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const HELP_FLAG: &str = "help h";
const VERSION_FLAG: &str = "version v";
const DONT_PERSIST: &str = "d";
pub struct Flags {
pub help: bool,
pub version: bool,
pub dont_persist: bool,
pub arg_count: usize
}
/// Parses an list of String arguments into a set of flags that can be used by crab
/// #### Arguments
/// * `args` - The list of String arguments
/// #### Returns
/// * `None` - If there is an invalid argument in the list
/// * `Some(Flags)` - If the arguments were secussfully parsed, returning the flags
pub fn parse(args: &[String]) -> Option<Flags> {
let mut flags = Flags {
help: false,
version: false,
dont_persist: false,
arg_count: 0
};
for arg in args {
if !is_arg(&arg) { break; }
flags.arg_count += 1;
if arg.starts_with("--") {
let flag = &arg[2..];
if !set_flag(&flag, &mut flags) {
eprintln!("Invalid argument: {}", arg);
return None
}
} else {
let flag = &arg[1..];
for char in flag.chars() {
if !set_flag(&char.to_string(), &mut flags) {
eprintln!("Invalid argument: {}", arg);
return None
}
}
}
}
Some(flags)
}
/// Checks if a given string is a given argument
fn is_arg(arg: &str) -> bool {
return arg.starts_with("-");
}
/// Sets a flag in a `Flags` struct
/// #### Arguments
/// * `arg` - The argument to check
/// * `flags` - The `Flags` stuct to update
/// #### Returns
/// * `true` - If the argument passed is a valid flag
/// * `false` - If the argument passed is not a valid flag
fn set_flag(arg: &str, flags: &mut Flags) -> bool {
if has_flag_set(&arg, HELP_FLAG) {
flags.help = true;
return true
} else if has_flag_set(&arg, VERSION_FLAG) {
flags.version = true;
return true
} else if has_flag_set(&arg, DONT_PERSIST) {
flags.dont_persist = true;
return true
}
false
}
/// Returns if a given argument is a certain flag
/// #### Arguments
/// * `arg` - The arch to check
/// #### Returns
/// * `true` - If the argument matches the flag
/// * `false` - If the argument doesn't match the flag
fn has_flag_set(arg: &str, check: &str) -> bool {
for check_arg in check.split(" ") {
if check_arg == arg {
return true
}
}
return false
}
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