Support for trailing commas.

README.md

@@ -1607,6 +1607,8 @@ The following methods (mostly defined in the [`BasicArrayPackage`](#packages) bu
 ```rust
 let y = [2, 3];         // array literal with 2 elements
 
+let y = [2, 3,];        // trailing comma is OK
+
 y.insert(0, 1);         // insert element at the beginning
 y.insert(999, 4);       // insert element at the end
 
@@ -1751,6 +1753,8 @@ ts.obj = y;             // object maps can be assigned completely (by value copy
 let foo = ts.list.a;
 foo == 42;
 
+let foo = #{ a:1,};     // trailing comma is OK
+
 let foo = #{ a:1, b:2, c:3 }["a"];
 foo == 1;
 
@@ -2115,7 +2119,12 @@ fn add(x, y) {
     return x + y;
 }
 
-print(add(2, 3));
+fn sub(x, y,) {             // trailing comma in parameters list is OK
+    return x - y;
+}
+
+print(add(2, 3));           // prints 5
+print(sub(2, 3,));          // prints -1 - trailing comma in arguments list is OK
 ```
 
 ### Implicit return

RELEASES.md

@@ -22,6 +22,7 @@ New features
 * Indexers are now split into getters and setters (which now support updates).  The API is split into `Engine::register_indexer_get` and `Engine::register_indexer_set` with `Engine::register_indexer_get_set` being a shorthand.  Similarly, `Module::set_indexer_get_fn` and `Module::set_indexer_set_fn` are added.
 * `Engine:register_fn` and `Engine:register_result_fn` accepts functions that take parameters of type `&str` (immutable string slice), which maps directly to `ImmutableString`. This is to avoid needing wrappers for functions taking string parameters.
 * Set maximum limit on data sizes: `Engine::set_max_string_size`, `Engine::set_max_array_size` and `Engine::set_max_map_size`.
+* Supports trailing commas on array literals, object map literals, function definitions and function calls.
 
 
 Version 0.15.0

src/fn_native.rs

@@ -126,7 +126,7 @@ impl CallableFunction {
     pub fn get_native_fn(&self) -> &FnAny {
         match self {
             Self::Pure(f) | Self::Method(f) => f.as_ref(),
-            Self::Iterator(_) | Self::Script(_) => panic!(),
+            Self::Iterator(_) | Self::Script(_) => unreachable!(),
         }
     }
     /// Get a shared reference to a script-defined function definition.
@@ -136,7 +136,7 @@ impl CallableFunction {
     /// Panics if the `CallableFunction` is not `Script`.
     pub fn get_shared_fn_def(&self) -> Shared<ScriptFnDef> {
         match self {
-            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => panic!(),
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => unreachable!(),
             Self::Script(f) => f.clone(),
         }
     }
@@ -147,7 +147,7 @@ impl CallableFunction {
     /// Panics if the `CallableFunction` is not `Script`.
     pub fn get_fn_def(&self) -> &ScriptFnDef {
         match self {
-            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => panic!(),
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => unreachable!(),
             Self::Script(f) => f,
         }
     }
@@ -159,7 +159,7 @@ impl CallableFunction {
     pub fn get_iter_fn(&self) -> IteratorFn {
         match self {
             Self::Iterator(f) => *f,
-            Self::Pure(_) | Self::Method(_) | Self::Script(_) => panic!(),
+            Self::Pure(_) | Self::Method(_) | Self::Script(_) => unreachable!(),
         }
     }
     /// Create a new `CallableFunction::Pure`.

src/parser.rs

@@ -518,7 +518,7 @@ impl Expr {
                 )))
             }
 
-            _ => panic!("cannot get value of non-constant expression"),
+            _ => unreachable!("cannot get value of non-constant expression"),
         }
     }
 
