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