Empty rules are minified away. Passing all YUI tests!

Author: ReFreezed

README.md

@@ -1,5 +1,7 @@
 # LuaCss
 
+![version 1.0](https://img.shields.io/badge/version-1.0-green.svg)
+
 CSS tokenizing and minimizing library for Lua 5.1.
 No external dependencies - only pure Lua.
 The library tries to closely follow the [CSS3 specification](https://www.w3.org/TR/css-syntax-3/).
@@ -79,6 +81,12 @@ end
 Note that all instances of U+0000 (NULL) code points are converted to U+FFFD (replacement character) per the specification.
 
 
+### _VERSION
+`version = _VERSION`
+
+Not a function! Get the version of the library, i.e. `"1.0.2"`.
+
+
 
 ## Options
 `options` is a table that can have any of these fields:

css.lua

@@ -86,7 +86,7 @@ local utf8 = require((path.."utf8"):sub(2))
 
 local F = string.format
 
-local css = {VERSION="0.1.0"}
+local css = {_VERSION="1.0.0"}
 
 
 
@@ -1754,15 +1754,15 @@ function css.minimize(tokensIn, options)
 				end
 
 			elseif tokType == "semicolon" then
+				cb(token, tokType, i)
+
 				if isAt"rule" then
 					currentProperty = nil
 					colonsAfterProp = 0
 				end
 
 				currentAtKeyword = nil -- Possible end of @charset ""; or similar.
 
-				cb(token, tokType, i)
-
 			elseif tokType == "atKeyword" then
 				token = cb(token, tokType, i) or token
 				currentAtKeyword = token.value
@@ -1822,9 +1822,9 @@ function css.minimize(tokensIn, options)
 
 	local function printPeek(tokens, i, count)
 		print("----------------")
-		for j = i, math.min(i+count, #tokens) do
+		for j = math.min(i+count, i), math.max(i+count, i) do
 			if not tokens[j] then  break  end
-			print(j-i, tokens[j].type, tokens[j].value)
+			print(j-i, tokens[j].type, tokens[j].value or "")
 		end
 		print("----------------")
 	end
@@ -1998,7 +1998,7 @@ function css.minimize(tokensIn, options)
 
 				-- Note: It seems CSS4 will add #RRGGBBAA and #RGBA formats, so this code will probably have to be updated.
 				if not isAny(#tokOut.value, 3,6) then
-					print("Warning: Color value looks incorrect: #"..tokOut.value)
+					print("[css] Warning: Color value looks incorrect: #"..tokOut.value)
 				end
 
 				return tokOut
@@ -2012,8 +2012,8 @@ function css.minimize(tokensIn, options)
 			local tokNext = getNextNonWsToken(tokensIn, i+1, 1)
 
 			if
-				tokNext and tokNext.type ~= "}" and tokNext.type ~= "semicolon"
-				and not (tokPrev and tokPrev.type == "{")
+				tokNext and not isAny(tokNext.type, "}","semicolon")
+				and not (tokPrev and isAny(tokPrev.type, "{","}"))
 			then
 				add(tokIn)
 			end
@@ -2072,6 +2072,61 @@ function css.minimize(tokensIn, options)
 		end
 	end)
 
+	-- Remove empty rules.
+	--------------------------------
+	local ruleBeginnings = {}
+	local ruleDepth      = 0
+	local lastRuleStart  = 0
+	local isInSomethingInFileScope = false
+
+	tokensIn  = tokensOut
+	tokensOut = {}
+
+	eachToken(tokensIn, nil, nil, nil, function(tokIn, tokType, i)
+		add(tokIn)
+
+		if not isInSomethingInFileScope and tokType ~= "comment" then
+			lastRuleStart = #tokensOut
+			isInSomethingInFileScope = true
+
+		elseif tokType == "{" then
+			table.insert(ruleBeginnings, lastRuleStart)
+			ruleDepth = ruleDepth+1
+
+			lastRuleStart = #tokensOut+1
+
+		elseif tokType == "}" then
+			local ruleStart = table.remove(ruleBeginnings)
+			ruleDepth = ruleDepth-1
+
+			if not ruleStart then
+				error("[css] Uneven curly brackets.")
+			end
+
+			local tokPrev = getNextToken(tokensOut, #tokensOut-1, -1)
+			if tokPrev.type == "{" then
+				for j = #tokensOut, ruleStart, -1 do
+					table.remove(tokensOut, j)
+				end
+			end
+
+			lastRuleStart = #tokensOut+1
+			if ruleDepth == 0 then
+				isInSomethingInFileScope = false
+			end
+
+		elseif tokType == "semicolon" and currentAtKeyword then
+			lastRuleStart = #tokensOut+1
+			if ruleDepth == 0 then
+				isInSomethingInFileScope = false
+			end
+		end
+	end)
+
+	if tokensOut[1] and tokensOut[#tokensOut].type == "semicolon" then
+		table.remove(tokensOut)
+	end
+
 	-- Minimize specific properties.
 	--------------------------------
 
