Adds most of the toolsHEADmaster

15 files changed, 1199 insertions, 0 deletions

diff --git a/v_windows/v/old/vlib/flag/README.md b/v_windows/v/old/vlib/flag/README.md
new file mode 100644
index 0000000..1122f77
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/README.md
@@ -0,0 +1,36 @@
+The `flag` module helps command-line flag parsing.
+Main features are:
+- parses flags like `-f` or '--flag' or '--stuff=things' or '--things stuff'.
+- handles bool, int, float and string args.
+- can print usage information listing all the declrared flags.
+- handles 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('v0.0.1')
+	fp.limit_free_args(0, 0) // comment this, if you expect arbitrary texts after the options
+	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, 0o123, 'some int to define 0o123 is its default value')
+	a_bool := fp.bool('a_bool', 0, false, 'some boolean flag. --a_bool will set it to true.')
+	a_float := fp.float('a_float', 0, 1.0, 'some floating point value, by default 1.0 .')
+	a_string := fp.string('a_string', `a`, 'no text', 'finally, some text with ' +
+		' `-a` as an abbreviation, so you can pass --a_string abc or just -a abc')
+	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())
+}
+```
diff --git a/v_windows/v/old/vlib/flag/default_flag_options_test.v b/v_windows/v/old/vlib/flag/default_flag_options_test.v
new file mode 100644
index 0000000..fb0a423
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/default_flag_options_test.v
@@ -0,0 +1,35 @@
+import os
+
+const source = 'vlib/flag/testdata/simplest_flag_program.v'
+
+const simple_flag_app_executable = os.real_path(os.join_path(os.cache_dir(), 'simple_flag_app.exe'))
+
+fn testsuite_begin() {
+	os.chdir(@VMODROOT)
+	os.rm(simple_flag_app_executable) or {}
+	res := os.execute('${@VEXE} -o $simple_flag_app_executable $source')
+	assert res.exit_code == 0
+	assert os.execute(simple_flag_app_executable).exit_code == 0
+}
+
+fn testsuite_end() {
+	os.rm(simple_flag_app_executable) or {}
+	assert true
+}
+
+fn check_program(opts string, extension string) {
+	result := source.replace('.v', extension)
+	res := os.execute('$simple_flag_app_executable $opts')
+	lines := os.read_lines(result) or { panic(err) }
+	assert res.exit_code == 0
+	assert res.output.split_into_lines() == lines
+}
+
+fn test_default_builtin_flag_options() {
+	check_program('', '.out')
+	check_program(' -- --help', '.dashdash.help.out')
+	check_program(' -- --version', '.dashdash.version.out')
+	check_program(' -h', '.help.out')
+	check_program(' --help', '.help.out')
+	check_program(' --version', '.version.out')
+}
diff --git a/v_windows/v/old/vlib/flag/flag.v b/v_windows/v/old/vlib/flag/flag.v
new file mode 100644
index 0000000..85bb09d
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/flag.v
@@ -0,0 +1,624 @@
+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 '<arg>' that appears in usage,
+	// and also the default value, when the flag is not given
+}
+
+struct UnkownFlagError {
+	msg  string
+	code int
+}
+
+struct MinimumArgsCountError {
+	msg  string
+	code int
+}
+
+struct MaximumArgsCountError {
+	msg  string
+	code int
+}
+
+struct NoArgsExpectedError {
+	msg  string
+	code int
+}
+
+[unsafe]
+fn (mut f Flag) free() {
+	unsafe {
+		f.name.free()
+		f.usage.free()
+		f.val_desc.free()
+	}
+}
+
+pub fn (f Flag) str() string {
+	return '' + '    flag:\n' + '            name: $f.name\n' +
+		'            abbr: `$f.abbr.ascii_str()`\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:
+	original_args      []string // the original arguments to be parsed
+	idx_dashdash       int      // the index of a `--`, -1 if there is not any
+	all_after_dashdash []string // all options after `--` are ignored, and will be passed to the application unmodified
+pub mut:
+	usage_examples []string // when set, --help will print:
+	// Usage: $appname $usage_examples[0]`
+	//    or: $appname $usage_examples[1]`
+	// etc
+	default_help_label      string = 'display this help and exit'
+	default_version_label   string = 'output version information and exit'
+	args                    []string // the current list of processed args
+	max_free_args           int
+	flags                   []Flag // registered flags
+	application_name        string
+	application_version     string
+	application_description string
+	min_free_args           int
+	args_description        string
+	allow_unknown_args      bool     // whether passing undescribed arguments is allowed
+	footers                 []string // when set, --help will display all the collected footers at the bottom.
