bp2build/build_conversion.go - platform/build/soong - Git at Google

 // Copyright 2020 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 bp2build

 import (
 	"android/soong/android"
 	"android/soong/bazel"
 	"fmt"
 	"reflect"
 	"sort"
 	"strings"

 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
 )

 type BazelAttributes struct {
 	Attrs map[string]string
 }

 type BazelTarget struct {
 	name            string
 	content         string
 	ruleClass       string
 	bzlLoadLocation string
 	handcrafted     bool
 }

 // IsLoadedFromStarlark determines if the BazelTarget's rule class is loaded from a .bzl file,
 // as opposed to a native rule built into Bazel.
 func (t BazelTarget) IsLoadedFromStarlark() bool {
 	return t.bzlLoadLocation != ""
 }

 // BazelTargets is a typedef for a slice of BazelTarget objects.
 type BazelTargets []BazelTarget

 // HasHandcraftedTargetsreturns true if a set of bazel targets contain
 // handcrafted ones.
 func (targets BazelTargets) hasHandcraftedTargets() bool {
 	for _, target := range targets {
 		if target.handcrafted {
 			return true
 		}
 	}
 	return false
 }

 // sort a list of BazelTargets in-place, by name, and by generated/handcrafted types.
 func (targets BazelTargets) sort() {
 	sort.Slice(targets, func(i, j int) bool {
 		if targets[i].handcrafted != targets[j].handcrafted {
 			// Handcrafted targets will be generated after the bp2build generated targets.
 			return targets[j].handcrafted
 		}
 		// This will cover all bp2build generated targets.
 		return targets[i].name < targets[j].name
 	})
 }

 // String returns the string representation of BazelTargets, without load
 // statements (use LoadStatements for that), since the targets are usually not
 // adjacent to the load statements at the top of the BUILD file.
 func (targets BazelTargets) String() string {
 	var res string
 	for i, target := range targets {
 		// There is only at most 1 handcrafted "target", because its contents
 		// represent the entire BUILD file content from the tree. See
 		// build_conversion.go#getHandcraftedBuildContent for more information.
 		//
 		// Add a header to make it easy to debug where the handcrafted targets
 		// are in a generated BUILD file.
 		if target.handcrafted {
 			res += "# -----------------------------\n"
 			res += "# Section: Handcrafted targets. \n"
 			res += "# -----------------------------\n\n"
 		}

 		res += target.content
 		if i != len(targets)-1 {
 			res += "\n\n"
 		}
 	}
 	return res
 }

 // LoadStatements return the string representation of the sorted and deduplicated
 // Starlark rule load statements needed by a group of BazelTargets.
 func (targets BazelTargets) LoadStatements() string {
 	bzlToLoadedSymbols := map[string][]string{}
 	for _, target := range targets {
 		if target.IsLoadedFromStarlark() {
 			bzlToLoadedSymbols[target.bzlLoadLocation] =
 				append(bzlToLoadedSymbols[target.bzlLoadLocation], target.ruleClass)
 		}
 	}

 	var loadStatements []string
 	for bzl, ruleClasses := range bzlToLoadedSymbols {
 		loadStatement := "load(\""
 		loadStatement += bzl
 		loadStatement += "\", "
 		ruleClasses = android.SortedUniqueStrings(ruleClasses)
 		for i, ruleClass := range ruleClasses {
 			loadStatement += "\"" + ruleClass + "\""
 			if i != len(ruleClasses)-1 {
 				loadStatement += ", "
 			}
 		}
 		loadStatement += ")"
 		loadStatements = append(loadStatements, loadStatement)
 	}
 	return strings.Join(android.SortedUniqueStrings(loadStatements), "\n")
 }

 type bpToBuildContext interface {
 	ModuleName(module blueprint.Module) string
 	ModuleDir(module blueprint.Module) string
 	ModuleSubDir(module blueprint.Module) string
 	ModuleType(module blueprint.Module) string

 	VisitAllModules(visit func(blueprint.Module))
 	VisitDirectDeps(module blueprint.Module, visit func(blueprint.Module))
 }

 type CodegenContext struct {
 	config         android.Config
 	context        android.Context
 	mode           CodegenMode
 	additionalDeps []string
 }

 func (c *CodegenContext) Mode() CodegenMode {
 	return c.mode
 }

 // CodegenMode is an enum to differentiate code-generation modes.
 type CodegenMode int

 const (
 	// Bp2Build: generate BUILD files with targets buildable by Bazel directly.
 	//
 	// This mode is used for the Soong->Bazel build definition conversion.
 	Bp2Build CodegenMode = iota

 	// QueryView: generate BUILD files with targets representing fully mutated
 	// Soong modules, representing the fully configured Soong module graph with
 	// variants and dependency endges.
 	//
 	// This mode is used for discovering and introspecting the existing Soong
 	// module graph.
 	QueryView
 )

 func (mode CodegenMode) String() string {
 	switch mode {
 	case Bp2Build:
 		return "Bp2Build"
 	case QueryView:
 		return "QueryView"
 	default:
 		return fmt.Sprintf("%d", mode)
 	}
 }

 // AddNinjaFileDeps adds dependencies on the specified files to be added to the ninja manifest. The
 // primary builder will be rerun whenever the specified files are modified. Allows us to fulfill the
 // PathContext interface in order to add dependencies on hand-crafted BUILD files. Note: must also
 // call AdditionalNinjaDeps and add them manually to the ninja file.
 func (ctx *CodegenContext) AddNinjaFileDeps(deps ...string) {
 	ctx.additionalDeps = append(ctx.additionalDeps, deps...)
 }

