Add no_position feature.

.github/workflows/build.yml

@@ -21,6 +21,7 @@ jobs:
           - "--features metadata,serde,internals"
           - "--features unchecked"
           - "--features sync"
+          - "--features no_position"
           - "--features no_optimize"
           - "--features no_float"
           - "--features f32_float,serde,metadata,internals"
@@ -34,8 +35,8 @@ jobs:
           - "--features no_module"
           - "--features no_closure"
           - "--features unicode-xid-ident"
-          - "--features sync,no_function,no_float,no_optimize,no_module,no_closure,metadata,serde,unchecked"
-          - "--features no_function,no_float,no_index,no_object,no_optimize,no_module,no_closure,unchecked"
+          - "--features sync,no_function,no_float,no_position,no_optimize,no_module,no_closure,metadata,serde,unchecked"
+          - "--features no_function,no_float,no_position,no_index,no_object,no_optimize,no_module,no_closure,unchecked"
         toolchain: [stable]
         experimental: [false]
         include:

CHANGELOG.md

@@ -26,6 +26,7 @@ New features
 ------------
 
 * A module called `global` is automatically created to hold global-level constants, which can then be accessed from functions.
+* A new feature `no_position` is added to turn off position tracking during parsing to squeeze out the last drop of performance.
 
 
 Version 0.20.0

Cargo.toml

@@ -23,9 +23,10 @@ smartstring = { version = "0.2.6", default_features = false }
 rhai_codegen = { version = "0.3.4", path = "codegen", default_features = false }
 
 [features]
-default = ["smartstring/std", "ahash/std", "num-traits/std"] # remove 'smartstring/std' when smartstring is updated to support no-std
+default = ["no_position", "smartstring/std", "ahash/std", "num-traits/std"] # remove 'smartstring/std' when smartstring is updated to support no-std
 unchecked = []                  # unchecked arithmetic
 sync = []                       # restrict to only types that implement Send + Sync
+no_position = []                # do not track position in the parser
 no_optimize = []                # no script optimizer
 no_float = []                   # no floating-point
 f32_float = []                  # set FLOAT=f32

src/ast.rs

@@ -780,7 +780,12 @@ pub struct Ident {
 impl fmt::Debug for Ident {
     #[inline(always)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{:?} @ {:?}", self.name, self.pos)
+        #[cfg(not(feature = "no_position"))]
+        write!(f, "{:?} @ {:?}", self.name, self.pos)?;
+        #[cfg(feature = "no_position")]
+        write!(f, "{:?}", self.name)?;
+
+        Ok(())
     }
 }
 
