SumTypeDescriptor.java

package scotch.symbol.type;

import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;

import java.util.List;
import java.util.Set;
import java.util.function.Function;
import com.google.common.collect.ImmutableList;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import scotch.symbol.Symbol;
import scotch.util.Pair;

@EqualsAndHashCode(callSuper = false)
public class SumTypeDescriptor extends TypeDescriptor {

    @Getter private final Symbol               symbol;
    @Getter private final List<TypeDescriptor> parameters;

    SumTypeDescriptor(Symbol symbol, List<? extends TypeDescriptor> parameters) {
        this.symbol = symbol;
        this.parameters = ImmutableList.copyOf(parameters);
    }

    @Override
    public <T> T accept(Visitor<T> visitor) {
        return visitor.visit(this);
    }

    @Override
    public Set<Symbol> getContext() {
        return parameters.stream()
            .map(TypeDescriptor::getContext)
            .flatMap(Set::stream)
            .collect(toSet());
    }

    @Override
    public TypeDescriptor mapVariables(Function<TypeDescriptor, TypeDescriptor> function) {
        return new SumTypeDescriptor(symbol, parameters.stream()
            .map(parameter -> parameter.mapVariables(function))
            .collect(toList()));
    }

    @Override
    protected Set<Pair<VariableTypeDescriptor, Symbol>> gatherContext_() {
        return parameters.stream()
            .flatMap(parameter -> parameter.gatherContext_().stream())
            .collect(toSet());
    }

    @Override
    protected String toParenthesizedString() {
        return toString_();
    }

    @Override
    protected String toString_() {
        if (symbol.isTuple()) {
            return "(" + parameters.stream().map(TypeDescriptor::toString_).collect(joining(", ")) + ")";
        } else if (symbol.isList()) {
            return "[" + parameters.stream().map(TypeDescriptor::toString_).collect(joining(", ")) + "]";
        } else if (parameters.isEmpty()) {
            return symbol.getSimpleName();
        } else {
            return symbol.getSimpleName() + " " + parameters.stream().map(TypeDescriptor::toString_).collect(joining(" "));
        }
    }
}