yash-builtin 0.4.0

// This file is part of yash, an extended POSIX shell.
// Copyright (C) 2023 WATANABE Yuki
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

//! Command line argument parsing for the `unalias` built-in

use super::Command;
use crate::common::syntax::parse_arguments;
use crate::common::syntax::Mode;
use crate::common::syntax::OptionSpec;
use thiserror::Error;
use yash_env::semantics::Field;
use yash_env::Env;
use yash_syntax::source::pretty::Annotation;
use yash_syntax::source::pretty::AnnotationType;
use yash_syntax::source::pretty::Message;
use yash_syntax::source::Location;

/// List of all options supported by the `unalias` built-in
pub const OPTION_SPECS: &[OptionSpec] = &[OptionSpec::new().short('a')];

/// Errors that can occur while parsing command line arguments
#[derive(Clone, Debug, Eq, Error, PartialEq)]
pub enum Error {
    /// An error occurred while parsing arguments.
    #[error(transparent)]
    CommonError(#[from] crate::common::syntax::ParseError<'static>),

    /// The `-a` option was specified with other operands.
    #[error("cannot specify `-a` with other operands")]
    ConflictingOptionAndOperand(Location),

    /// No option or operand was specified.
    #[error("no option or operand specified")]
    MissingArgument,
}

impl Error {
    /// Converts the error into a [`Message`].
    pub fn to_message(&self) -> Message {
        let (title, annotations) = match self {
            Error::CommonError(e) => return e.into(),

            Error::ConflictingOptionAndOperand(location) => (
                "cannot specify `-a` with other operands".into(),
                vec![Annotation::new(
                    AnnotationType::Error,
                    "cannot specify `-a` with other operands".into(),
                    location,
                )],
            ),

            Error::MissingArgument => ("no option or operand specified".into(), vec![]),
        };

        Message {
            r#type: AnnotationType::Error,
            title,
            annotations,
            footers: vec![],
        }
    }
}

impl<'a> From<&'a Error> for Message<'a> {
    #[inline]
    fn from(e: &'a Error) -> Self {
        e.to_message()
    }
}

/// Parses command line arguments for the `unalias` built-in.
pub fn parse(env: &Env, args: Vec<Field>) -> Result<Command, Error> {
    let mode = Mode::with_env(env);
    let (mut options, operands) = parse_arguments(OPTION_SPECS, mode, args)?;

    for option in &options {
        debug_assert_eq!(option.spec.get_short(), Some('a'));
    }

    match (options.pop(), operands.is_empty()) {
        (None, true) => Err(Error::MissingArgument),
        (None, false) => Ok(Command::Remove(operands)),
        (Some(_), true) => Ok(Command::RemoveAll),
        (Some(option), false) => Err(Error::ConflictingOptionAndOperand(option.location)),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn all_option() {
        let env = Env::new_virtual();
        let result = parse(&env, Field::dummies(["-a"]));
        assert_eq!(result, Ok(Command::RemoveAll));
    }

    #[test]
    fn operands() {
        let env = Env::new_virtual();
        let operands = Field::dummies(["foo", "bar"]);
        let result = parse(&env, operands.clone());
        assert_eq!(result, Ok(Command::Remove(operands)));
    }

    #[test]
    fn missing_arguments() {
        let env = Env::new_virtual();
        let result = parse(&env, vec![]);
        assert_eq!(result, Err(Error::MissingArgument));
    }

    #[test]
    fn option_and_operand() {
        let env = Env::new_virtual();
        let args = Field::dummies(["-a", "foo"]);
        let result = parse(&env, args);
        assert_eq!(
            result,
            Err(Error::ConflictingOptionAndOperand(Location::dummy("-a"))),
        );
    }
}