aurasphere/gomorra-sql

package co.aurasphere.gomorrasql.states;

import java.util.Arrays;
import java.util.List;
import java.util.function.Function;

import co.aurasphere.gomorrasql.model.CaggiaFaException;
import co.aurasphere.gomorrasql.model.QueryInfo;

/**
 * State that parses a list of values, separed by a comma. It stops when there's
 * no more comma and checks if the token after is the expected one (set in the
 * constructor). It can be configured to be a final state.
 * 
 * @author Donato Rimenti
 *
 */
public class CommaSeparedValuesState extends AbstractState {

    private boolean lastWasComma = false;
    private List<String> collector;
    private String nextToken;
    private Function<QueryInfo, AbstractState> transitionFunction;
    private String expectedToken;
    private boolean canBeFinalState = false;
    private boolean optionalValues = false;

    public CommaSeparedValuesState(QueryInfo queryInfo, List<String> collector, String nextToken, String expectedToken,
            Function<QueryInfo, AbstractState> transitionFunction) {
        super(queryInfo);
        this.collector = collector;
        this.nextToken = nextToken;
        this.transitionFunction = transitionFunction;
        this.expectedToken = expectedToken;
    }

    public CommaSeparedValuesState(QueryInfo queryInfo, List<String> collector, String nextToken, String expectedToken,
            boolean lastWasComma, boolean canBeFinalState, Function<QueryInfo, AbstractState> transitionFunction) {
        this(queryInfo, collector, nextToken, expectedToken, transitionFunction);

        // Used when the first token is not consumed by the previous state.
        this.lastWasComma = lastWasComma;
        this.canBeFinalState = canBeFinalState;
        this.optionalValues = true;
    }

    @Override
    public AbstractState transitionToNextState(String token) throws CaggiaFaException {
        if (token.equals(",")) {
            if (lastWasComma) {
                // Case ", ,"
                throw new CaggiaFaException(expectedToken, token);
            } else {
                // Case "%expectedToken% ,"
                lastWasComma = true;
                return this;
            }
        }

        // Case ", %expectedToken%"
        if (lastWasComma) {
            if (optionalValues && token.equalsIgnoreCase(nextToken)) {
                return transitionFunction.apply(queryInfo);
            } else {
                optionalValues = false;
            }
            collector.add(token);
            lastWasComma = false;
            return this;
        }

        // Case "%expectedToken% %nextToken%"
        if (token.equalsIgnoreCase(nextToken)) {
            return transitionFunction.apply(queryInfo);
        }

        // Case "%expectedToken% %WRONG_TOKEN%"
        throw new CaggiaFaException(Arrays.asList(",", nextToken), token);
    }

    @Override
    public boolean isFinalState() {
        return canBeFinalState;
    }
}