vis: use file(1) for file type detection

File type detection works as follows:

 1) strip off suffixes to be ignored and test against a
    set of known file extensions

 2) run `file -bL --mime-type` and check against a set
    of known mime types

 3) read out the first few bytes of the file and pass
    them to custom Lua file type detection functions

For now the configured file extensions are literal strings
which are matched against the end of the file name. Maybe
we should use Lua patterns instead.

We will need to add more mime types to our mapping table.
For now only the `bash` file type was associated with the
text/x-shellscript mime type.

1 files changed, 384 insertions, 174 deletions

diff --git a/vis.lua b/vis.lua
index 4445ce8..bc5b618 100644
--- a/vis.lua
+++ b/vis.lua
@@ -71,144 +71,371 @@ end)
 
 vis.ftdetect = {}
 
-vis.ftdetect.ignoresuffixes = "~|.orig|.bak|.old|.new|.dpkg-dist|.dpkg-old|.dpkg-new|.dpkg-bak|.pacsave|.pacnew"
-
-vis.ftdetect.filetypes = {
-	actionscript = { ext = ".as|.asc" },
-	ada          = { ext = ".adb|.ads" },
-	ansi_c       = { ext = ".c|.C|.h" },
-	antlr        = { ext = ".g|.g4" },
-	apdl         = { ext = ".ans|.inp|.mac" },
-	apl          = { ext = ".apl" },
-	applescript  = { ext = ".applescript" },
-	asm          = { ext = ".asm|.ASM|.s|.S" },
-	asp          = { ext = ".asa|.asp|.hta" },
-	autoit       = { ext = ".au3|.a3x" },
-	awk          = { ext = ".awk", app = "awk|nawk|mawk|gawk" },
-	bash         = { ext = ".bash|.csh|.sh|.zsh", name = "%.bashrc|%.bash_profile|%.configure", app = "bash|csh|sh|zsh|ash|dash|tcsh" },
-	batch        = { ext = ".bat|.cmd" },
-	bibtex       = { ext = ".bib" },
-	boo          = { ext = ".boo" },
-	caml         = { ext = ".caml|.ml|.mli|.mll|.mly" },
-	chuck        = { ext = ".ck" },
-	cmake        = { ext = ".cmake|.cmake.in|.ctest|.ctest.in" },
-	coffeescript = { ext = ".coffee", app = "coffee" },
-	cpp          = { ext = ".cpp|.cxx|.c++|.cc|.hh|.hpp|.hxx|.h++" },
-	crystal      = { ext = ".cr" },
-	csharp       = { ext = ".cs" },
-	css          = { ext = ".css" },
-	cuda         = { ext = ".cu|.cuh" },
-	dart         = { ext = ".dart", app = "dart" },
-	desktop      = { ext = ".desktop" },
-	diff         = { ext = ".diff|.patch" },
-	dmd          = { ext = ".d|.di", app = "rdmd" },
-	dockerfile   = { name = "Dockerfile" },
-	dot          = { ext = ".dot" },
-	dsv          = { name = "group|gshadow|passwd|shadow" },
-	eiffel       = { ext = ".e|.eif" },
-	elixir       = { ext = ".ex|.exs" },
-	erlang       = { ext = ".erl|.hrl", app = "escript" },
-	faust        = { ext = ".dsp" },
-	fish         = { ext = ".fish", app = "fish" },
-	forth        = { ext = ".forth|.frt|.fs", app = "gforth" },
-	fortran      = { ext = ".f|.for|.ftn|.fpp|.f77|.f90|.f95|.f03|.f08" },
-	fsharp       = { ext = ".fs" },
-	fstab        = { name = "fstab" },
-	gap          = { ext = ".g|.gd|.gi|.gap" },
-	gettext      = { ext = ".po|.pot" },
-	gherkin      = { ext = ".feature" },
-	glsl         = { ext = ".glslf|.glslv" },
-	gnuplot      = { ext = ".dem|.plt" },
-	go           = { ext = ".go" },
-	groovy       = { ext = ".groovy|.gvy", app = "groovy" },
-	gtkrc        = { name = "%.?gtkrc.*" },
-	haskell      = { ext = ".hs", app = "ghci" },