 // AdditionalNinjaDeps returns additional ninja deps added by CodegenContext
 func (ctx *CodegenContext) AdditionalNinjaDeps() []string {
 	return ctx.additionalDeps
 }

 func (ctx *CodegenContext) Config() android.Config   { return ctx.config }
 func (ctx *CodegenContext) Context() android.Context { return ctx.context }

 // NewCodegenContext creates a wrapper context that conforms to PathContext for
 // writing BUILD files in the output directory.
 func NewCodegenContext(config android.Config, context android.Context, mode CodegenMode) *CodegenContext {
 	return &CodegenContext{
 		context: context,
 		config:  config,
 		mode:    mode,
 	}
 }

 // props is an unsorted map. This function ensures that
 // the generated attributes are sorted to ensure determinism.
 func propsToAttributes(props map[string]string) string {
 	var attributes string
 	for _, propName := range android.SortedStringKeys(props) {
 		if shouldGenerateAttribute(propName) {
 			attributes += fmt.Sprintf("    %s = %s,\n", propName, props[propName])
 		}
 	}
 	return attributes
 }

 func GenerateBazelTargets(ctx *CodegenContext, generateFilegroups bool) (map[string]BazelTargets, CodegenMetrics) {
 	buildFileToTargets := make(map[string]BazelTargets)
 	buildFileToAppend := make(map[string]bool)

 	// Simple metrics tracking for bp2build
 	metrics := CodegenMetrics{
 		RuleClassCount: make(map[string]int),
 	}

 	dirs := make(map[string]bool)

 	bpCtx := ctx.Context()
 	bpCtx.VisitAllModules(func(m blueprint.Module) {
 		dir := bpCtx.ModuleDir(m)
 		dirs[dir] = true

 		var t BazelTarget

 		switch ctx.Mode() {
 		case Bp2Build:
 			if b, ok := m.(android.Bazelable); ok && b.HasHandcraftedLabel() {
 				metrics.handCraftedTargetCount += 1
 				metrics.TotalModuleCount += 1
 				pathToBuildFile := getBazelPackagePath(b)
 				// We are using the entire contents of handcrafted build file, so if multiple targets within
 				// a package have handcrafted targets, we only want to include the contents one time.
 				if _, exists := buildFileToAppend[pathToBuildFile]; exists {
 					return
 				}
 				var err error
 				t, err = getHandcraftedBuildContent(ctx, b, pathToBuildFile)
 				if err != nil {
 					panic(fmt.Errorf("Error converting %s: %s", bpCtx.ModuleName(m), err))
 				}
 				// TODO(b/181575318): currently we append the whole BUILD file, let's change that to do
 				// something more targeted based on the rule type and target
 				buildFileToAppend[pathToBuildFile] = true
 			} else if btm, ok := m.(android.BazelTargetModule); ok {
 				t = generateBazelTarget(bpCtx, m, btm)
 				metrics.RuleClassCount[t.ruleClass] += 1
 			} else {
 				metrics.TotalModuleCount += 1
 				return
 			}
 		case QueryView:
 			// Blocklist certain module types from being generated.
 			if canonicalizeModuleType(bpCtx.ModuleType(m)) == "package" {
 				// package module name contain slashes, and thus cannot
 				// be mapped cleanly to a bazel label.
 				return
 			}
 			t = generateSoongModuleTarget(bpCtx, m)
 		default:
 			panic(fmt.Errorf("Unknown code-generation mode: %s", ctx.Mode()))
 		}

 		buildFileToTargets[dir] = append(buildFileToTargets[dir], t)
 	})
 	if generateFilegroups {
 		// Add a filegroup target that exposes all sources in the subtree of this package
 		// NOTE: This also means we generate a BUILD file for every Android.bp file (as long as it has at least one module)
 		for dir, _ := range dirs {
 			buildFileToTargets[dir] = append(buildFileToTargets[dir], BazelTarget{
 				name:      "bp2build_all_srcs",
 				content:   `filegroup(name = "bp2build_all_srcs", srcs = glob(["**/*"]))`,
 				ruleClass: "filegroup",
 			})
 		}
 	}

 	return buildFileToTargets, metrics
 }

 func getBazelPackagePath(b android.Bazelable) string {
 	label := b.HandcraftedLabel()
 	pathToBuildFile := strings.TrimPrefix(label, "//")
 	pathToBuildFile = strings.Split(pathToBuildFile, ":")[0]
 	return pathToBuildFile
 }

 func getHandcraftedBuildContent(ctx *CodegenContext, b android.Bazelable, pathToBuildFile string) (BazelTarget, error) {
 	p := android.ExistentPathForSource(ctx, pathToBuildFile, HandcraftedBuildFileName)
 	if !p.Valid() {
 		return BazelTarget{}, fmt.Errorf("Could not find file %q for handcrafted target.", pathToBuildFile)
 	}
 	c, err := b.GetBazelBuildFileContents(ctx.Config(), pathToBuildFile, HandcraftedBuildFileName)
 	if err != nil {
 		return BazelTarget{}, err
 	}
 	// TODO(b/181575318): once this is more targeted, we need to include name, rule class, etc
 	return BazelTarget{
 		content:     c,
 		handcrafted: true,
 	}, nil
 }

 func generateBazelTarget(ctx bpToBuildContext, m blueprint.Module, btm android.BazelTargetModule) BazelTarget {
 	ruleClass := btm.RuleClass()
 	bzlLoadLocation := btm.BzlLoadLocation()

