Refactor BazelTargetModule

This eliminates the need to remove quotes, delete attributes, and
re-checking that name has correct prefix. Additionally, this allows
assignment directly to the BazelTargetModuleProperties struct, which
allows defaulting unused fields and clarity of which field is being set.

Test: go test soong tests
Test: ran ./build/bazel/scripts/milestone-2/demo.sh
Change-Id: Ia9bfcce76234c793a4ddd5f29a661150f83341c9
diff --git a/android/filegroup.go b/android/filegroup.go
index 674a196..c3bf6f8 100644
--- a/android/filegroup.go
+++ b/android/filegroup.go
@@ -57,9 +57,9 @@
 		Srcs: BazelLabelForModuleSrcExcludes(ctx, fg.properties.Srcs, fg.properties.Exclude_srcs),
 	}
 
-	props := bazel.NewBazelTargetModuleProperties(fg.Name(), "filegroup", "")
+	props := bazel.BazelTargetModuleProperties{Rule_class: "filegroup"}
 
-	ctx.CreateBazelTargetModule(BazelFileGroupFactory, props, attrs)
+	ctx.CreateBazelTargetModule(BazelFileGroupFactory, fg.Name(), props, attrs)
 }
 
 type fileGroupProperties struct {
diff --git a/android/module.go b/android/module.go
index bf74cad..58675d4 100644
--- a/android/module.go
+++ b/android/module.go
@@ -507,13 +507,17 @@
 type BazelTargetModule interface {
 	Module
 
-	BazelTargetModuleProperties() *bazel.BazelTargetModuleProperties
+	bazelTargetModuleProperties() *bazel.BazelTargetModuleProperties
+	SetBazelTargetModuleProperties(props bazel.BazelTargetModuleProperties)
+
+	RuleClass() string
+	BzlLoadLocation() string
 }
 
 // InitBazelTargetModule is a wrapper function that decorates BazelTargetModule
 // with property structs containing metadata for bp2build conversion.
 func InitBazelTargetModule(module BazelTargetModule) {
-	module.AddProperties(module.BazelTargetModuleProperties())
+	module.AddProperties(module.bazelTargetModuleProperties())
 	InitAndroidModule(module)
 }
 
@@ -524,11 +528,26 @@
 	Properties bazel.BazelTargetModuleProperties
 }
 
-// BazelTargetModuleProperties getter.
-func (btmb *BazelTargetModuleBase) BazelTargetModuleProperties() *bazel.BazelTargetModuleProperties {
+// bazelTargetModuleProperties getter.
+func (btmb *BazelTargetModuleBase) bazelTargetModuleProperties() *bazel.BazelTargetModuleProperties {
 	return &btmb.Properties
 }
 
+// SetBazelTargetModuleProperties setter for BazelTargetModuleProperties
+func (btmb *BazelTargetModuleBase) SetBazelTargetModuleProperties(props bazel.BazelTargetModuleProperties) {
+	btmb.Properties = props
+}
+
+// RuleClass returns the rule class for this Bazel target
+func (b *BazelTargetModuleBase) RuleClass() string {
+	return b.bazelTargetModuleProperties().Rule_class
+}
+
+// BzlLoadLocation returns the rule class for this Bazel target
+func (b *BazelTargetModuleBase) BzlLoadLocation() string {
+	return b.bazelTargetModuleProperties().Bzl_load_location
+}
+
 // Qualified id for a module
 type qualifiedModuleName struct {
 	// The package (i.e. directory) in which the module is defined, without trailing /
diff --git a/android/mutator.go b/android/mutator.go
index c387193..b023001 100644
--- a/android/mutator.go
+++ b/android/mutator.go
@@ -283,7 +283,7 @@
 	// factory method, just like in CreateModule, but also requires
 	// BazelTargetModuleProperties containing additional metadata for the
 	// bp2build codegenerator.
-	CreateBazelTargetModule(ModuleFactory, bazel.BazelTargetModuleProperties, interface{}) BazelTargetModule
+	CreateBazelTargetModule(ModuleFactory, string, bazel.BazelTargetModuleProperties, interface{}) BazelTargetModule
 }
 
