add cmd/dataunit, example

cmd/dataunit/dataunit.v

@@ -0,0 +1,88 @@
+// This is free and unencumbered software released into the public domain.
+
+// Anyone is free to copy, modify, publish, use, compile, sell, or
+// distribute this software, either in source code form or as a compiled
+// binary, for any purpose, commercial or non-commercial, and by any
+// means.
+
+// In jurisdictions that recognize copyright laws, the author or authors
+// of this software dedicate any and all copyright interest in the
+// software to the public domain. We make this dedication for the benefit
+// of the public at large and to the detriment of our heirs and
+// successors. We intend this dedication to be an overt act of
+// relinquishment in perpetuity of all present and future rights to this
+// software under copyright law.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+
+// For more information, please refer to <https://unlicense.org/>
+
+/*
+	dataunit - a simple CLI tool for data units convertion.
+*/
+
+module main
+
+import os
+import flag
+import dataunits
+
+@[name: 'dataunit']
+struct FlagConfig {
+	help bool
+	from string @[short: f]
+	to   string @[short: t]
+mut:
+	value f64 @[ignore]
+}
+
+fn main() {
+	mut flags, no_matches := flag.to_struct[FlagConfig](os.args, skip: 1, style: .v) or {
+		eprintln('cmdline parsing error, see -help for info')
+		exit(2)
+	}
+	if no_matches.len > 1 {
+		eprintln('unrecognized arguments: ${no_matches[1..]}')
+		exit(2)
+	} else if no_matches.len == 1 {
+		flags.value = no_matches[0].f64()
+	}
+	if flags.help {
+		println('convert the value between data size units.')
+		println('usage: dataunit -f <unit> -t <unit> <value>')
+		println('options:')
+		println('  -help      print this help message and exit')
+		println('  -f, -from  source data unit')
+		println('  -t, -to    destination data unit')
+		exit(0)
+	}
+	if flags.from == '' || flags.to == '' {
+		eprintln('no -from or -to flag set, see -help for info')
+		exit(2)
+	}
+	if flags.value == 0 {
+		eprintln('no value passed, see -help for info')
+		exit(2)
+	}
+	src := dataunits.from_string(flags.from, case_insensitive: true) or {
+		eprintln('invalid source unit: ${err}')
+		exit(1)
+	}
+	dst := dataunits.from_string(flags.to, case_insensitive: true) or {
+		eprintln('invalid destination unit: ${err}')
+		exit(1)
+	}
+	result := '${dataunits.convert(flags.value, src, dst):.20f}'
+	splitted := result.split('.')
+	if splitted[1].contains_only('0') {
+		println(splitted[0])
+	} else {
+		println(result.trim_right('0'))
+	}
+}