module flag // data object storing information about a defined flag pub struct Flag { pub: name string // name as it appears on command line abbr byte // shortcut usage string // help message val_desc string // something like '' that appears in usage, // and also the default value, when the flag is not given } pub fn (f Flag) str() string { return '' + ' flag:\n' + ' name: $f.name\n' + ' abbr: $f.abbr\n' + ' usag: $f.usage\n' + ' desc: $f.val_desc' } pub fn (af []Flag) str() string { mut res := []string{} res << '\n []Flag = [' for f in af { res << f.str() } res << ' ]' return res.join('\n') } // pub struct FlagParser { pub mut: args []string // the arguments to be parsed max_free_args int flags []Flag // registered flags application_name string application_version string application_description string min_free_args int args_description string } pub const ( // used for formating usage message space = ' ' underline = '-----------------------------------------------' max_args_number = 4048 ) // create a new flag set for parsing command line arguments // TODO use INT_MAX some how pub fn new_flag_parser(args []string) &FlagParser { return &FlagParser{ args: args.clone() max_free_args: flag.max_args_number } } // change the application name to be used in 'usage' output pub fn (mut fs FlagParser) application(name string) { fs.application_name = name } // change the application version to be used in 'usage' output pub fn (mut fs FlagParser) version(vers string) { fs.application_version = vers } // change the application version to be used in 'usage' output pub fn (mut fs FlagParser) description(desc string) { fs.application_description = desc } // in most cases you do not need the first argv for flag parsing pub fn (mut fs FlagParser) skip_executable() { fs.args.delete(0) } // private helper to register a flag fn (mut fs FlagParser) add_flag(name string, abbr byte, usage string, desc string) { fs.flags << Flag{ name: name abbr: abbr usage: usage val_desc: desc } } // private: general parsing a single argument // - search args for existence // if true // extract the defined value as string // else // return an (dummy) error -> argument is not defined // // - the name, usage are registered // - found arguments and corresponding values are removed from args list fn (mut fs FlagParser) parse_value(longhand string, shorthand byte) []string { full := '--$longhand' mut found_entries := []string{} mut to_delete := []int{} mut should_skip_one := false for i, arg in fs.args { if should_skip_one { should_skip_one = false continue } if arg == '--' { // End of input. We're done here. break } if arg[0] != `-` { continue } if (arg.len == 2 && arg[0] == `-` && arg[1] == shorthand) || arg == full { if i + 1 >= fs.args.len { return [] } nextarg := fs.args[i + 1] if nextarg.len > 2 && nextarg[..2] == '--' { // It could be end of input (--) or another argument (--abc). // Both are invalid so die. return [] } found_entries << fs.args[i + 1] to_delete << i to_delete << i + 1 should_skip_one = true continue } if arg.len > full.len + 1 && arg[..full.len + 1] == '$full=' { found_entries << arg[full.len + 1..] to_delete << i continue } } for i, del in to_delete { // i entrys are deleted so it's shifted left i times. fs.args.delete(del - i) } return found_entries } // special parsing for bool values // see also: parse_value // // special: it is allowed to define bool flags without value // -> '--flag' is parsed as true // -> '--flag' is equal to '--flag=true' fn (mut fs FlagParser) parse_bool_value(longhand string, shorthand byte) ?string { full := '--$longhand' for i, arg in fs.args { if arg == '--' { // End of input. We're done. break } if arg.len == 0 { continue } if arg[0] != `-` { continue } if (arg.len == 2 && arg[0] == `-` && arg[1] == shorthand) || arg == full { if fs.args.len > i + 1 && (fs.args[i + 1] in ['true', 'false']) { val := fs.args[i + 1] fs.args.delete(i + 1) fs.args.delete(i) return val } else { fs.args.delete(i) return 'true' } } if arg.len > full.len + 1 && arg[..full.len + 1] == '$full=' { // Flag abc=true val := arg[full.len + 1..] fs.args.delete(i) return val } if arg.len > 1 && arg[0] == `-` && arg[1] != `-` && arg.index_byte(shorthand) != -1 { // -abc is equivalent to -a -b -c return 'true' } } return error("parameter '$longhand' not found") } // bool_opt returns an optional that returns the value associated with the flag. // In the situation that the flag was not provided, it returns null. pub fn (mut fs FlagParser) bool_opt(name string, abbr byte, usage string) ?bool { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_bool_value(name, abbr) or { return error("parameter '$name' not provided") } return parsed == 'true' } // defining and parsing a bool flag // if defined // the value is returned (true/false) // else // the default value is returned // version with abbr // TODO error handling for invalid string to bool conversion pub fn (mut fs FlagParser) bool(name string, abbr byte, bdefault bool, usage string) bool { value := fs.bool_opt(name, abbr, usage) or { return bdefault } return value } // int_multi returns all instances of values associated with the flags provided // In the case that none were found, it returns an empty array. pub fn (mut fs FlagParser) int_multi(name string, abbr byte, usage string) []int { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) mut value := []int{} for val in parsed { value << val.int() } return value } // int_opt returns an optional that returns the value associated with the flag. // In the situation that the flag was not provided, it returns null. pub fn (mut fs FlagParser) int_opt(name string, abbr byte, usage string) ?int { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) if parsed.len == 0 { return error("parameter '$name' not provided") } return parsed[0].int() } // defining and parsing an int flag // if defined // the value is returned (int) // else // the default value is returned // version with abbr // TODO error handling for invalid string to