@@ -543,7 +543,7 @@ impl Expr {
 
             Self::Array(x) if x.0.iter().all(Self::is_constant) => "array".to_string(),
 
-            _ => panic!("cannot get value of non-constant expression"),
+            _ => unreachable!("cannot get value of non-constant expression"),
         }
     }
 
@@ -728,7 +728,7 @@ fn eat_token(input: &mut TokenStream, token: Token) -> Position {
     let (t, pos) = input.next().unwrap();
 
     if t != token {
-        panic!(
+        unreachable!(
             "expecting {} (found {}) at {}",
             token.syntax(),
             t.syntax(),
@@ -836,7 +836,11 @@ fn parse_call_expr(
     let settings = settings.level_up();
 
     loop {
-        args.push(parse_expr(input, state, settings)?);
+        match input.peek().unwrap() {
+            // id(...args, ) - handle trailing comma
+            (Token::RightParen, _) => (),
+            _ => args.push(parse_expr(input, state, settings)?),
+        }
 
         match input.peek().unwrap() {
             // id(...args)
@@ -1082,7 +1086,6 @@ fn parse_array_literal(
 
     let mut arr = StaticVec::new();
 
-    if !match_token(input, Token::RightBracket)? {
     while !input.peek().unwrap().0.is_eof() {
         if state.max_array_size > 0 && arr.len() >= state.max_array_size {
             return Err(PERR::LiteralTooLarge(
@@ -1092,15 +1095,22 @@ fn parse_array_literal(
             .into_err(input.peek().unwrap().1));
         }
 
-            let expr = parse_expr(input, state, settings.level_up())?;
-            arr.push(expr);
-
         match input.peek().unwrap() {
-                (Token::Comma, _) => eat_token(input, Token::Comma),
             (Token::RightBracket, _) => {
                 eat_token(input, Token::RightBracket);
                 break;
             }
+            _ => {
+                let expr = parse_expr(input, state, settings.level_up())?;
+                arr.push(expr);
+            }
+        }
+
+        match input.peek().unwrap() {
+            (Token::Comma, _) => {
+                eat_token(input, Token::Comma);
+            }
+            (Token::RightBracket, _) => (),
             (Token::EOF, pos) => {
                 return Err(PERR::MissingToken(
                     Token::RightBracket.into(),
@@ -1118,7 +1128,6 @@ fn parse_array_literal(
             }
         };
     }
-    }
 
     Ok(Expr::Array(Box::new((arr, settings.pos))))
 }
@@ -1133,25 +1142,32 @@ fn parse_map_literal(
 
     let mut map = StaticVec::new();
 
-    if !match_token(input, Token::RightBrace)? {
     while !input.peek().unwrap().0.is_eof() {
         const MISSING_RBRACE: &str = "to end this object map literal";
 
+        match input.peek().unwrap() {
+            (Token::RightBrace, _) => {
+                eat_token(input, Token::RightBrace);
+                break;
+            }
+            _ => {
                 let (name, pos) = match input.next().unwrap() {
                     (Token::Identifier(s), pos) => (s, pos),
                     (Token::StringConst(s), pos) => (s, pos),
                     (Token::LexError(err), pos) => return Err(err.into_err(pos)),
                     (_, pos) if map.is_empty() => {
-                    return Err(
+                        return Err(PERR::MissingToken(
-                        PERR::MissingToken(Token::RightBrace.into(), MISSING_RBRACE.into())
+                            Token::RightBrace.into(),
-                            .into_err(pos),
+                            MISSING_RBRACE.into(),
                         )
+                        .into_err(pos))
                     }
                     (Token::EOF, pos) => {
-                    return Err(
+                        return Err(PERR::MissingToken(
-                        PERR::MissingToken(Token::RightBrace.into(), MISSING_RBRACE.into())
+                            Token::RightBrace.into(),
-                            .into_err(pos),
+                            MISSING_RBRACE.into(),
                         )
+                        .into_err(pos))
                     }
                     (_, pos) => return Err(PERR::PropertyExpected.into_err(pos)),
                 };
@@ -1181,15 +1197,14 @@ fn parse_map_literal(
 