 	// extract the bazel attributes from the module.
 	props := getBuildProperties(ctx, m)

 	delete(props.Attrs, "bp2build_available")

 	// Return the Bazel target with rule class and attributes, ready to be
 	// code-generated.
 	attributes := propsToAttributes(props.Attrs)
 	targetName := targetNameForBp2Build(ctx, m)
 	return BazelTarget{
 		name:            targetName,
 		ruleClass:       ruleClass,
 		bzlLoadLocation: bzlLoadLocation,
 		content: fmt.Sprintf(
 			bazelTarget,
 			ruleClass,
 			targetName,
 			attributes,
 		),
 		handcrafted: false,
 	}
 }

 // Convert a module and its deps and props into a Bazel macro/rule
 // representation in the BUILD file.
 func generateSoongModuleTarget(ctx bpToBuildContext, m blueprint.Module) BazelTarget {
 	props := getBuildProperties(ctx, m)

 	// TODO(b/163018919): DirectDeps can have duplicate (module, variant)
 	// items, if the modules are added using different DependencyTag. Figure
 	// out the implications of that.
 	depLabels := map[string]bool{}
 	if aModule, ok := m.(android.Module); ok {
 		ctx.VisitDirectDeps(aModule, func(depModule blueprint.Module) {
 			depLabels[qualifiedTargetLabel(ctx, depModule)] = true
 		})
 	}
 	attributes := propsToAttributes(props.Attrs)

 	depLabelList := "[\n"
 	for depLabel, _ := range depLabels {
 		depLabelList += fmt.Sprintf("        %q,\n", depLabel)
 	}
 	depLabelList += "    ]"

 	targetName := targetNameWithVariant(ctx, m)
 	return BazelTarget{
 		name: targetName,
 		content: fmt.Sprintf(
 			soongModuleTarget,
 			targetName,
 			ctx.ModuleName(m),
 			canonicalizeModuleType(ctx.ModuleType(m)),
 			ctx.ModuleSubDir(m),
 			depLabelList,
 			attributes),
 	}
 }

 func getBuildProperties(ctx bpToBuildContext, m blueprint.Module) BazelAttributes {
 	var allProps map[string]string
 	// TODO: this omits properties for blueprint modules (blueprint_go_binary,
 	// bootstrap_go_binary, bootstrap_go_package), which will have to be handled separately.
 	if aModule, ok := m.(android.Module); ok {
 		allProps = ExtractModuleProperties(aModule)
 	}

 	return BazelAttributes{
 		Attrs: allProps,
 	}
 }

 // Generically extract module properties and types into a map, keyed by the module property name.
 func ExtractModuleProperties(aModule android.Module) map[string]string {
 	ret := map[string]string{}

 	// Iterate over this android.Module's property structs.
 	for _, properties := range aModule.GetProperties() {
 		propertiesValue := reflect.ValueOf(properties)
 		// Check that propertiesValue is a pointer to the Properties struct, like
 		// *cc.BaseLinkerProperties or *java.CompilerProperties.
 		//
 		// propertiesValue can also be type-asserted to the structs to
 		// manipulate internal props, if needed.
 		if isStructPtr(propertiesValue.Type()) {
 			structValue := propertiesValue.Elem()
 			for k, v := range extractStructProperties(structValue, 0) {
 				ret[k] = v
 			}
 		} else {
 			panic(fmt.Errorf(
 				"properties must be a pointer to a struct, got %T",
 				propertiesValue.Interface()))
 		}
 	}

 	return ret
 }

 func isStructPtr(t reflect.Type) bool {
 	return t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct
 }

 // prettyPrint a property value into the equivalent Starlark representation
 // recursively.
 func prettyPrint(propertyValue reflect.Value, indent int) (string, error) {
 	if isZero(propertyValue) {
 		// A property value being set or unset actually matters -- Soong does set default
 		// values for unset properties, like system_shared_libs = ["libc", "libm", "libdl"] at
 		// https://cs.android.com/android/platform/superproject/+/master:build/soong/cc/linker.go;l=281-287;drc=f70926eef0b9b57faf04c17a1062ce50d209e480
 		//
 		// In Bazel-parlance, we would use "attr.<type>(default = <default
 		// value>)" to set the default value of unset attributes. In the cases
 		// where the bp2build converter didn't set the default value within the
 		// mutator when creating the BazelTargetModule, this would be a zero
 		// value. For those cases, we return an empty string so we don't
 		// unnecessarily generate empty values.
 		return "", nil
 	}

 	var ret string
 	switch propertyValue.Kind() {
 	case reflect.String:
 		ret = fmt.Sprintf("\"%v\"", escapeString(propertyValue.String()))
 	case reflect.Bool:
 		ret = strings.Title(fmt.Sprintf("%v", propertyValue.Interface()))
 	case reflect.Int, reflect.Uint, reflect.Int64:
 		ret = fmt.Sprintf("%v", propertyValue.Interface())
 	case reflect.Ptr:
 		return prettyPrint(propertyValue.Elem(), indent)
 	case reflect.Slice:
 		if propertyValue.Len() == 0 {
 			return "[]", nil
 		}