+}
+
+[unsafe]
+fn (mut f FlagParser) free() {
+	unsafe {
+		for a in f.args {
+			a.free()
+		}
+		f.args.free()
+		//
+		for flag in f.flags {
+			flag.free()
+		}
+		f.flags.free()
+		//
+		f.application_name.free()
+		f.application_version.free()
+		f.application_description.free()
+		f.args_description.free()
+	}
+}
+
+pub const (
+	// used for formating usage message
+	space           = '                            '
+	underline       = '-----------------------------------------------'
+	max_args_number = 4048
+)
+
+// create a new flag set for parsing command line arguments
+pub fn new_flag_parser(args []string) &FlagParser {
+	original_args := args.clone()
+	idx_dashdash := args.index('--')
+	mut all_before_dashdash := args.clone()
+	mut all_after_dashdash := []string{}
+	if idx_dashdash >= 0 {
+		all_before_dashdash.trim(idx_dashdash)
+		if idx_dashdash < original_args.len {
+			all_after_dashdash = original_args[idx_dashdash + 1..]
+		}
+	}
+	return &FlagParser{
+		original_args: original_args
+		idx_dashdash: idx_dashdash
+		all_after_dashdash: all_after_dashdash
+		args: all_before_dashdash
+		max_free_args: flag.max_args_number
+	}
+}
+
+// usage_example - add an usage example
+// All examples will be listed in the help screen.
+// If you do not give any examples, then a default usage
+// will be shown, based on whether the application takes
+// options and expects additional parameters.
+pub fn (mut fs FlagParser) usage_example(example string) {
+	fs.usage_examples << example
+}
+
+// add_footer - add a footnote, that will be shown
+// at the bottom of the help screen.
+pub fn (mut fs FlagParser) footer(footer string) {
+	fs.footers << footer
+}
+
+// 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
+}
+
+// description appends to the application description lines, shown
+// in the help/usage screen
+pub fn (mut fs FlagParser) description(desc string) {
+	if fs.application_description.len == 0 {
+		fs.application_description = desc
+	} else {
+		fs.application_description += '\n$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)
+}
+
+// allow_unknown_args - if your program has sub commands, that have
+// their own arguments, you can call .allow_unknown_args(), so that
+// the subcommand arguments (which generally are not known to your
+// parent program), will not cause the validation in .finalize() to fail.
+pub fn (mut fs FlagParser) allow_unknown_args() {
+	fs.allow_unknown_args = true
+}
+
+// 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
+[manualfree]
+fn (mut fs FlagParser) parse_value(longhand string, shorthand byte) []string {
+	full := '--$longhand'
+	defer {
+		unsafe { full.free() }
+	}
+	mut found_entries := []string{}
+	mut to_delete := []int{}
+	defer {
+		unsafe { to_delete.free() }
+	}
+	mut should_skip_one := false
+	for i, arg in fs.args {
+		if should_skip_one {
+			should_skip_one = false
+			continue
+		}
+		if arg.len == 0 || arg[0] != `-` {
+			continue
+		}
+		if (arg.len == 2 && arg[0] == `-` && arg[1] == shorthand) || arg == full {
+			if i + 1 >= fs.args.len {
+				return []
+			}
+			nextarg := fs.args[i + 1]
+			if nextarg.len > 2 {
+				nextarg_rest := nextarg[..2]
+				if nextarg_rest == '--' {
+					// It could be end of input (--) or another argument (--abc).
+					// Both are invalid so die.
+					unsafe { nextarg_rest.free() }
+					return []
+				}
+				unsafe { nextarg_rest.free() }
+			}
+			found_entries << fs.args[i + 1]
+			to_delete << i
+			to_delete << i + 1
+			should_skip_one = true
+			continue
+		}
+		if arg.len > full.len + 1 && arg[..full.len + 1] == '$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 := '--$longhand'
+		for i, arg in fs.args {
+			if arg.len == 0 {
+				continue
+			}
+			if arg[0] != `-` {
+				continue
+			}
+			if (arg.len == 2 && arg[0] == `-` && arg[1] == shorthand) || arg == full {
+				if fs.args.len > i + 1 && (fs.args[i + 1] in ['true', 'false']) {
+					val := fs.args[i + 1]
+					fs.args.delete(i + 1)
+					fs.args.delete(i)
+					return val
+				} else {
+					fs.args.delete(i)
+					return 'true'
+				}
+			}
+			if arg.len > full.len + 1 && arg[..full.len + 1] == '$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 '$longhand' not found")
+}
+
+// bool_opt returns an optional that returns the value associated with the flag.
+// In the situation that the flag was not provided, it returns null.
