Struct rhai::Expression

pub struct Expression<'a>(_);

An expression sub-tree in an AST.

Implementations

impl Expression<'_>

pub fn eval_with_context( &self, context: &mut EvalContext<'_, '_, '_, '_, '_, '_> ) -> Result<Dynamic, Box<EvalAltResult>>

Evaluate this expression tree within an evaluation context.

WARNING - Low Level API

This function is very low level. It evaluates an expression from an AST.

pub fn eval_with_context_raw( &self, context: &mut EvalContext<'_, '_, '_, '_, '_, '_>, rewind_scope: bool ) -> Result<Dynamic, Box<EvalAltResult>>

👎Deprecated: This API is NOT deprecated, but it is considered volatile and may change in the future.

Evaluate this expression tree within an evaluation context.

The following option is available:

• whether to rewind the Scope after evaluation if the expression is a StmtBlock

WARNING - Unstable API

This API is volatile and may change in the future.

WARNING - Low Level API

This function is extremely low level. It evaluates an expression from an AST.

pub fn get_string_value(&self) -> Option<&str>

Get the value of this expression if it is a variable name or a string constant.

Returns None also if the constant is not of the specified type.

pub const fn position(&self) -> Position

Get the position of this expression.

pub fn get_literal_value<T: Variant>(&self) -> Option<T>

Get the value of this expression if it is a literal constant.

Supports INT, FLOAT, (), char, bool and ImmutableString.

Returns None also if the constant is not of the specified type.

impl Expression<'_>

pub fn get_variable_name(&self) -> Option<&str>

👎Deprecated since 1.4.0: use <code>get_string_value</code> instead

If this expression is a variable name, return it. Otherwise None.

Deprecated

This method is deprecated. Use get_string_value instead.

This method will be removed in the next major version.

Methods from Deref<Target = Expr>

pub fn get_literal_value(&self) -> Option<Dynamic>

Get the Dynamic value of a literal constant expression.

Returns None if the expression is not a literal constant.

pub fn options(&self) -> ASTFlags

Get the options of the expression.

pub fn position(&self) -> Position

Get the position of the expression.

pub fn start_position(&self) -> Position

Get the starting position of the expression. For a binary expression, this will be the left-most LHS instead of the operator.

pub fn is_pure(&self) -> bool

Is the expression pure?

A pure expression has no side effects.

pub fn is_unit(&self) -> bool

Is the expression the unit () literal?

pub fn is_constant(&self) -> bool

Is the expression a constant?

pub fn is_valid_postfix(&self, token: &Token) -> bool

Is a particular token allowed as a postfix operator to this expression?

pub fn walk<'a>( &'a self, path: &mut Vec<ASTNode<'a>>, on_node: &mut impl FnMut(&[ASTNode<'_>]) -> bool ) -> bool

Recursively walk this expression. Return false from the callback to terminate the walk.

Trait Implementations

impl AsRef<Expr> for Expression<'_>

fn as_ref(&self) -> &Expr

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<Expr> for Expression<'_>

fn borrow(&self) -> &Expr

Immutably borrows from an owned value.

impl<'a> Clone for Expression<'a>

fn clone(&self) -> Expression<'a>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Debug for Expression<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for Expression<'_>

type Target = Expr

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'a> From<&'a Expr> for Expression<'a>

fn from(expr: &'a Expr) -> Self

Converts to this type from the input type.