💡 RFC: Comparing different chordpro syntax to support

[isaiahdahl]

Alright below is the same song across various formats. Trying to identify conflicts between the different types and gauge whether or not we can support all the types in a single lezer grammar for syntax highlighting.

ChordPro (with backslashes)

{t: Rattle}
{artist: Elevation Worship}
{key: Eb}
{c:Intro (5x)}
[Eb(no3)][/][/][/][|][/][/][/][/][|]

{c:Verse 1}
[Eb]Saturday was silent, [Ebsus]surely it was [Eb]through
[Cm] But since when has im - [Bb]possible\ [Ab2]ever [Eb/G]stopped [Eb]You[/][/][/][/]
[Eb]Friday’s disappointment\ is Sun - [Ebsus]day’s empty [Eb]tomb
[Cm] Since when has im - [Bb]possible\ [Ab2]ever [Eb/G]stopped [Eb]You
[Ab2][-][Eb/G][Eb][/]

{c:Chorus 1}
[Eb5]This is the sound\ of dry bones rattling[/Bb][-][/Ab][Eb5]
[Eb5]This is the praise\ make a dead man walk again[/Bb][-][/Ab][Eb5]
Open the [Cm]grave, I'm coming [Bb]out
I'm gonna [Ab]live, gonna live a - [Eb]gain
[Eb5]This is the sound\ of dry bones rattling[Ab][-][Eb/G][Eb5]

Chords Over Words

title: Rattle
artist: Elevation Worship
key: Eb

Intro (5x)
Eb(no3) / / / | / / / / |

Verse 1
Eb                   Ebsus         Eb      
Saturday was silent, surely it was through
Cm                         Bb        Ab2  Eb/G    Eb  / / / / 
   But since when has im - possible\ ever stopped You
Eb                                Ebsus       Eb   
Friday’s disappointment\ is Sun - day’s empty tomb
Cm                     Bb        Ab2  Eb/G    Eb  
   Since when has im - possible\ ever stopped You
Ab2 - Eb/G Eb /

Chorus 1
Eb5                                     /Bb - /Ab Eb5 
This is the sound\ of dry bones rattling
Eb5                                           /Bb - /Ab Eb5 
This is the praise\ make a dead man walk again
         Cm                Bb  
Open the grave, I'm coming out
          Ab                   Eb   
I'm gonna live, gonna live a - gain
Eb5                                     Ab - Eb/G Eb5 
This is the sound\ of dry bones rattling
Ab - Eb/G Eb5 / | Ab - Eb/G Eb5 /

OnSong

Suports chords over words & chords & chordpro

{t: Rattle}
{artist: Elevation Worship}
{key: Eb}

Intro (5x):

Verse 1:
[Eb]Saturday was silent, [Ebsus]surely it was [Eb]through
[Cm] But since when has im - [Bb]possible [Ab2]ever [Eb/G]stopped [Eb]You[/][/][/][/]
[Eb]Friday’s disappointment is Sun - [Ebsus]day’s empty [Eb]tomb
[Cm] Since when has im - [Bb]possible [Ab2]ever [Eb/G]stopped [Eb]You
[Ab2][-][Eb/G][Eb][/]

Chorus 1:
[Eb5]This is the sound of dry bones rattling[/Bb][-][/Ab][Eb5]
[Eb5]This is the praise make a dead man walk again[/Bb][-][/Ab][Eb5]
Open the [Cm]grave, I'm coming [Bb]out
I'm gonna [Ab]live, gonna live a - [Eb]gain
[Eb5]This is the sound of dry bones rattling[Ab][-][Eb/G][Eb5]

{t: Rattle}
{artist: Elevation Worship}
{key: Eb}
Intro (5x):
Eb(no3) / / / | / / / / |

Verse 1:
Eb                   Ebsus         Eb      
Saturday was silent, surely it was through
Cm                         Bb        Ab2  Eb/G    Eb  / / / / 
   But since when has im - possible ever stopped You
Eb                                Ebsus       Eb   
Friday’s disappointment is Sun - day’s empty tomb
Cm                     Bb        Ab2  Eb/G    Eb  
   Since when has im - possible ever stopped You
Ab2 - Eb/G Eb /

Chorus 1:
Eb5                                     /Bb - /Ab Eb5 
This is the sound of dry bones rattling
Eb5                                           /Bb - /Ab Eb5 
This is the praise make a dead man walk again
         Cm                Bb  
Open the grave, I'm coming out
          Ab                   Eb   
I'm gonna live, gonna live a - gain
Eb5                                     Ab - Eb/G Eb5 
This is the sound of dry bones rattling
Ab - Eb/G Eb5 / | Ab - Eb/G Eb5 /

