unpack.go - platform/build/blueprint - Gitiles

 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package blueprint

 import (
 	"blueprint/parser"
 	"blueprint/proptools"
 	"fmt"
 	"reflect"
 	"strings"
 )

 type packedProperty struct {
 	property *parser.Property
 	unpacked bool
 }

 func unpackProperties(propertyDefs []*parser.Property,
 	propertiesStructs ...interface{}) (map[string]*parser.Property, []error) {

 	propertyMap := make(map[string]*packedProperty)
 	errs := buildPropertyMap("", propertyDefs, propertyMap)
 	if len(errs) > 0 {
 		return nil, errs
 	}

 	for _, properties := range propertiesStructs {
 		propertiesValue := reflect.ValueOf(properties)
 		if propertiesValue.Kind() != reflect.Ptr {
 			panic("properties must be a pointer to a struct")
 		}

 		propertiesValue = propertiesValue.Elem()
 		if propertiesValue.Kind() != reflect.Struct {
 			panic("properties must be a pointer to a struct")
 		}

 		newErrs := unpackStructValue("", propertiesValue, propertyMap)
 		errs = append(errs, newErrs...)

 		if len(errs) >= maxErrors {
 			return nil, errs
 		}
 	}

 	// Report any properties that didn't have corresponding struct fields as
 	// errors.
 	result := make(map[string]*parser.Property)
 	for name, packedProperty := range propertyMap {
 		result[name] = packedProperty.property
 		if !packedProperty.unpacked {
 			err := &Error{
 				Err: fmt.Errorf("unrecognized property %q", name),
 				Pos: packedProperty.property.Pos,
 			}
 			errs = append(errs, err)
 		}
 	}

 	if len(errs) > 0 {
 		return nil, errs
 	}

 	return result, nil
 }

 func buildPropertyMap(namePrefix string, propertyDefs []*parser.Property,
 	propertyMap map[string]*packedProperty) (errs []error) {

 	for _, propertyDef := range propertyDefs {
 		name := namePrefix + propertyDef.Name.Name
 		if first, present := propertyMap[name]; present {
 			if first.property == propertyDef {
 				// We've already added this property.
 				continue
 			}

 			errs = append(errs, &Error{
 				Err: fmt.Errorf("property %q already defined", name),
 				Pos: propertyDef.Pos,
 			})
 			errs = append(errs, &Error{
 				Err: fmt.Errorf("<-- previous definition here"),
 				Pos: first.property.Pos,
 			})
 			if len(errs) >= maxErrors {
 				return errs
 			}
 			continue
 		}

 		propertyMap[name] = &packedProperty{
 			property: propertyDef,
 			unpacked: false,
 		}

 		// We intentionally do not rescursively add MapValue properties to the
 		// property map here.  Instead we add them when we encounter a struct
 		// into which they can be unpacked.  We do this so that if we never
 		// encounter such a struct then the "unrecognized property" error will
 		// be reported only once for the map property and not for each of its
 		// sub-properties.
 	}

 	return
 }

 func unpackStructValue(namePrefix string, structValue reflect.Value,
 	propertyMap map[string]*packedProperty) []error {

 	structType := structValue.Type()

 	var errs []error
 	for i := 0; i < structValue.NumField(); i++ {
 		fieldValue := structValue.Field(i)
 		field := structType.Field(i)

 		if field.PkgPath != "" {
 			// This is an unexported field, so just skip it.
 			continue
 		}

 		if !fieldValue.CanSet() {
 			panic(fmt.Errorf("field %s is not settable", field.Name))
 		}

 		// To make testing easier we validate the struct field's type regardless
 		// of whether or not the property was specified in the parsed string.
 		switch kind := fieldValue.Kind(); kind {
 		case reflect.Bool, reflect.String, reflect.Struct:
 			// Do nothing
 		case reflect.Slice:
 			elemType := field.Type.Elem()
 			if elemType.Kind() != reflect.String {
 				panic(fmt.Errorf("field %s is a non-string slice", field.Name))
 			}
 		case reflect.Interface:
 			if fieldValue.IsNil() {
 				panic(fmt.Errorf("field %s contains a nil interface",
 					field.Name))
 			}
 			fieldValue = fieldValue.Elem()
 			elemType := fieldValue.Type()
 			if elemType.Kind() != reflect.Ptr {
 				panic(fmt.Errorf("field %s contains a non-pointer interface",
 					field.Name))
 			}
 			fallthrough
 		case reflect.Ptr:
 			if fieldValue.IsNil() {
 				panic(fmt.Errorf("field %s contains a nil pointer",
 					field.Name))
 			}
 			fieldValue = fieldValue.Elem()
 			elemType := fieldValue.Type()
 			if elemType.Kind() != reflect.Struct {
 				panic(fmt.Errorf("field %s contains a non-struct pointer",
 					field.Name))
 			}
 		case reflect.Int, reflect.Uint:
 			if !hasTag(field, "blueprint", "mutated") {
 				panic(fmt.Errorf(`int field %s must be tagged blueprint:"mutated"`, field.Name))
 			}