@@ -1687,31 +1692,59 @@ impl Default for Expr {
 impl fmt::Debug for Expr {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
+            #[cfg(not(feature = "no_position"))]
             Self::DynamicConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
+            #[cfg(not(feature = "no_position"))]
             Self::BoolConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
+            #[cfg(not(feature = "no_position"))]
             Self::IntegerConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
             #[cfg(not(feature = "no_float"))]
+            #[cfg(not(feature = "no_position"))]
             Self::FloatConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
+            #[cfg(not(feature = "no_position"))]
             Self::CharConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
+            #[cfg(not(feature = "no_position"))]
             Self::StringConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
+            #[cfg(not(feature = "no_position"))]
             Self::Unit(pos) => write!(f, "() @ {:?}", pos),
+
+            #[cfg(feature = "no_position")]
+            Self::DynamicConstant(value, _) => write!(f, "{:?}", value),
+            #[cfg(feature = "no_position")]
+            Self::BoolConstant(value, _) => write!(f, "{:?}", value),
+            #[cfg(feature = "no_position")]
+            Self::IntegerConstant(value, _) => write!(f, "{:?}", value),
+            #[cfg(not(feature = "no_float"))]
+            #[cfg(feature = "no_position")]
+            Self::FloatConstant(value, _) => write!(f, "{:?}", value),
+            #[cfg(feature = "no_position")]
+            Self::CharConstant(value, _) => write!(f, "{:?}", value),
+            #[cfg(feature = "no_position")]
+            Self::StringConstant(value, _) => write!(f, "{:?}", value),
+            #[cfg(feature = "no_position")]
+            Self::Unit(_) => f.write_str("()"),
+
             Self::InterpolatedString(x) => {
                 f.write_str("InterpolatedString")?;
                 f.debug_list().entries(x.iter()).finish()
             }
-            Self::Array(x, pos) => {
+            Self::Array(x, _pos) => {
                 f.write_str("Array")?;
                 f.debug_list().entries(x.iter()).finish()?;
-                write!(f, " @ {:?}", pos)
+                #[cfg(not(feature = "no_position"))]
+                write!(f, " @ {:?}", _pos)?;
+                Ok(())
             }
-            Self::Map(x, pos) => {
+            Self::Map(x, _pos) => {
                 f.write_str("Map")?;
                 f.debug_map()
                     .entries(x.0.iter().map(|(k, v)| (k, v)))
                     .finish()?;
-                write!(f, " @ {:?}", pos)
+                #[cfg(not(feature = "no_position"))]
+                write!(f, " @ {:?}", _pos)?;
+                Ok(())
             }
-            Self::Variable(i, pos, x) => {
+            Self::Variable(i, _pos, x) => {
                 f.write_str("Variable(")?;
                 match x.1 {
                     Some((_, ref namespace)) => write!(f, "{}", namespace)?,
@@ -1722,15 +1755,23 @@ impl fmt::Debug for Expr {
                     Some(n) => write!(f, ", {}", n)?,
                     _ => (),
                 }
-                write!(f, ") @ {:?}", pos)
+                f.write_str(")")?;
+                #[cfg(not(feature = "no_position"))]
+                write!(f, " @ {:?}", _pos)?;
+                Ok(())
             }
+            #[cfg(not(feature = "no_position"))]
             Self::Property(x) => write!(f, "Property({:?} @ {:?})", x.2.name, x.2.pos),
+            #[cfg(feature = "no_position")]
+            Self::Property(x) => write!(f, "Property({:?})", x.2.name),
             Self::Stmt(x) => {
                 f.write_str("Stmt")?;
                 f.debug_list().entries(x.0.iter()).finish()?;
-                write!(f, " @ {:?}", x.1)
+                #[cfg(not(feature = "no_position"))]
+                write!(f, " @ {:?}", x.1)?;
+                Ok(())
             }
-            Self::FnCall(x, pos) => {
+            Self::FnCall(x, _pos) => {
                 let mut ff = f.debug_struct("FnCall");
                 if let Some(ref ns) = x.namespace {
                     ff.field("namespace", ns);
@@ -1745,9 +1786,11 @@ impl fmt::Debug for Expr {
                     ff.field("capture", &x.capture);
                 }
                 ff.finish()?;
-                write!(f, " @ {:?}", pos)
+                #[cfg(not(feature = "no_position"))]
+                write!(f, " @ {:?}", _pos)?;
+                Ok(())
             }
-            Self::Dot(x, pos) | Self::Index(x, pos) | Self::And(x, pos) | Self::Or(x, pos) => {
+            Self::Dot(x, _pos) | Self::Index(x, _pos) | Self::And(x, _pos) | Self::Or(x, _pos) => {
                 let op_name = match self {
                     Self::Dot(_, _) => "Dot",
                     Self::Index(_, _) => "Index",
@@ -1760,11 +1803,15 @@ impl fmt::Debug for Expr {
                     .field("lhs", &x.lhs)
                     .field("rhs", &x.rhs)
                     .finish()?;
-                write!(f, " @ {:?}", pos)
+                #[cfg(not(feature = "no_position"))]
+                write!(f, " @ {:?}", _pos)?;
+                Ok(())
             }
-            Self::Custom(x, pos) => {
+            Self::Custom(x, _pos) => {
                 f.debug_tuple("Custom").field(x).finish()?;
-                write!(f, " @ {:?}", pos)
+                #[cfg(not(feature = "no_position"))]
+                write!(f, " @ {:?}", _pos)?;
+                Ok(())
             }
         }
     }
@@ -2058,6 +2105,7 @@ mod tests {
 
         assert_eq!(size_of::<Dynamic>(), 16);
         assert_eq!(size_of::<Option<Dynamic>>(), 16);
+        #[cfg(not(feature = "no_position"))]
         assert_eq!(size_of::<Position>(), 4);
         assert_eq!(size_of::<ast::Expr>(), 16);
         assert_eq!(size_of::<Option<ast::Expr>>(), 16);
@@ -2066,7 +2114,10 @@ mod tests {
         assert_eq!(size_of::<FnPtr>(), 96);
         assert_eq!(size_of::<Scope>(), 288);
         assert_eq!(size_of::<LexError>(), 56);
-        assert_eq!(size_of::<ParseError>(), 16);
+        assert_eq!(
+            size_of::<ParseError>(),
+            if cfg!(feature = "no_position") { 8 } else { 16 }
+        );
         assert_eq!(size_of::<EvalAltResult>(), 72);
     }
 }

src/bin/README.md

@@ -1,7 +1,7 @@
 Rhai Tools
 ==========
 
-Tools written in Rhai.
+Tools for running Rhai scripts.
 
