//! Minimal, flexible command-line parser
//!
//! As opposed to a declarative parser, this processes arguments as a stream of tokens. As lexing
//! a command-line is not context-free, we rely on the caller to decide how to interpret the
//! arguments.
//!
//! # Examples
//!
//! ```rust
//! use std::path::PathBuf;
//! use std::ffi::OsStr;
//!
//! type BoxedError = Box<dyn std::error::Error + Send + Sync>;
//!
//! #[derive(Debug)]
//! struct Args {
//! paths: Vec<PathBuf>,
//! color: Color,
//! verbosity: usize,
//! }
//!
//! #[derive(Debug)]
//! enum Color {
//! Always,
//! Auto,
//! Never,
//! }
//!
//! impl Color {
//! fn parse(s: Option<&OsStr>) -> Result<Self, BoxedError> {
//! let s = s.map(|s| s.to_str().ok_or(s));
//! match s {
//! Some(Ok("always")) | Some(Ok("")) | None => {
//! Ok(Color::Always)
//! }
//! Some(Ok("auto")) => {
//! Ok(Color::Auto)
//! }
//! Some(Ok("never")) => {
//! Ok(Color::Never)
//! }
//! Some(invalid) => {
//! Err(format!("Invalid value for `--color`, {invalid:?}").into())
//! }
//! }
//! }
//! }
//!
//! fn parse_args(
//! raw: impl IntoIterator<Item=impl Into<std::ffi::OsString>>
//! ) -> Result<Args, BoxedError> {
//! let mut args = Args {
//! paths: Vec::new(),
//! color: Color::Auto,
//! verbosity: 0,
//! };
//!
//! let raw = clap_lex::RawArgs::new(raw);
//! let mut cursor = raw.cursor();
//! raw.next(&mut cursor); // Skip the bin
//! while let Some(arg) = raw.next(&mut cursor) {
//! if arg.is_escape() {
//! args.paths.extend(raw.remaining(&mut cursor).map(PathBuf::from));
//! } else if arg.is_stdio() {
//! args.paths.push(PathBuf::from("-"));
//! } else if let Some((long, value)) = arg.to_long() {
//! match long {
//! Ok("verbose") => {
//! if let Some(value) = value {
//! return Err(format!("`--verbose` does not take a value, got `{value:?}`").into());
//! }
//! args.verbosity += 1;
//! }
//! Ok("color") => {
//! args.color = Color::parse(value)?;
//! }
//! _ => {
//! return Err(
//! format!("Unexpected flag: --{}", arg.display()).into()
//! );
//! }
//! }
//! } else if let Some(mut shorts) = arg.to_short() {
//! while let Some(short) = shorts.next_flag() {
//! match short {
//! Ok('v') => {
//! args.verbosity += 1;
//! }
//! Ok('c') => {
//! let value = shorts.next_value_os();
//! args.color = Color::parse(value)?;
//! }
//! Ok(c) => {
//! return Err(format!("Unexpected flag: -{c}").into());
//! }
//! Err(e) => {
//! return Err(format!("Unexpected flag: -{}", e.to_string_lossy()).into());
//! }
//! }
//! }
//! } else {
//! args.paths.push(PathBuf::from(arg.to_value_os().to_owned()));
//! }
//! }
//!
//! Ok(args)
//! }
//!
//! let args = parse_args(["bin", "--hello", "world"]);
//! println!("{args:?}");
//! ```
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
#![warn(missing_docs)]
#![warn(clippy::print_stderr)]
#![warn(clippy::print_stdout)]
mod ext;
use std::ffi::OsStr;
use std::ffi::OsString;
pub use std::io::SeekFrom;
pub use ext::OsStrExt;
/// Command-line arguments
#[derive(Default, Clone, Debug, PartialEq, Eq)]
pub struct RawArgs {
items: Vec<OsString>,
}
impl RawArgs {
//// Create an argument list to parse
///
/// **NOTE:** The argument returned will be the current binary.
///
/// # Example
///
/// ```rust,no_run
/// # use std::path::PathBuf;
/// let raw = clap_lex::RawArgs::from_args();
/// let mut cursor = raw.cursor();
/// let _bin = raw.next_os(&mut cursor);
///
/// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
/// println!("{paths:?}");
/// ```
pub fn from_args() -> Self {
Self::new(std::env::args_os())
}
//// Create an argument list to parse
///
/// # Example
///
/// ```rust,no_run
/// # use std::path::PathBuf;
/// let raw = clap_lex::RawArgs::new(["bin", "foo.txt"]);
/// let mut cursor = raw.cursor();
/// let _bin = raw.next_os(&mut cursor);
///
/// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
/// println!("{paths:?}");
/// ```
pub fn new(iter: impl IntoIterator<Item = impl Into<OsString>>) -> Self {
let iter = iter.into_iter();
Self::from(iter)
}
/// Create a cursor for walking the arguments
///
/// # Example
///
/// ```rust,no_run
/// # use std::path::PathBuf;
/// let raw = clap_lex::RawArgs::new(["bin", "foo.txt"]);
/// let mut cursor = raw.cursor();
/// let _bin = raw.next_os(&mut cursor);
///
/// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
/// println!("{paths:?}");
/// ```
pub fn cursor(&self) -> ArgCursor {
ArgCursor::new()
}
/// Advance the cursor, returning the next [`ParsedArg`]
pub fn next(&self, cursor: &mut ArgCursor) -> Option<ParsedArg<'_>> {
self.next_os(cursor).map(ParsedArg::new)
}
/// Advance the cursor, returning a raw argument value.