 		default:
 			panic(fmt.Errorf("unsupported kind for field %s: %s",
 				field.Name, kind))
 		}

 		// Get the property value if it was specified.
 		propertyName := namePrefix + proptools.PropertyNameForField(field.Name)
 		packedProperty, ok := propertyMap[propertyName]
 		if !ok {
 			// This property wasn't specified.
 			continue
 		}

 		var newErrs []error

 		if hasTag(field, "blueprint", "mutated") {
 			errs = append(errs,
 				fmt.Errorf("mutated field %s cannot be set in a Blueprint file", propertyName))
 			if len(errs) >= maxErrors {
 				return errs
 			}
 			continue
 		}

 		packedProperty.unpacked = true

 		switch kind := fieldValue.Kind(); kind {
 		case reflect.Bool:
 			newErrs = unpackBool(fieldValue, packedProperty.property)
 		case reflect.String:
 			newErrs = unpackString(fieldValue, packedProperty.property)
 		case reflect.Slice:
 			newErrs = unpackSlice(fieldValue, packedProperty.property)
 		case reflect.Struct:
 			newErrs = unpackStruct(propertyName+".", fieldValue,
 				packedProperty.property, propertyMap)
 		case reflect.Ptr, reflect.Interface:
 			structValue := fieldValue.Elem()
 			newErrs = unpackStruct(propertyName+".", structValue,
 				packedProperty.property, propertyMap)
 		}
 		errs = append(errs, newErrs...)
 		if len(errs) >= maxErrors {
 			return errs
 		}
 	}

 	return errs
 }

 func unpackBool(boolValue reflect.Value, property *parser.Property) []error {
 	if property.Value.Type != parser.Bool {
 		return []error{
 			fmt.Errorf("%s: can't assign %s value to %s property %q",
 				property.Value.Pos, property.Value.Type, parser.Bool,
 				property.Name),
 		}
 	}
 	boolValue.SetBool(property.Value.BoolValue)
 	return nil
 }

 func unpackString(stringValue reflect.Value,
 	property *parser.Property) []error {

 	if property.Value.Type != parser.String {
 		return []error{
 			fmt.Errorf("%s: can't assign %s value to %s property %q",
 				property.Value.Pos, property.Value.Type, parser.String,
 				property.Name),
 		}
 	}
 	stringValue.SetString(property.Value.StringValue)
 	return nil
 }

 func unpackSlice(sliceValue reflect.Value, property *parser.Property) []error {
 	if property.Value.Type != parser.List {
 		return []error{
 			fmt.Errorf("%s: can't assign %s value to %s property %q",
 				property.Value.Pos, property.Value.Type, parser.List,
 				property.Name),
 		}
 	}

 	var list []string
 	for _, value := range property.Value.ListValue {
 		if value.Type != parser.String {
 			// The parser should not produce this.
 			panic("non-string value found in list")
 		}
 		list = append(list, value.StringValue)
 	}

 	sliceValue.Set(reflect.ValueOf(list))
 	return nil
 }

 func unpackStruct(namePrefix string, structValue reflect.Value,
 	property *parser.Property,
 	propertyMap map[string]*packedProperty) []error {

 	if property.Value.Type != parser.Map {
 		return []error{
 			fmt.Errorf("%s: can't assign %s value to %s property %q",
 				property.Value.Pos, property.Value.Type, parser.Map,
 				property.Name),
 		}
 	}

 	errs := buildPropertyMap(namePrefix, property.Value.MapValue, propertyMap)
 	if len(errs) > 0 {
 		return errs
 	}