-	html         = { ext = ".htm|.html|.shtm|.shtml|.xhtml" },
-	icon         = { ext = ".icn" },
-	idl          = { ext = ".idl|.odl" },
-	inform       = { ext = ".inf|.ni" },
-	ini          = { ext = ".cfg|.cnf|.inf|.ini|.reg" },
-	io_lang      = { ext = ".io" },
-	java         = { ext = ".bsh|.java" },
-	javascript   = { ext = ".js|.jsfl", app = "jsc|node|rhino" },
-	json         = { ext = ".json" },
-	jsp          = { ext = ".jsp" },
-	latex        = { ext = ".bbl|.dtx|.ins|.ltx|.tex|.sty" },
-	ledger       = { ext = ".ledger|.journal" },
-	less         = { ext = ".less" },
-	lilypond     = { ext = ".lily|.ly" },
-	lisp         = { ext = ".cl|.el|.lisp|.lsp", app = "sbcl|clisp" },
-	litcoffee    = { ext = ".litcoffee" },
-	lua          = { ext = ".lua", app = "lua" },
-	makefile     = { ext = ".iface|.mak|.mk", name = "GNUmakefile|makefile|Makefile" },
-	man          = { ext = ".1|.2|.3|.4|.5|.6|.7|.8|.9|.1x|.2x|.3x|.4x|.5x|.6x|.7x|.8x|.9x" },
-	markdown     = { ext = ".md|.markdown" },
-	moonscript   = { ext = ".moon" },
-	nemerle      = { ext = ".n" },
-	networkd     = { ext = ".link|.network|.netdev" },
-	nim          = { ext = ".nim", app = "nim" },
-	nsis         = { ext = ".nsh|.nsi|.nsis" },
-	objective_c  = { ext = ".m|.mm|.objc" },
-	pascal       = { ext = ".dpk|.dpr|.p|.pas" },
-	perl         = { ext = ".al|.perl|.pl|.pm|.pod", app = "perl[%d.%a-]*|rakudo" },
-	php          = { ext = ".inc|.php|.php3|.php4|.phtml", app = "php[%d]*" },
-	pico8        = { ext = ".p8" },
-	pike         = { ext = ".pike|.pmod" },
-	pkgbuild     = { name = "PKGBUILD" },
-	powershell   = { ext = ".ps1" },
-	prolog       = { ext = ".prolog" },
-	props        = { ext = ".props|.properties" },
-	protobuf     = { ext = ".proto" },
-	ps           = { ext = ".eps|.ps" },
-	pure         = { ext = ".pure" },
-	python       = { ext = ".sc|.py|.pyw", app = "python[%d.]*" },
-	rebol        = { ext = ".r|.reb" },
-	rest         = { ext = ".rst" },
-	rexx         = { ext = ".orx|.rex" },
-	rhtml        = { ext = ".erb|.rhtml" },
-	rstats       = { ext = ".R|.Rout|.Rhistory|.Rt|Rout.save|Rout.fail" },
-	ruby         = { ext = ".Rakefile|.rake|.rb|.rbw", app = "ruby" },
-	rust         = { ext = ".rs" },
-	sass         = { ext = ".sass|.scss" },
-	scala        = { ext = ".scala" },
-	scheme       = { ext = ".sch|.scm" },
-	smalltalk    = { ext = ".changes|.st|.sources" },
-	sml          = { ext = ".sml|.fun|.sig" },
-	snobol4      = { ext = ".sno|.SNO" },
-	sql          = { ext = ".ddl|.sql" },
-	systemd      = { ext = ".automount|.device|.mount|.path|.scope|.service|.slice|.socket|.swap|.target|.timer" },
-	taskpaper    = { ext = ".taskpaper" },
-	tcl          = { ext = ".tcl|.tk" },
-	texinfo      = { ext = ".texi" },
-	toml         = { ext = ".toml" },
-	vala         = { ext = ".vala" },
-	vb           = { ext = ".asa|.bas|.cls|.ctl|.dob|.dsm|.dsr|.frm|.pag|.vb|.vba|.vbs" },
-	vcard        = { ext = ".vcf|.vcard" },
-	verilog      = { ext = ".v|.ver" },
-	vhdl         = { ext = ".vh|.vhd|.vhdl" },
-	wsf          = { ext = ".wsf" },
-	xml          = { ext = ".dtd|.svg|.xml|.xsd|.xsl|.xslt|.xul" },
-	xtend        = { ext = ".xtend" },
-	yaml         = { ext = ".yaml" },
+vis.ftdetect.ignoresuffixes = {
+	"~", ".orig", ".bak", ".old", ".new"
 }
 
