graphql.language.AstZipper Maven / Gradle / Ivy

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package graphql.language;


import graphql.PublicApi;

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

import static graphql.Assert.assertNotNull;

/**
 * A zipper is a specific node inside a tree together with a list of breadcrumbs to pinpoint
 * the exact location of this node inside the tree from the root.
 * 
 * It is used by {@link AstMultiZipper} and {@link AstTransformer} to allow for an easy way to "manipulate" the
 * immutable Ast.
 */
@PublicApi
public class AstZipper {

    private final Node curNode;
    // reverse: the breadCrumbs start from curNode upwards
    private final List breadcrumbs;


    public AstZipper(Node curNode, List breadcrumbs) {
        this.curNode = curNode;
        this.breadcrumbs = assertNotNull(breadcrumbs);
    }

    public Node getCurNode() {
        return curNode;
    }

    public List getBreadcrumbs() {
        return new ArrayList<>(breadcrumbs);
    }

    public Node getParent() {
        return breadcrumbs.get(0).getNode();
    }

    public static AstZipper rootZipper(Node rootNode) {
        return new AstZipper(rootNode, new ArrayList<>());
    }

    public AstZipper modifyNode(Function transform) {
        return new AstZipper(transform.apply(curNode), breadcrumbs);
    }

    public AstZipper withNewNode(Node newNode) {
        return new AstZipper(newNode, breadcrumbs);
    }

    public Node toRoot() {
        Node curNode = this.curNode;
        for (AstBreadcrumb breadcrumb : breadcrumbs) {
            // just handle replace
            NodeChildrenContainer newChildren = breadcrumb.getNode().getNamedChildren();
            final Node newChild = curNode;
            newChildren = newChildren.transform(builder -> {
                NodeLocation location = breadcrumb.getLocation();
                builder.replaceChild(location.getName(), location.getIndex(), newChild);
            });
            curNode = breadcrumb.getNode().withNewChildren(newChildren);
        }
        return curNode;
    }


}