 	return unpackStructValue(namePrefix, structValue, propertyMap)
 }

 func hasTag(field reflect.StructField, name, value string) bool {
 	tag := field.Tag.Get(name)
 	for _, entry := range strings.Split(tag, ",") {
 		if entry == value {
 			return true
 		}
 	}

 	return false
 }
	// Copyright 2014 Google Inc. All rights reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package blueprint

	import (
	"blueprint/parser"
	"blueprint/proptools"
	"fmt"
	"reflect"
	"strings"
	)

	type packedProperty struct {
	property *parser.Property
	unpacked bool
	}

	func unpackProperties(propertyDefs []*parser.Property,
	propertiesStructs ...interface{}) (map[string]*parser.Property, []error) {

	propertyMap := make(map[string]*packedProperty)
	errs := buildPropertyMap("", propertyDefs, propertyMap)
	if len(errs) > 0 {
	return nil, errs
	}

	for _, properties := range propertiesStructs {
	propertiesValue := reflect.ValueOf(properties)
	if propertiesValue.Kind() != reflect.Ptr {
	panic("properties must be a pointer to a struct")
	}

	propertiesValue = propertiesValue.Elem()
	if propertiesValue.Kind() != reflect.Struct {
	panic("properties must be a pointer to a struct")
	}

	newErrs := unpackStructValue("", propertiesValue, propertyMap)
	errs = append(errs, newErrs...)

	if len(errs) >= maxErrors {
	return nil, errs
	}
	}

	// Report any properties that didn't have corresponding struct fields as
	// errors.
	result := make(map[string]*parser.Property)
	for name, packedProperty := range propertyMap {
	result[name] = packedProperty.property
	if !packedProperty.unpacked {
	err := &Error{
	Err: fmt.Errorf("unrecognized property %q", name),
	Pos: packedProperty.property.Pos,
	}
	errs = append(errs, err)
	}
	}

	if len(errs) > 0 {
	return nil, errs
	}

	return result, nil
	}

	func buildPropertyMap(namePrefix string, propertyDefs []*parser.Property,
	propertyMap map[string]*packedProperty) (errs []error) {

	for _, propertyDef := range propertyDefs {
	name := namePrefix + propertyDef.Name.Name
	if first, present := propertyMap[name]; present {
	if first.property == propertyDef {
	// We've already added this property.
	continue
	}

	errs = append(errs, &Error{
	Err: fmt.Errorf("property %q already defined", name),
	Pos: propertyDef.Pos,
	})
	errs = append(errs, &Error{
	Err: fmt.Errorf("<-- previous definition here"),
	Pos: first.property.Pos,
	})
	if len(errs) >= maxErrors {
	return errs
	}
	continue
	}

	propertyMap[name] = &packedProperty{
	property: propertyDef,
	unpacked: false,
	}

	// We intentionally do not rescursively add MapValue properties to the
	// property map here. Instead we add them when we encounter a struct
	// into which they can be unpacked. We do this so that if we never
	// encounter such a struct then the "unrecognized property" error will
	// be reported only once for the map property and not for each of its
	// sub-properties.
	}

	return
	}

	func unpackStructValue(namePrefix string, structValue reflect.Value,
	propertyMap map[string]*packedProperty) []error {

	structType := structValue.Type()

	var errs []error
	for i := 0; i < structValue.NumField(); i++ {
	fieldValue := structValue.Field(i)
	field := structType.Field(i)

	if field.PkgPath != "" {
	// This is an unexported field, so just skip it.
	continue
	}

	if !fieldValue.CanSet() {
	panic(fmt.Errorf("field %s is not settable", field.Name))
	}

	// To make testing easier we validate the struct field's type regardless
	// of whether or not the property was specified in the parsed string.
	switch kind := fieldValue.Kind(); kind {
	case reflect.Bool, reflect.String, reflect.Struct:
	// Do nothing
	case reflect.Slice:
	elemType := field.Type.Elem()
	if elemType.Kind() != reflect.String {
	panic(fmt.Errorf("field %s is a non-string slice", field.Name))
	}
	case reflect.Interface:
	if fieldValue.IsNil() {
	panic(fmt.Errorf("field %s contains a nil interface",
	field.Name))
	}
	fieldValue = fieldValue.Elem()
	elemType := fieldValue.Type()
	if elemType.Kind() != reflect.Ptr {
	panic(fmt.Errorf("field %s contains a non-pointer interface",
	field.Name))
	}
	fallthrough
	case reflect.Ptr:
	if fieldValue.IsNil() {
	panic(fmt.Errorf("field %s contains a nil pointer",
	field.Name))
	}
	fieldValue = fieldValue.Elem()
	elemType := fieldValue.Type()
	if elemType.Kind() != reflect.Struct {
	panic(fmt.Errorf("field %s contains a non-struct pointer",
	field.Name))
	}
	case reflect.Int, reflect.Uint:
	if !hasTag(field, "blueprint", "mutated") {
	panic(fmt.Errorf(`int field %s must be tagged blueprint:"mutated"`, field.Name))
	}

