planning

node_modules/graphql/utilities/separateOperations.js.flow

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+// @flow strict
+import type { ObjMap } from '../jsutils/ObjMap';
+
+import type {
+  DocumentNode,
+  OperationDefinitionNode,
+  SelectionSetNode,
+} from '../language/ast';
+import { Kind } from '../language/kinds';
+import { visit } from '../language/visitor';
+
+/**
+ * separateOperations accepts a single AST document which may contain many
+ * operations and fragments and returns a collection of AST documents each of
+ * which contains a single operation as well the fragment definitions it
+ * refers to.
+ */
+export function separateOperations(
+  documentAST: DocumentNode,
+): ObjMap<DocumentNode> {
+  const operations: Array<OperationDefinitionNode> = [];
+  const depGraph: DepGraph = Object.create(null);
+
+  // Populate metadata and build a dependency graph.
+  for (const definitionNode of documentAST.definitions) {
+    switch (definitionNode.kind) {
+      case Kind.OPERATION_DEFINITION:
+        operations.push(definitionNode);
+        break;
+      case Kind.FRAGMENT_DEFINITION:
+        depGraph[definitionNode.name.value] = collectDependencies(
+          definitionNode.selectionSet,
+        );
+        break;
+    }
+  }
+
+  // For each operation, produce a new synthesized AST which includes only what
+  // is necessary for completing that operation.
+  const separatedDocumentASTs = Object.create(null);
+  for (const operation of operations) {
+    const dependencies = new Set();
+
+    for (const fragmentName of collectDependencies(operation.selectionSet)) {
+      collectTransitiveDependencies(dependencies, depGraph, fragmentName);
+    }
+
+    // Provides the empty string for anonymous operations.
+    const operationName = operation.name ? operation.name.value : '';
+
+    // The list of definition nodes to be included for this operation, sorted
+    // to retain the same order as the original document.
+    separatedDocumentASTs[operationName] = {
+      kind: Kind.DOCUMENT,
+      definitions: documentAST.definitions.filter(
+        (node) =>
+          node === operation ||
+          (node.kind === Kind.FRAGMENT_DEFINITION &&
+            dependencies.has(node.name.value)),
+      ),
+    };
+  }
+
+  return separatedDocumentASTs;
+}
+
+type DepGraph = ObjMap<Array<string>>;
+
+// From a dependency graph, collects a list of transitive dependencies by
+// recursing through a dependency graph.
+function collectTransitiveDependencies(
+  collected: Set<string>,
+  depGraph: DepGraph,
+  fromName: string,
+): void {
+  if (!collected.has(fromName)) {
+    collected.add(fromName);
+
+    const immediateDeps = depGraph[fromName];
+    if (immediateDeps !== undefined) {
+      for (const toName of immediateDeps) {
+        collectTransitiveDependencies(collected, depGraph, toName);
+      }
+    }
+  }
+}
+
+function collectDependencies(selectionSet: SelectionSetNode): Array<string> {
+  const dependencies = [];
+
+  visit(selectionSet, {
+    FragmentSpread(node) {
+      dependencies.push(node.name.value);
+    },
+  });
+  return dependencies;
+}