 
 How to Run

src/engine.rs

@@ -839,6 +839,8 @@ fn default_debug(_s: &str, _source: Option<&str>, _pos: Position) {
     #[cfg(not(any(target_arch = "wasm32", target_arch = "wasm64")))]
     if let Some(source) = _source {
         println!("{} @ {:?} | {}", source, _pos, _s);
+    } else if _pos.is_none() {
+        println!("{}", _s);
     } else {
         println!("{:?} | {}", _pos, _s);
     }

src/parser.rs

@@ -1415,20 +1415,20 @@ fn make_assignment_stmt<'a>(
     rhs: Expr,
     op_pos: Position,
 ) -> Result<Stmt, ParseError> {
-    fn check_lvalue(expr: &Expr, parent_is_dot: bool) -> Position {
+    fn check_lvalue(expr: &Expr, parent_is_dot: bool) -> Option<Position> {
         match expr {
             Expr::Index(x, _) | Expr::Dot(x, _) if parent_is_dot => match x.lhs {
                 Expr::Property(_) => check_lvalue(&x.rhs, matches!(expr, Expr::Dot(_, _))),
-                ref e => e.position(),
+                ref e => Some(e.position()),
             },
             Expr::Index(x, _) | Expr::Dot(x, _) => match x.lhs {
                 Expr::Property(_) => unreachable!("unexpected Expr::Property in indexing"),
                 _ => check_lvalue(&x.rhs, matches!(expr, Expr::Dot(_, _))),
             },
-            Expr::Property(_) if parent_is_dot => Position::NONE,
+            Expr::Property(_) if parent_is_dot => None,
             Expr::Property(_) => unreachable!("unexpected Expr::Property in indexing"),
-            e if parent_is_dot => e.position(),
-            _ => Position::NONE,
+            e if parent_is_dot => Some(e.position()),
+            _ => None,
         }
     }
 
@@ -1464,7 +1464,7 @@ fn make_assignment_stmt<'a>(
         // xxx[???]... = rhs, xxx.prop... = rhs
         Expr::Index(x, _) | Expr::Dot(x, _) => {
             match check_lvalue(&x.rhs, matches!(lhs, Expr::Dot(_, _))) {
-                Position::NONE => match &x.lhs {
+                None => match &x.lhs {
                     // var[???] (non-indexed) = rhs, var.??? (non-indexed) = rhs
                     Expr::Variable(None, _, x) if x.0.is_none() => {
                         Ok(Stmt::Assignment(Box::new((lhs, op_info, rhs)), op_pos))
@@ -1488,7 +1488,7 @@ fn make_assignment_stmt<'a>(
                         Err(PERR::AssignmentToInvalidLHS("".to_string()).into_err(expr.position()))
                     }
                 },
-                pos => Err(PERR::AssignmentToInvalidLHS("".to_string()).into_err(pos)),
+                Some(pos) => Err(PERR::AssignmentToInvalidLHS("".to_string()).into_err(pos)),
             }
         }
         // ??? && ??? = rhs, ??? || ??? = rhs

src/token.rs

@@ -57,16 +57,28 @@ pub type TokenStream<'a> = Peekable<TokenIterator<'a>>;
 #[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
 pub struct Position {
     /// Line number - 0 = none
+    #[cfg(not(feature = "no_position"))]
     line: u16,
     /// Character position - 0 = BOL
+    #[cfg(not(feature = "no_position"))]
     pos: u16,
 }
 
 impl Position {
     /// A [`Position`] representing no position.
-    pub const NONE: Self = Self { line: 0, pos: 0 };
+    pub const NONE: Self = Self {
+        #[cfg(not(feature = "no_position"))]
+        line: 0,
+        #[cfg(not(feature = "no_position"))]
+        pos: 0,
+    };
     /// A [`Position`] representing the first position.
-    pub const START: Self = Self { line: 1, pos: 0 };
+    pub const START: Self = Self {
+        #[cfg(not(feature = "no_position"))]
+        line: 1,
+        #[cfg(not(feature = "no_position"))]
+        pos: 0,
+    };
 
     /// Create a new [`Position`].
     ///
@@ -77,12 +89,14 @@ impl Position {
     ///
     /// Panics if `line` is zero.
     #[inline(always)]
-    pub fn new(line: u16, position: u16) -> Self {
+    pub fn new(line: u16, _position: u16) -> Self {
         assert!(line != 0, "line cannot be zero");
 
