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162 lines
7.2 KiB
ReStructuredText
162 lines
7.2 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/4.2/doc/tools/make_rst.py.
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.. XML source: https://github.com/godotengine/godot/tree/4.2/doc/classes/Expression.xml.
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.. _class_Expression:
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Expression
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==========
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**继承：** :ref:`RefCounted<class_RefCounted>` **<** :ref:`Object<class_Object>`
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存储你可以执行的表达式的类。
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.. rst-class:: classref-introduction-group
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描述
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----
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表达式可以由任何算术运算、内置数学函数调用、传递实例的方法调用或内置类型构造调用组成。
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一个使用内置数学函数的示例表达式文本可以是 ``sqrt(pow(3, 2) + pow(4, 2))``\ 。
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在下面的示例中，我们使用 :ref:`LineEdit<class_LineEdit>` 节点来编写表达式并显示结果。
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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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教程
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----
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- :doc:`表达式求值 <../tutorials/scripting/evaluating_expressions>`
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.. rst-class:: classref-reftable-group
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方法
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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>` **(** :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 **)** |
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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>` **(** :ref:`String<class_String>` expression, :ref:`PackedStringArray<class_PackedStringArray>` input_names=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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方法说明
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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** **(** :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 **)**
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执行之前由 :ref:`parse<class_Expression_method_parse>` 解析的表达式，并返回结果。在使用返回的对象之前，应该通过调用 :ref:`has_execute_failed<class_Expression_method_has_execute_failed>` 来检查方法是否失败。
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如果你在 :ref:`parse<class_Expression_method_parse>` 中定义了输入变量，你可以在输入数组中以同样的顺序指定它们的值。
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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|
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如果 :ref:`parse<class_Expression_method_parse>` 或 :ref:`execute<class_Expression_method_execute>` 失败，则返回错误文本。
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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|
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如果 :ref:`execute<class_Expression_method_execute>` 失败，返回 ``true``\ 。
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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** **(** :ref:`String<class_String>` expression, :ref:`PackedStringArray<class_PackedStringArray>` input_names=PackedStringArray() **)**
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解析表达式并返回 :ref:`Error<enum_@GlobalScope_Error>` 代码。
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你也可以选择用 ``input_names`` 来指定可能出现在表达式中的变量名称，这样就可以在执行表达式时进行绑定。
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.. |virtual| replace:: :abbr:`virtual (本方法通常需要用户覆盖才能生效。)`
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.. |const| replace:: :abbr:`const (本方法没有副作用。不会修改该实例的任何成员变量。)`
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.. |vararg| replace:: :abbr:`vararg (本方法除了在此处描述的参数外，还能够继续接受任意数量的参数。)`
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.. |constructor| replace:: :abbr:`constructor (本方法用于构造某个类型。)`
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.. |static| replace:: :abbr:`static (调用本方法无需实例，所以可以直接使用类名调用。)`
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.. |operator| replace:: :abbr:`operator (本方法描述的是使用本类型作为左操作数的有效操作符。)`
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.. |bitfield| replace:: :abbr:`BitField (这个值是由下列标志构成的位掩码整数。)`
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