StringLeftFunction (EvalEx 3.5.0 API)

java.lang.Object
- com.ezylang.evalex.functions.AbstractFunction
- - com.ezylang.evalex.functions.string.StringLeftFunction

All Implemented Interfaces:

FunctionIfc
```
@FunctionParameter(name="string") @FunctionParameter(name="length")
public class StringLeftFunction
extends AbstractFunction
```
Represents a function that extracts a substring from the left side of a given string. This class extends the AbstractFunction and implements the logic for the `LEFT` string function, which returns a specified number of characters from the beginning (left) of the input string.
Two parameters are required for this function:
- string - The input string from which the substring will be extracted.
- length - The number of characters to extract from the left side of the string. If the specified length is greater than the string's length, the entire string is returned. If the length is negative or zero, an empty string is returned.
Example usage: If the input string is "hello" and the length is 2, the result will be "he".

Field Summary
- Fields inherited from class com.ezylang.evalex.functions.AbstractFunction
  MINUS_ONE

Constructor Summary

Constructors
Constructor Description

StringLeftFunction()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`EvaluationValue`	`evaluate(Expression expression, Token functionToken, EvaluationValue... parameterValues)`	Evaluates the `LEFT` string function by extracting a substring from the left side of the given string.

Methods inherited from class com.ezylang.evalex.functions.AbstractFunction
getFunctionParameterDefinitions, hasVarArgs, validatePreEvaluation

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.ezylang.evalex.functions.FunctionIfc
getCountOfNonVarArgParameters, isParameterLazy

- Constructor Detail
  - StringLeftFunction
```
public StringLeftFunction()
```
- Method Detail
  - evaluate
```
public EvaluationValue evaluate(Expression expression,
                                Token functionToken,
                                EvaluationValue... parameterValues)
```
    Evaluates the `LEFT` string function by extracting a substring from the left side of the given string.
    
    Parameters:
    
    expression - the current expression being evaluated
    
    functionToken - the token representing the function being called
    
    parameterValues - the parameters passed to the function; expects exactly two parameters: a string and a numeric value for length
    
    Returns:
    
    the substring extracted from the left side of the input string as an EvaluationValue