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Inherits: :ref:`RefCounted<class_RefCounted>` < :ref:`Object<class_Object>`
A class that stores an expression you can execute.
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An expression can be made of any arithmetic operation, built-in math function call, method call of a passed instance, or built-in type construction call.
An example expression text using the built-in math functions could be sqrt(pow(3, 2) + pow(4, 2)).
In the following example we use a :ref:`LineEdit<class_LineEdit>` node to write our expression and show the result.
.. tabs::
.. code-tab:: gdscript
var expression = Expression.new()
func _ready():
$LineEdit.text_submitted.connect(self._on_text_submitted)
func _on_text_submitted(command):
var error = expression.parse(command)
if error != OK:
print(expression.get_error_text())
return
var result = expression.execute()
if not expression.has_execute_failed():
$LineEdit.text = str(result)
.. code-tab:: csharp
private Expression _expression = new Expression();
public override void _Ready()
{
GetNode<LineEdit>("LineEdit").TextSubmitted += OnTextEntered;
}
private void OnTextEntered(string command)
{
Error error = _expression.Parse(command);
if (error != Error.Ok)
{
GD.Print(_expression.GetErrorText());
return;
}
Variant result = _expression.Execute();
if (!_expression.HasExecuteFailed())
{
GetNode<LineEdit>("LineEdit").Text = result.ToString();
}
}
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.. rst-class:: classref-reftable-group
| :ref:`Variant<class_Variant>` | :ref:`execute<class_Expression_method_execute>` ( :ref:`Array<class_Array>` inputs=[], :ref:`Object<class_Object>` base_instance=null, :ref:`bool<class_bool>` show_error=true, :ref:`bool<class_bool>` const_calls_only=false ) |
| :ref:`String<class_String>` | :ref:`get_error_text<class_Expression_method_get_error_text>` ( ) |const| |
| :ref:`bool<class_bool>` | :ref:`has_execute_failed<class_Expression_method_has_execute_failed>` ( ) |const| |
| :ref:`Error<enum_@GlobalScope_Error>` | :ref:`parse<class_Expression_method_parse>` ( :ref:`String<class_String>` expression, :ref:`PackedStringArray<class_PackedStringArray>` input_names=PackedStringArray() ) |
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:ref:`Variant<class_Variant>` execute ( :ref:`Array<class_Array>` inputs=[], :ref:`Object<class_Object>` base_instance=null, :ref:`bool<class_bool>` show_error=true, :ref:`bool<class_bool>` const_calls_only=false )
Executes the expression that was previously parsed by :ref:`parse<class_Expression_method_parse>` and returns the result. Before you use the returned object, you should check if the method failed by calling :ref:`has_execute_failed<class_Expression_method_has_execute_failed>`.
If you defined input variables in :ref:`parse<class_Expression_method_parse>`, you can specify their values in the inputs array, in the same order.
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:ref:`String<class_String>` get_error_text ( ) |const|
Returns the error text if :ref:`parse<class_Expression_method_parse>` or :ref:`execute<class_Expression_method_execute>` has failed.
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:ref:`bool<class_bool>` has_execute_failed ( ) |const|
Returns true if :ref:`execute<class_Expression_method_execute>` has failed.
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.. rst-class:: classref-method
:ref:`Error<enum_@GlobalScope_Error>` parse ( :ref:`String<class_String>` expression, :ref:`PackedStringArray<class_PackedStringArray>` input_names=PackedStringArray() )
Parses the expression and returns an :ref:`Error<enum_@GlobalScope_Error>` code.
You can optionally specify names of variables that may appear in the expression with input_names, so that you can bind them when it gets executed.