A parser for the visual format string

a.m

@import AppKit;
@import Foundation;

#include <stdio.h>

int main(int argc, char *argv[]) {
    @try {
        if (argc < 2) {
            printf("Usage: %s [visual format for a 'view']\n", argv[0]);
            return 0;
        }
        NSString * const visualFormat = [[NSString alloc] initWithUTF8String:argv[1]];
        NSView * const view = [[NSView alloc] init];
        NSArray * const constraints =
            [NSLayoutConstraint constraintsWithVisualFormat:visualFormat
                                                    options:0
                                                    metrics:nil
                                                      views:@{@"view": view}];
        for (NSLayoutConstraint * const constraint in constraints) {
            printf("%s\n", constraint.description.UTF8String);
        }
    } @catch(NSException *exception) {
        printf("Error: %s\n", exception.reason.UTF8String);
        return 1;
    }
}