+pub fn (mut fs FlagParser) bool_opt(name string, abbr byte, usage string) ?bool {
+	mut res := false
+	{
+		fs.add_flag(name, abbr, usage, '<bool>')
+		parsed := fs.parse_bool_value(name, abbr) or {
+			return error("parameter '$name' not provided")
+		}
+		res = parsed == 'true'
+	}
+	return res
+}
+
+// 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, '<multiple ints>')
+	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 {
+	mut res := 0
+	{
+		fs.add_flag(name, abbr, usage, '<int>')
+		parsed := fs.parse_value(name, abbr)
+		if parsed.len == 0 {
+			return error("parameter '$name' not provided")
+		}
+		parsed0 := parsed[0]
+		res = parsed0.int()
+	}
+	return res
+}
+
+// defining and parsing an int flag
+// if defined
+// the value is returned (int)
+// else
+// the default value is returned
+// version with abbr
+// TODO error handling for invalid string to int conversion
+pub fn (mut fs FlagParser) int(name string, abbr byte, idefault int, usage string) int {
+	value := fs.int_opt(name, abbr, usage) or { return idefault }
+	return value
+}
+
+// float_multi returns all instances of values associated with the flags provided
+// In the case that none were found, it returns an empty array.
+pub fn (mut fs FlagParser) float_multi(name string, abbr byte, usage string) []f64 {
+	fs.add_flag(name, abbr, usage, '<multiple floats>')
+	parsed := fs.parse_value(name, abbr)
+	mut value := []f64{}
+	for val in parsed {
+		value << val.f64()
+	}
+	return value
+}
+
+// float_opt returns an optional that returns the value associated with the flag.
+// In the situation that the flag was not provided, it returns null.
+pub fn (mut fs FlagParser) float_opt(name string, abbr byte, usage string) ?f64 {
+	mut res := 0.0
+	{
+		fs.add_flag(name, abbr, usage, '<float>')
+		parsed := fs.parse_value(name, abbr)
+		if parsed.len == 0 {
+			return error("parameter '$name' not provided")
+		}
+		res = parsed[0].f64()
+	}
+	return res
+}
+
+// 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, '<multiple strings>')
+	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 {
+	mut res := ''
+	{
+		fs.add_flag(name, abbr, usage, '<string>')
+		parsed := fs.parse_value(name, abbr)
+		if parsed.len == 0 {
+			return error("parameter '$name' not provided")
+		}
+		res = parsed[0]
+	}
+	return res
+}
+
+// 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 >= $max')
+	}
+	fs.min_free_args = min
+	fs.max_free_args = max
+}
+
+pub fn (mut fs FlagParser) arguments_description(description string) {
+	fs.args_description = description
+}
+
+// collect all given information and
+pub fn (fs FlagParser) usage() string {
+	positive_min_arg := (fs.min_free_args > 0)
+	positive_max_arg := (fs.max_free_args > 0 && fs.max_free_args != flag.max_args_number)
+	no_arguments := (fs.min_free_args == 0 && fs.max_free_args == 0)
+	mut adesc := if fs.args_description.len > 0 { fs.args_description } else { '[ARGS]' }
+	if no_arguments {
+		adesc = ''
+	}
+	mut use := []string{}
+	if fs.application_version != '' {
+		use << '$fs.application_name $fs.application_version'
+		use << '$flag.underline'
+	}
+	if fs.usage_examples.len == 0 {
+		use << 'Usage: $fs.application_name [options] $adesc'
+	} else {
+		for i, example in fs.usage_examples {
+			if i == 0 {
+				use << 'Usage: $fs.application_name $example'
+			} else {
+				use << '   or: $fs.application_name $example'
+			}
+		}
+	}
+	use << ''
+	if fs.application_description != '' {
+		use << 'Description: $fs.application_description'
+		use << ''
+	}
+	// 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'
+			use << ''
+		} else {
+			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 $sargs in number.'
+			use << ''
+		}
+	}
+	if fs.flags.len > 0 {
+		use << 'Options:'
+		for f in fs.flags {
+			mut onames := []string{}
+			if f.abbr != 0 {
+				onames << '-$f.abbr.ascii_str()'
+			}
+			if f.name != '' {
+				if !f.val_desc.contains('<bool>') {
+					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$flag.space'
+			} else {
+				xspace = flag.space[option_names.len..]
+			}
+			fdesc := '$option_names$xspace$f.usage'
+			use << fdesc
+		}
+	}
+	for footer in fs.footers {
+		use << footer
+	}
+	return use.join('\n').replace('- ,', '   ')
+}
+
+fn (mut fs FlagParser) find_existing_flag(fname string) ?Flag {
+	for f in fs.flags {
+		if f.name == fname {
+			return f
+		}
+	}
+	return error('no such flag')
+}
+
+fn (mut fs FlagParser) handle_builtin_options() {
+	mut show_version := false
+	mut show_help := false
+	fs.find_existing_flag('help') or {
+		show_help = fs.bool('help', `h`, false, fs.default_help_label)
+	}
+	fs.find_existing_flag('version') or {
+		show_version = fs.bool('version', 0, false, fs.default_version_label)
+	}
+	if show_help {
+		println(fs.usage())
+		exit(0)
+	}
+	if show_version {
+		println('$fs.application_name $fs.application_version')
+		exit(0)
+	}
+}
+
+// finalize - return all remaining arguments (non options).
