From 6fc1a9b117ad6983a536980eea68852a0686f587 Mon Sep 17 00:00:00 2001
From: Belleve Invis <belleve@typeof.net>
Date: Sat, 4 Apr 2020 13:06:00 -0700
Subject: [PATCH] Expand the ligation set for colons to all dotty operators
 (#476).

---
 changes/3.0.0-rc.6.md         |  3 +-
 glyphs/symbol-punctuation.ptl | 30 +++++++++---
 ligation-set.toml             | 24 +++++-----
 otl/gsub-ligation.ptl         | 89 +++++++++++++++++++++++++++++------
 4 files changed, 112 insertions(+), 34 deletions(-)

diff --git a/changes/3.0.0-rc.6.md b/changes/3.0.0-rc.6.md
index a669c7a387..ebd5518415 100644
--- a/changes/3.0.0-rc.6.md
+++ b/changes/3.0.0-rc.6.md
@@ -7,4 +7,5 @@
  * Fixed missing `TM` and `SM` symbol.
  * Fixed weight of dotted numbers.
  * Fix APL symbols' metric under Aile.
- * Make `m.shortleg` more distinctive (#471).
\ No newline at end of file
+ * Make `m.shortleg` more distinctive (#471).
+ * Expand the ligation set for colons to all dotty operators (#476).
\ No newline at end of file
diff --git a/glyphs/symbol-punctuation.ptl b/glyphs/symbol-punctuation.ptl
index 1fcd54e79e..faadae62cc 100644
--- a/glyphs/symbol-punctuation.ptl
+++ b/glyphs/symbol-punctuation.ptl
@@ -401,19 +401,12 @@ glyph-block Symbol-Punctuation : begin
 			include : refer-glyph "period"
 			include : refer-glyph "xhPeriod"
 			save 'colon' ':'
-			save 'colon.dmid'
 
 			branch
 				apply-transform : Upright
 				apply-transform : Translate 0 (symbolMid - XH / 2)
 				apply-transform : Italify
 				save 'colon.mid'
-			branch
-				local delta : Math.max 0 : WIDTH / 2 - (XH - PERIODSIZE) / 2
-				apply-transform : Translate delta 0
-				save 'colon.dright'
-				apply-transform : Translate (-2 * delta) 0
-				save 'colon.dleft'
 
 		sketch # holowColon
 			define sw : adviceBlackness 5
@@ -1382,3 +1375,26 @@ glyph-block Symbol-Punctuation : begin
 				quadcontrols  0.5 0
 				g4 (RIGHTSB - OX) 0
 			save "undertie" 0x203F
+
+	do "Ligation Variants"
+		define dotLikePunctuations : list
+			* "colon"
+			* "semicolon"
+			* "period"
+			* "period.center"
+			* "comma"
+			* "question"
+			* "exclam"
+
+		foreach [baseName : items-of dotLikePunctuations] : sketch
+			include [refer-glyph baseName] AS_BASE ALSO_METRICS
+			save (baseName + ".lig.dMid")
+			local delta : Math.max 0 : WIDTH / 2 - (XH - PERIODSIZE) / 2
+			apply-transform : Translate delta 0
+			save (baseName + '.lig.dRight')
+			apply-transform : Translate (-delta / 2) 0
+			save (baseName + '.lig.dRightHalf')
+			apply-transform : Translate (-delta) 0
+			save (baseName + '.lig.dLeftHalf')
+			apply-transform : Translate (-delta / 2) 0
+			save (baseName + '.lig.dLeft')
diff --git a/ligation-set.toml b/ligation-set.toml
index fe3e06c09a..b692f99558 100644
--- a/ligation-set.toml
+++ b/ligation-set.toml
@@ -66,9 +66,9 @@ desc = 'Center asterisk in `(*` and `*)`'
 ligGroup =  "plusplus"
 desc = 'Enable ligation for `++` and further plus-chaining'
 
-[simple.calt-colons]
-ligGroup =  "colons"
-desc = 'Enable ligation for `::` and `:::`'
+[simple.calt-kern-dotty]
+ligGroup =  "kern-dotty"
+desc = 'Move connecting dotty punctuations closer, like for `::`, `:::` and `...`.'
 
