import { GraphQLError } from "../../error/GraphQLError.mjs"; export function NoFragmentCyclesRule(context) { // Tracks already visited fragments to maintain O(N) and to ensure that cycles // are not redundantly reported. var visitedFrags = Object.create(null); // Array of AST nodes used to produce meaningful errors var spreadPath = []; // Position in the spread path var spreadPathIndexByName = Object.create(null); return { OperationDefinition: function OperationDefinition() { return false; }, FragmentDefinition: function 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; } var fragmentName = fragment.name.value; visitedFrags[fragmentName] = true; var spreadNodes = context.getFragmentSpreads(fragment.selectionSet); if (spreadNodes.length === 0) { return; } spreadPathIndexByName[fragmentName] = spreadPath.length; for (var _i2 = 0; _i2 < spreadNodes.length; _i2++) { var spreadNode = spreadNodes[_i2]; var spreadName = spreadNode.name.value; var cycleIndex = spreadPathIndexByName[spreadName]; spreadPath.push(spreadNode); if (cycleIndex === undefined) { var spreadFragment = context.getFragment(spreadName); if (spreadFragment) { detectCycleRecursive(spreadFragment); } } else { var cyclePath = spreadPath.slice(cycleIndex); var viaPath = cyclePath.slice(0, -1).map(function (s) { return '"' + s.name.value + '"'; }).join(', '); context.reportError(new GraphQLError("Cannot spread fragment \"".concat(spreadName, "\" within itself") + (viaPath !== '' ? " via ".concat(viaPath, ".") : '.'), cyclePath)); } spreadPath.pop(); } spreadPathIndexByName[fragmentName] = undefined; } }