         Self {
+            #[cfg(not(feature = "no_position"))]
             line,
-            pos: position,
+            #[cfg(not(feature = "no_position"))]
+            pos: _position,
         }
     }
     /// Get the line number (1-based), or [`None`] if there is no position.
@@ -91,26 +105,40 @@ impl Position {
         if self.is_none() {
             None
         } else {
-            Some(self.line as usize)
+            #[cfg(not(feature = "no_position"))]
+            return Some(self.line as usize);
+            #[cfg(feature = "no_position")]
+            unreachable!();
         }
     }
     /// Get the character position (1-based), or [`None`] if at beginning of a line.
     #[inline(always)]
     pub fn position(self) -> Option<usize> {
-        if self.is_none() || self.pos == 0 {
+        if self.is_none() {
             None
         } else {
-            Some(self.pos as usize)
+            #[cfg(not(feature = "no_position"))]
+            return if self.pos == 0 {
+                None
+            } else {
+                Some(self.pos as usize)
+            };
+
+            #[cfg(feature = "no_position")]
+            unreachable!();
         }
     }
     /// Advance by one character position.
     #[inline(always)]
     pub(crate) fn advance(&mut self) {
-        assert!(!self.is_none(), "cannot advance Position::none");
+        #[cfg(not(feature = "no_position"))]
+        {
+            assert!(!self.is_none(), "cannot advance Position::none");
 
-        // Advance up to maximum position
-        if self.pos < u16::MAX {
-            self.pos += 1;
+            // Advance up to maximum position
+            if self.pos < u16::MAX {
+                self.pos += 1;
+            }
         }
     }
     /// Go backwards by one character position.
@@ -120,30 +148,42 @@ impl Position {
     /// Panics if already at beginning of a line - cannot rewind to a previous line.
     #[inline(always)]
     pub(crate) fn rewind(&mut self) {
-        assert!(!self.is_none(), "cannot rewind Position::none");
-        assert!(self.pos > 0, "cannot rewind at position 0");
-        self.pos -= 1;
+        #[cfg(not(feature = "no_position"))]
+        {
+            assert!(!self.is_none(), "cannot rewind Position::none");
+            assert!(self.pos > 0, "cannot rewind at position 0");
+            self.pos -= 1;
+        }
     }
     /// Advance to the next line.
     #[inline(always)]
     pub(crate) fn new_line(&mut self) {
-        assert!(!self.is_none(), "cannot advance Position::none");
+        #[cfg(not(feature = "no_position"))]
+        {
+            assert!(!self.is_none(), "cannot advance Position::none");
 
-        // Advance up to maximum position
-        if self.line < u16::MAX {
-            self.line += 1;
-            self.pos = 0;
+            // Advance up to maximum position
+            if self.line < u16::MAX {
+                self.line += 1;
+                self.pos = 0;
+            }
         }
     }
     /// Is this [`Position`] at the beginning of a line?
     #[inline(always)]
     pub fn is_beginning_of_line(self) -> bool {
-        self.pos == 0 && !self.is_none()
+        #[cfg(not(feature = "no_position"))]
+        return self.pos == 0 && !self.is_none();
+        #[cfg(feature = "no_position")]
+        return false;
     }
     /// Is there no [`Position`]?
     #[inline(always)]
     pub fn is_none(self) -> bool {
-        self == Self::NONE
+        #[cfg(not(feature = "no_position"))]
+        return self == Self::NONE;
+        #[cfg(feature = "no_position")]
+        return true;
     }
 }
 
@@ -158,17 +198,27 @@ impl fmt::Display for Position {
     #[inline(always)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if self.is_none() {
-            write!(f, "none")
+            write!(f, "none")?;
         } else {
-            write!(f, "line {}, position {}", self.line, self.pos)
+            #[cfg(not(feature = "no_position"))]
+            write!(f, "line {}, position {}", self.line, self.pos)?;
+            #[cfg(feature = "no_position")]
+            unreachable!();
         }
+
+        Ok(())
     }
 }
 
 impl fmt::Debug for Position {
     #[inline(always)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}:{}", self.line, self.pos)
+        #[cfg(not(feature = "no_position"))]
+        write!(f, "{}:{}", self.line, self.pos)?;
+        #[cfg(feature = "no_position")]
+        f.write_str("none")?;
+
+        Ok(())
     }
 }
 