	default:
	panic(fmt.Errorf("unsupported kind for field %s: %s",
	field.Name, kind))
	}

	// Get the property value if it was specified.
	propertyName := namePrefix + proptools.PropertyNameForField(field.Name)
	packedProperty, ok := propertyMap[propertyName]
	if !ok {
	// This property wasn't specified.
	continue
	}

	var newErrs []error

	if hasTag(field, "blueprint", "mutated") {
	errs = append(errs,
	fmt.Errorf("mutated field %s cannot be set in a Blueprint file", propertyName))
	if len(errs) >= maxErrors {
	return errs
	}
	continue
	}

	packedProperty.unpacked = true

	switch kind := fieldValue.Kind(); kind {
	case reflect.Bool:
	newErrs = unpackBool(fieldValue, packedProperty.property)
	case reflect.String:
	newErrs = unpackString(fieldValue, packedProperty.property)
	case reflect.Slice:
	newErrs = unpackSlice(fieldValue, packedProperty.property)
	case reflect.Struct:
	newErrs = unpackStruct(propertyName+".", fieldValue,
	packedProperty.property, propertyMap)
	case reflect.Ptr, reflect.Interface:
	structValue := fieldValue.Elem()
	newErrs = unpackStruct(propertyName+".", structValue,
	packedProperty.property, propertyMap)
	}
	errs = append(errs, newErrs...)
	if len(errs) >= maxErrors {
	return errs
	}
	}

	return errs
	}

	func unpackBool(boolValue reflect.Value, property *parser.Property) []error {
	if property.Value.Type != parser.Bool {
	return []error{
	fmt.Errorf("%s: can't assign %s value to %s property %q",
	property.Value.Pos, property.Value.Type, parser.Bool,
	property.Name),
	}
	}
	boolValue.SetBool(property.Value.BoolValue)
	return nil
	}

	func unpackString(stringValue reflect.Value,
	property *parser.Property) []error {

	if property.Value.Type != parser.String {
	return []error{
	fmt.Errorf("%s: can't assign %s value to %s property %q",
	property.Value.Pos, property.Value.Type, parser.String,
	property.Name),
	}
	}
	stringValue.SetString(property.Value.StringValue)
	return nil
	}

	func unpackSlice(sliceValue reflect.Value, property *parser.Property) []error {
	if property.Value.Type != parser.List {
	return []error{
	fmt.Errorf("%s: can't assign %s value to %s property %q",
	property.Value.Pos, property.Value.Type, parser.List,
	property.Name),
	}
	}

	var list []string
	for _, value := range property.Value.ListValue {
	if value.Type != parser.String {
	// The parser should not produce this.
	panic("non-string value found in list")
	}
	list = append(list, value.StringValue)
	}

	sliceValue.Set(reflect.ValueOf(list))
	return nil
	}

	func unpackStruct(namePrefix string, structValue reflect.Value,
	property *parser.Property,
	propertyMap map[string]*packedProperty) []error {

	if property.Value.Type != parser.Map {
	return []error{
	fmt.Errorf("%s: can't assign %s value to %s property %q",
	property.Value.Pos, property.Value.Type, parser.Map,
	property.Name),
	}
	}

	errs := buildPropertyMap(namePrefix, property.Value.MapValue, propertyMap)
	if len(errs) > 0 {
	return errs
	}

	return unpackStructValue(namePrefix, structValue, propertyMap)
	}

	func hasTag(field reflect.StructField, name, value string) bool {
	tag := field.Tag.Get(name)
	for _, entry := range strings.Split(tag, ",") {
	if entry == value {
	return true
	}
	}

	return false
	}