                 let expr = parse_expr(input, state, settings.level_up())?;
                 map.push(((name, pos), expr));
+            }
+        }
 
         match input.peek().unwrap() {
             (Token::Comma, _) => {
                 eat_token(input, Token::Comma);
             }
-                (Token::RightBrace, _) => {
+            (Token::RightBrace, _) => (),
-                    eat_token(input, Token::RightBrace);
-                    break;
-                }
             (Token::Identifier(_), pos) => {
                 return Err(PERR::MissingToken(
                     Token::Comma.into(),
@@ -1206,7 +1221,6 @@ fn parse_map_literal(
             }
         }
     }
-    }
 
     // Check for duplicating properties
     map.iter()
@@ -1309,7 +1323,7 @@ fn parse_primary(
                 parse_index_chain(input, state, expr, settings.level_up())?
             }
             // Unknown postfix operator
-            (expr, token) => panic!(
+            (expr, token) => unreachable!(
                 "unknown postfix operator '{}' for {:?}",
                 token.syntax(),
                 expr
@@ -2290,7 +2304,7 @@ fn parse_stmt(
             let return_type = match input.next().unwrap() {
                 (Token::Return, _) => ReturnType::Return,
                 (Token::Throw, _) => ReturnType::Exception,
-                _ => panic!("token should be return or throw"),
+                _ => unreachable!(),
             };
 
             match input.peek().unwrap() {
@@ -2356,15 +2370,20 @@ fn parse_fn(
         let sep_err = format!("to separate the parameters of function '{}'", name);
 
         loop {
-            match input.next().unwrap() {
+            match input.peek().unwrap() {
+                (Token::RightParen, _) => (),
+                _ => match input.next().unwrap() {
                     (Token::Identifier(s), pos) => {
                         state.push((s.clone(), ScopeEntryType::Normal));
                         params.push((s, pos))
                     }
                     (Token::LexError(err), pos) => return Err(err.into_err(pos)),
                     (_, pos) => {
-                    return Err(PERR::MissingToken(Token::RightParen.into(), end_err).into_err(pos))
+                        return Err(
+                            PERR::MissingToken(Token::RightParen.into(), end_err).into_err(pos)
+                        )
                     }
+                },
             }
 
             match input.next().unwrap() {

src/scope.rs

@@ -417,7 +417,7 @@ impl<'a> Scope<'a> {
     pub fn set_value<T: Variant + Clone>(&mut self, name: &'a str, value: T) {
         match self.get_index(name) {
             None => self.push(name, value),
-            Some((_, EntryType::Constant)) => panic!("variable {} is constant", name),
+            Some((_, EntryType::Constant)) => unreachable!("variable {} is constant", name),
             Some((index, EntryType::Normal)) => {
                 self.0.get_mut(index).unwrap().value = Dynamic::from(value)
             }

src/token.rs

@@ -294,7 +294,7 @@ impl Token {
                 Export => "export",
                 As => "as",
                 EOF => "{EOF}",
-                _ => panic!("operator should be match in outer scope"),
+                _ => unreachable!("operator should be match in outer scope"),
             })
             .into(),
         }
@@ -548,7 +548,7 @@ impl<'a> TokenIterator<'a> {
                         'x' => 2,
                         'u' => 4,
                         'U' => 8,
-                        _ => panic!("should be 'x', 'u' or 'U'"),
+                        _ => unreachable!(),
                     };
 
                     for _ in 0..len {
@@ -667,14 +667,14 @@ impl<'a> TokenIterator<'a> {
                                         '0', '1', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_',
                                         '_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_',
                                     ],
-                                    _ => panic!("unexpected character {}", ch),
+                                    _ => unreachable!(),
                                 };
 
                                 radix_base = Some(match ch {
                                     'x' | 'X' => 16,
                                     'o' | 'O' => 8,
                                     'b' | 'B' => 2,
-                                    _ => panic!("unexpected character {}", ch),
+                                    _ => unreachable!(),
                                 });
 