int conversion pub fn (mut fs FlagParser) int(name string, abbr byte, idefault int, usage string) int { value := fs.int_opt(name, abbr, usage) or { return idefault } return value } // float_multi returns all instances of values associated with the flags provided // In the case that none were found, it returns an empty array. pub fn (mut fs FlagParser) float_multi(name string, abbr byte, usage string) []f64 { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) mut value := []f64{} for val in parsed { value << val.f64() } return value } // float_opt returns an optional that returns the value associated with the flag. // In the situation that the flag was not provided, it returns null. pub fn (mut fs FlagParser) float_opt(name string, abbr byte, usage string) ?f64 { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) if parsed.len == 0 { return error("parameter '$name' not provided") } return parsed[0].f64() } // defining and parsing a float flag // if defined // the value is returned (float) // else // the default value is returned // version with abbr // TODO error handling for invalid string to float conversion pub fn (mut fs FlagParser) float(name string, abbr byte, fdefault f64, usage string) f64 { value := fs.float_opt(name, abbr, usage) or { return fdefault } return value } // string_multi returns all instances of values associated with the flags provided // In the case that none were found, it returns an empty array. pub fn (mut fs FlagParser) string_multi(name string, abbr byte, usage string) []string { fs.add_flag(name, abbr, usage, '') return fs.parse_value(name, abbr) } // string_opt returns an optional that returns the value associated with the flag. // In the situation that the flag was not provided, it returns null. pub fn (mut fs FlagParser) string_opt(name string, abbr byte, usage string) ?string { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) if parsed.len == 0 { return error("parameter '$name' not provided") } return parsed[0] } // defining and parsing a string flag // if defined // the value is returned (string) // else // the default value is returned // version with abbr pub fn (mut fs FlagParser) string(name string, abbr byte, sdefault string, usage string) string { value := fs.string_opt(name, abbr, usage) or { return sdefault } return value } pub fn (mut fs FlagParser) limit_free_args_to_at_least(n int) { if n > flag.max_args_number { panic('flag.limit_free_args_to_at_least expect n to be smaller than $flag.max_args_number') } if n <= 0 { panic('flag.limit_free_args_to_at_least expect n to be a positive number') } fs.min_free_args = n } pub fn (mut fs FlagParser) limit_free_args_to_exactly(n int) { if n > flag.max_args_number { panic('flag.limit_free_args_to_exactly expect n to be smaller than $flag.max_args_number') } if n < 0 { panic('flag.limit_free_args_to_exactly expect n to be a non negative number') } fs.min_free_args = n fs.max_free_args = n } // this will cause an error in finalize() if free args are out of range // (min, ..., max) pub fn (mut fs FlagParser) limit_free_args(min int, max int) { if min > max { panic('flag.limit_free_args expect min < max, got $min >= $max') } fs.min_free_args = min fs.max_free_args = max } pub fn (mut fs FlagParser) arguments_description(description string) { fs.args_description = description } // collect all given information and pub fn (fs FlagParser) usage() string { positive_min_arg := (fs.min_free_args > 0) positive_max_arg := (fs.max_free_args > 0 && fs.max_free_args != flag.max_args_number) no_arguments := (fs.min_free_args == 0 && fs.max_free_args == 0) mut adesc := if fs.args_description.len > 0 { fs.args_description } else { '[ARGS]' } if no_arguments { adesc = '' } mut use := '' if fs.application_version != '' { use += '$fs.application_name $fs.application_version\n' use += '$flag.underline\n' } use += 'Usage: $fs.application_name [options] $adesc\n' use += '\n' if fs.application_description != '' { use += 'Description:\n' use += '$fs.application_description' use += '\n\n' } // show a message about the [ARGS]: if positive_min_arg || positive_max_arg || no_arguments { if no_arguments { use += 'This application does not expect any arguments\n\n' goto end_of_arguments_handling } mut s := []string{} if positive_min_arg { s << 'at least $fs.min_free_args' } if positive_max_arg { s << 'at most $fs.max_free_args' } if positive_min_arg && positive_max_arg && fs.min_free_args == fs.max_free_args { s = ['exactly $fs.min_free_args'] } sargs := s.join(' and ') use += 'The arguments should be $sargs in number.\n\n' } end_of_arguments_handling: if fs.flags.len > 0 { use += 'Options:\n' for f in fs.flags { mut onames := []string{} if f.abbr != 0 { onames << '-$f.abbr.ascii_str()' } if f.name != '' { if !f.val_desc.contains('') { onames << '--$f.name $f.val_desc' } else { onames << '--$f.name' } } option_names := ' ' + onames.join(', ') mut xspace := '' if option_names.len > flag.space.len - 2 { xspace = '\n$flag.space' } else { xspace = flag.space[option_names.len..] } use += '$option_names$xspace$f.usage\n' } } return use.replace('- ,', ' ') } // finalize argument parsing -> call after all arguments are defined // // all remaining arguments are returned in the same order they are defined on // command line // // if additional flag are found (things starting with '--') an error is returned // error handling is up to the application developer pub fn (fs FlagParser) finalize() ?[]string { for a in fs.args { if a.len >= 2 && a[..2] == '--' { return error("Unknown argument \'${a[2..]}\'") } } if fs.args.len < fs.min_free_args && fs.min_free_args > 0 { return error('Expected at least $fs.min_free_args arguments, but given $fs.args.len') } if fs.args.len > fs.max_free_args && fs.max_free_args > 0 { return error('Expected at most $fs.max_free_args arguments, but given $fs.args.len') } if fs.args.len > 0 && fs.max_free_args == 0 && fs.min_free_args == 0 { return error('Expected no arguments, but given $fs.args.len') } return fs.args }