//! Module implementing custom syntax for [`Engine`].
use crate::ast::Expr;
use crate::engine::EvalContext;
use crate::fn_native::SendSync;
use crate::stdlib::{boxed::Box, format, string::ToString};
use crate::token::{is_valid_identifier, Token};
use crate::{
Engine, Identifier, ImmutableString, LexError, ParseError, Position, RhaiResult, Shared,
StaticVec,
};
pub const MARKER_EXPR: &str = "$expr$";
pub const MARKER_BLOCK: &str = "$block$";
pub const MARKER_IDENT: &str = "$ident$";
/// A general expression evaluation trait object.
#[cfg(not(feature = "sync"))]
pub type FnCustomSyntaxEval = dyn Fn(&mut EvalContext, &[Expression]) -> RhaiResult;
/// A general expression evaluation trait object.
#[cfg(feature = "sync")]
pub type FnCustomSyntaxEval = dyn Fn(&mut EvalContext, &[Expression]) -> RhaiResult + Send + Sync;
/// A general expression parsing trait object.
#[cfg(not(feature = "sync"))]
pub type FnCustomSyntaxParse =
dyn Fn(&[ImmutableString], &str) -> Result