lib: implement multi-match

Allow match to take a table of pattern -> handlers instead, and match the
earliest and longest pattern that we find in the output buffer.

Signed-off-by: Kyle Evans <[email protected]>

examples/cat-multi.orch

@@ -0,0 +1,30 @@
+-- Executed like `./orch -f cat-multi.orch -- cat` -- this one won't spawn
+-- anything itself, so it must be done on the command line.
+
+-- We get released on first match anyways, so this doesn't need to be called:
+-- release()
+
+write "Send One Two\r"
+match {
+	One = function()
+		write "LOL\r"
+
+		debug "Matched one"
+		match "LOL" {
+			callback = function()
+				debug "lol"
+				write "Foo\r"
+			end
+		}
+		-- Also valid:
+		-- write "Foo"
+		match "Foo" {
+			callback = function()
+				debug "foo matched too"
+			end
+		}
+	end,
+	Two = function()
+		debug "Called two"
+	end,
+}

lib/porch.lua

@@ -28,7 +28,10 @@ porch.run_script = scripter.run_script
 porch.sleep = core.sleep
 
 -- spawn(cmd...): spawn the given command, returning a process that may be
--- manipulated as needed.
+-- manipulated as needed.  This is the primary interface we expose to users of
+-- the lib; most of the things one would do with the scripting interface are
+-- broken out via methods on the DirectProcess instead to provide a more
+-- object-oriented feel.
 porch.spawn = direct.spawn
 
 -- Reset all of the state; this largely means resetting the scripting bits, as

lib/porch/actions.lua

@@ -46,9 +46,40 @@ function MatchAction:dump(level)
 	end
 end
 function MatchAction:matches(buffer)
-	local matcher_arg = self.pattern_obj or self.pattern
+	local first, last, cb
+	local len
+
+	for pattern, def in pairs(self.patterns) do
+		local matcher_arg = def._compiled or pattern
+
+		-- We use the earliest and longest match, rather than the first to
+		-- match, to provide predictable semantics.  If any more control than
+		-- that is desired, it should be split up into multiple distinct matches
+		-- or, in a scripter context, switched to a one() block.
+		local tfirst, tlast = self.matcher.match(matcher_arg, buffer)
+		if not tfirst then
+			goto next
+		end
+
+		if len and tfirst > first then
+			-- Earlier matches take precedence.
+			goto next
+		end
+
+		local tlen = tlast - tfirst
+		if tfirst == first and tlen <= len then
+			-- Longer matches take precedence.  If we have two
+			-- patterns that managed to result in the same match,
+			-- then we arbitrarily choose the first one we noticed.
+			goto next
+		end
+
+		first, last, cb = tfirst, tlast, def.callback
+		len = tlen
+::next::
+	end
 
-	return self.matcher.match(matcher_arg, buffer)
+	return first, last, cb
 end
 
 actions.MatchAction = MatchAction

lib/porch/direct.lua

@@ -44,13 +44,14 @@ function DirectProcess:match(pattern, matcher)
 	matcher = matcher or matchers.available.default
 
 	local action = actions.MatchAction:new("match")
+	local patterns = { [pattern] = {} }
 	action.timeout = self.timeout
-	action.pattern = pattern
 	action.matcher = matcher
 
 	if matcher.compile then
-		action.pattern_obj = action.matcher.compile(pattern)
+		patterns[pattern]._compiled = action.matcher.compile(pattern)
 	end
+	action.patterns = patterns
 
 	return self._process:match(action)
 end

lib/porch/process.lua

@@ -18,7 +18,7 @@ function MatchBuffer:new(process, ctx)
 	return obj
 end
 function MatchBuffer:_matches(action)
-	local first, last = action:matches(self.buffer)
+	local first, last, callback = action:matches(self.buffer)
 
 	if not first then
 		return false
@@ -29,8 +29,9 @@ function MatchBuffer:_matches(action)
 	self.buffer = self.buffer:sub(last + 1)
 
 	-- Return value is not significant, ignored.
-	if action.callback then
-		self.ctx:execute(action.callback)
+	callback = callback or action.callback
+	if callback then
+		self.ctx:execute(callback)
 	end
 
 	return true

lib/porch/scripter.lua

@@ -19,6 +19,12 @@ local CTX_CALLBACK = 3
 
 local current_ctx
 
+-- Configuration keys valid for an individual pattern specified to a match
+local match_pattern_valid_cfg = {
+	callback = true,
+}
+
+-- Configuration keys valid for a single match statement
 local match_valid_cfg = {
 	callback = true,
 	timeout = true,
@@ -423,17 +429,52 @@ local extra_actions = {
 	},
 	match = {
 		print_diagnostics = function(action)
+			local ppat = ""
+			local first = true
+
+			for pattern in pairs(action.patterns) do
+				if not first then
+					ppat = ppat .. "|"
+				end
+
+				ppat = ppat .. pattern
+			end
+
 			io.stderr:write(string.format("[%s]:%d: match (pattern '%s') failed\n",
-			    action.src, action.line, action.pattern))
+			    action.src, action.line, ppat))
 		end,
 		init = function(action, args)
 			local pattern = args[1]
 
-			action.pattern = pattern
 			action.timeout = action.ctx.timeout
+			if type(pattern) == "table" then
+				-- The table version allows any of the patterns
+				-- to trigger this match, while also allowing
+				for pat, cfg in pairs(pattern) do
+					if type(cfg) == "function" then
+						cfg = { callback = cfg }
+						pattern[pat] = cfg
+					end
+
+					for k in pairs(cfg) do
+						if not match_pattern_valid_cfg[k] then
+							error(k .. " is not a valid pattern cfg field")
+						end
+					end
+					if action.matcher.compile then
+						cfg._compiled = action.matcher.compile(pattern)
+					end
+				end
+
+				action.patterns = pattern
+			else
+				local patterns = { [pattern] = {} }
+
+				if action.matcher.compile then
+					patterns[pattern]._compiled = action.matcher.compile(pattern)
+				end
 
-			if action.matcher.compile then
-				action.pattern_obj = action.matcher.compile(pattern)
+				action.patterns = patterns
 			end
 
 			local function set_cfg(cfg)

tests/simple_multimatch.orch

@@ -0,0 +1,14 @@
+-- What we write to cat(1) should come straight back to us.
+write "Hello\rPANIC: at the disco\r"
+
+match {
+	PANIC = function()
+		exit(1)
+	end,
+	Hello = function()
+		-- Should trigger on Hello every time, since it's the earliest match.
+	end,
+}
+
+-- Make sure that we didn't flush PANIC from the buffer.
+match "PANIC"