Support for number charts, transposition when generating charts.

pco_chords.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "0.4.1"
+version       = "0.5.0"
 author        = "Jonathan Bernard"
 description   = "Chord chart formatter compatible with Planning Center Online"
 license       = "MIT"

src/pco_chords.nim

@@ -34,11 +34,16 @@ when isMainModule:
     $ast & "\p" &
     "-".repeat(16) & "\p"
 
-  let outputHtml = ast.toHtml()
+  let transpose =
+    if args["--transpose"]: parseInt($args["--transpose"])
+    else: 0
+
+  let outputHtml = ast.toHtml(transpose, args["--number-chart"])
+
   if args["--output"]: writeFile($args["--output"], outputHtml)
   else: stdout.write(outputHtml)
 
- except:
+ except CatchableError:
   fatal getCurrentExceptionMsg()
   debug getCurrentException().getStackTrace()
   quit(QuitFailure)

src/pco_chordspkg/ast.nim

@@ -4,7 +4,7 @@ import zero_functional
 type
   ChordChartMetadata* = object
     title*: string
-    key*: ChordChartPitch
+    key*: ChordChartChord
     optionalProps: StringTableRef
 
   ChordChart* = ref object
@@ -26,7 +26,7 @@ type
   ChordChartPitch* = enum Af, A, Bf, B, C, Df, D, Ef, E, F, Fs, G
 
   ChordChartChord* = object
-    original*: string
+    original*: Option[string]
     rootPitch*: ChordChartPitch
     flavor*: Option[string]
     bassPitch*: Option[ChordChartPitch]
@@ -133,13 +133,15 @@ func dump*(ccn: ChordChartNode, indent = ""): string =
     if ccn.chord.isSome:
       let chord = ccn.chord.get
       result &= "["
-      if chord.flavor.isNone and chord.bassPitch.isNone:
+      if chord.original.isSome and chord.flavor.isNone and
-        result &= chord.original
+         chord.bassPitch.isNone:
+        result &= chord.original.get
       else:
+        result &= $chord.rootPitch
         if chord.flavor.isSome:
-          result &= $chord.rootPitch & "_" & chord.flavor.get
+          result &= "_" & chord.flavor.get
         if chord.bassPitch.isSome:
-          result &= $chord.rootPitch & "/" & $chord.bassPitch.get
+          result &= "/" & $chord.bassPitch.get
       result &= "]"
 
     if ccn.word.isSome: result &= ccn.word.get
@@ -185,8 +187,9 @@ template addToCurSection(n: ChordChartNode): untyped =
   if ctx.curSection.kind == ccnkSection: ctx.curSection.sectionContents.add(n)
   else: result.add(n)
 
-func parsePitch*(ctx: ParserContext, keyValue: string): ChordChartPitch =
+proc parsePitch*(ctx: ParserContext, keyValue: string): ChordChartPitch =
-  case keyValue.strip.toLower
+  let normK = keyValue.strip.toLower
+  case normK
   of "gs", "gis", "g#", "ab", "a♭", "af", "aes": return ChordChartPitch.Af
   of "g𝄪", "a", "a♮", "b𝄫": return ChordChartPitch.A
   of "as", "ais", "a#", "bf", "bb", "b♭", "bes", "c𝄫": return ChordChartPitch.Bf
@@ -199,6 +202,13 @@ func parsePitch*(ctx: ParserContext, keyValue: string): ChordChartPitch =
   of "es", "eis", "e#", "f", "g𝄫": return ChordChartPitch.F
   of "e𝄪", "fs", "fis", "f#", "gf", "gb", "ges": return ChordChartPitch.Fs
   of "f𝄪", "g", "a𝄫": return ChordChartPitch.G
+  of "1": return ctx.curKeyCenter
+  of "2": return ctx.curKeyCenter + 2
+  of "3": return ctx.curKeyCenter + 4
+  of "4": return ctx.curKeyCenter + 5
+  of "5": return ctx.curKeyCenter + 7
+  of "6": return ctx.curKeyCenter + 9
+  of "7": return ctx.curKeyCenter + 11
   else: raise ctx.makeError(keyValue.strip & " is not a recognized key.")
 
