Feb 15th 2023 update

external/graphqlparser/go/.gitignore

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+go

external/graphqlparser/go/README.md

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+# About
+This directory contains an example using the libgraphqlparser C library from [Go](https://golang.org/project/).
+
+For an overview of binding to C libraries in Go, please see the [cgo documentation](https://github.com/golang/go/wiki/cgo).
+Specifically, please read the overview of [Function pointer callbacks](https://github.com/golang/go/wiki/cgo#function-pointer-callbacks) in Go and C.
+
+## Building and Running
+
+To build with Go, please ensure that you have `pkg-config` installed for your
+system.
+
+Assuming pkg-config has been installed, it should be possible to then build
+using Go in the normal fashion:
+```sh
+$ cd libgraphqlparser/go
+$ go build
+$ ./go
+field : myfield
+Example error: 1.18-19: syntax error, unexpected on, expecting ( or @ or {
+```

external/graphqlparser/go/callbacks.go

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+/**
+ * Copyright 2019-present, GraphQL Foundation
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+package main
+
+/*
+struct GraphQLAstField;
+
+int printField(struct GraphQLAstField *field, void *unused);
+
+int printField_cgo(struct GraphQLAstField *field, void *unused) {
+  return printField(field, unused);
+}
+*/
+import "C"

external/graphqlparser/go/gotest.go

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+/**
+ * Copyright 2019-present, GraphQL Foundation
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+package main
+
+/*
+#cgo pkg-config: libgraphqlparser
+
+#include "c/GraphQLAst.h"
+#include "c/GraphQLAstNode.h"
+#include "c/GraphQLAstVisitor.h"
+#include "c/GraphQLParser.h"
+#include <stdlib.h>
+
+int printField_cgo(struct GraphQLAstField *field, void *unused);
+*/
+import "C"
+
+import "errors"
+import "fmt"
+import "unsafe"
+
+//export printField
+func printField(field *C.struct_GraphQLAstField, unused unsafe.Pointer) int {
+	fmt.Printf("field : %s\n", C.GoString(C.GraphQLAstName_get_value(C.GraphQLAstField_get_name(field))))
+	return 0
+}
+
+func parse(query string) (*C.struct_GraphQLAstNode, error) {
+	graphql := C.CString(query)
+	cError := (*C.char)(nil)
+	ast := C.graphql_parse_string(graphql, &cError)
+	C.free(unsafe.Pointer(graphql))
+
+	if ast == nil {
+		err := errors.New(C.GoString(cError))
+		C.graphql_error_free(cError)
+		return nil, err
+	}
+	return ast, nil
+}
+
+func main() {
+	ast, err := parse("query myquery { myfield }")
+	if err != nil {
+		fmt.Printf("BUG: unexpected parse error: %s", err)
+		return
+	}
+	visitor_callbacks := C.struct_GraphQLAstVisitorCallbacks{visit_field: (C.visit_field_func)(C.printField_cgo)}
+	C.graphql_node_visit(ast, &visitor_callbacks, nil)
+
+	C.graphql_node_free(ast)
+
+	ast2, err2 := parse("query errorQuery on oops { myfield }")
+	if err2 != nil {
+		fmt.Printf("Example error: %s\n", err2)
+	}
+	if ast2 != nil {
+		fmt.Printf("BUG: we should have got a null AST back, but we got %s\n", ast2)
+	}
+}