Draft: Add sequence generators

Add the first draft of the new sequence generator. Includes the new Sequence class which can be updated via a visitor pattern. Additionally, adds the first visitor. Change pom.xml to include the minimal Expression Parser Exp4j, which allows to parse Strings into mathematical functions.

Closes #160

src/evoal/plugins/de.evoal.generator.main/src/main/java/de/evoal/pipeline/components/Sequence.java

+import java.util.Iterator;
+
+import org.eclipse.emf.ecore.EStructuralFeature;
+
+import de.evoal.pipeline.api.model.ComponentImpl;
+import de.evoal.pipeline.api.model.TypedEObject;
+import lombok.NonNull;
+import net.objecthunter.exp4j.Expression;
+import net.objecthunter.exp4j.ExpressionBuilder;
+
+
+
+public class Sequence extends ComponentImpl implements Visitable{
+
+    private double start_value;
+    private String sequence;
+    private String params;
+    private double step_size;
+    private double current_value;
+    private Expression exp;
+
+    public Sequence(double start_value, String sequence, String params, double step_size) {
+        this.start_value = start_value;
+        this.sequence = sequence;
+        this.params = params;
+        this.step_size = step_size;
+        this.current_value = this.start_value;
+        exp = new ExpressionBuilder(sequence).variable(params).build();
+    }
+
+    public double getCurrent_value() {
+        return current_value;
+    }
+
+    public void setCurrent_value(double current_value) {
+        this.current_value = current_value;
+    }
+
+
+    public double getStart_value() {
+        return start_value;
+    }
+    public void setStart_value(double start_value) {
+        this.start_value = start_value;
+    }
+    public String getSequence() {
+        return sequence;
+    }
+    public void setSequence(String sequence) {
+        this.sequence = sequence;
+    }
+    public String getParams() {
+        return params;
+    }
+    public void setParams(String params) {
+        this.params = params;
+    }
+    public double getStep_size() {
+        return step_size;
+    }
+    public void setStep_size(double step_size) {
+        this.step_size = step_size;
+    }
+
+    private double getValueOf(double StartValue)
+    {
+        return exp.setVariable(this.params,StartValue).evaluate();
+    }
+
+
+    public double getNextValueOfSequence()
+    {
+        double result = exp.setVariable(this.params,this.current_value).evaluate();
+        System.out.println("Next calculated Value of "+ this.sequence + " we started at "+ this.start_value +" the new value we plugged in is "+ this.current_value +" the result is " + result);
+        this.current_value=this.current_value + this.step_size;
+        return result;
+    }
+
+    public double getNextValue()
+    {
+        double old=this.current_value;
+        this.current_value=this.current_value + this.step_size;
+        double result = exp.setVariable(this.params,this.current_value).evaluate();
+        System.out.println("Next calculated Value of "+ this.sequence + " we started at "+ old +" the new value we plugged in is "+ this.current_value +" the result is " + result);
+        return result;
+    }
+
+    @Override
+    public void accept(Visitor visitor)
+    {
+        visitor.visit(this);
+    }
+    
+    //I am a bit confused as to how this works or even how this plays into the whole set up.
+	@Override
+	public @NonNull TypedEObject apply(@NonNull TypedEObject object) {
+		//Currently I want to do the BEAR MINIMUM just get a number back
+		final Iterator<EStructuralFeature> iterator = getWrites().iterator(); //iterator that lets us walk over variable that we need to write
+		while(iterator.hasNext())
+		{
+			final EStructuralFeature feature = iterator.next();
+			double value= this.getNextValueOfSequence();
+			object.eSet(feature, value);
+		}
+
+		return object;
+	}
+	
+}
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