 		if propertyValue.Len() == 1 {
 			// Single-line list for list with only 1 element
 			ret += "["
 			indexedValue, err := prettyPrint(propertyValue.Index(0), indent)
 			if err != nil {
 				return "", err
 			}
 			ret += indexedValue
 			ret += "]"
 		} else {
 			// otherwise, use a multiline list.
 			ret += "[\n"
 			for i := 0; i < propertyValue.Len(); i++ {
 				indexedValue, err := prettyPrint(propertyValue.Index(i), indent+1)
 				if err != nil {
 					return "", err
 				}

 				if indexedValue != "" {
 					ret += makeIndent(indent + 1)
 					ret += indexedValue
 					ret += ",\n"
 				}
 			}
 			ret += makeIndent(indent)
 			ret += "]"
 		}

 	case reflect.Struct:
 		// Special cases where the bp2build sends additional information to the codegenerator
 		// by wrapping the attributes in a custom struct type.
 		if attr, ok := propertyValue.Interface().(bazel.Attribute); ok {
 			return prettyPrintAttribute(attr, indent)
 		} else if label, ok := propertyValue.Interface().(bazel.Label); ok {
 			return fmt.Sprintf("%q", label.Label), nil
 		}

 		ret = "{\n"
 		// Sort and print the struct props by the key.
 		structProps := extractStructProperties(propertyValue, indent)
 		if len(structProps) == 0 {
 			return "", nil
 		}
 		for _, k := range android.SortedStringKeys(structProps) {
 			ret += makeIndent(indent + 1)
 			ret += fmt.Sprintf("%q: %s,\n", k, structProps[k])
 		}
 		ret += makeIndent(indent)
 		ret += "}"
 	case reflect.Interface:
 		// TODO(b/164227191): implement pretty print for interfaces.
 		// Interfaces are used for for arch, multilib and target properties.
 		return "", nil
 	default:
 		return "", fmt.Errorf(
 			"unexpected kind for property struct field: %s", propertyValue.Kind())
 	}
 	return ret, nil
 }

 // Converts a reflected property struct value into a map of property names and property values,
 // which each property value correctly pretty-printed and indented at the right nest level,
 // since property structs can be nested. In Starlark, nested structs are represented as nested
 // dicts: https://docs.bazel.build/skylark/lib/dict.html
 func extractStructProperties(structValue reflect.Value, indent int) map[string]string {
 	if structValue.Kind() != reflect.Struct {
 		panic(fmt.Errorf("Expected a reflect.Struct type, but got %s", structValue.Kind()))
 	}

 	ret := map[string]string{}
 	structType := structValue.Type()
 	for i := 0; i < structValue.NumField(); i++ {
 		field := structType.Field(i)
 		if shouldSkipStructField(field) {
 			continue
 		}

 		fieldValue := structValue.Field(i)
 		if isZero(fieldValue) {
 			// Ignore zero-valued fields
 			continue
 		}

 		propertyName := proptools.PropertyNameForField(field.Name)
 		prettyPrintedValue, err := prettyPrint(fieldValue, indent+1)
 		if err != nil {
 			panic(
 				fmt.Errorf(
 					"Error while parsing property: %q. %s",
 					propertyName,
 					err))
 		}
 		if prettyPrintedValue != "" {
 			ret[propertyName] = prettyPrintedValue
 		}
 	}

 	return ret
 }

 func isZero(value reflect.Value) bool {
 	switch value.Kind() {
 	case reflect.Func, reflect.Map, reflect.Slice:
 		return value.IsNil()
 	case reflect.Array:
 		valueIsZero := true
 		for i := 0; i < value.Len(); i++ {
 			valueIsZero = valueIsZero && isZero(value.Index(i))
 		}
 		return valueIsZero
 	case reflect.Struct:
 		valueIsZero := true
 		for i := 0; i < value.NumField(); i++ {
 			valueIsZero = valueIsZero && isZero(value.Field(i))
 		}
 		return valueIsZero
 	case reflect.Ptr:
 		if !value.IsNil() {
 			return isZero(reflect.Indirect(value))
 		} else {
 			return true
 		}
 	// Always print bools, if you want a bool attribute to be able to take the default value, use a
 	// bool pointer instead
 	case reflect.Bool:
 		return false
 	default:
 		if !value.IsValid() {
 			return true
 		}
 		zeroValue := reflect.Zero(value.Type())
 		result := value.Interface() == zeroValue.Interface()
 		return result
 	}
 }

 func escapeString(s string) string {
 	s = strings.ReplaceAll(s, "\\", "\\\\")

 	// b/184026959: Reverse the application of some common control sequences.
 	// These must be generated literally in the BUILD file.
 	s = strings.ReplaceAll(s, "\t", "\\t")
 	s = strings.ReplaceAll(s, "\n", "\\n")
 	s = strings.ReplaceAll(s, "\r", "\\r")

 	return strings.ReplaceAll(s, "\"", "\\\"")
 }

 func makeIndent(indent int) string {
 	if indent < 0 {
 		panic(fmt.Errorf("indent column cannot be less than 0, but got %d", indent))
 	}
 	return strings.Repeat("    ", indent)
 }

 func targetNameForBp2Build(c bpToBuildContext, logicModule blueprint.Module) string {
 	return strings.Replace(c.ModuleName(logicModule), bazel.BazelTargetModuleNamePrefix, "", 1)
 }

 func targetNameWithVariant(c bpToBuildContext, logicModule blueprint.Module) string {
 	name := ""
 	if c.ModuleSubDir(logicModule) != "" {
 		// TODO(b/162720883): Figure out a way to drop the "--" variant suffixes.
 		name = c.ModuleName(logicModule) + "--" + c.ModuleSubDir(logicModule)
 	} else {
 		name = c.ModuleName(logicModule)
 	}

 	return strings.Replace(name, "//", "", 1)
 }

 func qualifiedTargetLabel(c bpToBuildContext, logicModule blueprint.Module) string {
 	return fmt.Sprintf("//%s:%s", c.ModuleDir(logicModule), targetNameWithVariant(c, logicModule))
 }
	// Copyright 2020 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 bp2build

	import (
	"android/soong/android"
	"android/soong/bazel"
	"fmt"
	"reflect"
	"sort"
	"strings"