                                 while let Some(next_char_in_hex) = self.peek_next() {
@@ -1077,7 +1077,7 @@ impl<'a> TokenIterator<'a> {
                 }
                 ('~', _) => return Some((Token::PowerOf, pos)),
 
-                ('\0', _) => panic!("should not be EOF"),
+                ('\0', _) => unreachable!(),
 
                 (ch, _) if ch.is_whitespace() => (),
                 (ch, _) => return Some((Token::LexError(Box::new(LERR::UnexpectedChar(ch))), pos)),

tests/arrays.rs

@@ -6,6 +6,7 @@ fn test_arrays() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
 
     assert_eq!(engine.eval::<INT>("let x = [1, 2, 3]; x[1]")?, 2);
+    assert_eq!(engine.eval::<INT>("let x = [1, 2, 3,]; x[1]")?, 2);
     assert_eq!(engine.eval::<INT>("let y = [1, 2, 3]; y[1] = 5; y[1]")?, 5);
     assert_eq!(
         engine.eval::<char>(r#"let y = [1, [ 42, 88, "93" ], 3]; y[1][2][1]"#)?,

tests/call_fn.rs

@@ -68,7 +68,7 @@ fn test_call_fn_private() -> Result<(), Box<EvalAltResult>> {
     let r: INT = engine.call_fn(&mut scope, &ast, "add", (40 as INT, 2 as INT))?;
     assert_eq!(r, 42);
 
-    let ast = engine.compile("private fn add(x, n) { x + n }")?;
+    let ast = engine.compile("private fn add(x, n, ) { x + n }")?;
 
     assert!(matches!(
         *engine.call_fn::<_, INT>(&mut scope, &ast, "add", (40 as INT, 2 as INT))
@@ -83,7 +83,7 @@ fn test_call_fn_private() -> Result<(), Box<EvalAltResult>> {
 fn test_anonymous_fn() -> Result<(), Box<EvalAltResult>> {
     let calc_func = Func::<(INT, INT, INT), INT>::create_from_script(
         Engine::new(),
-        "fn calc(x, y, z) { (x + y) * z }",
+        "fn calc(x, y, z,) { (x + y) * z }",
         "calc",
     )?;
 

tests/functions.rs

@@ -7,6 +7,11 @@ fn test_functions() -> Result<(), Box<EvalAltResult>> {
 
     assert_eq!(engine.eval::<INT>("fn add(x, n) { x + n } add(40, 2)")?, 42);
 
+    assert_eq!(
+        engine.eval::<INT>("fn add(x, n,) { x + n } add(40, 2,)")?,
+        42
+    );
+
     assert_eq!(
         engine.eval::<INT>("fn add(x, n) { x + n } let a = 40; add(a, 2); a")?,
         40

tests/internal_fn.rs

@@ -10,6 +10,12 @@ fn test_internal_fn() -> Result<(), Box<EvalAltResult>> {
         engine.eval::<INT>("fn add_me(a, b) { a+b } add_me(3, 4)")?,
         7
     );
+
+    assert_eq!(
+        engine.eval::<INT>("fn add_me(a, b,) { a+b } add_me(3, 4,)")?,
+        7
+    );
+
     assert_eq!(engine.eval::<INT>("fn bob() { return 4; 5 } bob()")?, 4);
 
     Ok(())

tests/maps.rs

@@ -12,6 +12,10 @@ fn test_map_indexing() -> Result<(), Box<EvalAltResult>> {
             engine.eval::<INT>(r#"let x = #{a: 1, b: 2, c: 3}; x["b"]"#)?,
             2
         );
+        assert_eq!(
+            engine.eval::<INT>(r#"let x = #{a: 1, b: 2, c: 3,}; x["b"]"#)?,
+            2
+        );
         assert_eq!(
             engine.eval::<char>(
                 r#"