 [simple.calt-logic]
 ligGroup =  "logic"
@@ -97,24 +97,24 @@ desc = 'Enable ligation for `<!--` and `<!---`'
 [composite.ligset-calt]
 disableHives = true
 tag     = 'calt'
-buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeq', 'ineq', 'exeq',  'plusplus', 'colons']
+buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeq', 'ineq', 'exeq',  'plusplus', 'kern-dotty']
 brief   = 'Default'
 desc    = 'Default setting in text editors'
 
 [composite.ligset-dlig]
 tag     = 'dlig'
-buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'arrow2', 'llgg', 'eqeq', 'ineq', 'exeq', 'ltgt-diamond', 'plusplus', 'colons', 'dotoper', 'logic', 'brst']
+buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'arrow2', 'llgg', 'eqeq', 'ineq', 'exeq', 'ltgt-diamond', 'plusplus', 'kern-dotty', 'dotoper', 'logic', 'brst']
 brief   = 'Discretionary'
 desc    = 'Discretionary ligatures'
 
 [composite.ligset-javascript]
 tag     = 'JSPT'
-buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeqeq', 'eqeq', 'ineq', 'exeqeq', 'exeq', 'plusplus', 'colons']
+buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeqeq', 'eqeq', 'ineq', 'exeqeq', 'exeq', 'plusplus', 'kern-dotty']
 desc    = 'JavaScript'
 
 [composite.ligset-php]
 tag     = 'PHPX'
-buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeqeq', 'eqeq', 'ineq', 'exeqeq', 'exeq', 'plusplus', 'colons']
+buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeqeq', 'eqeq', 'ineq', 'exeqeq', 'exeq', 'plusplus', 'kern-dotty']
 desc    = 'PHP'
 
 [composite.ligset-ml]
@@ -134,22 +134,22 @@ desc    = 'F*'
 
 [composite.ligset-haskell]
 tag     = 'HSKL'
-buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'colons', 'logic']
+buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'kern-dotty', 'logic']
 desc    = 'Haskell'
 
 [composite.ligset-idris]
 tag     = 'IDRS'
-buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'colons', 'logic']
+buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'kern-dotty', 'logic']
 desc    = 'Idris'
 
 [composite.ligset-elm]
 tag     = 'ELMX'
-buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'colons', 'logic']
+buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'kern-dotty', 'logic']
 desc    = 'Elm'
 
 [composite.ligset-purescript]
 tag     = 'PURS'
-buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'colons', 'logic']
+buildup = ['center-ops', 'arrow', 'arrow2', 'trig', 'llgg', 'eqeq', 'ineq', 'slasheq', 'ltgt-diamond', 'plusplus', 'dotoper', 'kern-dotty', 'logic']
 desc    = 'PureScript'
 
 [composite.ligset-patel]
@@ -169,5 +169,5 @@ desc    = 'Coq'
 
 [composite.ligset-matlab]
 tag     = 'MTLB'
-buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeq', 'ineq', 'tildeeq', 'plusplus', 'colons']
+buildup = ['center-ops', 'arrow', 'html-comment', 'trig', 'llgg', 'eqeq', 'ineq', 'tildeeq', 'plusplus', 'kern-dotty']
 desc    = 'Matlab'
diff --git a/otl/gsub-ligation.ptl b/otl/gsub-ligation.ptl
index 3119fd7d40..e96f5abcc4 100644
--- a/otl/gsub-ligation.ptl
+++ b/otl/gsub-ligation.ptl
@@ -16,6 +16,13 @@ export : define [buildLigations sink para plm glyphs] : foreach [ {featureName m
 	define arrowStick  {'hyphen' 'equal'}
 	define [stick style] : {'hyphen' 'equal'} ~> [lsx style]
 	define [stickClass style] : [lsx style] {'hyphen' 'equal'}
+	define [anyStartingWith names] : begin
+		local result {}
+		foreach [name : items-of names] : begin
+			local re : new RegExp "^\(name)(?:\.|$)"
+			foreach [name : items-of : Object.keys glyphs]
+				if [re.test name] : result.push name
+		return result
 
