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forked from bonsai/harakit
coreutils/lib/getopt-rs/parser.rs
2024-03-31 00:12:21 +05:45

383 lines
13 KiB
Rust

/*
* Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
* SPDX-License-Identifier: AGPL-3.0-or-later
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU Affero General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
* details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*
* This file incorporates work covered by the following copyright and permission
* notice:
* The Clear BSD License
*
* Copyright © 2017-2023 David Wildasin
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted (subject to the limitations in the disclaimer
* below) provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions, and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
* BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
use std::collections::HashMap;
use crate::{ error::Error, errorkind::ErrorKind, opt::Opt, result::Result };
/// The core of the `getopt` crate.
///
/// `Parser` is implemented as an iterator over the options present in the given
/// argument vector.
///
/// The method [`next`](#method.next) does the heavy lifting.
///
/// # Examples
///
/// ## Simplified usage:
/// ```
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// use getopt::Opt;
///
/// // args = ["program", "-abc", "foo"];
/// # let args: Vec<String> = vec!["program", "-abc", "foo"]
/// # .into_iter()
/// # .map(String::from)
/// # .collect();
/// let mut opts = getopt::Parser::new(&args, "ab:c");
///
/// assert_eq!(Some(Opt('a', None)), opts.next().transpose()?);
/// assert_eq!(1, opts.index());
/// assert_eq!(Some(Opt('b', Some("c".to_string()))), opts.next().transpose()?);
/// assert_eq!(2, opts.index());
/// assert_eq!(None, opts.next());
/// assert_eq!(2, opts.index());
/// assert_eq!("foo", args[opts.index()]);
/// # Ok(())
/// # }
/// ```
///
/// ## A more idiomatic example:
/// ```
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// use getopt::Opt;
///
/// // args = ["program", "-abc", "-d", "foo", "-e", "bar"];
/// # let mut args: Vec<String> = vec!["program", "-abc", "-d", "foo", "-e", "bar"]
/// # .into_iter()
/// # .map(String::from)
/// # .collect();
/// let mut opts = getopt::Parser::new(&args, "ab:cd:e");
///
/// let mut a_flag = false;
/// let mut b_flag = String::new();
/// let mut c_flag = false;
/// let mut d_flag = String::new();
/// let mut e_flag = false;
///
/// loop {
/// match opts.next().transpose()? {
/// None => break,
/// Some(opt) => match opt {
/// Opt('a', None) => a_flag = true,
/// Opt('b', Some(arg)) => b_flag = arg.clone(),
/// Opt('c', None) => c_flag = true,
/// Opt('d', Some(arg)) => d_flag = arg.clone(),
/// Opt('e', None) => e_flag = true,
/// _ => unreachable!(),
/// },
/// }
/// }
///
/// let new_args = args.split_off(opts.index());
///
/// assert_eq!(true, a_flag);
/// assert_eq!("c", b_flag);
/// assert_eq!(false, c_flag);
/// assert_eq!("foo", d_flag);
/// assert_eq!(true, e_flag);
///
/// assert_eq!(1, new_args.len());
/// assert_eq!("bar", new_args.first().unwrap());
/// # Ok(())
/// # }
/// ```
#[derive(Debug, Eq, PartialEq)]
pub struct Parser {
opts: HashMap<char, bool>,
args: Vec<Vec<char>>,
index: usize,
point: usize,
}
impl Parser {
/// Create a new `Parser`, which will process the arguments in `args`
/// according to the options specified in `optstring`.
///
/// For compatibility with
/// [`std::env::args`](https://doc.rust-lang.org/std/env/fn.args.html),
/// valid options are expected to begin at the second element of `args`, and
/// `index` is
/// initialised to `1`.
/// If `args` is structured differently, be sure to call
/// [`set_index`](#method.set_index) before the first invocation of
/// [`next`](#method.next).
///
/// `optstring` is a string of recognised option characters; if a character
/// is followed by a colon (`:`), that option takes an argument.
///
/// # Note:
/// Transforming the OS-specific argument strings into a vector of `String`s
/// is the sole responsibility of the calling program, as it involves some
/// level of potential information loss (which this crate does not presume
/// to handle unilaterally) and error handling (which would complicate the
/// interface).
pub fn new(args: &[String], optstring: &str) -> Self {
let optstring: Vec<char> = optstring.chars().collect();
let mut opts = HashMap::new();
let mut i = 0;
let len = optstring.len();
while i < len {
let j = i + 1;
if j < len && optstring[j] == ':' {
opts.insert(optstring[i], true);
i += 1;
} else {
opts.insert(optstring[i], false);
}
i += 1;
}
Self {
opts,
// "explode" the args into a vector of character vectors, to allow
// indexing
args: args.iter().map(|e| e.chars().collect()).collect(),
index: 1,
point: 0,
}
}
/// Return the current `index` of the parser.
