Treat -i and -r args as regex

Often the columns to ignore or put on the right axis are, like,
resistance_0, resistance_1, resistance_2... and being able to wrangle
the lot of them in one argument is handy.

src/main.c

@@ -7,12 +7,13 @@
 #include <gtk/gtk.h>
 #include <pango/pangocairo.h>
 #include <time.h>
+#include <regex.h>
 
 /* TYPES!!! */
 
 struct column_list {
 	struct column_list* next;
-	char* header;
+	regex_t regex;
 };
 
 struct data {
@@ -37,7 +38,7 @@ struct context {
 	struct data* data;
 	struct data* data_end;
 
-	struct column_list* left_columns;
+	struct column_list* right_columns;
 	struct column_list* ignore_columns;
 
 	struct {
@@ -170,18 +171,18 @@ int main( int argc, char** argv ) {
 			.flags = G_OPTION_FLAG_IN_MAIN,
 			.arg = G_OPTION_ARG_CALLBACK,
 			.arg_data = &add_to_column_list,
-			.description = "Use right axis for column "
+			.description = "Use right axis for columns matching regex "
 				"(can be given multiple times)",
-			.arg_description = "column"
+			.arg_description = "regex"
 		}, {
 			.long_name = "ignore",
 			.short_name = 'i',
 			.flags = G_OPTION_FLAG_IN_MAIN,
 			.arg = G_OPTION_ARG_CALLBACK,
 			.arg_data = &add_to_column_list,
-			.description = "Do not plot the data in column "
+			.description = "Ignore columns matching regex "
 				"(can be given multiple times)",
-			.arg_description = "column"
+			.arg_description = "regex"
 		}, {
 			.long_name = "font",
 			.short_name = 'f',
@@ -269,12 +270,15 @@ static bool add_to_column_list( const char* option_name,
 	(void) error;
 
 	struct column_list* item = calloc( 1, sizeof *item );
-	item->header = strdup( value );
+	if ( 0 != regcomp( &( item->regex ), value, REG_EXTENDED ) ) {
+		fprintf( stderr, "Invalid column regex: '%s'\n", value );
+		return false;
+	}
 
 	if ( 0 == strcmp( option_name, "-r" ) ||
 			0 == strcmp( option_name, "--right" ) ) {
-		item->next = context->left_columns;
-		context->left_columns = item;
+		item->next = context->right_columns;
+		context->right_columns = item;
 	} else if ( 0 == strcmp( option_name, "-i" ) ||
 			0 == strcmp( option_name, "--ignore" ) ) {
 		item->next = context->ignore_columns;
@@ -691,10 +695,11 @@ static void parse_headers( struct context* context ) {
 
 			context->columns[n].type = LEFT_AXIS;
 
-			for ( struct column_list* item = context->left_columns;
+			for ( struct column_list* item = context->right_columns;
 					NULL != item;
 					item = item->next ) {
-				if ( 0 == strcmp( stripped_header, item->header ) ) {
+				if ( 0 == regexec( &( item->regex ), stripped_header,
+						0, NULL, 0 ) ) {
 					context->columns[n].type = RIGHT_AXIS;
 					break;
 				}
@@ -703,7 +708,8 @@ static void parse_headers( struct context* context ) {
 			for ( struct column_list* item = context->ignore_columns;
 					NULL != item;
 					item = item->next ) {
-				if ( 0 == strcmp( stripped_header, item->header ) ) {
+				if ( 0 == regexec( &( item->regex ), stripped_header,
+						0, NULL, 0 ) ) {
 					context->columns[n].type = IGNORE;
 					break;
 				}