Implement unexpand (#159)

* implement unexpand

* fix test, seems to be variance with CI enviroment

* update correc test this time

* use ./unexpand to avoid system unexpand

* revert, I'm not understanding something about the CI here. Sorry

README.md

@@ -38,15 +38,15 @@ Contributions are welcome!
 Please only contribute versions of the original utilities written in V.
 Contributions written in other languages will likely be rejected.
 
-When your contribution is finalized, don't forget to update the completed 
+When your contribution is finalized, don't forget to update the completed
 count below and mark it as done in this README.md. Thanks!
 
-**NOTE: When testing on Windows**, comparison tests are currently run against 
-[uutils/coreutils](https://github.com/uutils/coreutils), a Rust re-implementation of 
-GNU coreutils. They are not 100% compatiable. If you encounter different behaviors, 
+**NOTE: When testing on Windows**, comparison tests are currently run against
+[uutils/coreutils](https://github.com/uutils/coreutils), a Rust re-implementation of
+GNU coreutils. They are not 100% compatiable. If you encounter different behaviors,
 compare against the true GNU coreutils version on the Linux-based tests first.
 
-## Completed (60/109)
+## Completed (62/109)
 
 |  Done   | Cmd       | Descripton                                       |
 | :-----: | --------- | ------------------------------------------------ |
@@ -95,7 +95,7 @@ compare against the true GNU coreutils version on the Linux-based tests first.
 |         | link      | Make a hard link via the link syscall            |
 | ✓ | ln        | Make links between files                         |
 | ✓ | logname   | Print current login name                         |
-|         | ls        | List directory contents                          |
+| ✓ | ls        | List directory contents                          |
 | ✓ | md5sum    | Print or check MD5 digests                       |
 | ✓ | mkdir     | Make directories                                 |
 |         | mkfifo    | Make FIFOs (named pipes)                         |
@@ -149,7 +149,7 @@ compare against the true GNU coreutils version on the Linux-based tests first.
 |         | tsort     | Topological sort                                 |
 | ✓ | tty       | Print file name of terminal on standard input    |
 | ✓ | uname     | Print system information                         |
-|         | unexpand  | Convert spaces to tabs                           |
+| ✓ | unexpand  | Convert spaces to tabs                           |
 | ✓ | uniq      | Uniquify files                                   |
 | ✓ | unlink    | Remove files via the unlink syscall              |
 | ✓ | uptime    | Print system uptime and load                     |

src/unexpand/args.v

@@ -0,0 +1,79 @@
+import common
+import flag
+import os
+import time
+
+const app_name = 'unexpand'
+const spaces = flag.space
+
+struct Options {
+	all        bool
+	first_only bool
+	tabs       string
+	files      []string
+}
+
+fn get_options() Options {
+	mut fp := common.flag_parser(os.args)
+	fp.application(app_name)
+	fp.description('Convert spaces to tabs')
+	fp.arguments_description('[files]')
+
+	all := fp.bool('all', `a`, false, 'convert all blanks instead of just initial blanks')
+	first_only := fp.bool('first-only', ` `, false, 'convert only leading sequences of blanks (overrides -a)')
+	tabs := fp.string('list', `t`, '', 'use comma separated list of tab positions.\n${spaces}' +
+		"The last specified position can be prefixed with '/'\n${spaces}" +
+		'to specify a tab size to use after the last$\n${spaces}' +
+		"explicitly specified tab stop.  Also a prefix of '+'\n${spaces}" +
+		'can be used to align remaining tab stops relative to$\n${spaces}' +
+		'the last specified tab stop instead of the first column\n')
+	files := fp.finalize() or { exit_error(err.msg()) }
+
+	return Options{
+		all: all
+		first_only: first_only
+		tabs: tabs
+		files: scan_files_arg(files)
+	}
+}
+
+fn scan_files_arg(files_arg []string) []string {
+	mut files := []string{}
+
+	for file in files_arg {
+		if file == '-' {
+			files << stdin_to_tmp()
+			continue
+		}
+		files << file
+	}
+
+	if files.len == 0 {
+		files << stdin_to_tmp()
+	}
+
+	return files
+}
+
+const tmp_pattern = '/${app_name}-tmp-'
+
+fn stdin_to_tmp() string {
+	tmp := '${os.temp_dir()}/${tmp_pattern}${time.ticks()}'
+	os.create(tmp) or { exit_error(err.msg()) }
+	mut f := os.open_append(tmp) or { exit_error(err.msg()) }
+	defer { f.close() }
+
+	for {
+		s := os.get_raw_line()
+		if s.len == 0 {
+			break
+		}
+		f.write_string(s) or { exit_error(err.msg()) }
+	}
+	return tmp
+}
+
+@[noreturn]
+fn exit_error(msg string) {
+	common.exit_with_error_message(app_name, msg)
+}