Struct evalexpr::EmptyContext

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pub struct EmptyContext;
Expand description

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

Trait Implementations§

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impl Context for EmptyContext

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fn are_builtin_functions_disabled(&self) -> bool

Builtin functions are always disabled for EmptyContext.

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

Builtin functions can’t be enabled for EmptyContext.

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

Returns the value that is linked to the given identifier.
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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.
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impl Debug for EmptyContext

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

Formats the value using the given formatter. Read more
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impl Default for EmptyContext

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fn default() -> EmptyContext

Returns the “default value” for a type. Read more
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impl IterateVariablesContext for EmptyContext

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

The iterator type for iterating over variable name-value pairs.
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type VariableNameIterator<'a> = Empty<String>

The iterator type for iterating over variable names.
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fn iter_variables(&self) -> Self::VariableIterator<'_>

Returns an iterator over pairs of variable names and values.
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fn iter_variable_names(&self) -> Self::VariableNameIterator<'_>

Returns an iterator over variable names.

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.