+// Call .finalize() after all arguments are defined.
+// The remaining arguments are returned in the same order they are
+// defined on the command line. If additional flags are found, i.e.
+// (things starting with '--' or '-'), it returns an error.
+pub fn (mut fs FlagParser) finalize() ?[]string {
+	fs.handle_builtin_options()
+	mut remaining := fs.args.clone()
+	if !fs.allow_unknown_args {
+		for a in remaining {
+			if (a.len >= 2 && a[..2] == '--') || (a.len == 2 && a[0] == `-`) {
+				return IError(&UnkownFlagError{
+					msg: 'Unknown flag `$a`'
+				})
+			}
+		}
+	}
+	if remaining.len < fs.min_free_args && fs.min_free_args > 0 {
+		return IError(&MinimumArgsCountError{
+			msg: 'Expected at least $fs.min_free_args arguments, but given $remaining.len'
+		})
+	}
+	if remaining.len > fs.max_free_args && fs.max_free_args > 0 {
+		return IError(&MaximumArgsCountError{
+			msg: 'Expected at most $fs.max_free_args arguments, but given $remaining.len'
+		})
+	}
+	if remaining.len > 0 && fs.max_free_args == 0 && fs.min_free_args == 0 {
+		return IError(&NoArgsExpectedError{
+			msg: 'Expected no arguments, but given $remaining.len'
+		})
+	}
+	remaining << fs.all_after_dashdash
+	return remaining
+}
+
+// remaining_parameters will return all remaining parameters.
+// Call .remaining_parameters() *AFTER* you have defined all options
+// that your program needs. remaining_parameters will also print any
+// parsing errors and stop the program. Use .finalize() instead, if
+// you want more control over the error handling.
+pub fn (mut fs FlagParser) remaining_parameters() []string {
+	return fs.finalize() or {
+		eprintln(err.msg)
+		println(fs.usage())
+		exit(1)
+	}
+}
diff --git a/v_windows/v/old/vlib/flag/flag_test.v b/v_windows/v/old/vlib/flag/flag_test.v
new file mode 100644
index 0000000..8326193
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/flag_test.v
@@ -0,0 +1,412 @@
+import flag
+
+fn test_if_flag_not_given_return_default_values() {
+	mut fp := flag.new_flag_parser([])
+	assert false == fp.bool('a_bool', 0, false, '')
+	assert 42 == fp.int('an_int', 0, 42, '')
+	assert 1.0 == fp.float('a_float', 0, 1.0, '')
+	assert 'stuff' == fp.string('a_string', 0, 'stuff', '')
+}
+
+fn test_could_define_application_name_and_version() {
+	mut fp := flag.new_flag_parser([])
+	fp.application('test app')
+	fp.version('0.0.42')
+	fp.description('some text')
+	assert fp.application_name == 'test app'
+	assert fp.application_version == '0.0.42'
+	assert fp.application_description == 'some text'
+}
+
+fn test_bool_flags_do_not_need_an_value() {
+	mut fp := flag.new_flag_parser(['--a_bool'])
+	assert true == fp.bool('a_bool', 0, false, '')
+}
+
+fn test_flags_could_be_defined_with_eq() {
+	mut fp := flag.new_flag_parser([
+		'--an_int=42',
+		'--a_float=2.0',
+		'--bool_without',
+		'--a_string=stuff',
+		'--a_bool=true',
+	])
+	assert 42 == fp.int('an_int', 0, 0o666, '')
+	assert true == fp.bool('a_bool', 0, false, '')
+	assert true == fp.bool('bool_without', 0, false, '')
+	assert 2.0 == fp.float('a_float', 0, 1.0, '')
+	assert 'stuff' == fp.string('a_string', 0, 'not_stuff', '')
+}
+
+fn test_values_could_be_defined_without_eq() {
+	mut fp := flag.new_flag_parser([
+		'--an_int',
+		'42',
+		'--a_float',
+		'2.0',
+		'--bool_without',
+		'--a_string',
+		'stuff',
+		'--a_bool',
+		'true',
+	])
+	assert 42 == fp.int('an_int', 0, 0o666, '')
+	assert true == fp.bool('a_bool', 0, false, '')
+	assert true == fp.bool('bool_without', 0, false, '')
