allows the usage of metadata in Lilypond files

compiler/compile.go

@@ -17,7 +17,6 @@ package compiler
 import (
 	"os"
 	"path/filepath"
-	"strings"
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/jjdekker/ponder/helpers"
@@ -69,31 +68,36 @@ func CompileDir(path string, opts *settings.Settings) {
 
 func generateScores() func(string, os.FileInfo) error {
 	return func(path string, file os.FileInfo) error {
+		var (
+			score *settings.Score
+			err   error
+		)
 		switch filepath.Ext(path) {
 		case ".ly":
 			log.WithFields(log.Fields{"path": path}).Info("adding lilypond file")
-			scores = append(scores, settings.Score{
-				Name:         filepath.Base(path)[:strings.LastIndex(filepath.Base(path), ".")],
-				Path:         path,
-				LastModified: file.ModTime(),
-			})
+			score, err = settings.FromLy(path)
+			if score != nil {
+				score.LastModified = file.ModTime()
+			}
 
 		case ".json":
 			if filepath.Base(path) != "ponder.json" {
 				log.WithFields(log.Fields{"path": path}).Info("adding json file")
-				if score, err := settings.FromJSON(path); err != nil {
-					log.WithFields(log.Fields{
-						"error": err,
-						"path":  path,
-					}).Warning("unable to parse score settings, skipping...")
-				} else {
-					scores = append(scores, *score)
-				}
+				score, err = settings.FromJSON(path)
 			}
 
 		default:
 			log.WithFields(log.Fields{"path": path}).Debug("ignoring file")
 		}
+
+		if err != nil {
+			log.WithFields(log.Fields{
+				"error": err,
+				"path":  path,
+			}).Warning("unable to parse score settings, skipping...")
+		} else if score != nil {
+			scores = append(scores, *score)
+		}
 		return nil
 	}
 }

settings/score.go

@@ -15,8 +15,10 @@
 package settings
 
 import (
+	"bufio"
 	"encoding/json"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strings"
 	"time"
@@ -25,6 +27,8 @@ import (
 	"github.com/jjdekker/ponder/helpers"
 )
 
+const lyToken = "% PONDER"
+
 // Score represents the settings for a specific score file
 type Score struct {
 	Name         string    // The name of the score in the songbook
@@ -51,6 +55,41 @@ func FromJSON(path string) (*Score, error) {
 	return &s, nil
 }
 
+// FromLy reads the score metadata from a lilypond file.
+// The metadata should be on one line preceded by the lyToken.
+// The data itself should be in json format.
+func FromLy(path string) (*Score, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	scan := bufio.NewScanner(file)
+	var line string
+	for scan.Scan() {
+		if strings.Contains(scan.Text(), lyToken) {
+			line = strings.TrimLeftFunc(scan.Text(), func(r rune) bool {
+				return r != '{'
+			})
+			break
+		}
+	}
+	file.Close()
+
+	var s Score
+	if line != "" {
+		err = json.Unmarshal([]byte(line), &s)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if s.Name == "" {
+		s.Name = filepath.Base(path)[:strings.LastIndex(filepath.Base(path), ".")]
+	}
+	s.Path = path
+
+	return &s, nil
+}
+
 // CreateScore creates a json file for a score given its path
 func CreateScore(path, workDir string) {
 	if filepath.Ext(path) != ".pdf" {