Don't depend on a standalone C preprocessor

And get rid of the sed insanity.

CMakeLists.txt

@@ -10,6 +10,14 @@ endif ()
 # For custom modules
 set (CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/liberty/cmake)
 
+# Collect important build toggles for our simple preprocessor
+# (cpp(1) isn't part of POSIX, otherwise we could reuse config.h)
+set (options)
+macro (add_option variable help value)
+	option (${ARGV})
+	list (APPEND options "${variable}=$<BOOL:${${variable}}>")
+endmacro ()
+
 # Dependencies
 find_package (Ncursesw REQUIRED)
 find_package (PkgConfig REQUIRED)
@@ -19,7 +27,7 @@ pkg_check_modules (curl REQUIRED libcurl)
 include (AddThreads)
 
 find_package (Termo QUIET NO_MODULE)
-option (USE_SYSTEM_TERMO
+add_option (USE_SYSTEM_TERMO
 	"Don't compile our own termo library, use the system one" ${Termo_FOUND})
 if (USE_SYSTEM_TERMO)
 	if (NOT Termo_FOUND)
@@ -41,7 +49,7 @@ else ()
 endif ()
 
 pkg_check_modules (fftw fftw3 fftw3f)
-option (WITH_FFTW "Use FFTW to enable spectrum visualisation" ${fftw_FOUND})
+add_option (WITH_FFTW "Use FFTW to enable spectrum visualisation" ${fftw_FOUND})
 if (WITH_FFTW)
 	if (NOT fftw_FOUND)
 		message (FATAL_ERROR "FFTW not found")
@@ -50,7 +58,8 @@ if (WITH_FFTW)
 endif ()
 
 pkg_check_modules (libpulse libpulse)
-option (WITH_PULSE "Enable control of PulseAudio sink volume" ${libpulse_FOUND})
+add_option (WITH_PULSE
+	"Enable PulseAudio sink volume control" ${libpulse_FOUND})
 if (WITH_PULSE)
 	if (NOT libpulse_FOUND)
 		message (FATAL_ERROR "libpulse not found")
@@ -59,7 +68,7 @@ if (WITH_PULSE)
 endif ()
 
 pkg_check_modules (x11 x11 xrender xft fontconfig)
-option (WITH_X11 "Use FFTW to enable spectrum visualisation" ${x11_FOUND})
+add_option (WITH_X11 "Use FFTW to enable spectrum visualisation" ${x11_FOUND})
 if (WITH_X11)
 	if (NOT x11_FOUND)
 		message (FATAL_ERROR "Some X11 libraries were not found")
@@ -99,20 +108,13 @@ configure_file (${PROJECT_SOURCE_DIR}/config.h.in
 	${PROJECT_BINARY_DIR}/config.h)
 include_directories (${PROJECT_SOURCE_DIR} ${PROJECT_BINARY_DIR})
 
-# Assuming a Unix-compatible system with a standalone preprocessor
 set (actions_list ${PROJECT_SOURCE_DIR}/nncmpp.actions)
+set (actions_awk ${PROJECT_SOURCE_DIR}/nncmpp.actions.awk)
 set (actions ${PROJECT_BINARY_DIR}/nncmpp-actions.h)
 add_custom_command (OUTPUT ${actions}
-	COMMAND cpp -I${PROJECT_BINARY_DIR} -P ${actions_list}
+	COMMAND env LC_ALL=C ${options}
-		| grep . | tr [[\n]] ^ | sed -ne [[h; s/,[^^]*/,/g]] -e [[s/$/COUNT/]]
+		awk -f ${actions_awk} ${actions_list} > ${actions}
-			-e [[s/[^^]*/\tACTION_&/g]] -e [[s/.*/enum action {\n&\n};\n/p]]
+	DEPENDS ${actions_awk} ${actions_list} VERBATIM)
-			-e [[g; s/,[^^]*//g; y/_/-/]] -e [[s/[^^]\{1,\}/\t"&",/g]]
-			-e [[s/.*/static const char *g_action_names[] = {\n&};\n/p]]
-			-e [[g; s/[^^]*, *//g;]] -e [[s/[^^]\{1,\}/\t"&",/g]]
-			-e [[s/.*/static const char *g_action_descriptions[] = {\n&};/p]]
-		| tr ^ [[\n]] > ${actions}
-	COMMAND test -s ${actions}
-	DEPENDS ${actions_list} ${PROJECT_BINARY_DIR}/config.h VERBATIM)
 
 # Build the main executable and link it
 add_executable (${PROJECT_NAME} ${PROJECT_NAME}.c ${actions})

nncmpp.actions

@@ -1,5 +1,3 @@
-#include "config.h"
-
 NONE,               Do nothing
 
 QUIT,               Quit
@@ -28,11 +26,11 @@ MPD_CONSUME,        Toggle consume
 MPD_UPDATE_DB,      Update MPD database
 MPD_COMMAND,        Send raw command to MPD
 
