NichtHaskell/Source/abstractSyntaxTree/Statement/IfElseStatement.java

package abstractSyntaxTree.Statement;

import TypeCheck.TypeCheckResult;
import TypeCheck.AbstractType;
import abstractSyntaxTree.Expression.IExpression;
import org.objectweb.asm.*;

public class IfElseStatement extends AbstractType implements IStatement{
    IExpression condition;
    IStatement ifStatement;
    IStatement elseStatement;

    public IfElseStatement(IExpression condition, IStatement ifStatement, IStatement elseStatement) {
        this.condition = condition;
        this.ifStatement = ifStatement;
        this.elseStatement = elseStatement;
    }

    @Override
    public TypeCheckResult typeCheck() throws Exception {
        TypeCheckResult result = new TypeCheckResult();

        TypeCheckResult conditionType = condition.typeCheck();

        if (!conditionType.equals("bool")) {
            throw new IllegalArgumentException("should be boolean");
        }

        TypeCheckResult ifStatementType = ifStatement.typeCheck();
        TypeCheckResult elseStatementType = elseStatement.typeCheck();

        if (!ifStatementType.equals(elseStatementType)) {
            throw new IllegalArgumentException("if and else have different types");
        }

        result.type = elseStatementType.type;
        return result;
    }

    @Override
    public void codeGen(MethodVisitor mv) throws Exception {

        Label conditionFalse = new Label();
        Label statementEnd = new Label();

        condition.codeGen(mv);

        mv.visitJumpInsn(Opcodes.IFEQ, conditionFalse); //Checks if the condition is false (0)
        ifStatement.codeGen(mv); //If the condition is true, execute the ifBlock
        mv.visitJumpInsn(Opcodes.GOTO, statementEnd); //Jump to the end of the if-else statement

        mv.visitLabel(conditionFalse);
        elseStatement.codeGen(mv); //If the condition is false, execute the elseBlock

        mv.visitLabel(statementEnd); //End of the if-else statement

    }
}