1 file changed, 14 insertions, 53 deletions
diff --git a/custom/extensions/syntax-highlight.lua b/custom/extensions/syntax-highlight.lua
index 8a1e7ab..7414b63 100644
--- a/custom/extensions/syntax-highlight.lua
+++ b/custom/extensions/syntax-highlight.lua
@@ -1,4 +1,4 @@
--- Server-side syntax highlighting for cgit's tree and blob views, named by
+-- Server-side syntax highlighting for cgit's tree and blame pages, named by
 -- the source-filter setting and run inside cgit's embedded Lua interpreter
 -- so a coloured blob costs no extra process per request. Tokens come from the
 -- Scintillua lexers and reach the page wrapped in span elements carrying the
@@ -28,7 +28,8 @@ local scintillua_env = "CGIT_SCINTILLUA_PATH"
 -- directory next to cgitrc is enough for it to be found. The lexers come
 -- from https://orbitalquark.github.io/scintillua/ and need lpeg, built for
 -- the Lua cgit is linked against. Forgetting that is the usual reason
--- nothing is coloured.
+-- nothing is coloured. A file is coloured only when Scintillua's detect()
+-- names its lexer, so an older Scintillua without detect() colours nothing.
 --
 --     # Debian and Ubuntu
 --     sudo apt install lua-lpeg
@@ -74,25 +75,6 @@ local css = {
 	pseudoelement = "hl-func",
 }
 
--- Extension to lexer name fixes for the fallback path, reached only when
--- this Scintillua has no detect(). Most extensions already equal their lexer
--- name and these are the frequent exceptions.
-local ext_lexer = {
-	py = "python",
-	js = "javascript",
-	ts = "typescript",
-	rb = "ruby",
-	pl = "perl",
-	pm = "perl",
-	sh = "bash",
-	md = "markdown",
-	htm = "html",
-	yml = "yaml",
-	rs = "rust",
-	c = "ansi_c",
-	h = "ansi_c",
-}
-
 
 local scintillua = nil
 local filename = ""
@@ -170,37 +152,13 @@ local function load_scintillua()
 	return nil
 end
 
--- Loading a lexer runs its Lua, and one written for another Scintillua can
--- raise, so a failure here just leaves this file uncoloured.
-local function load_lexer_name(name)
-	if name == nil then
-		return nil
-	end
-	local ok, lexer = pcall(scintillua.load, name)
-	if ok and lexer then
-		return lexer
-	end
-	return nil
-end
-
+-- The first line goes along to detect(), so a script with no extension is
+-- still known by its shebang. detect() matches an extension by its case, so
+-- a name in capitals such as MAIN.C is tried again in lower case.
 local function lexer_for(name, text)
-	if type(scintillua.detect) == "function" then
-		-- The first line goes along, so a script with no extension is still
-		-- known by its shebang.
-		local ok, lang = pcall(scintillua.detect, name, text:match("^[^\n]*"))
-		if ok and lang then
-			local lexer = load_lexer_name(lang)
-			if lexer then
-				return lexer
-			end
-		end
-	end
-	local ext = string.match(name, "%.([^.]+)$")
-	if not ext then
-		return nil
-	end
-	ext = string.lower(ext)
-	return load_lexer_name(ext_lexer[ext]) or load_lexer_name(ext)
+	local first = string.match(text, "^[^\n]*")
+	local lang = scintillua.detect(name, first) or scintillua.detect(string.lower(name), first)
+	return lang and scintillua.load(lang)
 end
 
 local function highlight(text)
@@ -208,8 +166,8 @@ local function highlight(text)
 	if not lexer then
 		return nil
 	end
-	local ok, tokens = pcall(lexer.lex, lexer, text)
-	if not ok or type(tokens) ~= "table" then
+	local tokens = lexer:lex(text)
+	if type(tokens) ~= "table" then
 		return nil
 	end
 	local out = {}
@@ -262,6 +220,9 @@ function filter_close()
 			scintillua = load_scintillua() or false
 		end
 		if scintillua then
+			-- Every step of highlight runs Scintillua's own Lua, and code
+			-- written for another version of it can raise, so a failure
+			-- anywhere there just leaves this file uncoloured.
 			local ok, marked = pcall(highlight, text)
 			if ok and marked then
 				html(marked)