Function pruneSchema

packages/utils/src/prune.ts:25–109

(
  schema: GraphQLSchema,
  options: PruneSchemaOptions = {},
)

 * @param options Additional options for removing unused types from the schema
 */
export function pruneSchema(
  schema: GraphQLSchema,
  options: PruneSchemaOptions = {},
): GraphQLSchema {
  const {
    skipEmptyCompositeTypePruning,
    skipEmptyUnionPruning,
    skipPruning,
    skipUnimplementedInterfacesPruning,
    skipUnusedTypesPruning,
  } = options;
  let prunedTypes: string[] = []; // Pruned types during mapping
  let prunedSchema: GraphQLSchema = schema;

  do {
    let visited = visitSchema(prunedSchema);

    // Custom pruning  was defined, so we need to pre-emptively revisit the schema accounting for this
    if (skipPruning) {
      const revisit: string[] = [];

      for (const typeName in prunedSchema.getTypeMap()) {
        if (typeName.startsWith('__')) {
          continue;
        }

        const type = prunedSchema.getType(typeName);

        // if we want to skip pruning for this type, add it to the list of types to revisit
        if (type && skipPruning(type)) {
          revisit.push(typeName);
        }
      }

      visited = visitQueue(revisit, prunedSchema, visited); // visit again
    }

    prunedTypes = [];

    prunedSchema = mapSchema(prunedSchema, {
      [MapperKind.TYPE]: type => {
        if (!visited.has(type.name) && !isSpecifiedScalarType(type)) {
          if (
            isUnionType(type) ||
            isInputObjectType(type) ||
            isInterfaceType(type) ||
            isObjectType(type) ||
            isScalarType(type)
          ) {
            // skipUnusedTypesPruning: skip pruning unused types
            if (skipUnusedTypesPruning) {
              return type;
            }
            // skipEmptyUnionPruning: skip pruning empty unions
            if (
              isUnionType(type) &&
              skipEmptyUnionPruning &&
              !Object.keys(type.getTypes()).length