+	assert 2.0 == fp.float('a_float', 0, 1.0, '')
+	assert 'stuff' == fp.string('a_string', 0, 'not_stuff', '')
+}
+
+fn test_values_could_be_defined_mixed() {
+	mut fp := flag.new_flag_parser([
+		'--an_int',
+		'42',
+		'--a_float=2.0',
+		'--bool_without',
+		'--a_string',
+		'stuff',
+		'--a_bool=true',
+	])
+	assert 42 == fp.int('an_int', 0, 0o666, '')
+	assert true == fp.bool('a_bool', 0, false, '')
+	assert true == fp.bool('bool_without', 0, false, '')
+	assert 2.0 == fp.float('a_float', 0, 1.0, '')
+	assert 'stuff' == fp.string('a_string', 0, 'not_stuff', '')
+}
+
+fn test_beaware_for_argument_names_with_same_prefix() {
+	mut fp := flag.new_flag_parser([
+		'--short',
+		'5',
+		'--shorter=7',
+	])
+	assert 5 == fp.int('short', 0, 0o666, '')
+	assert 7 == fp.int('shorter', 0, 0o666, '')
+}
+
+fn test_beaware_for_argument_names_with_same_prefix_inverse() {
+	mut fp := flag.new_flag_parser([
+		'--shorter=7',
+		'--short',
+		'5',
+	])
+	assert 5 == fp.int('short', 0, 0o666, '')
+	assert 7 == fp.int('shorter', 0, 0o666, '')
+}
+
+fn test_allow_to_skip_executable_path() {
+	mut fp := flag.new_flag_parser(['./path/to/execuable'])
+	fp.skip_executable()
+	args := fp.finalize() or {
+		assert false
+		return
+	}
+	assert !args.contains('./path/to/execuable')
+}
+
+fn test_none_flag_arguments_are_allowed() {
+	mut fp := flag.new_flag_parser([
+		'file1',
+		'--an_int=2',
+		'file2',
+		'file3',
+		'--bool_without',
+		'file4',
+		'--outfile',
+		'outfile',
+	])
+	assert 2 == fp.int('an_int', 0, 0o666, '')
+	assert 'outfile' == fp.string('outfile', 0, 'bad', '')
+	assert true == fp.bool('bool_without', 0, false, '')
+}
+
+fn test_finalize_returns_none_flag_arguments_ordered() {
+	mut fp := flag.new_flag_parser(['d', 'b', 'x', 'a', '--outfile', 'outfile'])
+	fp.string('outfile', 0, 'bad', '')
+	finalized := fp.finalize() or {
+		assert false
+		return
+	}
+	expected := ['d', 'b', 'x', 'a']
+	for i, v in finalized {
+		assert v == expected[i]
+	}
+}
+
+fn test_finalize_returns_error_for_unknown_flags_long() {
+	mut fp := flag.new_flag_parser(['--known', '--unknown'])
+	fp.bool('known', 0, false, '')
+	finalized := fp.finalize() or {
+		assert err.msg == 'Unknown flag `--unknown`'
+		return
+	}
+	assert finalized.len < 0 // expect error to be returned
+}
+
+fn test_finalize_returns_error_for_unknown_flags_short() {
+	mut fp := flag.new_flag_parser(['--known', '-x'])
+	fp.bool('known', 0, false, '')
+	finalized := fp.finalize() or {
+		assert err.msg == 'Unknown flag `-x`'
+		return
+	}
+	assert finalized.len < 0 // expect error to be returned
+}
+
+fn test_allow_to_build_usage_message() {
+	mut fp := flag.new_flag_parser([])
+	fp.limit_free_args(1, 4)
+	fp.application('flag_tool')
+	fp.version('v0.0.0')
+	fp.description('some short information about this tool')
+	fp.int('an_int', 0, 0o666, 'some int to define')
+	fp.bool('a_bool', 0, false, 'some bool to define')
+	fp.bool('bool_without_but_really_big', 0, false, 'this should appear on the next line')
+	fp.float('a_float', 0, 1.0, 'some float as well')
+	fp.string('a_string', 0, 'not_stuff', 'your credit card number')
+	usage := fp.usage()
+	mut all_strings_found := true
+	for s in ['flag_tool', 'v0.0.0', 'an_int <int>', 'a_bool', 'bool_without', 'a_float <float>',
+		'a_string <string>', 'some int to define', 'some bool to define',
+		'this should appear on the next line', 'some float as well', 'your credit card number',