pub fn next_os(&self, cursor: &mut ArgCursor) -> Option<&OsStr> {
let next = self.items.get(cursor.cursor).map(|s| s.as_os_str());
cursor.cursor = cursor.cursor.saturating_add(1);
next
}
/// Return the next [`ParsedArg`]
pub fn peek(&self, cursor: &ArgCursor) -> Option<ParsedArg<'_>> {
self.peek_os(cursor).map(ParsedArg::new)
}
/// Return a raw argument value.
pub fn peek_os(&self, cursor: &ArgCursor) -> Option<&OsStr> {
self.items.get(cursor.cursor).map(|s| s.as_os_str())
}
/// Return all remaining raw arguments, advancing the cursor to the end
///
/// # Example
///
/// ```rust,no_run
/// # use std::path::PathBuf;
/// let raw = clap_lex::RawArgs::new(["bin", "foo.txt"]);
/// let mut cursor = raw.cursor();
/// let _bin = raw.next_os(&mut cursor);
///
/// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
/// println!("{paths:?}");
/// ```
pub fn remaining(&self, cursor: &mut ArgCursor) -> impl Iterator<Item = &OsStr> {
let remaining = self.items[cursor.cursor..].iter().map(|s| s.as_os_str());
cursor.cursor = self.items.len();
remaining
}
/// Adjust the cursor's position
pub fn seek(&self, cursor: &mut ArgCursor, pos: SeekFrom) {
let pos = match pos {
SeekFrom::Start(pos) => pos,
SeekFrom::End(pos) => (self.items.len() as i64).saturating_add(pos).max(0) as u64,
SeekFrom::Current(pos) => (cursor.cursor as i64).saturating_add(pos).max(0) as u64,
};
let pos = (pos as usize).min(self.items.len());
cursor.cursor = pos;
}
/// Inject arguments before the [`RawArgs::next`]
pub fn insert(
&mut self,
cursor: &ArgCursor,
insert_items: impl IntoIterator<Item = impl Into<OsString>>,
) {
self.items.splice(
cursor.cursor..cursor.cursor,
insert_items.into_iter().map(Into::into),
);
}
/// Any remaining args?
pub fn is_end(&self, cursor: &ArgCursor) -> bool {
self.peek_os(cursor).is_none()
}
}
impl<I, T> From<I> for RawArgs
where
I: Iterator<Item = T>,
T: Into<OsString>,
{
fn from(val: I) -> Self {
Self {
items: val.map(|x| x.into()).collect(),
}
}
}
/// Position within [`RawArgs`]
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct ArgCursor {
cursor: usize,
}
impl ArgCursor {
fn new() -> Self {
Self { cursor: 0 }
}
}
/// Command-line Argument
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct ParsedArg<'s> {
inner: &'s OsStr,
}
impl<'s> ParsedArg<'s> {
fn new(inner: &'s OsStr) -> Self {
Self { inner }
}
/// Argument is length of 0
pub fn is_empty(&self) -> bool {
self.inner.is_empty()
}
/// Does the argument look like a stdio argument (`-`)
pub fn is_stdio(&self) -> bool {
self.inner == "-"
}
/// Does the argument look like an argument escape (`--`)
pub fn is_escape(&self) -> bool {
self.inner == "--"
}
/// Does the argument look like a negative number?
///
/// This won't parse the number in full but attempts to see if this looks
/// like something along the lines of `-3`, `-0.3`, or `-33.03`
pub fn is_negative_number(&self) -> bool {
self.to_value()
.ok()
.and_then(|s| Some(is_number(s.strip_prefix('-')?)))
.unwrap_or_default()
}
/// Treat as a long-flag
pub fn to_long(&self) -> Option<(Result<&str, &OsStr>, Option<&OsStr>)> {
let raw = self.inner;
let remainder = raw.strip_prefix("--")?;
if remainder.is_empty() {
debug_assert!(self.is_escape());
return None;
}
let (flag, value) = if let Some((p0, p1)) = remainder.split_once("=") {
(p0, Some(p1))
} else {
(remainder, None)
};
let flag = flag.to_str().ok_or(flag);
Some((flag, value))
}
/// Can treat as a long-flag
pub fn is_long(&self) -> bool {
self.inner.starts_with("--") && !self.is_escape()
}
/// Treat as a short-flag
pub fn to_short(&self) -> Option<ShortFlags<'_>> {
if let Some(remainder_os) = self.inner.strip_prefix("-") {
if remainder_os.starts_with("-") {
None
} else if remainder_os.is_empty() {
debug_assert!(self.is_stdio());
None
} else {
Some(ShortFlags::new(remainder_os))
}
} else {
None
}
}
/// Can treat as a short-flag
pub fn is_short(&self) -> bool {
self.inner.starts_with("-") && !self.is_stdio() && !self.inner.starts_with("--")
}
/// Treat as a value
///
/// **NOTE:** May return a flag or an escape.