--- array of filetype detecting functions (win, filename, shebang, app) -> string
-vis.ftdetect.customdetectors = {
-	function(file, data)
-		if data:sub(1, 5) == '<?xml' then
-			return 'xml'
-		end
-	end,
+vis.ftdetect.filetypes = {
+	actionscript = {
+		ext = { ".as", ".asc" },
+	},
+	ada = {
+		ext = { ".adb", ".ads" },
+	},
+	ansi_c = {
+		ext = { ".c", ".C", ".h" },
+	},
+	antlr = {
+		ext = { ".g", ".g4" },
+	},
+	apdl = {
+		ext = { ".ans", ".inp", ".mac" },
+	},
+	apl = {
+		ext = { ".apl" }
+	},
+	applescript = {
+		ext = { ".applescript" },
+	},
+	asm = {
+		ext = { ".asm", ".ASM", ".s", ".S" },
+	},
+	asp = {
+		ext = { ".asa", ".asp", ".hta" },
+	},
+	autoit = {
+		ext = { ".au3", ".a3x" },
+	},
+	awk = {
+		ext = { ".awk" },
+	},
+	bash = {
+		ext = { ".bash", ".csh", ".sh", ".zsh" },
+		mime = { "text/x-shellscript" },
+	},
+	batch = {
+		ext = { ".bat", ".cmd" },
+	},
+	bibtex = {
+		ext = { ".bib" },
+	},
+	boo = {
+		ext = { ".boo" },
+	},
+	caml = {
+		ext = { ".caml", ".ml", ".mli", ".mll", ".mly" },
+	},
+	chuck = {
+		ext = { ".ck" },
+	},
+	cmake = {
+		ext = { ".cmake", ".cmake.in", ".ctest", ".ctest.in" },
+	},
+	coffeescript = {
+		ext = { ".coffee" },
+	},
+	cpp = {
+		ext = { ".cpp", ".cxx", ".c++", ".cc", ".hh", ".hpp", ".hxx", ".h++" },
+	},
+	crystal = {
+		ext = { ".cr" },
+	},
+	csharp = {
+		ext = { ".cs" },
+	},
+	css = {
+		ext = { ".css" },
+	},
+	cuda = {
+		ext = { ".cu", ".cuh" },
+	},
+	dart = {
+		ext = { ".dart" },
+	},
+	desktop = {
+		ext = { ".desktop" },
+	},
+	diff = {
+		ext = { ".diff", ".patch" },
+	},
+	dmd = {
+		ext = { ".d", ".di" },
+	},
+	dockerfile = {
+		ext = { "Dockerfile" },
+	},
+	dot = {
+		ext = { ".dot" },
+	},
+	dsv = {
+		ext = { "group", "gshadow", "passwd", "shadow" },
+	},
+	eiffel = {
+		ext = { ".e", ".eif" },
+	},
+	elixir = {
+		ext = { ".ex", ".exs" },
+	},
+	erlang = {
+		ext = { ".erl", ".hrl" },
+	},
+	faust = {
+		ext = { ".dsp" },
+	},
+	fish = {
+		ext = { ".fish" },
+	},
+	forth = {
+		ext = { ".forth", ".frt", ".fs" },
+	},
+	fortran = {
+		ext = { ".f", ".for", ".ftn", ".fpp", ".f77", ".f90", ".f95", ".f03", ".f08" },
+	},
+	fsharp = {
+		ext = { ".fs" },
+	},
+	fstab = {
+		ext = { "fstab" },
+	},
+	gap = {
+		ext = { ".g", ".gd", ".gi", ".gap" },
+	},
+	gettext = {
+		ext = { ".po", ".pot" },
+	},
+	gherkin = {
+		ext = { ".feature" },
+	},
+	glsl = {
+		ext = { ".glslf", ".glslv" },
+	},
+	gnuplot = {
+		ext = { ".dem", ".plt" },
+	},
+	go = {
+		ext = { ".go" },
+	},
+	groovy = {
+		ext = { ".groovy", ".gvy" },
+	},
+	gtkrc = {
+		ext = { ".gtkrc" },
+	},
+	haskell = {
+		ext = { ".hs" },
+	},
+	html = {
+		ext = { ".htm", ".html", ".shtm", ".shtml", ".xhtml" },
+	},
+	icon = {
+		ext = { ".icn" },
+	},
+	idl = {
+		ext = { ".idl", ".odl" },
+	},
+	inform = {
+		ext = { ".inf", ".ni" },
+	},
+	ini = {
+		ext = { ".cfg", ".cnf", ".inf", ".ini", ".reg" },
+	},
+	io_lang = {
+		ext = { ".io" },
+	},
+	java = {
+		ext = { ".bsh", ".java" },
+	},
+	javascript = {
+		ext = { ".js", ".jsfl" },
+	},
+	json = {
+		ext = { ".json" },
+	},
+	jsp = {
+		ext = { ".jsp" },
+	},
+	latex = {