 	define less {'less'}
 	define hyphen {'hyphen'}
@@ -47,6 +54,33 @@ export : define [buildLigations sink para plm glyphs] : foreach [ {featureName m
 		'slash' 'bar' 'at' 'ampersand' 'percent'
 		'numbersign' 'numbersign.upright' 'numbersign.slanted'
 	}
+	define dottyPunctuations : list
+		* "colon"
+		* "semicolon"
+		* "period"
+		* "period.center"
+		* "comma"
+		* "question"
+		* "exclam"
+	define widePunctuation : list
+		* 'parenLeft'
+		* 'parenRight'
+		* 'bracketLeft'
+		* 'bracketRight'
+		* 'braceLeft'
+		* 'braceRight'
+		* 'equal'
+		* 'hyphen'
+		* 'plus'
+		* 'less'
+		* 'greater'
+		* 'numbersign'
+		* 'slash'
+		* 'ampersand'
+		* 'asterisk'
+		* 'asciicaret'
+		* 'asciitilde'
+
 	define [asterisk_center]  ({'asterisk'}          ~> {'asterisk.dfltlow'})
 	define [colon_center]     ({'colon' 'colon.mid'} ~> {'colon.mid' 'colon.mid'})
 	define [caret_center]     ({'asciicaret'}        ~> {'asciicaret.low'})
@@ -172,20 +206,47 @@ export : define [buildLigations sink para plm glyphs] : foreach [ {featureName m
 				chain-rule alphabet [no_period_center]
 				chain-rule [no_period_center] alphabet
 
-	do "Colon chains" : includeLookup
-		.type 'gsub_chaining'
-		.subtables : list
-			# Colon chains
-			chain-rule
-				{'colon.dright' 'colon.dmid'} ~> preserved
-				{'colon'} ~> [only 'colons' {'colon.dmid'}]
-				{'colon'} ~> preserved
-			chain-rule
-				{'colon.dright' 'colon.dmid'} ~> preserved
-				{'colon'} ~> [only 'colons' {'colon.dleft'}]
-			chain-rule
-				{'colon'} ~> [only 'colons' {'colon.dright'}]
-				{'colon'} ~> preserved
+	do "Colon chains" : begin
+		define dLeft      : [lsx 'dLeft'] dottyPunctuations
+		define dRight     : [lsx 'dRight'] dottyPunctuations
+		define dLeftHalf  : [lsx 'dLeftHalf'] dottyPunctuations
+		define dRightHalf : [lsx 'dRightHalf'] dottyPunctuations
+		define dMid       : [lsx 'dMid'] dottyPunctuations
+		define boundary   : anyStartingWith widePunctuation
+
+		includeLookup
+			.type 'gsub_chaining'
+			.subtables : list
+				# Colon chains
+				chain-rule
+					[dRight.concat dMid] ~> preserved
+					dottyPunctuations ~> [only 'colons' dMid]
+					dottyPunctuations ~> preserved
+				chain-rule
+					[dRight.concat dMid] ~> preserved
+					dottyPunctuations ~> [only 'colons' dLeft]
+				chain-rule
+					dottyPunctuations ~> [only 'colons' dRight]
+					dottyPunctuations ~> preserved
+		includeLookup
+			.type 'gsub_chaining'
+			.subtables : list
+				# Colon chains
+				chain-rule
+					boundary             ~> preserved
+					dRight               ~> [only 'colons' dMid]
+					[dMid.concat dLeft]  ~> preserved
+				chain-rule
+					[dMid.concat dRight] ~> preserved
+					dLeft                ~> [only 'colons' dMid]
+					boundary             ~> preserved
+		includeLookup
+			.type 'gsub_chaining'
+			.subtables : list
+				# Colon chains
+				chain-rule
+					dRight ~> [only 'colons' dRightHalf]
+					dLeft  ~> [only 'colons' dLeftHalf]
 
 	do "Plus chains" : begin
 		includeLookup