pub fn to_value_os(&self) -> &OsStr {
self.inner
}
/// Treat as a value
///
/// **NOTE:** May return a flag or an escape.
pub fn to_value(&self) -> Result<&str, &OsStr> {
self.inner.to_str().ok_or(self.inner)
}
/// Safely print an argument that may contain non-UTF8 content
///
/// This may perform lossy conversion, depending on the platform. If you would like an implementation which escapes the path please use Debug instead.
pub fn display(&self) -> impl std::fmt::Display + '_ {
self.inner.to_string_lossy()
}
}
/// Walk through short flags within a [`ParsedArg`]
#[derive(Clone, Debug)]
pub struct ShortFlags<'s> {
inner: &'s OsStr,
utf8_prefix: std::str::CharIndices<'s>,
invalid_suffix: Option<&'s OsStr>,
}
impl<'s> ShortFlags<'s> {
fn new(inner: &'s OsStr) -> Self {
let (utf8_prefix, invalid_suffix) = split_nonutf8_once(inner);
let utf8_prefix = utf8_prefix.char_indices();
Self {
inner,
utf8_prefix,
invalid_suffix,
}
}
/// Move the iterator forward by `n` short flags
pub fn advance_by(&mut self, n: usize) -> Result<(), usize> {
for i in 0..n {
self.next().ok_or(i)?.map_err(|_| i)?;
}
Ok(())
}
/// No short flags left
pub fn is_empty(&self) -> bool {
self.invalid_suffix.is_none() && self.utf8_prefix.as_str().is_empty()
}
/// Does the short flag look like a number
///
/// Ideally call this before doing any iterator
pub fn is_negative_number(&self) -> bool {
self.invalid_suffix.is_none() && is_number(self.utf8_prefix.as_str())
}
/// Advance the iterator, returning the next short flag on success
///
/// On error, returns the invalid-UTF8 value
pub fn next_flag(&mut self) -> Option<Result<char, &'s OsStr>> {
if let Some((_, flag)) = self.utf8_prefix.next() {
return Some(Ok(flag));
}
if let Some(suffix) = self.invalid_suffix {
self.invalid_suffix = None;
return Some(Err(suffix));
}
None
}
/// Advance the iterator, returning everything left as a value
pub fn next_value_os(&mut self) -> Option<&'s OsStr> {
if let Some((index, _)) = self.utf8_prefix.next() {
self.utf8_prefix = "".char_indices();
self.invalid_suffix = None;
// SAFETY: `char_indices` ensures `index` is at a valid UTF-8 boundary
let remainder = unsafe { ext::split_at(self.inner, index).1 };
return Some(remainder);
}
if let Some(suffix) = self.invalid_suffix {
self.invalid_suffix = None;
return Some(suffix);
}
None
}
}
impl<'s> Iterator for ShortFlags<'s> {
type Item = Result<char, &'s OsStr>;
fn next(&mut self) -> Option<Self::Item> {
self.next_flag()
}
}
fn split_nonutf8_once(b: &OsStr) -> (&str, Option<&OsStr>) {
match b.try_str() {
Ok(s) => (s, None),
Err(err) => {
// SAFETY: `err.valid_up_to()`, which came from str::from_utf8(), is guaranteed
// to be a valid UTF8 boundary
let (valid, after_valid) = unsafe { ext::split_at(b, err.valid_up_to()) };
let valid = valid.try_str().unwrap();
(valid, Some(after_valid))
}
}
}
fn is_number(arg: &str) -> bool {
// Return true if this looks like an integer or a float where it's all
// digits plus an optional single dot after some digits.
//
// For floats allow forms such as `1.`, `1.2`, `1.2e10`, etc.
let mut seen_dot = false;
let mut position_of_e = None;
for (i, c) in arg.as_bytes().iter().enumerate() {
match c {
// Digits are always valid
b'0'..=b'9' => {}
// Allow a `.`, but only one, only if it comes before an
// optional exponent, and only if it's not the first character.
b'.' if !seen_dot && position_of_e.is_none() && i > 0 => seen_dot = true,
// Allow an exponent `e` but only at most one after the first
// character.
b'e' if position_of_e.is_none() && i > 0 => position_of_e = Some(i),
_ => return false,
}
}
// Disallow `-1e` which isn't a valid float since it doesn't actually have
// an exponent.
match position_of_e {
Some(i) => i != arg.len() - 1,
None => true,
}
}
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