be used in functions", s))
+                        .into_err(settings.pos),
+                );
+            } else {
+                Expr::Variable(Box::new(((s, settings.pos), None, 0, None)))
+            }
+        }
         Token::LeftParen => parse_paren_expr(input, state, lib, settings.level_up())?,
         #[cfg(not(feature = "no_index"))]
         Token::LeftBracket => parse_array_literal(input, state, lib, settings.level_up())?,
@@ -1538,6 +1555,7 @@ fn parse_primary(
         _ => (),
     }
 
+    // Make sure identifiers are valid
     Ok(root_expr)
 }
 
@@ -2315,16 +2333,6 @@ fn parse_let(
         (_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
     };
 
-    // Check if the name is allowed
-    match name.as_str() {
-        KEYWORD_THIS => {
-            return Err(
-                PERR::BadInput(LexError::MalformedIdentifier(name).to_string()).into_err(pos),
-            )
-        }
-        _ => (),
-    }
-
     // let name = ...
     if match_token(input, Token::Equals)? {
         // let name = expr
@@ -2598,6 +2606,7 @@ fn parse_stmt(
                         allow_stmt_expr: true,
                         allow_anonymous_fn: true,
                         is_global: false,
+                        is_function_scope: true,
                         is_breakable: false,
                         level: 0,
                         pos: pos,
@@ -2695,7 +2704,11 @@ fn parse_fn(
     settings.ensure_level_within_max_limit(state.max_expr_depth)?;
 
     let name = match input.next().unwrap() {
-        (Token::Identifier(s), _) | (Token::Custom(s), _) => s,
+        (Token::Identifier(s), _) | (Token::Custom(s), _) | (Token::Reserved(s), _)
+            if s != KEYWORD_THIS && is_valid_identifier(s.chars()) =>
+        {
+            s
+        }
         (_, pos) => return Err(PERR::FnMissingName.into_err(pos)),
     };
 
@@ -2790,6 +2803,7 @@ impl Engine {
             allow_stmt_expr: false,
             allow_anonymous_fn: false,
             is_global: true,
+            is_function_scope: false,
             is_breakable: false,
             level: 0,
             pos: Position::none(),
@@ -2829,6 +2843,7 @@ impl Engine {
                 allow_stmt_expr: true,
                 allow_anonymous_fn: true,
                 is_global: true,
+                is_function_scope: false,
                 is_breakable: false,
                 level: 0,
                 pos: Position::none(),

src/token.rs

@@ -1,6 +1,10 @@
 //! Main module defining the lexer and parser.
 
-use crate::engine::Engine;
+use crate::engine::{
+    Engine, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_FN_PTR_CALL, KEYWORD_PRINT,
+    KEYWORD_THIS, KEYWORD_TYPE_OF,
+};
+
 use crate::error::LexError;
 use crate::parser::INT;
 use crate::utils::StaticVec;
@@ -388,6 +392,8 @@ impl Token {
             "===" | "!==" | "->" | "<-" | "=>" | ":=" | "::<" | "(*" | "*)" | "#" => {
                 Reserved(syntax.into())
             }
+            KEYWORD_PRINT | KEYWORD_DEBUG | KEYWORD_TYPE_OF | KEYWORD_EVAL | KEYWORD_FN_PTR
+            | KEYWORD_FN_PTR_CALL | KEYWORD_THIS => Reserved(syntax.into()),
 
             _ => return None,
         })
@@ -1353,9 +1359,10 @@ impl<'a> Iterator for TokenIterator<'a, '_> {
                     "'#' is not a valid symbol. Should it be '#{'?"
                         .to_string(),
                 ))),
-                token => Token::LexError(Box::new(LERR::ImproperSymbol(
+                token if !is_valid_identifier(token.chars()) => Token::LexError(Box::new(LERR::ImproperSymbol(
-                    format!("'{}' is not a valid symbol.", token)
+                    format!("'{}' is a reserved symbol.", token)
                 ))),
+                _ => Token::Reserved(s)
             }, pos)),
             (r @ Some(_), None, None) => r,
             (Some((Token::Identifier(s), pos)), _, Some(custom)) if custom.contains_key(&s) => {

tests/functions.rs

@@ -52,12 +52,24 @@ fn test_functions() -> Result<(), Box<EvalAltResult>> {
 }
 
 #[test]
-#[cfg(not(feature = "no_object"))]
 fn test_function_pointers() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
 
     assert_eq!(engine.eval::<String>(r#"type_of(Fn("abc"))"#)?, "Fn");
 
+    assert_eq!(
+        engine.eval::<INT>(
+            r#"
+                fn foo(x) { 40 + x }
+
+                let f = Fn("foo");
+                call(f, 2)
+            "#
+        )?,
+        42
+    );
+
+    #[cfg(not(feature = "no_object"))]
     assert_eq!(
         engine.eval::<INT>(
             r#"
@@ -73,11 +85,13 @@ fn test_function_pointers() -> Result<(), Box<EvalAltResult>> {
         42
     );
 
+    #[cfg(not(feature = "no_object"))]
     assert!(matches!(
         *engine.eval::<INT>(r#"let f = Fn("abc"); f.call(0)"#).expect_err("should error"),
         EvalAltResult::ErrorFunctionNotFound(f, _) if f.starts_with("abc (")
     ));
 
+    #[cfg(not(feature = "no_object"))]
     assert_eq!(
         engine.eval::<INT>(
             r#"