+		'The arguments should be at least 1 and at most 4 in number.', 'Usage', 'Options:',
+		'Description:', 'some short information about this tool'] {
+		if !usage.contains(s) {
+			eprintln(" missing '$s' in usage message")
+			all_strings_found = false
+		}
+	}
+	assert all_strings_found
+}
+
+fn test_if_no_description_given_usage_message_does_not_contain_descpription() {
+	mut fp := flag.new_flag_parser([])
+	fp.application('flag_tool')
+	fp.version('v0.0.0')
+	fp.bool('a_bool', 0, false, '')
+	assert !fp.usage().contains('Description:')
+}
+
+fn test_if_no_options_given_usage_message_does_not_contain_options() {
+	mut fp := flag.new_flag_parser([])
+	fp.application('flag_tool')
+	fp.version('v0.0.0')
+	assert !fp.usage().contains('Options:')
+}
+
+fn test_free_args_could_be_limited() {
+	mut fp1 := flag.new_flag_parser(['a', 'b', 'c'])
+	fp1.limit_free_args(1, 4)
+	args := fp1.finalize() or {
+		assert false
+		return
+	}
+	assert args[0] == 'a'
+	assert args[1] == 'b'
+	assert args[2] == 'c'
+}
+
+fn test_error_for_to_few_free_args() {
+	mut fp1 := flag.new_flag_parser(['a', 'b', 'c'])
+	fp1.limit_free_args(5, 6)
+	args := fp1.finalize() or {
+		assert err.msg.starts_with('Expected at least 5 arguments')
+		return
+	}
+	assert args.len < 0 // expect an error and need to use args
+}
+
+fn test_error_for_to_much_free_args() {
+	mut fp1 := flag.new_flag_parser(['a', 'b', 'c'])
+	fp1.limit_free_args(1, 2)
+	args := fp1.finalize() or {
+		assert err.msg.starts_with('Expected at most 2 arguments')
+		return
+	}
+	assert args.len < 0 // expect an error and need to use args
+}
+
+fn test_could_expect_no_free_args() {
+	mut fp1 := flag.new_flag_parser(['a'])
+	fp1.limit_free_args(0, 0)
+	args := fp1.finalize() or {
+		assert err.msg.starts_with('Expected no arguments')
+		return
+	}
+	assert args.len < 0 // expect an error and need to use args
+}
+
+fn test_allow_abreviations() {
+	mut fp := flag.new_flag_parser(['-v', '-o', 'some_file', '-i', '42', '-f', '2.0'])
+	v := fp.bool('version', `v`, false, '')
+	o := fp.string('output', `o`, 'empty', '')
+	i := fp.int('count', `i`, 0, '')
+	f := fp.float('value', `f`, 0.0, '')
+	assert v == true
+	assert o == 'some_file'
+	assert i == 42
+	assert f == 2.0
+	u := fp.usage()
+	assert u.contains(' -v')
+	assert u.contains(' -o')
+	assert u.contains(' -i')
+	assert u.contains(' -f')
+	assert u.contains('  -o, --output <string>')
+	assert u.contains('  -i, --count <int>')
+	assert u.contains('  -f, --value <float>')
+}
+
+fn test_allow_kebab_options() {
+	default_value := 'this_is_the_default_value_of_long_option'
+	long_option_value := 'this_is_a_long_option_value_as_argument'
+	mut fp := flag.new_flag_parser(['--my-long-flag', 'true', '--my-long-option', long_option_value])
+	my_flag := fp.bool('my-long-flag', 0, false, 'flag with long-kebab-name')
+	my_option := fp.string('my-long-option', 0, default_value, 'string with long-kebab-name')
+	assert my_flag == true
+	assert my_option == long_option_value
+	u := fp.usage()
+	assert u.contains(' --my-long-flag')
+	assert u.contains(' --my-long-option')
+}
+
+fn test_not_provided_option_is_not_returned() {
+	mut fp := flag.new_flag_parser([])
+	fp.bool_opt('some-flag', `a`, '') or {
+		fp.int_opt('some-flag', `a`, '') or {
+			fp.float_opt('some-flag', `a`, '') or {
+				fp.string_opt('some-flag', `a`, '') or {
+					// Everything should not return
+					return
+				}
+				return
+			}
+			return
+		}
+		return
+	}
+	// If we reach here, one of them returned a value.
