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163 lines
7.7 KiB
ReStructuredText
163 lines
7.7 KiB
ReStructuredText
:github_url: hide
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.. DO NOT EDIT THIS FILE!!!
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.. Generated automatically from Godot engine sources.
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.. Generator: https://github.com/godotengine/godot/tree/master/doc/tools/make_rst.py.
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.. XML source: https://github.com/godotengine/godot/tree/master/doc/classes/Expression.xml.
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.. _class_Expression:
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Expression
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==========
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**Inherits:** :ref:`RefCounted<class_RefCounted>` **<** :ref:`Object<class_Object>`
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A class that stores an expression you can execute.
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.. rst-class:: classref-introduction-group
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Description
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-----------
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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.
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An example expression text using the built-in math functions could be ``sqrt(pow(3, 2) + pow(4, 2))``.
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In the following example we use a :ref:`LineEdit<class_LineEdit>` node to write our expression and show the result.
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.. tabs::
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.. code-tab:: gdscript
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var expression = Expression.new()
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func _ready():
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$LineEdit.text_submitted.connect(self._on_text_submitted)
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func _on_text_submitted(command):
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var error = expression.parse(command)
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if error != OK:
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print(expression.get_error_text())
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return
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var result = expression.execute()
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if not expression.has_execute_failed():
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$LineEdit.text = str(result)
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.. code-tab:: csharp
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private Expression _expression = new Expression();
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public override void _Ready()
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{
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GetNode<LineEdit>("LineEdit").TextSubmitted += OnTextEntered;
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}
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private void OnTextEntered(string command)
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{
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Error error = _expression.Parse(command);
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if (error != Error.Ok)
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{
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GD.Print(_expression.GetErrorText());
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return;
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}
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Variant result = _expression.Execute();
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if (!_expression.HasExecuteFailed())
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{
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GetNode<LineEdit>("LineEdit").Text = result.ToString();
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}
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}
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.. rst-class:: classref-introduction-group
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Tutorials
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---------
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- :doc:`Evaluating Expressions <../tutorials/scripting/evaluating_expressions>`
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.. rst-class:: classref-reftable-group
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Methods
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-------
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.. table::
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:widths: auto
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+---------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
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| :ref:`Variant<class_Variant>` | :ref:`execute<class_Expression_method_execute>`\ (\ inputs\: :ref:`Array<class_Array>` = [], base_instance\: :ref:`Object<class_Object>` = null, show_error\: :ref:`bool<class_bool>` = true, const_calls_only\: :ref:`bool<class_bool>` = false\ ) |
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+---------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
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| :ref:`String<class_String>` | :ref:`get_error_text<class_Expression_method_get_error_text>`\ (\ ) |const| |
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+---------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
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| :ref:`bool<class_bool>` | :ref:`has_execute_failed<class_Expression_method_has_execute_failed>`\ (\ ) |const| |
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+---------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
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| :ref:`Error<enum_@GlobalScope_Error>` | :ref:`parse<class_Expression_method_parse>`\ (\ expression\: :ref:`String<class_String>`, input_names\: :ref:`PackedStringArray<class_PackedStringArray>` = PackedStringArray()\ ) |
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+---------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
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.. rst-class:: classref-section-separator
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----
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.. rst-class:: classref-descriptions-group
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Method Descriptions
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-------------------
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.. _class_Expression_method_execute:
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.. rst-class:: classref-method
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:ref:`Variant<class_Variant>` **execute**\ (\ inputs\: :ref:`Array<class_Array>` = [], base_instance\: :ref:`Object<class_Object>` = null, show_error\: :ref:`bool<class_bool>` = true, const_calls_only\: :ref:`bool<class_bool>` = false\ ) :ref:`🔗<class_Expression_method_execute>`
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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>`.
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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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.. rst-class:: classref-item-separator
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----
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.. _class_Expression_method_get_error_text:
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.. rst-class:: classref-method
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:ref:`String<class_String>` **get_error_text**\ (\ ) |const| :ref:`🔗<class_Expression_method_get_error_text>`
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Returns the error text if :ref:`parse<class_Expression_method_parse>` or :ref:`execute<class_Expression_method_execute>` has failed.
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.. rst-class:: classref-item-separator
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----
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.. _class_Expression_method_has_execute_failed:
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.. rst-class:: classref-method
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:ref:`bool<class_bool>` **has_execute_failed**\ (\ ) |const| :ref:`🔗<class_Expression_method_has_execute_failed>`
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Returns ``true`` if :ref:`execute<class_Expression_method_execute>` has failed.
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.. rst-class:: classref-item-separator
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----
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.. _class_Expression_method_parse:
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.. rst-class:: classref-method
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:ref:`Error<enum_@GlobalScope_Error>` **parse**\ (\ expression\: :ref:`String<class_String>`, input_names\: :ref:`PackedStringArray<class_PackedStringArray>` = PackedStringArray()\ ) :ref:`🔗<class_Expression_method_parse>`
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Parses the expression and returns an :ref:`Error<enum_@GlobalScope_Error>` code.
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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.
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.. |virtual| replace:: :abbr:`virtual (This method should typically be overridden by the user to have any effect.)`
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.. |const| replace:: :abbr:`const (This method has no side effects. It doesn't modify any of the instance's member variables.)`
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.. |vararg| replace:: :abbr:`vararg (This method accepts any number of arguments after the ones described here.)`
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.. |constructor| replace:: :abbr:`constructor (This method is used to construct a type.)`
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.. |static| replace:: :abbr:`static (This method doesn't need an instance to be called, so it can be called directly using the class name.)`
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.. |operator| replace:: :abbr:`operator (This method describes a valid operator to use with this type as left-hand operand.)`
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.. |bitfield| replace:: :abbr:`BitField (This value is an integer composed as a bitmask of the following flags.)`
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.. |void| replace:: :abbr:`void (No return value.)`
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