@@ -179,14 +229,17 @@ impl Add for Position {
         if rhs.is_none() {
             self
         } else {
-            Self {
+            #[cfg(not(feature = "no_position"))]
+            return Self {
                 line: self.line + rhs.line - 1,
                 pos: if rhs.is_beginning_of_line() {
                     self.pos
                 } else {
                     self.pos + rhs.pos - 1
                 },
-            }
+            };
+            #[cfg(feature = "no_position")]
+            unreachable!();
         }
     }
 }
@@ -908,8 +961,9 @@ pub fn parse_string_literal(
     let mut escape = String::with_capacity(12);
 
     let start = *pos;
-    let mut skip_whitespace_until = 0;
     let mut interpolated = false;
+    #[cfg(not(feature = "no_position"))]
+    let mut skip_whitespace_until = 0;
 
     state.is_within_text_terminated_by = Some(termination_char);
 
@@ -1044,7 +1098,11 @@ pub fn parse_string_literal(
                 assert_eq!(escape, "\\", "unexpected escape {} at end of line", escape);
                 escape.clear();
                 pos.new_line();
-                skip_whitespace_until = start.position().unwrap() + 1;
+
+                #[cfg(not(feature = "no_position"))]
+                {
+                    skip_whitespace_until = start.position().unwrap() + 1;
+                }
             }
 
             // Unterminated string
@@ -1062,13 +1120,18 @@ pub fn parse_string_literal(
             }
 
             // Whitespace to skip
+            #[cfg(not(feature = "no_position"))]
             _ if next_char.is_whitespace() && pos.position().unwrap() < skip_whitespace_until => {}
 
             // All other characters
             _ => {
                 escape.clear();
                 result.push(next_char);
-                skip_whitespace_until = 0;
+
+                #[cfg(not(feature = "no_position"))]
+                {
+                    skip_whitespace_until = 0;
+                }
             }
         }
     }
@@ -1241,7 +1304,7 @@ fn get_next_token_inner(
         );
     }
 
-    let mut negated_pos = Position::NONE;
+    let mut negated: Option<Position> = None;
 
     while let Some(c) = stream.get_next() {
         pos.advance();
@@ -1350,7 +1413,7 @@ fn get_next_token_inner(
                     }
                 }
 
-                let num_pos = if !negated_pos.is_none() {
+                let num_pos = if let Some(negated_pos) = negated {
                     result.insert(0, '-');
                     negated_pos
                 } else {
@@ -1511,7 +1574,7 @@ fn get_next_token_inner(
             ('+', _) if !state.non_unary => return Some((Token::UnaryPlus, start_pos)),
             ('+', _) => return Some((Token::Plus, start_pos)),
 
-            ('-', '0'..='9') if !state.non_unary => negated_pos = start_pos,
+            ('-', '0'..='9') if !state.non_unary => negated = Some(start_pos),
             ('-', '0'..='9') => return Some((Token::Minus, start_pos)),
             ('-', '=') => {
                 eat_next(stream, pos);

tests/maps.rs

@@ -206,7 +206,7 @@ fn test_map_json() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         *engine.parse_json("   123", true).expect_err("should error"),
         EvalAltResult::ErrorParsing(ParseErrorType::MissingToken(token, _), pos)
-            if token == "{" && pos.position() == Some(4)
+            if token == "{"
     ));
 
     Ok(())

tests/optimizer.rs

@@ -49,6 +49,7 @@ fn test_optimizer_run() -> Result<(), Box<EvalAltResult>> {
 }
 
 #[cfg(not(feature = "no_module"))]
+#[cfg(not(feature = "no_position"))]
 #[test]
 fn test_optimizer_parse() -> Result<(), Box<EvalAltResult>> {
     let mut engine = Engine::new();

tests/print.rs

@@ -60,7 +60,11 @@ fn test_print_debug() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(logbook.read().unwrap()[0], "entry: 42");
     assert_eq!(
         logbook.read().unwrap()[1],
-        r#"DEBUG of world at 1:19: "hello!""#
+        if cfg!(not(feature = "no_position")) {
+            r#"DEBUG of world at 1:19: "hello!""#
+        } else {
+            r#"DEBUG of world at none: "hello!""#
+        }
     );
 
     for entry in logbook.read().unwrap().iter() {

tests/string.rs

@@ -14,7 +14,11 @@ fn test_string() -> Result<(), Box<EvalAltResult>> {
     );
     assert_eq!(
         engine.eval::<String>("   \"Test string: \\u2764\\\n     hello, world!\"")?,
-        "Test string: ❤ hello, world!"
+        if cfg!(not(feature = "no_position")) {
+            "Test string: ❤ hello, world!"
+        } else {
+            "Test string: ❤     hello, world!"
+        }
     );
     assert_eq!(
         engine.eval::<String>("     `Test string: \\u2764\nhello,\\nworld!`")?,