Struct evalexpr::EmptyContext

pub struct EmptyContext;

A context that returns None for each identifier. Builtin functions are disabled and cannot be enabled.

Trait Implementations

impl Context for EmptyContext

fn are_builtin_functions_disabled(&self) -> bool

Builtin functions are always disabled for EmptyContext.

fn set_builtin_functions_disabled( &mut self, disabled: bool ) -> EvalexprResult<()>

Builtin functions can’t be enabled for EmptyContext.

fn get_value(&self, _identifier: &str) -> Option<&Value>

Returns the value that is linked to the given identifier.

fn call_function( &self, identifier: &str, _argument: &Value ) -> EvalexprResult<Value>

Calls the function that is linked to the given identifier with the given argument. If no function with the given identifier is found, this method returns EvalexprError::FunctionIdentifierNotFound.

impl Debug for EmptyContext

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

Formats the value using the given formatter.

impl Default for EmptyContext

fn default() -> EmptyContext

Returns the “default value” for a type.

impl IterateVariablesContext for EmptyContext

type VariableIterator<'a> = Empty<(String, Value)>

The iterator type for iterating over variable name-value pairs.

type VariableNameIterator<'a> = Empty<String>

The iterator type for iterating over variable names.

fn iter_variables(&self) -> Self::VariableIterator<'_>

Returns an iterator over pairs of variable names and values.

fn iter_variable_names(&self) -> Self::VariableNameIterator<'_>

Returns an iterator over variable names.