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