+	assert false
+}
+
+fn test_provided_option_is_returned() {
+	mut fp := flag.new_flag_parser(['-a', '-b', '3', '-c', 'hello', '-d', '3.14'])
+	a := fp.bool_opt('some-flag', `a`, '') or { panic('bool_opt did not return a bool') }
+	b := fp.int_opt('some-flag', `b`, '') or { panic('int_opt did not return an int') }
+	c := fp.string_opt('some-flag', `c`, '') or { panic('string_opt did not return a string') }
+	d := fp.float_opt('some-flag', `d`, '') or { panic('float_opt did not return a float') }
+	assert true == a
+	assert b == 3
+	assert c == 'hello'
+	assert d == 3.14
+}
+
+fn test_multiple_arguments() {
+	mut fp := flag.new_flag_parser([
+		'-a',
+		'2',
+		'-a',
+		'3',
+		'-a',
+		'5',
+		'-b',
+		'a',
+		'-b',
+		'c',
+		'-b',
+		'b',
+		'-c',
+		'1.23',
+		'-c',
+		'2.34',
+		'-c',
+		'3.45',
+	])
+	// TODO Move to array comparison once it's implemented
+	// assert fp.int_multi('some-flag', `a`, '') == [2, 3, 5] &&
+	//	fp.string_multi('some-flag', `b`, '') == ['a', 'c', 'b'] &&
+	//	fp.float_multi('some-flag', `c`, '') == [1.23, 2.34, 3.45]
+	a := fp.int_multi('some-flag', `a`, '')
+	b := fp.string_multi('some-flag', `b`, '')
+	c := fp.float_multi('some-flag', `c`, '')
+	assert a.len == 3
+	assert b.len == 3
+	assert c.len == 3
+	assert a[0] == 2
+	assert a[1] == 3
+	assert a[2] == 5
+	assert b[0] == 'a'
+	assert b[1] == 'c'
+	assert b[2] == 'b'
+	assert c[0] == 1.23
+	assert c[1] == 2.34
+	assert c[2] == 3.45
+}
+
+fn test_long_options_that_start_with_the_same_letter_as_another_short_option() {
+	mut fp := flag.new_flag_parser([
+		'--vabc',
+		'/abc',
+	])
+	verbose := fp.bool('verbose', `v`, false, 'Be more verbose.')
+	vabc := fp.string('vabc', `x`, 'default', 'Another option that *may* conflict with v, but *should not*')
+	assert verbose == false
+	assert vabc == '/abc'
+}
+
+fn test_long_options_that_start_with_the_same_letter_as_another_short_option_both_set() {
+	mut fp := flag.new_flag_parser([
+		'-v',
+		'--vabc',
+		'/abc',
+	])
+	verbose := fp.bool('verbose', `v`, false, 'Be more verbose.')
+	vabc := fp.string('vabc', `x`, 'default', 'Another option that *may* conflict with v, but *should not*')
+	assert verbose == true
+	assert vabc == '/abc'
+}
+
+fn test_single_dash() {
+	mut fp := flag.new_flag_parser([
+		'-',
+	])
+	flag_update := fp.bool('update', `u`, false, 'Update tools')
+	assert flag_update == false
+}
+
+fn test_optional_flags() {
+	mut fp := flag.new_flag_parser(['-a', '10', '-b'])
+	fp.int_opt('some-flag', `a`, '') or {
+		assert false
+		return
+	}
+	b := fp.string_opt('another-flag', `b`, '') or { 'some_default_value' }
+	assert b == 'some_default_value'
+}
+
+fn test_dashdash_acts_as_parser_full_stop() ? {
+	mut fp := flag.new_flag_parser(['-b', '5', '--', '-d', '-x', '-b', '4', '-a', '-c', 'hello',
+		'some', 'other', 'parameters'])
+	a := fp.bool_opt('a-bool-flag', `a`, '') or { false }
+	b := fp.int_opt('an-int-flag', `b`, '') or { -1 }
+	c := fp.string_opt('a-string-flag', `c`, '') or { 'default' }
+	assert a == false
+	assert b == 5
+	assert c == 'default'
+	args := fp.finalize() ?
+	assert args.len > 0
+	assert args[0] != '--'
+	assert args == ['-d', '-x', '-b', '4', '-a', '-c', 'hello', 'some', 'other', 'parameters']
+}
+
+fn test_dashdash_acts_as_parser_full_stop_dashdash_at_end() ? {
+	mut fp := flag.new_flag_parser(['-b', '5', '-b', '4', 'other', 'params', '--'])
+	b := fp.int_multi('an-int-flag', `b`, '')
+	assert b == [5, 4]
+	args := fp.finalize() ?