Ultimate Guitar

[Intro]
Eb

[Verse 1]
Eb                   Ebsus         Eb
 Saturday was silent Surely it was through
Cm7                     Bbsus
 But since when has im--possible
 Ab   Eb/G    Eb
 Ever stopped you
Eb                          Ebsus          Eb
 Friday's disappointment is Sunday's empty tomb
Cm7                 Bbsus
 Since when has im--possible
 Ab     Eb/G  Eb    Ab  Eb/G  Eb
 Ever stopped you


[Chorus]
Eb
This is the sound
                      Bbsus Ab  Eb
of dry bones rattling
Eb
This is the praise
                          Bbsus Ab  Eb
Make a dead man walk again
         Cm7               Bbsus
Open the grave  I'm coming out
Bb          Ab                   Eb
  I'm gonna live, gonna live a - gain
Eb
This is the sound
                     Ab  Eb/G  Eb    Ab  Eb/G   Eb
of dry bones rattling

Planning Center

Intro (5x)
[Eb(no3)] [/] [/] [/] [|] [/] [/] [/] [/] [|]

Verse 1
[Eb]Saturday was silent, [Ebsus]surely it was [Eb]through
[Cm] But since when has im - [Bb]possible [Ab2]ever [Eb/G]stopped [Eb]You[/] [/] [/] [/]
[Eb]Friday’s disappointment is Sun - [Ebsus]day’s empty [Eb]tomb
[Cm] Since when has im - [Bb]possible [Ab2]ever [Eb/G]stopped [Eb]You
[Ab2] [-] [Eb/G] [Eb] [/]


Chorus 1
[Eb5]This is the sound of dry bones rattling[/Bb] [-] [/Ab] [Eb5]
[Eb5]This is the praise make a dead man walk again[/Bb] [-] [/Ab] [Eb5]
Open the [Cm]grave, I'm coming [Bb]out
I'm gonna [Ab]live, gonna live a - [Eb]gain
[Eb5]This is the sound of dry bones rattling[Ab] [-] [Eb/G] [Eb5]
[Ab] [-] [Eb/G] [Eb5] [/] [|] [Ab] [-] [Eb/G] [Eb5] [/]

[isaiahdahl]

Conflicts in grammar

1. OnSong sections and Chords Over Words metadata

In OnSong sections are written like Verse 1: But in chords over words that could be confused with a directive. You would want the syntax highlighting to know you were starting to write a directive when you only had title: written. Assuming for example that section headings (or comments in chordpro) were

1. {title: Rattle} 
2. {artist: Elevation Worship}
3. {key: Eb}
4. 
5. Intro (5x):
6. Eb(no3) / / / | / / / / |

Colors
1. {grey: red}
2. {grey: red}
3. {grey: red}
4. 
5. red
6. blue

VS

1. title: Rattle
2. artist: Elevation Worship
3. key: Eb
4. 
5. Intro (5x)
6. Eb(no3) / / / | / / / / |

Colors
1. grey: red
2. grey: red
3. grey: red
4. 
5. red
6. blue

2. Ultimate Guitar and ChordPro

Ultimate Guitar wraps section headings in brackets This could potentially be confused with chords.

[bkeepers]

1. OnSong sections and Chords Over Words metadata

In OnSong sections are written like Verse 1: But in chords over words that could be confused with a directive. You would want the syntax highlighting to know you were starting to write a directive when you only had title: written. Assuming for example that section headings (or comments in chordpro) were

While this could in theory lead to ambiguity while authoring, I don't think it will generally be a problem in practice.
The onsong docs specify that "metdata is expressed in the first section of the song before the first blank line or until no more metatags are encountered".

So the parser would have to give precedence to metadata until a newline is encountered and then give precedence to sections (but still parse as metadata if it has a value after :). I'm pretty sure Lezer can handle the ambiguity.

So given this example…

title: Obviously Metadata
key: 

year: 1999

Verse 1:

1. title is obviously metadata
2. key would parse as metadata
3. year: would initially parse as a section name until the 1 of 1999 is typed and then parse as metadata.
4. Verse 1: would parse as a section name

2. Ultimate Guitar and ChordPro

This one will be more challenging unless we're very strict about what is parsed as a chord.

[isaiahdahl]

So the parser would have to give precedence to metadata until a newline is encountered and then give precedence to sections (but still parse as metadata if it has a value after :). I'm pretty sure Lezer can handle the ambiguity.

Yea makes sense to me. I've been playing around with the ChordsOverWords pegjs parser that Martijns working on and wrote a bunch of tests searching for edge cases and has this task in my mind. Another scenario I came across is supporting things like the transpose or new key directive mid verse.

title: Let it be
key: C

Chorus 1:
       Am
Let it be
new_key: G 
       Em
Let it be

With that approach, new_key would be parsed as a directive because it has a value after the ':'

So I agree, that this scenario can be handled.

---

This one will be more challenging unless we're very strict about what is parsed as a chord.

I think it's possible we can figure out a way to do this. Intuitively I think we should be able to tell what is a chord (or a half typed Chord) and what is not a chord.

As long as we're the perfect amount strict, we can be strict haha!