Parsers register themselves like in database/sql.

idm/idm.go

@@ -27,6 +27,10 @@ import (
 	"github.com/bemasher/rtlamr/parse"
 )
 
+func init() {
+	parse.Register("idm", NewParser)
+}
+
 func NewPacketConfig(symbolLength int) (cfg decode.PacketConfig) {
 	cfg.CenterFreq = 912600155
 	cfg.DataRate = 32768
@@ -51,7 +55,7 @@ func (p *Parser) Cfg() *decode.PacketConfig {
 	return &p.Decoder.Cfg
 }
 
-func NewParser(symbolLength, decimation int) (p *Parser) {
+func NewParser(symbolLength, decimation int) (p parse.Parser) {
 	return &Parser{
 		decode.NewDecoder(NewPacketConfig(symbolLength), decimation),
 		crc.NewCRC("CCITT", 0xFFFF, 0x1021, 0x1D0F),

parse/parse.go

@@ -3,6 +3,7 @@ package parse
 import (
 	"fmt"
 	"strconv"
+	"sync"
 	"time"
 
 	"github.com/bemasher/rtlamr/decode"
@@ -14,6 +15,37 @@ const (
 	TimeFormat = "2006-01-02T15:04:05.000"
 )
 
+var (
+	parserMutex sync.Mutex
+	parsers     = make(map[string]NewParserFunc)
+)
+
+type NewParserFunc func(symbolLength, decimation int) Parser
+
+func Register(name string, parserFn NewParserFunc) {
+	parserMutex.Lock()
+	defer parserMutex.Unlock()
+
+	if parserFn == nil {
+		panic("parser: new parser func is nil")
+	}
+	if _, dup := parsers[name]; dup {
+		panic(fmt.Sprintf("parser: parser already registered (%s)", name))
+	}
+	parsers[name] = parserFn
+}
+
+func NewParser(name string, symbolLength, decimation int) (Parser, error) {
+	parserMutex.Lock()
+	defer parserMutex.Unlock()
+
+	if parserFn, exists := parsers[name]; exists {
+		return parserFn(symbolLength, decimation), nil
+	} else {
+		return nil, fmt.Errorf("invalid message type: %q\n", name)
+	}
+}
+
 type Data struct {
 	Bits  string
 	Bytes []byte

r900/r900.go

@@ -31,6 +31,10 @@ const (
 	PayloadSymbols = 42
 )
 
+func init() {
+	parse.Register("r900", NewParser)
+}
+
 func NewPacketConfig(symbolLength int) (cfg decode.PacketConfig) {
 	cfg.CenterFreq = 912380000
 	cfg.DataRate = 32768
@@ -52,8 +56,8 @@ type Parser struct {
 	quantized []byte
 }
 
-func NewParser(symbolLength, decimation int) (p *Parser) {
-	p = new(Parser)
+func NewParser(symbolLength, decimation int) parse.Parser {
+	p := new(Parser)
 
 	p.Decoder = decode.NewDecoder(NewPacketConfig(symbolLength), decimation)
 
@@ -64,7 +68,7 @@ func NewParser(symbolLength, decimation int) (p *Parser) {
 	p.filtered = make([][3]float64, p.Decoder.DecCfg.BufferLength)
 	p.quantized = make([]byte, p.Decoder.DecCfg.BufferLength)
 
-	return
+	return p
 }
 
 func (p Parser) Dec() decode.Decoder {

recv.go

@@ -25,15 +25,15 @@ import (
 	"os"
 	"os/signal"
 	"runtime/pprof"
-	"strings"
 	"time"
 
-	"github.com/bemasher/rtlamr/idm"
 	"github.com/bemasher/rtlamr/parse"
-	"github.com/bemasher/rtlamr/r900"
-	"github.com/bemasher/rtlamr/scm"
-	"github.com/bemasher/rtlamr/scmplus"
 	"github.com/bemasher/rtltcp"
+
+	_ "github.com/bemasher/rtlamr/idm"
+	_ "github.com/bemasher/rtlamr/r900"
+	_ "github.com/bemasher/rtlamr/scm"
+	_ "github.com/bemasher/rtlamr/scmplus"
 )
 
 var rcvr Receiver
@@ -45,17 +45,9 @@ type Receiver struct {
 }
 
 func (rcvr *Receiver) NewReceiver() {
-	switch strings.ToLower(*msgType) {
-	case "scm":
-		rcvr.p = scm.NewParser(*symbolLength, *decimation)
-	case "idm":
-		rcvr.p = idm.NewParser(*symbolLength, *decimation)
-	case "r900":
-		rcvr.p = r900.NewParser(*symbolLength, *decimation)
-	case "scm+":
-		rcvr.p = scmplus.NewParser(*symbolLength, *decimation)
-	default:
-		log.Fatalf("Invalid message type: %q\n", *msgType)
+	var err error
+	if rcvr.p, err = parse.NewParser(*msgType, *symbolLength, *decimation); err != nil {
+		log.Fatal(err)
 	}
 
 	// Connect to rtl_tcp server.

scm/scm.go

@@ -26,6 +26,10 @@ import (
 	"github.com/bemasher/rtlamr/parse"
 )
 
+func init() {
+	parse.Register("scm", NewParser)
+}
+
 func NewPacketConfig(symbolLength int) (cfg decode.PacketConfig) {
 	cfg.CenterFreq = 912600155
 	cfg.DataRate = 32768
@@ -42,7 +46,7 @@ type Parser struct {
 	crc.CRC
 }
 
-func NewParser(symbolLength, decimation int) (p *Parser) {
+func NewParser(symbolLength, decimation int) (p parse.Parser) {
 	return &Parser{
 		decode.NewDecoder(NewPacketConfig(symbolLength), decimation),
 		crc.NewCRC("BCH", 0, 0x6F63, 0),

scmplus/scmplus.go

@@ -27,6 +27,10 @@ import (
 	"github.com/bemasher/rtlamr/parse"
 )
 
+func init() {
+	parse.Register("scm+", NewParser)
+}
+
 func NewPacketConfig(symbolLength int) (cfg decode.PacketConfig) {
 	cfg.CenterFreq = 912600155
 	cfg.DataRate = 32768
@@ -51,7 +55,7 @@ func (p *Parser) Cfg() *decode.PacketConfig {
 	return &p.Decoder.Cfg
 }
 
-func NewParser(symbolLength, decimation int) (p *Parser) {
+func NewParser(symbolLength, decimation int) (p parse.Parser) {
 	return &Parser{
 		decode.NewDecoder(NewPacketConfig(symbolLength), decimation),
 		crc.NewCRC("CCITT", 0xFFFF, 0x1021, 0x1D0F),