///
/// `args[index]` will always point to the the next element of `args`; when
/// the parser is
/// finished with an element, it will increment `index`.
///
/// After the last option has been parsed (and [`next`](#method.next) is
/// returning `None`),
/// `index` will point to the first non-option argument.
pub fn index(&self) -> usize {
self.index
}
// `point` must be reset to 0 whenever `index` is changed
/// Modify the current `index` of the parser.
pub fn set_index(&mut self, value: usize) {
self.index = value;
self.point = 0;
}
/// Increment the current `index` of the parser.
///
/// This use case is common enough to warrant its own optimised method.
pub fn incr_index(&mut self) {
self.index += 1;
self.point = 0;
}
}
impl Iterator for Parser {
type Item = Result<Opt>;
/// Returns the next option, if any.
///
/// Returns an [`Error`](struct.Error.html) if an unexpected option is
/// encountered or if an
/// expected argument is not found.
///
/// Parsing stops at the first non-hyphenated argument; or at the first
/// argument matching "-";
/// or after the first argument matching "--".
///
/// When no more options are available, `next` returns `None`.
///
/// # Examples
///
/// ## "-"
/// ```
/// use getopt::Parser;
///
/// // args = ["program", "-", "-a"];
/// # let args: Vec<String> = vec!["program", "-", "-a"]
/// # .into_iter()
/// # .map(String::from)
/// # .collect();
/// let mut opts = Parser::new(&args, "a");
///
/// assert_eq!(None, opts.next());
/// assert_eq!("-", args[opts.index()]);
/// ```
///
/// ## "--"
/// ```
/// use getopt::Parser;
///
/// // args = ["program", "--", "-a"];
/// # let args: Vec<String> = vec!["program", "--", "-a"]
/// # .into_iter()
/// # .map(String::from)
/// # .collect();
/// let mut opts = Parser::new(&args, "a");
///
/// assert_eq!(None, opts.next());
/// assert_eq!("-a", args[opts.index()]);
/// ```
///
/// ## Unexpected option:
/// ```
/// use getopt::Parser;
///
/// // args = ["program", "-b"];
/// # let args: Vec<String> = vec!["program", "-b"]
/// # .into_iter()
/// # .map(String::from)
/// # .collect();
/// let mut opts = Parser::new(&args, "a");
///
/// assert_eq!(
/// "unknown option -- 'b'".to_string(),
/// opts.next().unwrap().unwrap_err().to_string()
/// );
/// ```
///
/// ## Missing argument:
/// ```
/// use getopt::Parser;
///
/// // args = ["program", "-a"];
/// # let args: Vec<String> = vec!["program", "-a"]
/// # .into_iter()
/// # .map(String::from)
/// # .collect();
/// let mut opts = Parser::new(&args, "a:");
///
/// assert_eq!(
/// "option requires an argument -- 'a'".to_string(),
/// opts.next().unwrap().unwrap_err().to_string()
/// );
/// ```
fn next(&mut self) -> Option<Result<Opt>> {
if self.point == 0 {
/*
* Rationale excerpts below taken verbatim from "The Open Group Base
* Specifications Issue 7, 2018 edition", IEEE Std 1003.1-2017
* (Revision of IEEE Std 1003.1-2008).
* Copyright © 2001-2018 IEEE and The Open Group.
*/
/*
* If, when getopt() is called:
* argv[optind] is a null pointer
* *argv[optind] is not the character '-'
* argv[optind] points to the string "-"
* getopt() shall return -1 without changing optind.
*/
if self.index >= self.args.len()
|| self.args[self.index].is_empty()
|| self.args[self.index][0] != '-'
|| self.args[self.index].len() == 1
{
return None;
}
/*
* If:
* argv[optind] points to the string "--"
* getopt() shall return -1 after incrementing index.
*/
if self.args[self.index][1] == '-' && self.args[self.index].len() == 2 {
self.incr_index();
return None;
}
// move past the starting '-'
self.point += 1;
}
let opt = self.args[self.index][self.point];
self.point += 1;
match self.opts.get(&opt) {
None => {
if self.point >= self.args[self.index].len() {
self.incr_index();
}
Some(Err(Error::new(ErrorKind::UnknownOption, opt)))
}
Some(false) => {
if self.point >= self.args[self.index].len() {
self.incr_index();
}
Some(Ok(Opt(opt, None)))
}
Some(true) => {
let arg: String = if self.point >= self.args[self.index].len() {
self.incr_index();
if self.index >= self.args.len() {
return Some(Err(Error::new(
ErrorKind::MissingArgument,
opt,
)));
}
self.args[self.index].iter().collect()
} else {
self.args[self.index]
.clone()
.split_off(self.point)
.iter()
.collect()
};
self.incr_index();
Some(Ok(Opt(opt, Some(arg))))
}
}
}
}