module flag // module flag for command-line flag parsing // // - parsing flags like '--flag' or '--stuff=things' or '--things stuff' // - handles bool, int, float and string args // - is able to print usage // - handled unknown arguments as error // // Usage example: // // ```v // module main // // import os // import flag // // fn main() { // mut fp := flag.new_flag_parser(os.args) // fp.application('flag_example_tool') // fp.version('v0.0.0') // fp.description('This tool is only designed to show how the flag lib is working') // // fp.skip_executable() // // an_int := fp.int('an_int', 0, 0o666, 'some int to define 0o666 is default') // a_bool := fp.bool('a_bool', 0, false, 'some \'real\' flag') // a_float := fp.float('a_float', 0, 1.0, 'also floats') // a_string := fp.string('a_string', `a`, 'no text', 'finally, some text with "a" an abbreviation') // // additional_args := fp.finalize() or { // eprintln(err) // println(fp.usage()) // return // } // // println(' // an_int: $an_int // a_bool: $a_bool // a_float: $a_float // a_string: \'$a_string\' // ') // println(additional_args.join_lines()) // } // ``` // 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: $f.val_desc' } pub fn (af []Flag) str() string { mut res := []string{} res << '\n []Flag = [' for f in af { res << f.str() } res << ' ]' return res.join('\n') } // pub struct FlagParser { pub mut: args []string // the arguments to be parsed flags []Flag // registered flags application_name string application_version string application_description string min_free_args int max_free_args int args_description string } pub const ( // used for formating usage message space = ' ' UNDERLINE = '-----------------------------------------------' MAX_ARGS_NUMBER = 4048 ) // create a new flag set for parsing command line arguments // TODO use INT_MAX some how pub fn new_flag_parser(args []string) &FlagParser { return &FlagParser{args: args.clone(), max_free_args: MAX_ARGS_NUMBER} } // change the application name to be used in 'usage' output pub fn (fs mut FlagParser) application(name string) { fs.application_name = name } // change the application version to be used in 'usage' output pub fn (fs mut FlagParser) version(vers string) { fs.application_version = vers } // change the application version to be used in 'usage' output pub fn (fs mut FlagParser) description(desc string) { fs.application_description = desc } // in most cases you do not need the first argv for flag parsing pub fn (fs mut FlagParser) skip_executable() { fs.args.delete(0) } // private helper to register a flag fn (fs mut FlagParser) add_flag(name string, abbr byte, usage string, desc string) { fs.flags << Flag{ name: name, abbr: abbr, usage: usage, val_desc: desc } } // private: general parsing a single argument // - search args for existence // if true // extract the defined value as string // else // return an (dummy) error -> argument is not defined // // - the name, usage are registered // - found arguments and corresponding values are removed from args list fn (fs mut FlagParser) parse_value(longhand string, shorthand byte) []string { full := '--$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 { panic("Missing argument for '$longhand'") } nextarg := fs.args[i+1] if nextarg.len > 2 && nextarg[..2] == '--' { //It could be end of input (--) or another argument (--abc). //Both are invalid so die. panic("Missing argument for '$longhand'") } 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] == '$full=' { found_entries << arg[full.len+1..] to_delete << i continue } } for i, del in to_delete { //i entrys are deleted so it's shifted left i times. fs.args.delete(del - i) } return found_entries } // special parsing for bool values // see also: parse_value // // special: it is allowed to define bool flags without value // -> '--flag' is parsed as true // -> '--flag' is equal to '--flag=true' fn (fs mut FlagParser) parse_bool_value(longhand string, shorthand byte) ?string { full := '--$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] == '$full=' { // Flag abc=true val := arg[full.len+1..] fs.args.delete(i) return val } if arg[0] == `-` && arg[1] != `-` && arg.index_byte(shorthand) != -1 { // -abc is equivalent to -a -b -c return 'true' } } return error("parameter '$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 (fs mut 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 '$name' not provided") } return parsed == 'true' } // defining and parsing a bool flag // if defined // the value is returned (true/false) // else // the default value is returned // version with abbr //TODO error handling for invalid string to bool conversion pub fn (fs mut FlagParser) bool(name string, abbr byte, bdefault bool, usage string) bool { value := fs.bool_opt(name, abbr, usage) or { return bdefault } return value } // int_multi returns all instances of values associated with the flags provided // In the case that none were found, it returns an empty array. pub fn (fs mut FlagParser) int_multi(name string, abbr byte, usage string) []int { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) mut value := []int{} for val in parsed { value << val.int() } return value } // int_opt returns an optional that returns the value associated with the flag. // In the situation that the flag was not provided, it returns null. pub fn (fs mut FlagParser) int_opt(name string, abbr byte, usage string) ?int { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) if parsed.len == 0 { return error("parameter '$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 (fs mut 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 (fs mut 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 (fs mut 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 '$name' not provided") } return parsed[0].f64() } // defining and parsing a float flag // if defined // the value is returned (float) // else // the default value is returned // version with abbr //TODO error handling for invalid string to float conversion pub fn (fs mut FlagParser) float(name string, abbr byte, fdefault f64, usage string) f64 { value := fs.float_opt(name, abbr, usage) or { return fdefault } return value } // string_multi returns all instances of values associated with the flags provided // In the case that none were found, it returns an empty array. pub fn (fs mut FlagParser) string_multi(name string, abbr byte, usage string) []string { fs.add_flag(name, abbr, usage, '') return fs.parse_value(name, abbr) } // string_opt returns an optional that returns the value associated with the flag. // In the situation that the flag was not provided, it returns null. pub fn (fs mut FlagParser) string_opt(name string, abbr byte, usage string) ?string { fs.add_flag(name, abbr, usage, '') parsed := fs.parse_value(name, abbr) if parsed.len == 0 { return error("parameter '$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 (fs mut 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 (fs mut FlagParser) limit_free_args_to_at_least(n int) { if n > MAX_ARGS_NUMBER { panic('flag.limit_free_args_to_at_least expect n to be smaller than $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 (fs mut FlagParser) limit_free_args_to_exactly(n int) { if n > MAX_ARGS_NUMBER { panic('flag.limit_free_args_to_exactly expect n to be smaller than $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 (fs mut FlagParser) limit_free_args(min, max int) { if min > max { panic('flag.limit_free_args expect min < max, got $min >= $max') } fs.min_free_args = min fs.max_free_args = max } pub fn (fs mut FlagParser) arguments_description(description string){ fs.args_description = description } // collect all given information and pub fn (fs FlagParser) usage() string { positive_min_arg := ( fs.min_free_args > 0 ) positive_max_arg := ( fs.max_free_args > 0 && fs.max_free_args != MAX_ARGS_NUMBER ) no_arguments := ( fs.min_free_args == 0 && fs.max_free_args == 0 ) mut adesc := if fs.args_description.len > 0 { fs.args_description } else { '[ARGS]' } if no_arguments { adesc = '' } mut use := '' if fs.application_version != '' { use += '$fs.application_name $fs.application_version\n' use += '$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.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 > space.len-2 { xspace = '\n${space}' } else { xspace = space[option_names.len..] } use += '${option_names}${xspace}${f.usage}\n' } } return use } // 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 }