Added support for square brackets around notes.

Part of the implementation for gregorio-project#844.

CHANGELOG.md

@@ -5,6 +5,7 @@ As of v3.0.0 this project adheres to [Semantic Versioning](http://semver.org/).
 [Unreleased][unreleased]
 ### Added
 - More cavum shapes are now available.  To use them, simply add `r` in gabc to any note in a glyph.  See [#844](https://github.com/gregorio-project/gregorio/issues/844).
+- Square brackets can be placed around notes by using `[[` and `]]` to surround said notes in gabc (see [#844](https://github.com/gregorio-project/gregorio/issues/844)).
 
 ### Removed
 - The gregorio and granapadano fonts are no longer distributed with the Gregorio distribution archive.  They will now be available for download separately (along with optional Dominican "-op" variants).  ***If there are other logistics, put them here or delete this statement before release.***  See [UPGRADE.md](UPGRADE.md) and [#844](https://github.com/gregorio-project/gregorio/issues/844) for details.

contrib/gabc.vim

@@ -37,6 +37,9 @@ syn match gabcSpace "z[-+0]\?" contained
 syn match gabcSpace "Z[-+]\?" contained
 syn match gabcSpace "/\[[^\]]*\]" contained extend
 syn match gabcCommand "@\@<!\[[^\]]*\]" contained extend
+syn match gabcCommand "[{}]" contained extend
+syn match gabcBracket "\[\[" contained
+syn match gabcBracket "\]\]" contained
 
 syn region gabcComment start="%" end="$" keepend extend
 syn region gabcAlt matchgroup=gabcTextMarkup start="<alt>" end="</alt>"
@@ -48,7 +51,7 @@ syn region gabcVerbatim matchgroup=gabcTextMarkup start="<v>" end="</v>"
 syn region gabcNabc matchgroup=gabcNabcCut start="|" end="[|)]" keepend
 syn cluster gabcFusible contains=gabcBasicNote,gabcAlteration,gabcBar,gabcSpace,
             \gabcComment,gabcCommand,gabcNoteError,gabcFuse,
-            \gabcTextOrNoteMarkup,gabcClef,gabcNabc
+            \gabcTextOrNoteMarkup,gabcClef,gabcNabc,gabcBracket
 syn region gabcFuseGroup matchGroup=gabcFuseGroup start="@\[" end="\]"
             \ contains=@gabcFusible,gabcFuseEnd contained keepend
 syn region gabcNotes matchgroup=gabcNote start="(" end=")"
@@ -79,6 +82,7 @@ hi def link gabcCommand             Type
 hi def link gabcBar                 Special
 hi def link gabcSpace               Special
 hi def link gabcNabcCut             Delimiter
+hi def link gabcBracket             Delimiter
 hi def link gabcFuse                Constant
 hi def link gabcFuseGroup           Constant
 hi def link gabcFuseEnd             Constant

doc/Command_Index_gregorio.tex

@@ -134,6 +134,18 @@ \section{Gregorio Controls}
   \#1 & string & Text to be typeset in bold.\\
 \end{argtable}
 
+\macroname{\textbackslash GreBracket}{\#1\#2\#3\#4}{gregoriotex-signs.tex}
+Typesets a bracket.
+
+\begin{argtable}
+  \#1 & \texttt{0} & Typeset a left bracket.\\
+      & \texttt{1} & Typeset a right bracket.\\
+  \#2 & integer    & The height of the lowest note within the brackets.\\
+  \#3 & integer    & The ambitus of the notes within the brackets.\\
+  \#4 & string     & the line, byte offset, and column address for textedit
+                     links when point-and-click is enabled.\\
+\end{argtable}
+
 \macroname{\textbackslash GreChangeClef}{\#1\#2\#3\#4\#5\#6\#7}{gregoriotex-signs.tex}
 Macro called when key changes
 

doc/GregorioRef.lua

@@ -29,6 +29,26 @@ local EXCLUDE = {
   nonmarkingreturn = true,
   AscendensOriscusLineBLTR = true,
   AscendensOriscusLineTR = true,
+  BracketLeftZero = true,
+  BracketLeftSix = true,
+  BracketLeftSeven = true,
+  BracketLeftEight = true,
+  BracketLeftNine = true,
+  BracketLeftTen = true,
+  BracketLeftEleven = true,
+  BracketLeftTwelve = true,
+  BracketLeftThirteen = true,
+  BracketLeftFourteen = true,
+  BracketRightZero = true,
+  BracketRightSix = true,
+  BracketRightSeven = true,
+  BracketRightEight = true,
+  BracketRightNine = true,
+  BracketRightTen = true,
+  BracketRightEleven = true,
+  BracketRightTwelve = true,
+  BracketRightThirteen = true,
+  BracketRightFourteen = true,
   PunctumAuctusLineBL = true,
   PunctumLineBLBR = true,
   PunctumLineBR = true,
@@ -72,6 +92,8 @@ local GABC = {
   AscendensPunctumInclinatum = [[G&&&1]],
   AuctumMora = [[\excluded{g}.]],
   BarBrace = [[\excluded{,}\_]],
+  BracketLeft = [=[[[\excluded{gh]]}]=],
+  BracketRight = [=[\excluded{[[gh}]]]=],
   CClef = [[c3]],
   CClefChange = [[c3]],
   Circulus = [[\excluded{g}r3]],