Merge commit '3985029fd63ff5abfef0a3d2b0eef64b2b3f6cea' as 'external/cflags'

external/cflags/examples/example.cpp

@@ -0,0 +1,64 @@
+#include "cflags.hpp"
+
+void parse_file(const char * filename)
+{
+    printf("parsing %s\n", filename);
+}
+
+int main(int argc, char * argv[])
+{
+    cflags::cflags flags;
+
+    bool help = false;
+    flags.add_bool('\0', "help", &help, "display this help and exit");
+
+    bool debug = false;
+    flags.add_bool('d', "debug", &debug, "enable debug mode");
+
+    int count = 0;
+    flags.add_int('c', "count", &count, "enter a number");
+
+    float amount = 0.f;
+    flags.add_float('a', "amount", &amount, "enter a float");
+
+    flags.add_bool('q', "really-long-argument-name", nullptr, "testing really long argument names");
+
+    flags.add_cstring_callback('f', "file", &parse_file, "process a file");
+
+    flags.add_string_callback('n', "name", 
+        [](std::string name) {
+            printf("Hello %s\n", name.c_str());
+        },
+        "say hello to name");
+
+    auto verbose = flags.add_bool('v', "verbose", NULL, "enables verbose output, repeat up to 4 times for more verbosity");
+
+    if (!flags.parse(argc, argv) || help || argc == 1) {
+        flags.print_usage(
+            "[OPTION]... [ARG]...", 
+            "Tests the cflags library.", 
+            "Additional information about this library can be found by contacting:\n"
+            "  sdl.slane@gmail.com");
+        return 1;
+    }
+
+    printf("help: %d\n", help);
+    printf("debug: %d\n", debug);
+
+    printf("count: %d\n", count);
+    printf("amount: %f\n", amount);
+
+    printf("verbosity: %d\n", verbose->count);
+
+    printf("args:\n");
+    for (auto& arg : flags.args) {
+        printf("Positional %s\n", arg.data());
+    }
+
+    printf("argc/argv:\n");
+    for (int i = 0; i < flags.argc; ++i) {
+        printf("positional %d: %s\n", i, flags.argv[i]);
+    }
+
+    return 0;
+}