Allow manually specifying translations for modules

Parse the comment block above each module or assignment looking
for directives in the form:
Android.mk:<directive>
If a block delimited by start and end directives is found, use it
as the Android.mk translation instead of trying to automatically
translate.  If an ignore directive is found, ignore the module
completely.

Change-Id: I34fe392899ed27ce3f640a2a71fbbaaedea67169

androidbp/cmd/androidbp.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"strings"
+	"text/scanner"
 
 	bpparser "github.com/google/blueprint/parser"
 )
@@ -377,6 +378,14 @@ func (w *androidMkWriter) mutateModule(module *Module) (modules []*Module, err e
 }
 
 func (w *androidMkWriter) handleModule(inputModule *bpparser.Module) error {
+	comment := w.getCommentBlock(inputModule.Type.Pos)
+	if translation, translated, err := getCommentTranslation(comment); err != nil {
+		return err
+	} else if translated {
+		w.WriteString(translation)
+		return nil
+	}
+
 	modules, err := w.mutateModule(newModule(inputModule))
 	if err != nil {
 		return err
@@ -403,6 +412,14 @@ func (w *androidMkWriter) handleSubdirs(value bpparser.Value) {
 }
 
 func (w *androidMkWriter) handleAssignment(assignment *bpparser.Assignment) error {
+	comment := w.getCommentBlock(assignment.Name.Pos)
+	if translation, translated, err := getCommentTranslation(comment); err != nil {
+		return err
+	} else if translated {
+		w.WriteString(translation)
+		return nil
+	}
+
 	if "subdirs" == assignment.Name.Name {
 		w.handleSubdirs(assignment.OrigValue)
 	} else if assignment.OrigValue.Type == bpparser.Map {
@@ -450,6 +467,91 @@ func (w *androidMkWriter) handleLocalPath() error {
 	return nil
 }
 
+// Returns any block comment on the line preceding pos as a string
+func (w *androidMkWriter) getCommentBlock(pos scanner.Position) string {
+	var buf []byte
+
+	comments := w.blueprint.Comments
+	for i, c := range comments {
+		if c.EndLine() == pos.Line-1 {
+			line := pos.Line
+			for j := i; j >= 0; j-- {
+				c = comments[j]
+				if c.EndLine() == line-1 {
+					buf = append([]byte(c.Text()), buf...)
+					line = c.Pos.Line
+				} else {
+					break
+				}
+			}
+		}
+	}
+
+	return string(buf)
+}
+
+func getCommentTranslation(comment string) (string, bool, error) {
+	lines := strings.Split(comment, "\n")
+
+	if directive, i, err := getCommentDirective(lines); err != nil {
+		return "", false, err
+	} else if directive != "" {
+		switch directive {
+		case "ignore":
+			return "", true, nil
+		case "start":
+			return getCommentTranslationBlock(lines[i+1:])
+		case "end":
+			return "", false, fmt.Errorf("Unexpected Android.mk:end translation directive")
+		default:
+			return "", false, fmt.Errorf("Unknown Android.mk module translation directive %q", directive)
+		}
+	}
+
+	return "", false, nil
+}
+
+func getCommentTranslationBlock(lines []string) (string, bool, error) {
+	var buf []byte
+
+	for _, line := range lines {
+		if directive := getLineCommentDirective(line); directive != "" {
+			switch directive {
+			case "end":
+				return string(buf), true, nil
+			default:
+				return "", false, fmt.Errorf("Unexpected Android.mk translation directive %q inside start", directive)
+			}
+		} else {
+			buf = append(buf, line...)
+			buf = append(buf, '\n')
+		}
+	}
+
+	return "", false, fmt.Errorf("Missing Android.mk:end translation directive")
+}
+
+func getCommentDirective(lines []string) (directive string, n int, err error) {
+	for i, line := range lines {
+		if directive := getLineCommentDirective(line); directive != "" {
+			return strings.ToLower(directive), i, nil
+		}
+	}
+
+	return "", -1, nil
+}
+
+func getLineCommentDirective(line string) string {
+	line = strings.TrimSpace(line)
+	if strings.HasPrefix(line, "Android.mk:") {
+		line = strings.TrimPrefix(line, "Android.mk:")
+		line = strings.TrimSpace(line)
+		return line
+	}
+
+	return ""
+}
+
 func (w *androidMkWriter) write(writer io.Writer) (err error) {
 	w.Writer = writer
 

androidbp/cmd/androidbp_test.go

@@ -117,6 +117,20 @@ var moduleTestCases = []struct {
 			    LOCAL_MODULE := test
 			    include $(BUILD_HOST_STATIC_LIBRARY)`,
 	},
+	// Manual translation
+	{
+		blueprint: `/* Android.mk:start
+					# Manual translation
+					Android.mk:end */
+					cc_library { name: "test", host_supported: true, }`,
+		androidmk: `# Manual translation`,
+	},
+	// Ignored translation
+	{
+		blueprint: `/* Android.mk:ignore */
+					cc_library { name: "test", host_supported: true, }`,
+		androidmk: ``,
+	},
 }
 
 func TestModules(t *testing.T) {