exa/src/options/parser.rs

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#![allow(unused_variables, dead_code)]
use std::ffi::{OsStr, OsString};
pub type ShortArg = u8;
pub type LongArg = &'static str;
#[derive(PartialEq, Debug)]
pub enum Flag {
Short(ShortArg),
Long(LongArg),
}
#[derive(PartialEq, Debug)]
pub enum Strictness {
ComplainAboutRedundantArguments,
UseLastArguments,
}
#[derive(Copy, Clone, PartialEq, Debug)]
pub enum TakesValue {
Necessary,
Forbidden,
}
#[derive(PartialEq, Debug)]
pub struct Arg {
short: Option<ShortArg>,
long: LongArg,
takes_value: TakesValue,
}
#[derive(PartialEq, Debug)]
pub struct Args(&'static [Arg]);
impl Args {
fn lookup_short<'a>(&self, short: ShortArg) -> Result<&Arg, ParseError<'a>> {
match self.0.into_iter().find(|arg| arg.short == Some(short)) {
Some(arg) => Ok(arg),
None => Err(ParseError::UnknownShortArgument { attempt: short })
}
}
fn lookup_long<'a>(&self, long: &'a OsStr) -> Result<&Arg, ParseError<'a>> {
match self.0.into_iter().find(|arg| arg.long == long) {
Some(arg) => Ok(arg),
None => Err(ParseError::UnknownArgument { attempt: long })
}
}
}
#[derive(PartialEq, Debug)]
pub struct Matches<'a> {
/// Long and short arguments need to be kept in the same vector, because
/// we usually want the one nearest the end to count.
flags: Vec<(Flag, Option<&'a OsStr>)>,
frees: Vec<&'a OsStr>,
}
#[derive(PartialEq, Debug)]
pub enum ParseError<'a> {
NeedsValue { flag: Flag },
ForbiddenValue { flag: Flag },
UnknownShortArgument { attempt: ShortArg },
UnknownArgument { attempt: &'a OsStr },
}
fn parse<'a>(args: Args, inputs: &'a [OsString]) -> Result<Matches<'a>, ParseError<'a>> {
use std::os::unix::ffi::OsStrExt;
use self::TakesValue::*;
let mut parsing = true;
let mut results = Matches {
flags: Vec::new(),
frees: Vec::new(),
};
let mut iter = inputs.iter();
while let Some(arg) = iter.next() {
let bytes = arg.as_bytes();
if !parsing {
results.frees.push(arg)
}
else if arg == "--" {
parsing = false;
}
else if bytes.starts_with(b"--") {
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let long_arg_name = OsStr::from_bytes(&bytes[2..]);
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if let Some((before, after)) = split_on_equals(long_arg_name) {
let arg = args.lookup_long(before)?;
let flag = Flag::Long(arg.long);
match arg.takes_value {
Necessary => results.flags.push((flag, Some(after))),
Forbidden => return Err(ParseError::ForbiddenValue { flag })
}
}
else {
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let arg = args.lookup_long(long_arg_name)?;
let flag = Flag::Long(arg.long);
match arg.takes_value {
Forbidden => results.flags.push((flag, None)),
Necessary => {
if let Some(next_arg) = iter.next() {
results.flags.push((flag, Some(next_arg)));
}
else {
return Err(ParseError::NeedsValue { flag })
}
}
}
}
}
else if bytes.starts_with(b"-") && arg != "-" {
let short_arg = OsStr::from_bytes(&bytes[1..]);
if let Some((before, after)) = split_on_equals(short_arg) {
// TODO: remember to deal with the other bytes!
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let arg = args.lookup_short(*before.as_bytes().last().unwrap())?;
let flag = Flag::Short(arg.short.unwrap());
match arg.takes_value {
Necessary => results.flags.push((flag, Some(after))),
Forbidden => return Err(ParseError::ForbiddenValue { flag })
}
}
else {
for byte in &bytes[1..] {
// TODO: gotta check that these don't take arguments
// like -c4
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let arg = args.lookup_short(*byte)?;
let flag = Flag::Short(*byte);
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match arg.takes_value {
Forbidden => results.flags.push((flag, None)),
Necessary => {
if let Some(next_arg) = iter.next() {
results.flags.push((flag, Some(next_arg)));
}
else {
return Err(ParseError::NeedsValue { flag })
}
}
}
}
}
}
else {
results.frees.push(arg)
}
}
Ok(results)
}
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/// Splits a string on its `=` character, returning the two substrings on
/// either side. Returns `None` if theres no equals or a string is missing.
fn split_on_equals(input: &OsStr) -> Option<(&OsStr, &OsStr)> {
use std::os::unix::ffi::OsStrExt;
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if let Some(index) = input.as_bytes().iter().position(|elem| *elem == b'=') {
let (before, after) = input.as_bytes().split_at(index);
// The after string contains the = that we need to remove.
if before.len() >= 1 && after.len() >= 2 {
return Some((OsStr::from_bytes(before),
OsStr::from_bytes(&after[1..])))
