Fix blank line translation once and for all

Track the position in the input makefile and output blueprint file
separately.  When parsing a new makefile line, increment the line in the
output position by the number of lines between the end of the last
makefile line and the beginning of this line.  Any extra blank lines
will be discarded by the blueprint printer.

Change-Id: I85c6e006667b5733b15e03b56b91caf29fbc0ea0

androidmk/cmd/androidmk/androidmk.go

@@ -23,8 +23,8 @@ type bpFile struct {
 	scope             mkparser.Scope
 	module            *bpparser.Module
 
-	pos            scanner.Position
-	prevLine, line int
+	mkPos scanner.Position // Position of the last handled line in the makefile
+	bpPos scanner.Position // Position of the last emitted line to the blueprint file
 
 	inModule bool
 }
@@ -32,36 +32,31 @@ type bpFile struct {
 func (f *bpFile) errorf(thing mkparser.MakeThing, s string, args ...interface{}) {
 	orig := thing.Dump()
 	s = fmt.Sprintf(s, args...)
-	f.comments = append(f.comments, bpparser.Comment{
+	c := bpparser.Comment{
 		Comment: []string{fmt.Sprintf("// ANDROIDMK TRANSLATION ERROR: %s", s)},
-		Pos:     f.pos,
-	})
+		Pos:     f.bpPos,
+	}
+
 	lines := strings.Split(orig, "\n")
 	for _, l := range lines {
-		f.incPos()
-		f.comments = append(f.comments, bpparser.Comment{
-			Comment: []string{"// " + l},
-			Pos:     f.pos,
-		})
+		c.Comment = append(c.Comment, "// "+l)
 	}
+	f.incBpPos(len(lines))
+
+	f.comments = append(f.comments, c)
 }
 
-func (f *bpFile) setPos(pos, endPos scanner.Position) {
-	f.pos = pos
-
-	f.line++
-	if f.pos.Line > f.prevLine+1 {
-		f.line++
+func (f *bpFile) setMkPos(pos, end scanner.Position) {
+	if pos.Line < f.mkPos.Line {
+		panic(fmt.Errorf("out of order lines, %q after %q", pos, f.mkPos))
 	}
-
-	f.pos.Line = f.line
-	f.prevLine = endPos.Line
+	f.bpPos.Line += (pos.Line - f.mkPos.Line)
+	f.mkPos = end
 }
 
-func (f *bpFile) incPos() {
-	f.pos.Line++
-	f.line++
-	f.prevLine++
+// Called when inserting extra lines into the blueprint file
+func (f *bpFile) incBpPos(lines int) {
+	f.bpPos.Line += lines
 }
 
 type conditional struct {
@@ -96,12 +91,12 @@ func main() {
 	var assignmentCond *conditional
 
 	for _, t := range things {
-		file.setPos(t.Pos(), t.EndPos())
+		file.setMkPos(t.Pos(), t.EndPos())
 
 		if comment, ok := t.AsComment(); ok {
 			file.comments = append(file.comments, bpparser.Comment{
-				Pos:     file.pos,
 				Comment: []string{"//" + comment.Comment},
+				Pos:     file.bpPos,
 			})
 		} else if assignment, ok := t.AsAssignment(); ok {
 			handleAssignment(file, assignment, assignmentCond)
@@ -275,7 +270,7 @@ func handleModuleConditionals(file *bpFile, directive mkparser.Directive, conds
 		disabledPrefix := conditionalTranslations[c.cond][!c.eq]
 
 		// Create a fake assignment with enabled = false
-		val, err := makeVariableToBlueprint(file, mkparser.SimpleMakeString("false", file.pos), bpparser.Bool)
+		val, err := makeVariableToBlueprint(file, mkparser.SimpleMakeString("false", file.bpPos), bpparser.Bool)
 		if err == nil {
 			err = setVariable(file, false, disabledPrefix, "enabled", val, true)
 		}
@@ -290,14 +285,14 @@ func makeModule(file *bpFile, t string) {
 		Name: t,
 		Pos:  file.module.LbracePos,
 	}
-	file.module.RbracePos = file.pos
+	file.module.RbracePos = file.bpPos
 	file.defs = append(file.defs, file.module)
 	file.inModule = false
 }
 
 func resetModule(file *bpFile) {
 	file.module = &bpparser.Module{}
-	file.module.LbracePos = file.pos
+	file.module.LbracePos = file.bpPos
 	file.localAssignments = make(map[string]*bpparser.Property)
 	file.inModule = true
 }
@@ -331,7 +326,7 @@ func setVariable(file *bpFile, plusequals bool, prefix, name string, value *bppa
 		name = prefix + "." + name
 	}
 
-	pos := file.pos
+	pos := file.bpPos
 
 	var oldValue *bpparser.Value
 	if local {