A `*query.Document` printer for https://github.com/graph-gophers/graphql-go library (internal work)

print.go

package query

// Goes in internal/query/print.go

import "fmt"

func PrintGraphQLDocument(document *Document) {
	if document == nil {
		fmt.Println("Document <nil>")
		return
	}

	for i, op := range document.Operations {
		if i != 0 {
			fmt.Println("")
		}

		PrintOperation(op)
	}
}

func PrintOperation(op *Operation) {
	if op == nil {
		fmt.Println("Operation <nil>")
		return
	}

	var printSelection func(string, Selection)
	printSelection = func(indent string, sel Selection) {
		fmt.Println(indent + "Selection")
		switch v := sel.(type) {
		case *Field:
			fmt.Printf(indent+"  Field %s (%s)\n", v.Name.Name, v.Alias.Name)
			for _, subSel := range v.Selections {
				printSelection(indent+"    ", subSel)
			}
			fmt.Println("End")
		case *InlineFragment:
			fmt.Println(indent+"  InlineFragment", v.Fragment.On.Name)
		case *FragmentSpread:
			fmt.Println(indent+"  FragmentSpread", v.Name.Name)
		default:
			fmt.Printf(indent+"  Unknown %T\n", v)
		}
		fmt.Println(indent + "End")
	}

	fmt.Println("Operation", op.Name.Name, op.Type)
	for _, sel := range op.Selections {
		printSelection("  ", sel)
	}
	fmt.Println("End")
}