	"github.com/google/blueprint"
	"github.com/google/blueprint/proptools"
	)

	type BazelAttributes struct {
	Attrs map[string]string
	}

	type BazelTarget struct {
	name string
	content string
	ruleClass string
	bzlLoadLocation string
	handcrafted bool
	}

	// IsLoadedFromStarlark determines if the BazelTarget's rule class is loaded from a .bzl file,
	// as opposed to a native rule built into Bazel.
	func (t BazelTarget) IsLoadedFromStarlark() bool {
	return t.bzlLoadLocation != ""
	}

	// BazelTargets is a typedef for a slice of BazelTarget objects.
	type BazelTargets []BazelTarget

	// HasHandcraftedTargetsreturns true if a set of bazel targets contain
	// handcrafted ones.
	func (targets BazelTargets) hasHandcraftedTargets() bool {
	for _, target := range targets {
	if target.handcrafted {
	return true
	}
	}
	return false
	}

	// sort a list of BazelTargets in-place, by name, and by generated/handcrafted types.
	func (targets BazelTargets) sort() {
	sort.Slice(targets, func(i, j int) bool {
	if targets[i].handcrafted != targets[j].handcrafted {
	// Handcrafted targets will be generated after the bp2build generated targets.
	return targets[j].handcrafted
	}
	// This will cover all bp2build generated targets.
	return targets[i].name < targets[j].name
	})
	}

	// String returns the string representation of BazelTargets, without load
	// statements (use LoadStatements for that), since the targets are usually not
	// adjacent to the load statements at the top of the BUILD file.
	func (targets BazelTargets) String() string {
	var res string
	for i, target := range targets {
	// There is only at most 1 handcrafted "target", because its contents
	// represent the entire BUILD file content from the tree. See
	// build_conversion.go#getHandcraftedBuildContent for more information.
	//
	// Add a header to make it easy to debug where the handcrafted targets
	// are in a generated BUILD file.
	if target.handcrafted {
	res += "# -----------------------------\n"
	res += "# Section: Handcrafted targets. \n"
	res += "# -----------------------------\n\n"
	}

	res += target.content
	if i != len(targets)-1 {
	res += "\n\n"
	}
	}
	return res
	}

	// LoadStatements return the string representation of the sorted and deduplicated
	// Starlark rule load statements needed by a group of BazelTargets.
	func (targets BazelTargets) LoadStatements() string {
	bzlToLoadedSymbols := map[string][]string{}
	for _, target := range targets {
	if target.IsLoadedFromStarlark() {
	bzlToLoadedSymbols[target.bzlLoadLocation] =
	append(bzlToLoadedSymbols[target.bzlLoadLocation], target.ruleClass)
	}
	}

	var loadStatements []string
	for bzl, ruleClasses := range bzlToLoadedSymbols {
	loadStatement := "load(\""
	loadStatement += bzl
	loadStatement += "\", "
	ruleClasses = android.SortedUniqueStrings(ruleClasses)
	for i, ruleClass := range ruleClasses {
	loadStatement += "\"" + ruleClass + "\""
	if i != len(ruleClasses)-1 {
	loadStatement += ", "
	}
	}
	loadStatement += ")"
	loadStatements = append(loadStatements, loadStatement)
	}
	return strings.Join(android.SortedUniqueStrings(loadStatements), "\n")
	}

	type bpToBuildContext interface {
	ModuleName(module blueprint.Module) string
	ModuleDir(module blueprint.Module) string
	ModuleSubDir(module blueprint.Module) string
	ModuleType(module blueprint.Module) string

	VisitAllModules(visit func(blueprint.Module))
	VisitDirectDeps(module blueprint.Module, visit func(blueprint.Module))
	}

	type CodegenContext struct {
	config android.Config
	context android.Context
	mode CodegenMode
	additionalDeps []string
	}

	func (c *CodegenContext) Mode() CodegenMode {
	return c.mode
	}

	// CodegenMode is an enum to differentiate code-generation modes.
	type CodegenMode int

	const (
	// Bp2Build: generate BUILD files with targets buildable by Bazel directly.
	//
	// This mode is used for the Soong->Bazel build definition conversion.
	Bp2Build CodegenMode = iota

	// QueryView: generate BUILD files with targets representing fully mutated
	// Soong modules, representing the fully configured Soong module graph with
	// variants and dependency endges.
	//
	// This mode is used for discovering and introspecting the existing Soong
	// module graph.
	QueryView
	)

	func (mode CodegenMode) String() string {
	switch mode {
	case Bp2Build:
	return "Bp2Build"
	case QueryView:
	return "QueryView"
	default:
	return fmt.Sprintf("%d", mode)
	}
	}