 type topDownMutatorContext struct {
@@ -513,17 +513,25 @@
 
 func (t *topDownMutatorContext) CreateBazelTargetModule(
 	factory ModuleFactory,
+	name string,
 	bazelProps bazel.BazelTargetModuleProperties,
 	attrs interface{}) BazelTargetModule {
-	if !strings.HasPrefix(*bazelProps.Name, bazel.BazelTargetModuleNamePrefix) {
+	if strings.HasPrefix(name, bazel.BazelTargetModuleNamePrefix) {
 		panic(fmt.Errorf(
-			"bp2build error: the bazel target module name must start with '%s': %s",
+			"The %s name prefix is added automatically, do not set it manually: %s",
 			bazel.BazelTargetModuleNamePrefix,
-			*bazelProps.Name,
-		))
+			name))
+	}
+	name = bazel.BazelTargetModuleNamePrefix + name
+	nameProp := struct {
+		Name *string
+	}{
+		Name: &name,
 	}
 
-	return t.CreateModule(factory, &bazelProps, attrs).(BazelTargetModule)
+	b := t.CreateModule(factory, &nameProp, attrs).(BazelTargetModule)
+	b.SetBazelTargetModuleProperties(bazelProps)
+	return b
 }
 
 func (t *topDownMutatorContext) AppendProperties(props ...interface{}) {
diff --git a/bazel/properties.go b/bazel/properties.go
index 8055306..a4df4bc 100644
--- a/bazel/properties.go
+++ b/bazel/properties.go
@@ -14,11 +14,6 @@
 
 package bazel
 
-import (
-	"fmt"
-	"strings"
-)
-
 type bazelModuleProperties struct {
 	// The label of the Bazel target replacing this Soong module.
 	Label string
@@ -37,32 +32,15 @@
 // BazelTargetModuleProperties contain properties and metadata used for
 // Blueprint to BUILD file conversion.
 type BazelTargetModuleProperties struct {
-	Name *string
-
 	// The Bazel rule class for this target.
-	Rule_class string
+	Rule_class string `blueprint:"mutated"`
 
 	// The target label for the bzl file containing the definition of the rule class.
-	Bzl_load_location string
+	Bzl_load_location string `blueprint:"mutated"`
 }
 
 const BazelTargetModuleNamePrefix = "__bp2build__"
 
-func NewBazelTargetModuleProperties(name string, ruleClass string, bzlLoadLocation string) BazelTargetModuleProperties {
-	if strings.HasPrefix(name, BazelTargetModuleNamePrefix) {
-		panic(fmt.Errorf(
-			"The %s name prefix is added automatically, do not set it manually: %s",
-			BazelTargetModuleNamePrefix,
-			name))
-	}
-	name = BazelTargetModuleNamePrefix + name
-	return BazelTargetModuleProperties{
-		Name:              &name,
-		Rule_class:        ruleClass,
-		Bzl_load_location: bzlLoadLocation,
-	}
-}
-
 // Label is used to represent a Bazel compatible Label. Also stores the original bp text to support
 // string replacement.
 type Label struct {
diff --git a/bp2build/build_conversion.go b/bp2build/build_conversion.go
index 41ad409..a4c4a0d 100644
--- a/bp2build/build_conversion.go
+++ b/bp2build/build_conversion.go
@@ -19,7 +19,6 @@
 	"android/soong/bazel"
 	"fmt"
 	"reflect"
-	"strconv"
 	"strings"
 