-#ifdef WITH_PULSE
+.ifdef WITH_PULSE
 PULSE_VOLUME_UP,    Increase PulseAudio volume
 PULSE_VOLUME_DOWN,  Decrease PulseAudio volume
 PULSE_MUTE,         Toggle PulseAudio sink mute
-#endif
+.endif
 
 CHOOSE,             Choose item
 DELETE,             Delete item

nncmpp.actions.awk

@@ -0,0 +1,106 @@
+# nncmpp.actions.awk: produce C code for a list of user actions
+#
+# Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
+# SPDX-License-Identifier: 0BSD
+#
+# Usage: env LC_ALL=C A=0 B=1 awk -f nncmpp.actions.awk \
+#  nncmpp.actions > nncmpp-actions.h
+
+# --- Preprocessor -------------------------------------------------------------
+
+function fatal(message) {
+	print "// " FILENAME ":" FNR ": fatal error: " message
+	print FILENAME ":" FNR ": fatal error: " message > "/dev/stderr"
+	exit 1
+}
+
+function condition(pass,    passing, a, i) {
+	split(substr($0, RSTART + RLENGTH), a, /[[:space:]]+/)
+	if (!(1 in a))
+		fatal("missing condition")
+
+	passing = 0
+	for (i in a)
+		if (a[i] && !pass == !ENVIRON[a[i]])
+			passing = 1
+
+	while (getline > 0) {
+		if (match($0, /^[[:space:]]*[.]endif[[:space:]]*$/))
+			return 1
+
+		if (match($0, /^[[:space:]]*[.]else[[:space:]]*$/))
+			passing = !passing
+		else if (!directive() && passing)
+			process()
+	}
+
+	fatal("unterminated condition body")
+}
+
+# Multiple arguments mean logical OR, multiple directives mean logical AND.
+# Similar syntax is also used by Exim, BSD make, or various assemblers.
+#
+# Looking at what others have picked for their preprocessor syntax:
+# {OpenGL, FreeBASIC} reuse #ifdef, which would be confusing with C code around,
+# {Mental Ray, RapidQ and UniVerse BASIC} use $ifdef, NSIS has !ifdef,
+# and Verilog went for `ifdef.  Not much more can be easily found.
+function directive() {
+	sub(/#.*/, "")
+	if (match($0, /^[[:space:]]*[.]ifdef[[:space:]]+/))
+		return condition(1)
+	if (match($0, /^[[:space:]]*[.]ifndef[[:space:]]+/))
+		return condition(0)
+	if (/^[[:space:]]*[.]/)
+		fatal("unexpected or unsupported directive")
+	return 0
+}
+
+!directive() {
+	process()
+}
+
+# --- Postprocessor ------------------------------------------------------------
+
+function strip(string) {
+	gsub(/^[[:space:]]*|[[:space:]]*$/, "", string)
+	return string
+}
+
+function process(    constant, name, description) {
+	if (match($0, /,/)) {
+		constant = name = strip(substr($0, 1, RSTART - 1))
+		description = strip(substr($0, RSTART + RLENGTH))
+		gsub(/_/, "-", name)
+
+		N++
+		Constants[N] = constant
+		Names[N] = tolower(name)
+		Descriptions[N] = description
+	} else if (/[^[:space:]]/) {
+		fatal("invalid action definition syntax")
+	}
+}
+
+function tocstring(string) {
+	gsub(/\\/, "\\\\", string)
+	gsub(/"/, "\\\"", string)
+	return "\"" string "\""
+}
+
+END {
+	print "enum action {"
+	for (i in Constants)
+		print "\t" "ACTION_" Constants[i] ","
+	print "\t" "ACTION_COUNT"
+	print "};"
+	print ""
+	print "static const char *g_action_names[] = {"
+	for (i in Names)
+		print "\t" tocstring(Names[i]) ","
+	print "};"
+	print ""
+	print "static const char *g_action_descriptions[] = {"
+	for (i in Descriptions)
+		print "\t" tocstring(Descriptions[i]) ","
+	print "};"
+}

nncmpp.c

@@ -4168,9 +4168,8 @@ help_tab_on_action (enum action action)
 
 	if (action == ACTION_DESCRIBE)
 	{
-		char *name = xstrdup (g_action_names[a]);
+		app_show_message (xstrdup ("Configuration name: "),
-		cstr_transform (name, tolower_ascii);
+			xstrdup (g_action_names[a]));
-		app_show_message (xstrdup ("Configuration name: "), name);
 		return true;
 	}
 	if (action != ACTION_CHOOSE || a == ACTION_CHOOSE /* avoid recursion */)