Add droiddoc_template

We prefer not to use absolute paths in modules, but to reference modules
that have associated paths. This a few benefits:

* it's easier to move a module than to update all the references
* if the module doesn't exist, we treat it as a normal missing
dependency, not having to deal with the missing dependency in path.go
* implementing visibility(etc) in the future would be simpler if there
was a module attached to the reference, so we don't have to do various
path-based lookups to try and match things up.

So define a `droiddoc_template` module, which takes a path, and will run
the glob once in that module. All of the `droiddoc` modules can then
specify it through the `custom_template` property, which will pull the
necessary data.

Also fix that htmldirs should be references from the local path, the
htmldir2 argument never being specified, and complain if more than two
htmldirs are specified, or if the custom template isn't specified.

Test: m core-docs
Test: out/soong/build.ninja is nearly identical
      - line numbers in comments
      - adds directories to droiddoc template dependency lists, which
        is more correct, since we need to rerun on added or removed
	files too.
Change-Id: Iff630bddb3818b8eeed439de7e41fc7fbe7cdcb0

java/droiddoc.go

@@ -18,7 +18,6 @@ import (
 	"android/soong/android"
 	"android/soong/java/config"
 	"fmt"
-	"path/filepath"
 	"strings"
 
 	"github.com/google/blueprint"
@@ -52,6 +51,7 @@ var (
 func init() {
 	android.RegisterModuleType("droiddoc", DroiddocFactory)
 	android.RegisterModuleType("droiddoc_host", DroiddocHostFactory)
+	android.RegisterModuleType("droiddoc_template", DroiddocTemplateFactory)
 	android.RegisterModuleType("javadoc", JavadocFactory)
 	android.RegisterModuleType("javadoc_host", JavadocHostFactory)
 }
@@ -82,7 +82,7 @@ type JavadocProperties struct {
 
 type DroiddocProperties struct {
 	// directory relative to top of the source tree that contains doc templates files.
-	Custom_template_dir *string `android:"arch_variant"`
+	Custom_template *string `android:"arch_variant"`
 
 	// directories relative to top of the source tree which contains html/jd files.
 	Html_dirs []string `android:"arch_variant"`
@@ -233,7 +233,7 @@ func (j *Javadoc) collectDeps(ctx android.ModuleContext) deps {
 			}
 		default:
 			switch tag {
-			case android.DefaultsDepTag, android.SourceDepTag:
+			case android.DefaultsDepTag, android.SourceDepTag, droiddocTemplateTag:
 				// Nothing to do
 			default:
 				ctx.ModuleErrorf("depends on non-java module %q", otherName)
@@ -319,6 +319,13 @@ func (j *Javadoc) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 func (d *Droiddoc) DepsMutator(ctx android.BottomUpMutatorContext) {
 	d.Javadoc.addDeps(ctx)
 
+	if String(d.properties.Custom_template) == "" {
+		// TODO: This is almost always droiddoc-templates-sdk
+		ctx.PropertyErrorf("custom_template", "must specify a template")
+	} else {
+		ctx.AddDependency(ctx.Module(), droiddocTemplateTag, String(d.properties.Custom_template))
+	}
+
 	// extra_arg_files may contains filegroup or genrule.
 	android.ExtractSourcesDeps(ctx, d.properties.Arg_files)
 
@@ -373,24 +380,32 @@ func (d *Droiddoc) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 		classpathArgs = "-classpath " + strings.Join(deps.classpath.Strings(), ":")
 	}
 
-	// templateDir (maybe missing) is relative to top of the source tree instead of current module.
-	templateDir := android.PathForSource(ctx, String(d.properties.Custom_template_dir)).String()
-	implicits = append(implicits, ctx.GlobFiles(filepath.Join(templateDir, "**/*"), nil)...)
+	var templateDir string
+	ctx.VisitDirectDepsWithTag(droiddocTemplateTag, func(m android.Module) {
+		if t, ok := m.(*DroiddocTemplate); ok {
+			implicits = append(implicits, t.deps...)
+			templateDir = t.dir.String()
+		} else {
+			ctx.PropertyErrorf("custom_template", "module %q is not a droiddoc_template", ctx.OtherModuleName(m))
+		}
+	})
 
 	var htmlDirArgs string
 	if len(d.properties.Html_dirs) > 0 {
-		// htmlDir is relative to top of the source tree instead of current module.
-		htmlDir := android.PathForSource(ctx, d.properties.Html_dirs[0]).String()
-		implicits = append(implicits, ctx.GlobFiles(filepath.Join(htmlDir, "**/*"), nil)...)
-		htmlDirArgs = "-htmldir " + htmlDir
+		htmlDir := android.PathForModuleSrc(ctx, d.properties.Html_dirs[0])
+		implicits = append(implicits, ctx.Glob(htmlDir.Join(ctx, "**/*").String(), nil)...)
+		htmlDirArgs = "-htmldir " + htmlDir.String()
 	}
 
 	var htmlDir2Args string
 	if len(d.properties.Html_dirs) > 1 {
-		// htmlDir2 is relative to top of the source tree instead of current module.
-		htmlDir2 := android.PathForSource(ctx, d.properties.Html_dirs[1]).String()
-		implicits = append(implicits, ctx.GlobFiles(filepath.Join(htmlDir2, "**/*"), nil)...)
-		htmlDirArgs = "-htmldir2 " + htmlDir2
+		htmlDir2 := android.PathForModuleSrc(ctx, d.properties.Html_dirs[1])
+		implicits = append(implicits, ctx.Glob(htmlDir2.Join(ctx, "**/*").String(), nil)...)
+		htmlDir2Args = "-htmldir2 " + htmlDir2.String()
+	}
+
+	if len(d.properties.Html_dirs) > 2 {
+		ctx.PropertyErrorf("html_dirs", "Droiddoc only supports up to 2 html dirs")
 	}
 
 	knownTags := ctx.ExpandSources(d.properties.Knowntags, nil)
@@ -451,3 +466,34 @@ func (d *Droiddoc) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 		},
 	})
 }
+
+var droiddocTemplateTag = dependencyTag{name: "droiddoc-template"}
+
+type DroiddocTemplateProperties struct {
+	// path to the directory containing the droiddoc templates.
+	Path *string
+}
+
+type DroiddocTemplate struct {
+	android.ModuleBase
+
+	properties DroiddocTemplateProperties
+
+	deps android.Paths
+	dir  android.Path
+}
+
+func DroiddocTemplateFactory() android.Module {
+	module := &DroiddocTemplate{}
+	module.AddProperties(&module.properties)
+	android.InitAndroidModule(module)
+	return module
+}
+
+func (d *DroiddocTemplate) DepsMutator(android.BottomUpMutatorContext) {}
+
+func (d *DroiddocTemplate) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	path := android.PathForModuleSrc(ctx, String(d.properties.Path))
+	d.dir = path
+	d.deps = ctx.Glob(path.Join(ctx, "**/*").String(), nil)
+}