	// AddNinjaFileDeps adds dependencies on the specified files to be added to the ninja manifest. The
	// primary builder will be rerun whenever the specified files are modified. Allows us to fulfill the
	// PathContext interface in order to add dependencies on hand-crafted BUILD files. Note: must also
	// call AdditionalNinjaDeps and add them manually to the ninja file.
	func (ctx *CodegenContext) AddNinjaFileDeps(deps ...string) {
	ctx.additionalDeps = append(ctx.additionalDeps, deps...)
	}

	// AdditionalNinjaDeps returns additional ninja deps added by CodegenContext
	func (ctx *CodegenContext) AdditionalNinjaDeps() []string {
	return ctx.additionalDeps
	}

	func (ctx *CodegenContext) Config() android.Config { return ctx.config }
	func (ctx *CodegenContext) Context() android.Context { return ctx.context }

	// NewCodegenContext creates a wrapper context that conforms to PathContext for
	// writing BUILD files in the output directory.
	func NewCodegenContext(config android.Config, context android.Context, mode CodegenMode) *CodegenContext {
	return &CodegenContext{
	context: context,
	config: config,
	mode: mode,
	}
	}

	// props is an unsorted map. This function ensures that
	// the generated attributes are sorted to ensure determinism.
	func propsToAttributes(props map[string]string) string {
	var attributes string
	for _, propName := range android.SortedStringKeys(props) {
	if shouldGenerateAttribute(propName) {
	attributes += fmt.Sprintf(" %s = %s,\n", propName, props[propName])
	}
	}
	return attributes
	}

	func GenerateBazelTargets(ctx *CodegenContext, generateFilegroups bool) (map[string]BazelTargets, CodegenMetrics) {
	buildFileToTargets := make(map[string]BazelTargets)
	buildFileToAppend := make(map[string]bool)

	// Simple metrics tracking for bp2build
	metrics := CodegenMetrics{
	RuleClassCount: make(map[string]int),
	}

	dirs := make(map[string]bool)

	bpCtx := ctx.Context()
	bpCtx.VisitAllModules(func(m blueprint.Module) {
	dir := bpCtx.ModuleDir(m)
	dirs[dir] = true

	var t BazelTarget

	switch ctx.Mode() {
	case Bp2Build:
	if b, ok := m.(android.Bazelable); ok && b.HasHandcraftedLabel() {
	metrics.handCraftedTargetCount += 1
	metrics.TotalModuleCount += 1
	pathToBuildFile := getBazelPackagePath(b)
	// We are using the entire contents of handcrafted build file, so if multiple targets within
	// a package have handcrafted targets, we only want to include the contents one time.
	if _, exists := buildFileToAppend[pathToBuildFile]; exists {
	return
	}
	var err error
	t, err = getHandcraftedBuildContent(ctx, b, pathToBuildFile)
	if err != nil {
	panic(fmt.Errorf("Error converting %s: %s", bpCtx.ModuleName(m), err))
	}
	// TODO(b/181575318): currently we append the whole BUILD file, let's change that to do
	// something more targeted based on the rule type and target
	buildFileToAppend[pathToBuildFile] = true
	} else if btm, ok := m.(android.BazelTargetModule); ok {
	t = generateBazelTarget(bpCtx, m, btm)
	metrics.RuleClassCount[t.ruleClass] += 1
	} else {
	metrics.TotalModuleCount += 1
	return
	}
	case QueryView:
	// Blocklist certain module types from being generated.
	if canonicalizeModuleType(bpCtx.ModuleType(m)) == "package" {
	// package module name contain slashes, and thus cannot
	// be mapped cleanly to a bazel label.
	return
	}
	t = generateSoongModuleTarget(bpCtx, m)
	default:
	panic(fmt.Errorf("Unknown code-generation mode: %s", ctx.Mode()))
	}

	buildFileToTargets[dir] = append(buildFileToTargets[dir], t)
	})
	if generateFilegroups {
	// Add a filegroup target that exposes all sources in the subtree of this package
	// NOTE: This also means we generate a BUILD file for every Android.bp file (as long as it has at least one module)
	for dir, _ := range dirs {
	buildFileToTargets[dir] = append(buildFileToTargets[dir], BazelTarget{
	name: "bp2build_all_srcs",
	content: `filegroup(name = "bp2build_all_srcs", srcs = glob(["*/"]))`,
	ruleClass: "filegroup",
	})
	}
	}

	return buildFileToTargets, metrics
	}

	func getBazelPackagePath(b android.Bazelable) string {
	label := b.HandcraftedLabel()
	pathToBuildFile := strings.TrimPrefix(label, "//")
	pathToBuildFile = strings.Split(pathToBuildFile, ":")[0]
	return pathToBuildFile
	}

	func getHandcraftedBuildContent(ctx *CodegenContext, b android.Bazelable, pathToBuildFile string) (BazelTarget, error) {
	p := android.ExistentPathForSource(ctx, pathToBuildFile, HandcraftedBuildFileName)
	if !p.Valid() {
	return BazelTarget{}, fmt.Errorf("Could not find file %q for handcrafted target.", pathToBuildFile)
	}
	c, err := b.GetBazelBuildFileContents(ctx.Config(), pathToBuildFile, HandcraftedBuildFileName)
	if err != nil {
	return BazelTarget{}, err
	}
	// TODO(b/181575318): once this is more targeted, we need to include name, rule class, etc
	return BazelTarget{
	content: c,
	handcrafted: true,
	}, nil
	}

	func generateBazelTarget(ctx bpToBuildContext, m blueprint.Module, btm android.BazelTargetModule) BazelTarget {
	ruleClass := btm.RuleClass()
	bzlLoadLocation := btm.BzlLoadLocation()

