//! 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

    ///

    /// <div class="warning">

    ///

    /// **NOTE:** The argument returned will be the current binary.

    ///

    /// </div>

    ///

    /// # 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());

Unexecuted instantiation: <clap_lex::RawArgs>::remaining::{closure#0}

Unexecuted instantiation: <clap_lex::RawArgs>::remaining::{closure#0}

        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),

        );

    }

Unexecuted instantiation: <clap_lex::RawArgs>::insert::<&alloc::string::String, [&alloc::string::String; 1]>

Unexecuted instantiation: <clap_lex::RawArgs>::insert::<_, _>

    /// 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

    ///

    /// <div class="warning">

    ///

    /// **NOTE:** May return a flag or an escape.

    ///

    /// </div>

    pub fn to_value_os(&self) -> &OsStr {

        self.inner

    }

    /// Treat as a value

    ///

    /// <div class="warning">

    ///

    /// **NOTE:** May return a flag or an escape.

    ///

    /// </div>

    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`/`E` but only at most one after the first

            // character.

            b'e' | 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,

    }

}