+		ext = { ".bbl", ".dtx", ".ins", ".ltx", ".tex", ".sty" },
+	},
+	ledger = {
+		ext = { ".ledger", ".journal" },
+	},
+	less = {
+		ext = { ".less" },
+	},
+	lilypond = {
+		ext = { ".lily", ".ly" },
+	},
+	lisp = {
+		ext = { ".cl", ".el", ".lisp", ".lsp" },
+	},
+	litcoffee = {
+		ext = { ".litcoffee" },
+	},
+	lua = {
+		ext = { ".lua" },
+	},
+	makefile = {
+		ext = { ".iface", ".mak", ".mk", "GNUmakefile", "makefile", "Makefile" },
+	},
+	man = {
+		ext = { ".1", ".2", ".3", ".4", ".5", ".6", ".7", ".8", ".9", ".1x", ".2x", ".3x", ".4x", ".5x", ".6x", ".7x", ".8x", ".9x" },
+	},
+	markdown = {
+		ext = { ".md", ".markdown" },
+	},
+	moonscript = {
+		ext = { ".moon" },
+	},
+	nemerle = {
+		ext = { ".n" },
+	},
+	networkd = {
+		ext = { ".link", ".network", ".netdev" },
+	},
+	nim = {
+		ext = { ".nim" },
+	},
+	nsis = {
+		ext = { ".nsh", ".nsi", ".nsis" },
+	},
+	objective_c = {
+		ext = { ".m", ".mm", ".objc" },
+	},
+	pascal = {
+		ext = { ".dpk", ".dpr", ".p", ".pas" },
+	},
+	perl = {
+		ext = { ".al", ".perl", ".pl", ".pm", ".pod" },
+	},
+	php = {
+		ext = { ".inc", ".php", ".php3", ".php4", ".phtml" },
+	},
+	pico8 = {
+		ext = { ".p8" },
+	},
+	pike = {
+		ext = { ".pike", ".pmod" },
+	},
+	pkgbuild = {
+		ext = { "PKGBUILD" },
+	},
+	powershell = {
+		ext = { ".ps1" },
+	},
+	prolog = {
+		ext = { ".prolog" },
+	},
+	props = {
+		ext = { ".props", ".properties" },
+	},
+	protobuf = {
+		ext = { ".proto" },
+	},
+	ps = {
+		ext = { ".eps", ".ps" },
+	},
+	pure = {
+		ext = { ".pure" },
+	},
+	python = {
+		ext = { ".sc", ".py", ".pyw" },
+	},
+	rebol = {
+		ext = { ".r", ".reb" },
+	},
+	rest = {
+		ext = { ".rst" },
+	},
+	rexx = {
+		ext = { ".orx", ".rex" },
+	},
+	rhtml = {
+		ext = { ".erb", ".rhtml" },
+	},
+	rstats = {
+		ext = { ".R", ".Rout", ".Rhistory", ".Rt", "Rout.save", "Rout.fail" },
+	},
+	ruby = {
+		ext = { ".Rakefile", ".rake", ".rb", ".rbw" },
+	},
+	rust = {
+		ext = { ".rs" },
+	},
+	sass = {
+		ext = { ".sass", ".scss" },
+	},
+	scala = {
+		ext = { ".scala" },
+	},
+	scheme = {
+		ext = { ".sch", ".scm" },
+	},
+	smalltalk = {
+		ext = { ".changes", ".st", ".sources" },
+	},
+	sml = {
+		ext = { ".sml", ".fun", ".sig" },
+	},
+	snobol4 = {
+		ext = { ".sno", ".SNO" },
+	},
+	sql= {
+		ext = { ".ddl", ".sql" },
+	},
+	systemd = {
+		ext = { ".automount", ".device", ".mount", ".path", ".scope", ".service", ".slice", ".socket", ".swap", ".target", ".timer" },
+	},
+	taskpaper = {
+		ext = { ".taskpaper" },
+	},
+	tcl = {
+		ext = { ".tcl", ".tk" },
+	},
+	texinfo = {
+		ext = { ".texi" },
+	},
+	toml = {
+		ext = { ".toml" },
+	},
+	vala = {
+		ext = { ".vala" }
+	},
+	vb = {
+		ext = { ".asa", ".bas", ".cls", ".ctl", ".dob", ".dsm", ".dsr", ".frm", ".pag", ".vb", ".vba", ".vbs" },
+	},
+	vcard = {
+		ext = { ".vcf", ".vcard" },
+	},
+	verilog = {
+		ext = { ".v", ".ver" },
+	},
+	vhdl = {
+		ext = { ".vh", ".vhd", ".vhdl" },
+	},
+	wsf = {
+		ext = { ".wsf" },
+	},
+	xml = {
+		ext = { ".dtd", ".svg", ".xml", ".xsd", ".xsl", ".xslt", ".xul" },
+	},
+	xtend = {
+		ext = {".xtend" },
+	},
+	yaml = {
+		ext = { ".yaml" },
+	},
 }
 