+	assert args.len > 0
+}
+
+fn test_empty_string_with_flag() {
+	mut fp := flag.new_flag_parser([''])
+	s := fp.string('something', `s`, 'default', 'Hey parse me')
+}
diff --git a/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.dashdash.help.out b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.dashdash.help.out
new file mode 100644
index 0000000..2529e9f
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.dashdash.help.out
@@ -0,0 +1 @@
+[vlib/flag/testdata/simplest_flag_program.v:13] rest_of_args: ['--help']
diff --git a/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.dashdash.version.out b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.dashdash.version.out
new file mode 100644
index 0000000..b0b4d65
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.dashdash.version.out
@@ -0,0 +1 @@
+[vlib/flag/testdata/simplest_flag_program.v:13] rest_of_args: ['--version']
diff --git a/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.help.out b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.help.out
new file mode 100644
index 0000000..9b5ab9e
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.help.out
@@ -0,0 +1,7 @@
+abc 0.0.1
+-----------------------------------------------
+Usage: abc [options] [ARGS]
+
+Options:
+  -h, --help                display this help and exit
+  --version                 output version information and exit
diff --git a/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.out b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.out
new file mode 100644
index 0000000..02b7cea
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.out
@@ -0,0 +1 @@
+[vlib/flag/testdata/simplest_flag_program.v:13] rest_of_args: []
diff --git a/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.v b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.v
new file mode 100644
index 0000000..cee2ff7
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.v
@@ -0,0 +1,14 @@
+import os
+import flag
+
+fn main() {
+	mut fp := flag.new_flag_parser(os.args)
+	fp.application('abc')
+	fp.version('0.0.1')
+	fp.skip_executable()
+	rest_of_args := fp.finalize() or {
+		eprintln(err)
+		exit(1)
+	}
+	dump(rest_of_args)
+}
diff --git a/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.version.out b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.version.out
new file mode 100644
index 0000000..de52cb0
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/simplest_flag_program.version.out
@@ -0,0 +1 @@
+abc 0.0.1
diff --git a/v_windows/v/old/vlib/flag/testdata/usage_example.help.out b/v_windows/v/old/vlib/flag/testdata/usage_example.help.out
new file mode 100644
index 0000000..b40047b
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/usage_example.help.out
@@ -0,0 +1,13 @@
+xyz 0.0.2
+-----------------------------------------------
+Usage: xyz [NUMBER]...
+   or: xyz OPTION
+
+Description: description line 1
+description line 2
+
+Options:
+  -h, --help                display this help and exit
+  --version                 output version information and exit
+footer 1
+footer 2
diff --git a/v_windows/v/old/vlib/flag/testdata/usage_example.out b/v_windows/v/old/vlib/flag/testdata/usage_example.out
new file mode 100644
index 0000000..b2fd000
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/usage_example.out
@@ -0,0 +1 @@
+[vlib/flag/testdata/usage_example.v:16] rest_of_args: ['abc', 'def']
diff --git a/v_windows/v/old/vlib/flag/testdata/usage_example.v b/v_windows/v/old/vlib/flag/testdata/usage_example.v
new file mode 100644
index 0000000..522b758
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/usage_example.v
@@ -0,0 +1,17 @@
+import os
+import flag
+
+fn main() {
+	mut fp := flag.new_flag_parser(os.args)
+	fp.skip_executable()
+	fp.application('xyz')
+	fp.version('0.0.2')
+	fp.usage_example('[NUMBER]...')
+	fp.usage_example('OPTION')
+	fp.description('description line 1')
+	fp.description('description line 2')
+	fp.footer('footer 1')
+	fp.footer('footer 2')
+	rest_of_args := fp.remaining_parameters()
+	dump(rest_of_args)
+}
diff --git a/v_windows/v/old/vlib/flag/testdata/usage_example.version.out b/v_windows/v/old/vlib/flag/testdata/usage_example.version.out
new file mode 100644
index 0000000..9196894
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/testdata/usage_example.version.out
@@ -0,0 +1 @@
+xyz 0.0.2
diff --git a/v_windows/v/old/vlib/flag/usage_example_test.v b/v_windows/v/old/vlib/flag/usage_example_test.v
new file mode 100644
index 0000000..30fbccc
--- /dev/null
+++ b/v_windows/v/old/vlib/flag/usage_example_test.v
@@ -0,0 +1,35 @@
+import os
+
+const the_source = 'vlib/flag/testdata/usage_example.v'
+
+const the_executable = os.real_path(os.join_path(os.cache_dir(), 'flag_usage_example_app.exe'))
+
+fn testsuite_begin() {
+	os.chdir(@VMODROOT)
+	os.rm(the_executable) or {}
+	res := os.execute('${@VEXE} -o $the_executable $the_source')
+	assert res.exit_code == 0
+	assert os.execute(the_executable).exit_code == 0
+	C.atexit(fn () {
+		os.rm(the_executable) or {}
+	})
+}
+
+fn normalise_lines(lines []string) string {
+	return '\n' + lines.join('\n')
+}
+
+fn check_program(opts string, extension string) {
+	result := the_source.replace('.v', extension)
+	res := os.execute('$the_executable $opts')
+	assert res.exit_code == 0
+	assert normalise_lines(res.output.split_into_lines()) == normalise_lines(os.read_lines(result) or {
+		panic(err)
+	})
+}
+
+fn test_normal_usage() {
+	check_program('abc def', '.out')
+	check_program(' --help', '.help.out')
+	check_program(' --version', '.version.out')
+}