 # see regexr.com/70nv1
@@ -226,7 +236,7 @@ proc parseChord*(
       else: none[ChordChartPitch]()
 
     return some(ChordChartChord(
-      original: chordValue,
+      original: some(chordValue),
       rootPitch: ctx.parsePitch(m.get.captures[0]),
       flavor: flavor,
       bassPitch: bassPitch))
@@ -236,8 +246,8 @@ let METADATA_END_PAT = re"^-+$"
 proc parseMetadata(ctx: var ParserContext): ChordChartMetadata =
 
   var title = "MISSING"
-  var songKey = "MISSING"
   var optProps = newStringTable()
+  var songKey: Option[ChordChartChord]
 
   while ctx.curLineNum < ctx.lines.len:
     let line = ctx.nextLine
@@ -252,18 +262,21 @@ proc parseMetadata(ctx: var ParserContext): ChordChartMetadata =
     let key = m.get.captures[0].strip.tolower
     let value = m.get.captures[1].strip
     if key == "title": title = value
-    elif key == "key": songKey = value
+    elif key == "key":
+      songKey = ctx.parseChord(value)
+      if songKey.isNone:
+        raise ctx.makeError("unrecognized key: " & value)
     else: optProps[key] = value
 
   if title == "MISSING":
     raise ctx.makeError("metadata is missing the 'title' property")
 
-  if songKey == "MISSING":
+  if songKey.isNone:
     raise ctx.makeError("metadata is missing the 'key' property")
 
   result = ChordChartMetadata(
     title: title,
-    key: ctx.parsePitch(songKey),
+    key: songKey.get,
     optionalProps: optProps)
 
 const KNOWN_SECTION_NAMES = [
@@ -447,7 +460,7 @@ proc parseChordChart*(s: string): ChordChart =
     unparsedLineParts: @[])
 
   let metadata = parseMetadata(parserCtx)
-  parserCtx.curKeyCenter = metadata.key
+  parserCtx.curKeyCenter = metadata.key.rootPitch
 
   result = ChordChart(
     rawContent: s,

src/pco_chordspkg/cliconstants.nim

@@ -1,4 +1,4 @@
-const PCO_CHORDS_VERSION* = "0.4.1"
+const PCO_CHORDS_VERSION* = "0.5.0"
 
 const USAGE* = """Usage:
   pco_chords [options]
@@ -6,12 +6,20 @@ const USAGE* = """Usage:
 
 Options:
 
-  -i, --input <in-file>     Read input from <in-file> (rather than from
+  -i, --input <in-file>       Read input from <in-file> (rather than from
                               STDIN, which is the default).
 
-  -o, --output <out-file>   Write output to <out-file> (rather than from
+  -o, --output <out-file>     Write output to <out-file> (rather than from
                               STDOUT, which is the default).
 
+  -t, --transpose <distance>  Transpose the chart by the given number of
+                              semitones. Distance can be expressed as a
+                              positive or negative number of semitones,
+                              for example: 4, +3 or -5.
+
+  -n, --number-chart          Write out a chart using the Nashville number
+                              system rather than explicit pitches.
+
   --help                      Print this usage information
   --debug                     Enable debug logging.
   --echo-args                 Echo the input parameters.

src/pco_chordspkg/html.nim

@@ -9,6 +9,8 @@ type
     currentKey: ChordChartPitch
     sourceKey: ChordChartPitch
     currentSection: ChordChartNode
+    numberChart: bool
+    transposeSteps: int
 
 const DEFAULT_STYLESHEET* = """
 <style>
@@ -69,6 +71,10 @@ h3 .section-text {
   margin-right: 0.5em;
 }
 
+.chord .flavor {
+  font-variant-position: super;
+}
+
 .song-order h3 {
   font-style: italic;
   font-weight: normal;
@@ -89,17 +95,58 @@ h3 .section-text {
 </style>
 """
 
-proc transpose(ctx: FormatContext, chord: ChordChartChord): string =
+func scaleDegree(root: ChordChartPitch, p: ChordChartPitch): string =
-  let distance = ctx.currentKey - ctx.sourceKey
+  let distance = p - root
+  case distance:
+  of 0: "1"
+  of 1: "♭2"
+  of 2: "2"
+  of 3: "♭3"
+  of 4: "3"
+  of 5: "4"
+  of 6: "♭5"
+  of 7: "5"
+  of 8: "♭6"
+  of 9: "6"
+  of 10: "♭7"
+  of 11: "7"
+  else: raise newException(Exception, "Impossible")
 