	// extract the bazel attributes from the module.
	props := getBuildProperties(ctx, m)

	delete(props.Attrs, "bp2build_available")

	// Return the Bazel target with rule class and attributes, ready to be
	// code-generated.
	attributes := propsToAttributes(props.Attrs)
	targetName := targetNameForBp2Build(ctx, m)
	return BazelTarget{
	name: targetName,
	ruleClass: ruleClass,
	bzlLoadLocation: bzlLoadLocation,
	content: fmt.Sprintf(
	bazelTarget,
	ruleClass,
	targetName,
	attributes,
	),
	handcrafted: false,
	}
	}

	// Convert a module and its deps and props into a Bazel macro/rule
	// representation in the BUILD file.
	func generateSoongModuleTarget(ctx bpToBuildContext, m blueprint.Module) BazelTarget {
	props := getBuildProperties(ctx, m)

	// TODO(b/163018919): DirectDeps can have duplicate (module, variant)
	// items, if the modules are added using different DependencyTag. Figure
	// out the implications of that.
	depLabels := map[string]bool{}
	if aModule, ok := m.(android.Module); ok {
	ctx.VisitDirectDeps(aModule, func(depModule blueprint.Module) {
	depLabels[qualifiedTargetLabel(ctx, depModule)] = true
	})
	}
	attributes := propsToAttributes(props.Attrs)

	depLabelList := "[\n"
	for depLabel, _ := range depLabels {
	depLabelList += fmt.Sprintf(" %q,\n", depLabel)
	}
	depLabelList += " ]"

	targetName := targetNameWithVariant(ctx, m)
	return BazelTarget{
	name: targetName,
	content: fmt.Sprintf(
	soongModuleTarget,
	targetName,
	ctx.ModuleName(m),
	canonicalizeModuleType(ctx.ModuleType(m)),
	ctx.ModuleSubDir(m),
	depLabelList,
	attributes),
	}
	}

	func getBuildProperties(ctx bpToBuildContext, m blueprint.Module) BazelAttributes {
	var allProps map[string]string
	// TODO: this omits properties for blueprint modules (blueprint_go_binary,
	// bootstrap_go_binary, bootstrap_go_package), which will have to be handled separately.
	if aModule, ok := m.(android.Module); ok {
	allProps = ExtractModuleProperties(aModule)
	}

	return BazelAttributes{
	Attrs: allProps,
	}
	}

	// Generically extract module properties and types into a map, keyed by the module property name.
	func ExtractModuleProperties(aModule android.Module) map[string]string {
	ret := map[string]string{}

	// Iterate over this android.Module's property structs.
	for _, properties := range aModule.GetProperties() {
	propertiesValue := reflect.ValueOf(properties)
	// Check that propertiesValue is a pointer to the Properties struct, like
	// cc.BaseLinkerProperties or java.CompilerProperties.
	//
	// propertiesValue can also be type-asserted to the structs to
	// manipulate internal props, if needed.
	if isStructPtr(propertiesValue.Type()) {
	structValue := propertiesValue.Elem()
	for k, v := range extractStructProperties(structValue, 0) {
	ret[k] = v
	}
	} else {
	panic(fmt.Errorf(
	"properties must be a pointer to a struct, got %T",
	propertiesValue.Interface()))
	}
	}

	return ret
	}

	func isStructPtr(t reflect.Type) bool {
	return t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct
	}

	// prettyPrint a property value into the equivalent Starlark representation
	// recursively.
	func prettyPrint(propertyValue reflect.Value, indent int) (string, error) {
	if isZero(propertyValue) {
	// A property value being set or unset actually matters -- Soong does set default
	// values for unset properties, like system_shared_libs = ["libc", "libm", "libdl"] at
	// https://cs.android.com/android/platform/superproject/+/master:build/soong/cc/linker.go;l=281-287;drc=f70926eef0b9b57faf04c17a1062ce50d209e480
	//
	// In Bazel-parlance, we would use "attr.<type>(default = <default
	// value>)" to set the default value of unset attributes. In the cases
	// where the bp2build converter didn't set the default value within the
	// mutator when creating the BazelTargetModule, this would be a zero
	// value. For those cases, we return an empty string so we don't
	// unnecessarily generate empty values.
	return "", nil
	}

	var ret string
	switch propertyValue.Kind() {
	case reflect.String:
	ret = fmt.Sprintf("\"%v\"", escapeString(propertyValue.String()))
	case reflect.Bool:
	ret = strings.Title(fmt.Sprintf("%v", propertyValue.Interface()))
	case reflect.Int, reflect.Uint, reflect.Int64:
	ret = fmt.Sprintf("%v", propertyValue.Interface())
	case reflect.Ptr:
	return prettyPrint(propertyValue.Elem(), indent)
	case reflect.Slice:
	if propertyValue.Len() == 0 {
	return "[]", nil
	}

	if propertyValue.Len() == 1 {
	// Single-line list for list with only 1 element
	ret += "["
	indexedValue, err := prettyPrint(propertyValue.Index(0), indent)
	if err != nil {
	return "", err
	}
	ret += indexedValue
	ret += "]"
	} else {
	// otherwise, use a multiline list.
	ret += "[\n"
	for i := 0; i < propertyValue.Len(); i++ {
	indexedValue, err := prettyPrint(propertyValue.Index(i), indent+1)
	if err != nil {
	return "", err
	}

