music: update comments

Update comments in ParsingUtil.

app/src/main/java/org/oxycblt/auxio/music/system/ExoPlayerBackend.kt

@@ -63,7 +63,7 @@ class ExoPlayerBackend(private val inner: MediaStoreBackend) : Indexer.Backend {
         val total = cursor.count
 
         while (cursor.moveToNext()) {
-            // Note: This call to buildAudio does not populate the genre field. This is
+            // Note: This call to buildRawSong does not populate the genre field. This is
             // because indexing genres is quite slow with MediaStore, and so keeping the
             // field blank on unsupported ExoPlayer formats ends up being preferable.
             val raw = inner.buildRawSong(context, cursor)
@@ -155,7 +155,7 @@ class Task(context: Context, private val raw: Song.Raw) {
 
         val metadata = format.metadata
         if (metadata != null) {
-            completeAudio(metadata)
+            completeRawSong(metadata)
         } else {
             logD("No metadata could be extracted for ${raw.name}")
         }
@@ -163,7 +163,7 @@ class Task(context: Context, private val raw: Song.Raw) {
         return Song(raw)
     }
 
-    private fun completeAudio(metadata: Metadata) {
+    private fun completeRawSong(metadata: Metadata) {
         val id3v2Tags = mutableMapOf<String, List<String>>()
         val vorbisTags = mutableMapOf<String, MutableList<String>>()
 

app/src/main/java/org/oxycblt/auxio/music/system/ParsingUtil.kt

@@ -33,6 +33,14 @@ fun String.parseTimestamp() = Date.from(this)
 private val SEPARATOR_REGEX = Regex("[^\\\\][\\[,;/+&]")
 private val ESCAPED_REGEX = Regex("\\\\[\\[,;/+&]")
 
+/**
+ * Fully parse a multi-value tag.
+ *
+ * If there is only one string in the tag, and if enabled, it will be parsed for any multi-value
+ * separators desired. Escaped separators will be ignored and replaced with their correct character.
+ *
+ * Alternatively, if there are several tags already, it will be returned without modification.
+ */
 fun List<String>.parseMultiValue() =
     if (size == 1) {
         get(0).parseSeparatorsImpl()
@@ -40,6 +48,9 @@ fun List<String>.parseMultiValue() =
         this
     }
 
+/**
+ * Parse a tag into multiple values using a series of generic separators. Will trim whitespace.
+ */
 private fun String.parseSeparatorsImpl() =
     // First split by non-escaped separators (No preceding \), and then split by escaped
     // separators.
@@ -47,13 +58,16 @@ private fun String.parseSeparatorsImpl() =
         ESCAPED_REGEX.replace(it) { match -> match.value.substring(1) }.trim()
     }
 
-fun List<String>.parseReleaseType() =
+/**
-    if (size == 1) {
+ * Parse a multi-value tag into a [ReleaseType], handling separators in the process.
-        ReleaseType.parse(get(0).parseSeparatorsImpl())
+ */
-    } else {
+fun List<String>.parseReleaseType() = ReleaseType.parse(parseMultiValue())
-        ReleaseType.parse(this)
-    }
 
+/**
+ * Parse a multi-value genre name using ID3v2 rules. If there is one value, the ID3v2.3
+ * rules will be used, followed by separator parsing. Otherwise, each value will be iterated
+ * through, and numeric values transformed into string values.
+ */
 fun List<String>.parseId3GenreNames() =
     if (size == 1) {
         get(0).parseId3GenreNames()
@@ -61,6 +75,9 @@ fun List<String>.parseId3GenreNames() =
         map { it.parseId3v1Genre() ?: it }
     }
 
+/**
+ * Parse a single genre name using ID3v2.3 rules.
+ */
 fun String.parseId3GenreNames() =
         parseId3v1Genre()?.let { listOf(it) } ?:
            parseId3v2Genre() ?:
@@ -84,7 +101,7 @@ private fun String.parseId3v2Genre(): List<String>? {
     val groups = (GENRE_RE.matchEntire(this) ?: return null).groupValues
     val genres = mutableSetOf<String>()
 
-    // ID3v2 genres are far more complex and require string grokking to properly implement.
+    // ID3v2.3 genres are far more complex and require string grokking to properly implement.
     // You can read the spec for it here: https://id3.org/id3v2.3.0#TCON
     // This implementation in particular is based off Mutagen's genre parser.