-  if distance != 0:
+func format(ctx: FormatContext, chord: ChordChartChord, useNumber = false): string =
-    result = $(chord.rootPitch + distance)
+  if not useNumber and chord.original.isSome: return chord.original.get
+
+  elif useNumber:
+    result = "<span class=root>" &
+      ctx.currentKey.scaleDegree(chord.rootPitch) & "</span>"
+
+    if chord.flavor.isSome:
+      result &= "<span class=flavor>" & chord.flavor.get & "</span>"
+
+    if chord.bassPitch.isSome:
+      result &= "<span class=bass>/" &
+        ctx.currentKey.scaleDegree(chord.bassPitch.get) & "</span>"
+
+  else:
+    result = $chord.rootPitch
     if chord.flavor.isSome: result &= chord.flavor.get
-    if chord.bassPitch.isSome: result &= "/" & $(chord.bassPitch.get + distance)
+    if chord.bassPitch.isSome: result &= "/" & $chord.bassPitch.get
     #debug "transposed " & $ctx.sourceKey & " -> " & $ctx.currentKey &
     #  " (distance " & $distance & ")\p\tchord: " & $chord & " to " & result
 
-  else: result = chord.original
+proc transpose(ctx: FormatContext, chord: ChordChartChord): ChordChartChord =
+  result = chord
+
+  let distance = ctx.currentKey - ctx.sourceKey
+  if distance != 0:
+    result = ChordChartChord(
+      original: none[string](),
+      rootPitch: chord.rootPitch + distance,
+      flavor:
+        if chord.flavor.isSome: some(chord.flavor.get)
+        else: none[string](),
+      bassPitch:
+        if chord.bassPitch.isSome: some(chord.bassPitch.get + distance)
+        else: none[ChordChartPitch]())
 
 func makeSongOrder(songOrder, indent: string): string =
   result = indent & "<section class=song-order>\p" &
@@ -143,7 +190,8 @@ proc toHtml(ctx: var FormatContext, node: ChordChartNode, indent: string): strin
     result &= "'>"
 
     if node.chord.isSome:
-      result &= "<span class=chord>" & ctx.transpose(node.chord.get) & "</span>"
+      result &= "<span class=chord>" &
+        ctx.format(ctx.transpose(node.chord.get), ctx.numberChart) & "</span>"
 
     result &= "<span class=lyric>"
     if node.word.isSome: result &= node.word.get
@@ -169,8 +217,8 @@ proc toHtml(ctx: var FormatContext, node: ChordChartNode, indent: string): strin
       result &= "</section><section>" & headingVal & "</section><section>"
 
   of ccnkRedefineKey:
-    let oldKey = ctx.sourceKey
+    let oldKey = ctx.currentKey
-    ctx.sourceKey = node.newKey
+    ctx.sourceKey = node.newKey + ctx.transposeSteps
     ctx.currentKey = ctx.sourceKey
 
     if oldKey != ctx.currentKey:
@@ -183,14 +231,21 @@ proc toHtml(ctx: var FormatContext, node: ChordChartNode, indent: string): strin
 
 proc toHtml*(
     cc: ChordChart,
+    transpose = 0,
+    numberChart = false,
     stylesheets = @[DEFAULT_STYLESHEET],
     scripts: seq[string] = @[]): string =
 
   var ctx = FormatContext(
     chart: cc,
-    currentKey: cc.metadata.key,
+    currentKey: cc.metadata.key.rootPitch + transpose,
-    sourceKey: cc.metadata.key,
+    sourceKey: cc.metadata.key.rootPitch,
-    currentSection: EMPTY_CHORD_CHART_NODE)
+    currentSection: EMPTY_CHORD_CHART_NODE,
+    numberChart: numberChart,
+    transposeSteps: transpose)
+
+  debug "Formatting:\p\tsource key: " & $ctx.sourceKey & "\p\ttransposing: " &
+    $transpose & "\p\ttarget key: " & $ctx.currentKey
 
   result = """<!doctype html>
 <html>
@@ -210,11 +265,11 @@ proc toHtml*(
   result &= "  </head>\p  <body>"
 
   var indent = "      "
-  #
+
   # Title
   result &= indent & "<h1>" & cc.metadata.title & "</h1>\p"
 
-  var metadataPieces = @["Key: " & $cc.metadata.key]
+  var metadataPieces = @["Key: " & ctx.format(ctx.transpose(cc.metadata.key))]
   if cc.metadata.contains("time signature"):
     metadataPieces.add(cc.metadata["time signature"])
   if cc.metadata.contains("bpm"):