Add "documentation" field to node specification

Use it as node type help message

graph.h

@@ -33,6 +33,7 @@ struct graph_node_specification {
 	void (*destroy)(GraphNodeSpecification * self, GraphNode * target);
 	void (*register_io)(GraphNodeSpecification * self, GraphNode * target, ProcessingState * state);
 	char *name;
+	char *documentation;
 };
 
 void graph_channel_init(GraphChannel * ch, GraphNode * start, size_t start_idx, GraphNode * end, size_t end_idx);

main.c

@@ -65,9 +65,9 @@ main(int argc, char ** argv)
 					fprintf(stderr, "Unknown node type \"%s\"\n", optarg);
 					return 1;
 				}
-				const char* module_help = NULL;
+				const char* module_help = spec->documentation;
 				if (module_help) {
-					printf("Help for module \"%s\":\n", optarg);
+					printf("Help for node type \"%s\":\n", optarg);
 					printf("%s\n", module_help);
 				} else {
 					printf("No help provided for node type \"%s\"\n", optarg);

nodes/evdev.c

@@ -139,6 +139,10 @@ GraphNodeSpecification nodespec_evdev = (GraphNodeSpecification) {
 	.destroy = &destroy,
 	.register_io = &register_io,
 	.name = "evdev",
+	.documentation = "Reads evdev events of the specified device\nDoes not accept events\nSends events on all connectors with major code, minor code, payload respectively set to evdev event type, code, value"
+	                 "\nOption 'namespace' (optional): set namespace for the generated events"
+	                 "\nOption 'file' (required): device file to read events from (like '/dev/input/eventN'), the process must have sufficient privileges to read the file"
+	,
 };
 
 MODULE_CONSTRUCTOR(init)

nodes/getchar.c

@@ -95,6 +95,9 @@ GraphNodeSpecification nodespec_getchar = (GraphNodeSpecification) {
 	.destroy = &destroy,
 	.register_io = &register_io,
 	.name = "getchar",
+	.documentation = "Converts stdin bytes to events\nDoes not accept events\nSends events on all connectors with major and minor codes (0, 1) and the read byte as payload"
+	                 "\nOption 'namespace' (optional): set namespace for the generated events"
+	,
 };
 
 MODULE_CONSTRUCTOR(init)

nodes/modifiers.c

@@ -91,6 +91,10 @@ GraphNodeSpecification nodespec_modifiers = (GraphNodeSpecification) {
 	.destroy = &destroy,
 	.register_io = NULL,
 	.name = "modifiers",
+	.documentation = "Sets/unsets/toggles modifiers in an event\nAccepts events on any connector\nSends events on all connectors"
+	                 "\nOption 'operation' (required): the operation to apply to the event modifier set ('set'/'unset'/'toggle')"
+	                 "\nOption 'modifiers' (required): collection of integers --- the set of modifiers to operate on"
+	,
 };
 
 MODULE_CONSTRUCTOR(init)

nodes/modify_predicate.c

@@ -94,6 +94,13 @@ GraphNodeSpecification nodespec_modify_predicate = (GraphNodeSpecification) {
 	.destroy = &destroy,
 	.register_io = NULL,
 	.name = "modify_predicate",
+	.documentation = "Changes 'enabled' and 'inverted' flags of a predicate\nAccepts events on any connector\nDoes not send events"
+	                 "\nOption 'target' (required): the predicate to modify"
+	                 "\nOption 'enable_on' (optional): the predicate, satisfying events of which set 'enabled' flag of the target predicate to 1"
+	                 "\nOption 'disable_on' (optional): the predicate, satisfying events of which set 'enabled' flag of the target predicate to 0"
+	                 "\nOption 'invert_on' (optional): the predicate, satisfying events of which set 'inverted' flag of the target predicate to 1"
+	                 "\nOption 'uninvert_on' (optional): the predicate, satisfying events of which set 'inverted' flag of the target predicate to 0"
+	,
 };
 
 MODULE_CONSTRUCTOR(init)

nodes/print.c

@@ -60,6 +60,8 @@ GraphNodeSpecification nodespec_print = (GraphNodeSpecification) {
 	.destroy = &destroy,
 	.register_io = NULL,
 	.name = "print",
+	.documentation = "Prints received events\nAccepts events on any connector\nDoes not send events"
+	,
 };
 
 MODULE_CONSTRUCTOR(init)

nodes/router.c

@@ -88,6 +88,9 @@ GraphNodeSpecification nodespec_router = (GraphNodeSpecification) {
 	.destroy = &destroy,
 	.register_io = NULL,
 	.name = "router",
+	.documentation = "Conditionally copies the received events\nAccepts events on any connector\nSends events on all connectors with configured predicates"
+	                 "\nOption 'predicates' (required): collection of predicates in the order of output connectors from zero, a received event is copied to the given connector iff it satisfies the predicate"
+	,
 };
 
 MODULE_CONSTRUCTOR(init)

nodes/tee.c

@@ -53,6 +53,8 @@ GraphNodeSpecification nodespec_tee = (GraphNodeSpecification) {
 	.destroy = &destroy,
 	.register_io = NULL,
 	.name = "tee",
+	.documentation = "Copies the received events\nAccepts events on any connector\nSends events on all connectors"
+	,
 };
 
 MODULE_CONSTRUCTOR(init)