package org.checkerframework.dataflow.cfg.node;

import com.sun.source.tree.Tree;
import java.util.Collection;
import java.util.Collections;
import java.util.Objects;
import javax.lang.model.type.TypeMirror;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A node for the string conversion operation. See JLS 5.1.11 for the definition of string
 * conversion.
 *
 * <p>A {@link StringConversionNode} does not correspond to any tree node in the parsed AST. It is
 * introduced when a value of non-string type appears in a context that requires a {@link String},
 * such as in a string concatenation. A {@link StringConversionNode} should be treated as a
 * potential call to the toString method of its operand, but does not necessarily call any method
 * because null is converted to the string "null".
 *
 * <p>Conversion of primitive types to Strings requires first boxing and then string conversion.
 */
public class StringConversionNode extends Node {

    protected final Tree tree;
    protected final Node operand;

    // TODO: The type of a string conversion should be a final
    // TypeMirror representing java.lang.String. Currently we require
    // the caller to pass in a TypeMirror instead of creating one
    // through the javax.lang.model.type.Types interface.
    public StringConversionNode(Tree tree, Node operand, TypeMirror type) {
        super(type);
        this.tree = tree;
        this.operand = operand;
    }

    public Node getOperand() {
        return operand;
    }

    @Override
    public Tree getTree() {
        return tree;
    }

    @Override
    public <R, P> R accept(NodeVisitor<R, P> visitor, P p) {
        return visitor.visitStringConversion(this, p);
    }

    @Override
    public String toString() {
        return "StringConversion(" + getOperand() + ")";
    }

    @Override
    public boolean equals(@Nullable Object obj) {
        if (!(obj instanceof StringConversionNode)) {
            return false;
        }
        StringConversionNode other = (StringConversionNode) obj;
        return getOperand().equals(other.getOperand());
    }

    @Override
    public int hashCode() {
        return Objects.hash(StringConversionNode.class, getOperand());
    }

    @Override
    public Collection<Node> getOperands() {
        return Collections.singletonList(getOperand());
    }
}
