feat(sdlmerge): add shared types for GraphQL schema handling

Introduce types for managing fielded, enum, union, and scalar shared types.
Implement functionality for comparing values and creating field sets.
Enhance schema extensions by integrating new visitors for enum types.

sdlmerge/shared_types.go

@@ -0,0 +1,167 @@
+package sdlmerge
+
+import "github.com/wundergraph/graphql-go-tools/v2/pkg/ast"
+
+type fieldlessSharedType interface {
+	areValuesIdentical(valueRefsToCompare []int) bool
+	valueRefs() []int
+	valueName(ref int) string
+}
+
+func createValueSet(f fieldlessSharedType) map[string]bool {
+	valueSet := make(map[string]bool)
+	for _, valueRef := range f.valueRefs() {
+		valueSet[f.valueName(valueRef)] = true
+	}
+	return valueSet
+}
+
+type fieldedSharedType struct {
+	document  *ast.Document
+	fieldKind ast.NodeKind
+	fieldRefs []int
+	fieldSet  map[string]int
+}
+
+func newFieldedSharedType(document *ast.Document, fieldKind ast.NodeKind, fieldRefs []int) fieldedSharedType {
+	f := fieldedSharedType{
+		document,
+		fieldKind,
+		fieldRefs,
+		nil,
+	}
+	f.createFieldSet()
+	return f
+}
+
+func (f fieldedSharedType) areFieldsIdentical(fieldRefsToCompare []int) bool {
+	if len(f.fieldRefs) != len(fieldRefsToCompare) {
+		return false
+	}
+	for _, fieldRef := range fieldRefsToCompare {
+		actualFieldName := f.fieldName(fieldRef)
+		expectedTypeRef, exists := f.fieldSet[actualFieldName]
+		if !exists {
+			return false
+		}
+		actualTypeRef := f.fieldTypeRef(fieldRef)
+		if !f.document.TypesAreCompatibleDeep(expectedTypeRef, actualTypeRef) {
+			return false
+		}
+	}
+	return true
+}
+
+func (f *fieldedSharedType) createFieldSet() {
+	fieldSet := make(map[string]int)
+	for _, fieldRef := range f.fieldRefs {
+		fieldSet[f.fieldName(fieldRef)] = f.fieldTypeRef(fieldRef)
+	}
+	f.fieldSet = fieldSet
+}
+
+func (f fieldedSharedType) fieldName(ref int) string {
+	switch f.fieldKind {
+	case ast.NodeKindInputValueDefinition:
+		return f.document.InputValueDefinitionNameString(ref)
+	default:
+		return f.document.FieldDefinitionNameString(ref)
+	}
+}
+
+func (f fieldedSharedType) fieldTypeRef(ref int) int {
+	switch f.fieldKind {
+	case ast.NodeKindInputValueDefinition:
+		return f.document.InputValueDefinitions[ref].Type
+	default:
+		return f.document.FieldDefinitions[ref].Type
+	}
+}
+
+type enumSharedType struct {
+	*ast.EnumTypeDefinition
+	document *ast.Document
+	valueSet map[string]bool
+}
+
+func newEnumSharedType(document *ast.Document, ref int) enumSharedType {
+	e := enumSharedType{
+		&document.EnumTypeDefinitions[ref],
+		document,
+		nil,
+	}
+	e.valueSet = createValueSet(e)
+	return e
+}
+
+func (e enumSharedType) areValuesIdentical(valueRefsToCompare []int) bool {
+	if len(e.valueRefs()) != len(valueRefsToCompare) {
+		return false
+	}
+	for _, valueRefToCompare := range valueRefsToCompare {
+		name := e.valueName(valueRefToCompare)
+		if !e.valueSet[name] {
+			return false
+		}
+	}
+	return true
+}
+
+func (e enumSharedType) valueRefs() []int {
+	return e.EnumValuesDefinition.Refs
+}
+
+func (e enumSharedType) valueName(ref int) string {
+	return e.document.EnumValueDefinitionNameString(ref)
+}
+
+type unionSharedType struct {
+	*ast.UnionTypeDefinition
+	document *ast.Document
+	valueSet map[string]bool
+}
+
+func newUnionSharedType(document *ast.Document, ref int) unionSharedType {
+	u := unionSharedType{
+		&document.UnionTypeDefinitions[ref],
+		document,
+		nil,
+	}
+	u.valueSet = createValueSet(u)
+	return u
+}
+
+func (u unionSharedType) areValuesIdentical(valueRefsToCompare []int) bool {
+	if len(u.valueRefs()) != len(valueRefsToCompare) {
+		return false
+	}
+	for _, refToCompare := range valueRefsToCompare {
+		name := u.valueName(refToCompare)
+		if !u.valueSet[name] {
+			return false
+		}
+	}
+	return true
+}
+
+func (u unionSharedType) valueRefs() []int {
+	return u.UnionMemberTypes.Refs
+}
+
+func (u unionSharedType) valueName(ref int) string {
+	return u.document.TypeNameString(ref)
+}
+
+type scalarSharedType struct{}
+
+func (_ scalarSharedType) areValuesIdentical(_ []int) bool {
+	return true
+}
+
+func (_ scalarSharedType) valueRefs() []int {
+	return nil
+}
+
+func (_ scalarSharedType) valueName(_ int) string {
+	return ""
+}