@graphql-tools/graphql/cjs/validation/rules/NoFragmentCyclesRule.js

Fork of GraphQL.js

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.NoFragmentCyclesRule = void 0;
const GraphQLError_js_1 = require("../../error/GraphQLError.js");
/**
 * No fragment cycles
 *
 * The graph of fragment spreads must not form any cycles including spreading itself.
 * Otherwise an operation could infinitely spread or infinitely execute on cycles in the underlying data.
 *
 * See https://spec.graphql.org/draft/#sec-Fragment-spreads-must-not-form-cycles
 */
function NoFragmentCyclesRule(context) {
    // Tracks already visited fragments to maintain O(N) and to ensure that cycles
    // are not redundantly reported.
    const visitedFrags = Object.create(null);
    // Array of AST nodes used to produce meaningful errors
    const spreadPath = [];
    // Position in the spread path
    const spreadPathIndexByName = Object.create(null);
    return {
        OperationDefinition: () => false,
        FragmentDefinition(node) {
            detectCycleRecursive(node);
            return false;
        },
    };
    // This does a straight-forward DFS to find cycles.
    // It does not terminate when a cycle was found but continues to explore
    // the graph to find all possible cycles.
    function detectCycleRecursive(fragment) {
        if (visitedFrags[fragment.name.value]) {
            return;
        }
        const fragmentName = fragment.name.value;
        visitedFrags[fragmentName] = true;
        const spreadNodes = context.getFragmentSpreads(fragment.selectionSet);
        if (spreadNodes.length === 0) {
            return;
        }
        spreadPathIndexByName[fragmentName] = spreadPath.length;
        for (const spreadNode of spreadNodes) {
            const spreadName = spreadNode.name.value;
            const cycleIndex = spreadPathIndexByName[spreadName];
            spreadPath.push(spreadNode);
            if (cycleIndex === undefined) {
                const spreadFragment = context.getFragment(spreadName);
                if (spreadFragment) {
                    detectCycleRecursive(spreadFragment);
                }
            }
            else {
                const cyclePath = spreadPath.slice(cycleIndex);
                const viaPath = cyclePath
                    .slice(0, -1)
                    .map(s => '"' + s.name.value + '"')
                    .join(', ');
                context.reportError(new GraphQLError_js_1.GraphQLError(`Cannot spread fragment "${spreadName}" within itself` + (viaPath !== '' ? ` via ${viaPath}.` : '.'), { nodes: cyclePath }));
            }
            spreadPath.pop();
        }
        spreadPathIndexByName[fragmentName] = undefined;
    }
}
exports.NoFragmentCyclesRule = NoFragmentCyclesRule;