swc/crates/swc_bundler/tests/.cache/deno/dc6d3dce7401159ca2464ee9c9ccbaf708abcf33.ts
2021-11-09 20:42:49 +09:00

62 lines
2.0 KiB
TypeScript

// Loaded from https://deno.land/x/graphql_deno@v15.0.0/lib/validation/rules/NoFragmentCyclesRule.js
import { GraphQLError } from '../../error/GraphQLError.js';
export 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(`Cannot spread fragment "${spreadName}" within itself` + (viaPath !== '' ? ` via ${viaPath}.` : '.'), cyclePath));
}
spreadPath.pop();
}
spreadPathIndexByName[fragmentName] = undefined;
}
}