 	"github.com/google/blueprint"
@@ -178,13 +177,14 @@
 
 		switch ctx.Mode() {
 		case Bp2Build:
-			if _, ok := m.(android.BazelTargetModule); !ok {
+			if b, ok := m.(android.BazelTargetModule); !ok {
 				// Only include regular Soong modules (non-BazelTargetModules) into the total count.
 				totalModuleCount += 1
 				return
+			} else {
+				t = generateBazelTarget(bpCtx, m, b)
+				ruleClassCount[t.ruleClass] += 1
 			}
-			t = generateBazelTarget(bpCtx, m)
-			ruleClassCount[t.ruleClass] += 1
 		case QueryView:
 			// Blocklist certain module types from being generated.
 			if canonicalizeModuleType(bpCtx.ModuleType(m)) == "package" {
@@ -208,36 +208,13 @@
 	return buildFileToTargets, metrics
 }
 
-// Helper method to trim quotes around strings.
-func trimQuotes(s string) string {
-	if s == "" {
-		// strconv.Unquote would error out on empty strings, but this method
-		// allows them, so return the empty string directly.
-		return ""
-	}
-	ret, err := strconv.Unquote(s)
-	if err != nil {
-		// Panic the error immediately.
-		panic(fmt.Errorf("Trying to unquote '%s', but got error: %s", s, err))
-	}
-	return ret
-}
+func generateBazelTarget(ctx bpToBuildContext, m blueprint.Module, b android.BazelTargetModule) BazelTarget {
+	ruleClass := b.RuleClass()
+	bzlLoadLocation := b.BzlLoadLocation()
 
-func generateBazelTarget(ctx bpToBuildContext, m blueprint.Module) BazelTarget {
 	// extract the bazel attributes from the module.
 	props := getBuildProperties(ctx, m)
 
-	// extract the rule class name from the attributes. Since the string value
-	// will be string-quoted, remove the quotes here.
-	ruleClass := trimQuotes(props.Attrs["rule_class"])
-	// Delete it from being generated in the BUILD file.
-	delete(props.Attrs, "rule_class")
-
-	// extract the bzl_load_location, and also remove the quotes around it here.
-	bzlLoadLocation := trimQuotes(props.Attrs["bzl_load_location"])
-	// Delete it from being generated in the BUILD file.
-	delete(props.Attrs, "bzl_load_location")
-
 	delete(props.Attrs, "bp2build_available")
 
 	// Return the Bazel target with rule class and attributes, ready to be
diff --git a/bp2build/testing.go b/bp2build/testing.go
index 9774915..cb50fc8 100644
--- a/bp2build/testing.go
+++ b/bp2build/testing.go
@@ -136,9 +136,11 @@
 			String_list_prop: m.props.String_list_prop,
 		}
 
-		props := bazel.NewBazelTargetModuleProperties(m.Name(), "custom", "")
+		props := bazel.BazelTargetModuleProperties{
+			Rule_class: "custom",
+		}
 
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, props, attrs)
+		ctx.CreateBazelTargetModule(customBazelModuleFactory, m.Name(), props, attrs)
 	}
 }
 
@@ -153,26 +155,23 @@
 		baseName := m.Name()
 		attrs := &customBazelModuleAttributes{}
 
-		myLibraryProps := bazel.NewBazelTargetModuleProperties(
-			baseName,
-			"my_library",
-			"//build/bazel/rules:rules.bzl",
-		)
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, myLibraryProps, attrs)
+		myLibraryProps := bazel.BazelTargetModuleProperties{
+			Rule_class:        "my_library",
+			Bzl_load_location: "//build/bazel/rules:rules.bzl",
+		}
+		ctx.CreateBazelTargetModule(customBazelModuleFactory, baseName, myLibraryProps, attrs)
 
-		protoLibraryProps := bazel.NewBazelTargetModuleProperties(
-			baseName+"_proto_library_deps",
-			"proto_library",
-			"//build/bazel/rules:proto.bzl",
-		)
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, protoLibraryProps, attrs)
+		protoLibraryProps := bazel.BazelTargetModuleProperties{
+			Rule_class:        "proto_library",
+			Bzl_load_location: "//build/bazel/rules:proto.bzl",
+		}
+		ctx.CreateBazelTargetModule(customBazelModuleFactory, baseName+"_proto_library_deps", protoLibraryProps, attrs)
 
