Add definition merging boilerplate code

package.json

@@ -73,6 +73,7 @@
     "@rollup/plugin-node-resolve": "^15.0.1",
     "@rollup/plugin-sucrase": "^5.0.1",
     "@rollup/plugin-terser": "^0.4.0",
+    "@types/node": "^20.10.8",
     "@typescript-eslint/eslint-plugin": "^6.18.1",
     "@typescript-eslint/parser": "^6.18.1",
     "dotenv": "^16.0.3",

src/api.ts

@@ -1,5 +1,5 @@
-import { parse as _parse } from '@0no-co/graphql.web';
-import type { DocumentNode } from '@0no-co/graphql.web';
+import { Kind, parse as _parse } from '@0no-co/graphql.web';
+import type { DocumentNode, DefinitionNode } from '@0no-co/graphql.web';
 
 import type {
   IntrospectionQuery,
@@ -59,9 +59,32 @@ function graphql<
   const Fragments extends readonly [...FragmentDefDecorationLike[]],
 >(
   input: In,
-  _fragments?: Fragments
+  fragments?: Fragments
 ): getDocumentNode<In, Schema, getFragmentsOfDocumentsRec<Fragments>> {
-  return _parse(input) as any;
+  const definitions = _parse(input).definitions as DefinitionNode[];
+  const fragmentNames = new Map<string, unknown>();
+  for (const document of fragments || []) {
+    for (const definition of document.definitions) {
+      if (definition.kind !== Kind.FRAGMENT_DEFINITION) {
+        /*noop*/
+      } else if (!fragmentNames.has(definition.name.value)) {
+        fragmentNames.set(definition.name.value, definition);
+        definitions.push(definition);
+      } else if (
+        process.env.NODE_ENV !== 'production' &&
+        fragmentNames.get(definition.name.value) !== definition
+      ) {
+        // Fragments with the same names is expected to have the same contents
+        console.warn(
+          '[WARNING: Duplicate Fragment] A fragment with name `' +
+            definition.name.value +
+            '` already exists in this document.\n' +
+            'While fragment names may not be unique across your source, each name must be unique per document.'
+        );
+      }
+    }
+  }
+  return { kind: Kind.DOCUMENT, definitions } as any;
 }
 
 /** A GraphQL `DocumentNode` with attached generics for its result data and variables.

src/namespace.ts

@@ -1,4 +1,4 @@
-import type { Kind } from '@0no-co/graphql.web';
+import type { Kind, DocumentNode } from '@0no-co/graphql.web';
 import type { DocumentNodeLike } from './parser';
 import type { obj } from './utils';
 
@@ -33,7 +33,7 @@ type getFragmentsOfDocumentsRec<Documents> = Documents extends readonly [
   infer Document,
   ...infer Rest,
 ]
-  ? (Document extends FragmentDefDecorationLike
+  ? (Document extends { [$tada.fragmentDef]?: any }
       ? Exclude<Document[$tada.fragmentDef], undefined> extends infer FragmentDef extends {
           kind: Kind.FRAGMENT_DEFINITION;
           name: any;
@@ -45,7 +45,7 @@ type getFragmentsOfDocumentsRec<Documents> = Documents extends readonly [
       getFragmentsOfDocumentsRec<Rest>
   : {};
 
-interface FragmentDefDecorationLike {
+interface FragmentDefDecorationLike extends DocumentNode {
   [$tada.fragmentDef]?: {
     readonly [$tada.fragmentId]: symbol;
     kind: Kind.FRAGMENT_DEFINITION;