}
}
None
}
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/// Creates an `OSString` (used in tests)
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#[cfg(test)]
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fn os(input: &'static str) -> OsString {
let mut os = OsString::new();
os.push(input);
os
}
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#[cfg(test)]
mod split_test {
use super::{split_on_equals, os};
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macro_rules! test_split {
($name:ident: $input:expr => None) => {
#[test]
fn $name() {
assert_eq!(split_on_equals(&os($input)),
None);
}
};
($name:ident: $input:expr => $before:expr, $after:expr) => {
#[test]
fn $name() {
assert_eq!(split_on_equals(&os($input)),
Some((&*os($before), &*os($after))));
}
};
}
test_split!(empty: "" => None);
test_split!(letter: "a" => None);
test_split!(just: "=" => None);
test_split!(intro: "=bbb" => None);
test_split!(denou: "aaa=" => None);
test_split!(equals: "aaa=bbb" => "aaa", "bbb");
test_split!(sort: "--sort=size" => "--sort", "size");
test_split!(more: "this=that=other" => "this", "that=other");
}
#[cfg(test)]
mod test {
use super::*;
static TEST_ARGS: &'static [Arg] = &[
Arg { short: Some(b'l'), long: "long", takes_value: TakesValue::Forbidden },
Arg { short: Some(b'c'), long: "count", takes_value: TakesValue::Necessary }
];
#[test]
fn empty() {
let bits = [ ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![] }))
}
#[test]
fn filename() {
let bits = [ os("exa") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![ os("exa").as_os_str() ], flags: vec![] }))
}
#[test]
fn the_dashes_do_nothing() {
let bits = [ os("--") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![] }))
}
#[test]
fn but_just_one_does() {
let bits = [ os("-") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![ os("-").as_os_str() ], flags: vec![] }))
}
// ----- long args --------
#[test]
fn as_filename() {
let bits = [ os("--"), os("--long") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![os("--long").as_os_str() ], flags: vec![] }))
}
#[test]
fn long() {
let bits = [ os("--long") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![ (Flag::Long("long"), None) ] }))
}
#[test]
fn long_equals() {
let bits = [ os("--long=equals") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Err(ParseError::ForbiddenValue { flag: Flag::Long("long") }))
}
#[test]
fn no_arg_separate() {
let bits = [ os("--long"), os("4") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![ os("4").as_os_str() ], flags: vec![ (Flag::Long("long"), None) ] }))
}
#[test]
fn no_arg_given() {
let bits = [ os("--count") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Err(ParseError::NeedsValue { flag: Flag::Long("count") }))
}
#[test]
fn arg_equals() {
let bits = [ os("--count=4") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![ (Flag::Long("count"), Some(os("4").as_os_str())) ] }))
}
#[test]
fn arg_separate() {
let bits = [ os("--count"), os("4") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![ (Flag::Long("count"), Some(os("4").as_os_str())) ] }))
}
// ----- short args --------
#[test]
fn short_as_filename() {
let bits = [ os("--"), os("-l") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![os("-l").as_os_str() ], flags: vec![] }))
}
#[test]
fn short_long() {
let bits = [ os("-l") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![ (Flag::Short(b'l'), None) ] }))
}
#[test]
fn short_long_equals() {
let bits = [ os("-l=equals") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Err(ParseError::ForbiddenValue { flag: Flag::Short(b'l') }))
}
#[test]
fn short_no_arg_separate() {
let bits = [ os("-l"), os("4") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![ os("4").as_os_str() ], flags: vec![ (Flag::Short(b'l'), None) ] }))
}
#[test]
fn short_no_arg_given() {
let bits = [ os("-c") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Err(ParseError::NeedsValue { flag: Flag::Short(b'c') }))
}
#[test]
fn short_arg_equals() {
let bits = [ os("-c=4") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![ (Flag::Short(b'c'), Some(os("4").as_os_str())) ] }))
}
#[test]
fn short_arg_separate() {
let bits = [ os("-c"), os("4") ];
let results = parse(Args(TEST_ARGS), &bits);
assert_eq!(results, Ok(Matches { frees: vec![], flags: vec![ (Flag::Short(b'c'), Some(os("4").as_os_str())) ] }))
}
}