@@ -2136,7 +2191,14 @@ function css.minimize(tokensIn, options)
 				table.insert(tokensOut, i+1, newTokenWhitespace(" "))
 			end
 
-			nextTokenIndex = i
+			-- We also don't need any space before anymore.
+			if tokensOut[i-1] and tokensOut[i-1].type == "whitespace" then
+				table.remove(tokensOut, i-1)
+				nextTokenIndex = i-1
+			else
+				nextTokenIndex = i
+			end
+
 			return
 		end
 

tests.lua

@@ -101,7 +101,7 @@ local function runTest(css, printCss)
 
 
 
-	--[[ Round-trip test.
+	-- [[ Round-trip test.
 	local cssAgain = cssLib.minimize(css)
 
 	if printCss then
@@ -288,5 +288,5 @@ end
 
 -- runSmallTest()
 -- runTestOnFile("test.css")
--- runTestOnFile("tests/yui/pseudo-first.css", true)
+-- runTestOnFile("tests/yui/issue205.css", true)
 runTestsuite(true)

tests/empty.css

@@ -0,0 +1,23 @@
+/*! preserved */
+emptiness {}
+
+@import "another.css";
+/* I'm empty - delete me */
+empty { ;}
+
+@media print {
+	.noprint { display: none; }
+}
+
+@media screen {
+	/* this rule should be removed, not simply minified.*/
+	.breakme {}
+	.printonly { display: none; }
+}
+
+@import "again.css";
+/* Empty @media group should be removed. */
+@media (not screen) {
+	.foo {}
+	.barf {; }
+}

tests/empty.css.min

@@ -0,0 +1 @@
+/*! preserved */@import"another.css";@media print{.noprint{display:none}}@media screen{.printonly{display:none}}@import"again.css"

tests/keep-percent.css.min

@@ -1 +1 @@
-.SB-messages .SB-message a{color:rgba(0%,50%,50%,.3);border-bottom:1px dotted #b96375;text-shadow:0 1px 0 hsl(0,0%,0%);flex-basis:0%;flex:0%}@keyframes fadeIn{0%{opacity:0}100%{opacity:.5}}
+.SB-messages .SB-message a{color:rgba(0%,50%,50%,.3);border-bottom:1px dotted#b96375;text-shadow:0 1px 0 hsl(0,0%,0%);flex-basis:0%;flex:0%}@keyframes fadeIn{0%{opacity:0}100%{opacity:.5}}

tests/yui/color.css.min

@@ -1 +1 @@
-.color{me:#7b7b7b;test-overflow:#fff;impressed:#fed;again:#abcdef;andagain:#a6c;background-color:#aa66ccc;filter:chroma(color="#FFFFFF");background:none repeat scroll 0 0 #f00;alpha:rgba(1,2,3,4);border-color:rgba(1,2,3,4);color:#12a}#AABBCC{background-color:#fe1;filter:chroma(color=#FFFFFF);color:#412;foo:#0f1#abc#abc#123344;border-color:#aa66ccc}.foo #AABBCC{background-color:#fe1;color:#412;border-color:#abc;filter:chroma(color=#FFFFFF)}.bar,#AABBCC{background-color:#fe1;border-color:#0f1#abcdef;filter:chroma(color=#11FFFFFF);color:#412}.foo,#AABBCC.foobar{background-color:#fe1;border-color:#0f1#abcdef#abc;color:#412}@media screen{.bar,#AABBCC{background-color:#fe1;color:#412}}
+.color{me:#7b7b7b;test-overflow:#fff;impressed:#fed;again:#abcdef;andagain:#a6c;background-color:#aa66ccc;filter:chroma(color="#FFFFFF");background:none repeat scroll 0 0#f00;alpha:rgba(1,2,3,4);border-color:rgba(1,2,3,4);color:#12a}#AABBCC{background-color:#fe1;filter:chroma(color=#FFFFFF);color:#412;foo:#0f1#abc#abc#123344;border-color:#aa66ccc}.foo #AABBCC{background-color:#fe1;color:#412;border-color:#abc;filter:chroma(color=#FFFFFF)}.bar,#AABBCC{background-color:#fe1;border-color:#0f1#abcdef;filter:chroma(color=#11FFFFFF);color:#412}.foo,#AABBCC.foobar{background-color:#fe1;border-color:#0f1#abcdef#abc;color:#412}@media screen{.bar,#AABBCC{background-color:#fe1;color:#412}}

tests/yui/issue205.css.min

@@ -1 +1 @@
-@charset "utf-8";a[id$=_foo]{abc:abc};
+@charset "utf-8";a[id$=_foo]{abc:abc}

tests/yui/media-empty-class.css.min

@@ -1 +1 @@
-/*! preserved */@import "another.css";@media print{.noprint{display:none}}@media screen{.printonly{display:none}}
+/*! preserved */@import"another.css";@media print{.noprint{display:none}}@media screen{.printonly{display:none}}