<?xml version="1.0" encoding="UTF-8" ?>
<class name="Expression" inherits="RefCounted" api_type="core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
<brief_description>
A class that stores an expression you can execute.
</brief_description>
<description>
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 [code]sqrt(pow(3, 2) + pow(4, 2))[/code].
In the following example we use a [LineEdit] node to write our expression and show the result.
[codeblocks]
[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():
$LineEdit.text = str(result)
[/gdscript]
[csharp]
private Expression _expression = new Expression();
public override void _Ready()
{
GetNode<LineEdit>("LineEdit").TextSubmitted += OnTextEntered;
}
private void OnTextEntered(string command)
{
Error error = _expression.Parse(command);
if (error != Error.Ok)
{
GD.Print(_expression.GetErrorText());
return;
}
Variant result = _expression.Execute();
if (!_expression.HasExecuteFailed())
{
GetNode<LineEdit>("LineEdit").Text = result.ToString();
}
}
[/csharp]
[/codeblocks]
</description>
<tutorials>
<link title="Evaluating Expressions">$DOCS_URL/tutorials/scripting/evaluating_expressions.html</link>
</tutorials>
<methods>
<method name="execute">
<return type="Variant" />
<param index="0" name="inputs" type="Array" default="[]" />
<param index="1" name="base_instance" type="Object" default="null" />
<param index="2" name="show_error" type="bool" default="true" />
<param index="3" name="const_calls_only" type="bool" default="false" />
<description>
Executes the expression that was previously parsed by [method parse] and returns the result. Before you use the returned object, you should check if the method failed by calling [method has_execute_failed].
If you defined input variables in [method parse], you can specify their values in the inputs array, in the same order.
</description>
</method>
<method name="get_error_text" qualifiers="const">
<return type="String" />
<description>
Returns the error text if [method parse] or [method execute] has failed.
</description>
</method>
<method name="has_execute_failed" qualifiers="const">
<return type="bool" />
<description>
Returns [code]true[/code] if [method execute] has failed.
</description>
</method>
<method name="parse">
<return type="int" enum="Error" />
<param index="0" name="expression" type="String" />
<param index="1" name="input_names" type="PackedStringArray" default="PackedStringArray()" />
<description>
Parses the expression and returns an [enum Error] code.
You can optionally specify names of variables that may appear in the expression with [param input_names], so that you can bind them when it gets executed.
</description>
</method>
</methods>
</class>