	if indexedValue != "" {
	ret += makeIndent(indent + 1)
	ret += indexedValue
	ret += ",\n"
	}
	}
	ret += makeIndent(indent)
	ret += "]"
	}

	case reflect.Struct:
	// Special cases where the bp2build sends additional information to the codegenerator
	// by wrapping the attributes in a custom struct type.
	if attr, ok := propertyValue.Interface().(bazel.Attribute); ok {
	return prettyPrintAttribute(attr, indent)
	} else if label, ok := propertyValue.Interface().(bazel.Label); ok {
	return fmt.Sprintf("%q", label.Label), nil
	}

	ret = "{\n"
	// Sort and print the struct props by the key.
	structProps := extractStructProperties(propertyValue, indent)
	if len(structProps) == 0 {
	return "", nil
	}
	for _, k := range android.SortedStringKeys(structProps) {
	ret += makeIndent(indent + 1)
	ret += fmt.Sprintf("%q: %s,\n", k, structProps[k])
	}
	ret += makeIndent(indent)
	ret += "}"
	case reflect.Interface:
	// TODO(b/164227191): implement pretty print for interfaces.
	// Interfaces are used for for arch, multilib and target properties.
	return "", nil
	default:
	return "", fmt.Errorf(
	"unexpected kind for property struct field: %s", propertyValue.Kind())
	}
	return ret, nil
	}

	// Converts a reflected property struct value into a map of property names and property values,
	// which each property value correctly pretty-printed and indented at the right nest level,
	// since property structs can be nested. In Starlark, nested structs are represented as nested
	// dicts: https://docs.bazel.build/skylark/lib/dict.html
	func extractStructProperties(structValue reflect.Value, indent int) map[string]string {
	if structValue.Kind() != reflect.Struct {
	panic(fmt.Errorf("Expected a reflect.Struct type, but got %s", structValue.Kind()))
	}

	ret := map[string]string{}
	structType := structValue.Type()
	for i := 0; i < structValue.NumField(); i++ {
	field := structType.Field(i)
	if shouldSkipStructField(field) {
	continue
	}

	fieldValue := structValue.Field(i)
	if isZero(fieldValue) {
	// Ignore zero-valued fields
	continue
	}

	propertyName := proptools.PropertyNameForField(field.Name)
	prettyPrintedValue, err := prettyPrint(fieldValue, indent+1)
	if err != nil {
	panic(
	fmt.Errorf(
	"Error while parsing property: %q. %s",
	propertyName,
	err))
	}
	if prettyPrintedValue != "" {
	ret[propertyName] = prettyPrintedValue
	}
	}

	return ret
	}

	func isZero(value reflect.Value) bool {
	switch value.Kind() {
	case reflect.Func, reflect.Map, reflect.Slice:
	return value.IsNil()
	case reflect.Array:
	valueIsZero := true
	for i := 0; i < value.Len(); i++ {
	valueIsZero = valueIsZero && isZero(value.Index(i))
	}
	return valueIsZero
	case reflect.Struct:
	valueIsZero := true
	for i := 0; i < value.NumField(); i++ {
	valueIsZero = valueIsZero && isZero(value.Field(i))
	}
	return valueIsZero
	case reflect.Ptr:
	if !value.IsNil() {
	return isZero(reflect.Indirect(value))
	} else {
	return true
	}
	// Always print bools, if you want a bool attribute to be able to take the default value, use a
	// bool pointer instead
	case reflect.Bool:
	return false
	default:
	if !value.IsValid() {
	return true
	}
	zeroValue := reflect.Zero(value.Type())
	result := value.Interface() == zeroValue.Interface()
	return result
	}
	}

	func escapeString(s string) string {
	s = strings.ReplaceAll(s, "\\", "\\\\")

	// b/184026959: Reverse the application of some common control sequences.
	// These must be generated literally in the BUILD file.
	s = strings.ReplaceAll(s, "\t", "\\t")
	s = strings.ReplaceAll(s, "\n", "\\n")
	s = strings.ReplaceAll(s, "\r", "\\r")

	return strings.ReplaceAll(s, "\"", "\\\"")
	}

	func makeIndent(indent int) string {
	if indent < 0 {
	panic(fmt.Errorf("indent column cannot be less than 0, but got %d", indent))
	}
	return strings.Repeat(" ", indent)
	}

	func targetNameForBp2Build(c bpToBuildContext, logicModule blueprint.Module) string {
	return strings.Replace(c.ModuleName(logicModule), bazel.BazelTargetModuleNamePrefix, "", 1)
	}

	func targetNameWithVariant(c bpToBuildContext, logicModule blueprint.Module) string {
	name := ""
	if c.ModuleSubDir(logicModule) != "" {
	// TODO(b/162720883): Figure out a way to drop the "--" variant suffixes.
	name = c.ModuleName(logicModule) + "--" + c.ModuleSubDir(logicModule)
	} else {
	name = c.ModuleName(logicModule)
	}

	return strings.Replace(name, "//", "", 1)
	}

	func qualifiedTargetLabel(c bpToBuildContext, logicModule blueprint.Module) string {
	return fmt.Sprintf("//%s:%s", c.ModuleDir(logicModule), targetNameWithVariant(c, logicModule))
	}