-		myProtoLibraryProps := bazel.NewBazelTargetModuleProperties(
-			baseName+"_my_proto_library_deps",
-			"my_proto_library",
-			"//build/bazel/rules:proto.bzl",
-		)
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, myProtoLibraryProps, attrs)
+		myProtoLibraryProps := bazel.BazelTargetModuleProperties{
+			Rule_class:        "my_proto_library",
+			Bzl_load_location: "//build/bazel/rules:proto.bzl",
+		}
+		ctx.CreateBazelTargetModule(customBazelModuleFactory, baseName+"_my_proto_library_deps", myProtoLibraryProps, attrs)
 	}
 }
 
diff --git a/cc/library_headers.go b/cc/library_headers.go
index e5a5557..03450c6 100644
--- a/cc/library_headers.go
+++ b/cc/library_headers.go
@@ -129,13 +129,12 @@
 		Deps:     headerLibLabels,
 	}
 
-	props := bazel.NewBazelTargetModuleProperties(
-		module.Name(),
-		"cc_library_headers",
-		"//build/bazel/rules:cc_library_headers.bzl",
-	)
+	props := bazel.BazelTargetModuleProperties{
+		Rule_class:        "cc_library_headers",
+		Bzl_load_location: "//build/bazel/rules:cc_library_headers.bzl",
+	}
 
-	ctx.CreateBazelTargetModule(BazelCcLibraryHeadersFactory, props, attrs)
+	ctx.CreateBazelTargetModule(BazelCcLibraryHeadersFactory, module.Name(), props, attrs)
 }
 
 func (m *bazelCcLibraryHeaders) Name() string {
diff --git a/cc/object.go b/cc/object.go
index d92e110..3a7af97 100644
--- a/cc/object.go
+++ b/cc/object.go
@@ -150,13 +150,12 @@
 		Local_include_dirs: localIncludeDirs,
 	}
 
-	props := bazel.NewBazelTargetModuleProperties(
-		m.Name(),
-		"cc_object",
-		"//build/bazel/rules:cc_object.bzl",
-	)
+	props := bazel.BazelTargetModuleProperties{
+		Rule_class:        "cc_object",
+		Bzl_load_location: "//build/bazel/rules:cc_object.bzl",
+	}
 
-	ctx.CreateBazelTargetModule(BazelObjectFactory, props, attrs)
+	ctx.CreateBazelTargetModule(BazelObjectFactory, m.Name(), props, attrs)
 }
 
 func (object *objectLinker) appendLdflags(flags []string) {
diff --git a/genrule/genrule.go b/genrule/genrule.go
index 9fa6c48..c743fc3 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -853,10 +853,12 @@
 		Tools: tools,
 	}
 
-	props := bazel.NewBazelTargetModuleProperties(m.Name(), "genrule", "")
+	props := bazel.BazelTargetModuleProperties{
+		Rule_class: "genrule",
+	}
 
 	// Create the BazelTargetModule.
-	ctx.CreateBazelTargetModule(BazelGenruleFactory, props, attrs)
+	ctx.CreateBazelTargetModule(BazelGenruleFactory, m.Name(), props, attrs)
 }
 
 func (m *bazelGenrule) Name() string {
diff --git a/sh/sh_binary.go b/sh/sh_binary.go
index 58f8cf6..3a5c7de 100644
--- a/sh/sh_binary.go
+++ b/sh/sh_binary.go
@@ -514,9 +514,11 @@
 		Srcs: srcs,
 	}
 
-	props := bazel.NewBazelTargetModuleProperties(m.Name(), "sh_binary", "")
+	props := bazel.BazelTargetModuleProperties{
+		Rule_class: "sh_binary",
+	}
 
-	ctx.CreateBazelTargetModule(BazelShBinaryFactory, props, attrs)
+	ctx.CreateBazelTargetModule(BazelShBinaryFactory, m.Name(), props, attrs)
 }
 
 func (m *bazelShBinary) Name() string {