 vis.filetype_detect = function(win)
+	local name = win.file.name
 	-- remove ignored suffixes from filename
-	local sanitizedfn = win.file.name
+	local sanitizedfn = name
 	if sanitizedfn ~= nil then
 		sanitizedfn = sanitizedfn:gsub('^.*/', '')
 		repeat
 			local changed = false
-			for pattern in vis.ftdetect.ignoresuffixes:gmatch('[^|]+') do
+			for _, pattern in pairs(vis.ftdetect.ignoresuffixes) do
 				if #sanitizedfn >= #pattern then
 					local s, e = sanitizedfn:find(pattern, -#pattern, true)
 					if e == #sanitizedfn then
@@ -220,34 +447,13 @@ vis.filetype_detect = function(win)
 		until not changed
 	end
 
-	local data = win.file:content(0, 256);
-
-	-- find out via shebang which application would run our file
-	local shebang
-	local app
-	if data:sub(1, 2) == '#!' then
-		shebang = data:gsub('^#!%s*', ''):gsub('\n.*$', '')
-		app = shebang:gsub('^/usr/bin/env%s*', ''):gsub('%s.*$', ''):gsub('^.*/', '')
-		if #app == 0 then
-			app = nil
-		end
-	end
-
-	-- call custom detectors if any
-	for _, func in pairs(vis.ftdetect.customdetectors) do
-		local fres = func(win.file, data, sanitizedfn, shebang, app)
-		if fres ~= nil then
-			win.syntax = fres
-			return
-		end
-	end
-
-	-- detect filetype by application mentioned in the shebang
-	if app ~= nil then
+	-- detect filetype by filename ending with a configured extension
+	if sanitizedfn ~= nil then
 		for lang, ft in pairs(vis.ftdetect.filetypes) do
-			if ft.app ~= nil then
-				for pattern in ft.app:gmatch('[^|]+') do
-					if app:match('^'..pattern..'$') ~= nil then
+			for _, pattern in pairs(ft.ext or {}) do
+				if #sanitizedfn >= #pattern then
+					local s, e = sanitizedfn:find(pattern, -#pattern, true)
+					if e == #sanitizedfn then
 						win.syntax = lang
 						return
 					end
@@ -256,26 +462,18 @@ vis.filetype_detect = function(win)
 		end
 	end
 
-	-- detect filetype by filename
-	if sanitizedfn ~= nil then
-		-- try filetypes recognizable by exact filename or filename pattern rather than extension
-		for lang, ft in pairs(vis.ftdetect.filetypes) do
-			if ft.name ~= nil then
-				for pattern in ft.name:gmatch('[^|]+') do
-					if sanitizedfn:match('^'..pattern..'$') ~= nil then
-						win.syntax = lang
-						return
-					end
-				end
+	-- run file(1) to determine mime type
+	if name ~= nil then
+		local file = io.popen(string.format("file -bL --mime-type -- '%s'", name:gsub("'", "'\\''")))
+		if file then
+			local mime = file:read('*all')
+			if mime then
+				mime = mime:gsub('%s*$', '')
 			end
-		end
-		-- then try to determine filetype by filename extention
-		for lang, ft in pairs(vis.ftdetect.filetypes) do
-			if ft.ext ~= nil then
-				for pattern in ft.ext:gmatch('[^|]+') do
-					if #sanitizedfn >= #pattern then
-						local s, e = sanitizedfn:find(pattern, -#pattern, true)
-						if e == #sanitizedfn then
+			if mime and #mime > 0 then
+				for lang, ft in pairs(vis.ftdetect.filetypes) do
+					for _, ft_mime in pairs(ft.mime or {}) do
+						if mime == ft_mime then
 							win.syntax = lang
 							return
 						end
@@ -285,6 +483,18 @@ vis.filetype_detect = function(win)
 		end
 	end
 
+	-- pass first few bytes of file to custom file type detector functions
+	local file = win.file
+	local data = file:content(0, 256)
+	if data and #data > 0 then
+		for lang, ft in pairs(vis.ftdetect.filetypes) do
+			if type(ft.detect) == 'function' and ft.detect(file, data) then
+				win.syntax = lang
+				return
+			end
+		end
+	end
+
 	win.syntax = nil
 end