Type built-in (#350)

yash-builtin/src/command.rs

@@ -106,6 +106,11 @@
 //!
 //! The `-p` option depends on [`System::confstr_path`] to obtain the standard
 //! search path. See [`RealSystem::confstr_path`] for the supported platforms.
+//!
+//! The [`type`] built-in is equivalent to the `command` built-in with the `-V`
+//! option.
+//!
+//! [`type`]: crate::type
 
 use crate::common::report_error;
 use enumset::EnumSet;

yash-builtin/src/command/syntax.rs

@@ -22,6 +22,7 @@ use super::Invoke;
 use super::Search;
 use crate::common::syntax::parse_arguments;
 use crate::common::syntax::Mode;
+use crate::common::syntax::OptionOccurrence;
 use crate::common::syntax::OptionSpec;
 use crate::common::syntax::ParseError;
 use thiserror::Error;
@@ -55,9 +56,13 @@ const OPTION_SPECS: &[OptionSpec] = &[
     OptionSpec::new().short('V').long("verbose-identify"),
 ];
 
-pub fn parse(env: &Env, args: Vec<Field>) -> Result<Command, Error> {
-    let (options, operands) = parse_arguments(OPTION_SPECS, Mode::with_env(env), args)?;
-
+/// Interprets the parsed command line arguments
+///
+/// This function converts the result of [`parse_arguments`] into a `Command`.
+pub fn interpret(
+    options: Vec<OptionOccurrence<'_>>,
+    operands: Vec<Field>,
+) -> Result<Command, Error> {
     // Interpret options
     let mut standard_path = false;
     let mut verbose_identify = None;
@@ -89,6 +94,12 @@ pub fn parse(env: &Env, args: Vec<Field>) -> Result<Command, Error> {
     }
 }
 
+/// Parses command line arguments of the `command` built-in
+pub fn parse(env: &Env, args: Vec<Field>) -> Result<Command, Error> {
+    let (options, operands) = parse_arguments(OPTION_SPECS, Mode::with_env(env), args)?;
+    interpret(options, operands)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

yash-builtin/src/lib.rs

@@ -76,6 +76,8 @@ pub mod shift;
 #[cfg(feature = "yash-semantics")]
 pub mod source;
 pub mod trap;
+#[cfg(feature = "yash-semantics")]
+pub mod r#type;
 pub mod typeset;
 pub mod unalias;
 pub mod unset;
@@ -270,6 +272,14 @@ pub const BUILTINS: &[(&str, Builtin)] = &[
             execute: |env, args| Box::pin(trap::main(env, args)),
         },
     ),
+    #[cfg(feature = "yash-semantics")]
+    (
+        "type",
+        Builtin {
+            r#type: Mandatory,
+            execute: |env, args| Box::pin(r#type::main(env, args)),
+        },
+    ),
     (
         "typeset",
         Builtin {

yash-builtin/src/type.rs

@@ -0,0 +1,104 @@
+// This file is part of yash, an extended POSIX shell.
+// Copyright (C) 2024 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/>.
+
+//! Type built-in
+//!
+//! The **`type`** built-in identifies the type of commands.
+//!
+//! # Synopsis
+//!
+//! ```sh
+//! type [name…]
+//! ```
+//!
+//! # Description
+//!
+//! The `type` built-in prints the description of the specified command names.
+//!
+//! # Options
+//!
+//! (TODO: Non-standard options are not supported yet.)
+//!
+//! # Operands
+//!
+//! The ***name*** operands specify the command names to identify.
+//!
+//! # Standard output
+//!
+//! The command descriptions are printed to the standard output.
+//!
+//! # Errors
+//!
+//! It is an error if the *name* is not found.
+//!
+//! # Exit status
+//!
+//! The exit status is zero if all the *name*s are found, and non-zero
+//! otherwise.
+//!
+//! # Portability
+//!
+//! POSIX requires that the *name* operand be specified, but many
+//! implementations allow it to be omitted, in which case the built-in does
+//! nothing.
+//!
+//! The format of the output is unspecified by POSIX. In this implementation,
+//! the `type` built-in is equivalent to the [`command`] built-in with the `-V`
+//! option.
+//!
+//! [`command`]: crate::command
+
+use crate::command::syntax::interpret;
+use crate::command::Command;
+use crate::common::report_error;
+use crate::common::syntax::parse_arguments;
+use crate::common::syntax::Mode;
+use crate::common::syntax::OptionOccurrence;
+use crate::common::syntax::OptionSpec;
+use yash_env::semantics::Field;
+use yash_env::Env;
+use yash_syntax::source::Location;
+
+const OPTION_SPECS: &[OptionSpec] = &[
+    // TODO: Non-standard options
+];
+
+fn parse(env: &mut Env, args: Vec<Field>) -> Result<Command, crate::command::syntax::Error> {
+    let (mut options, operands) = parse_arguments(OPTION_SPECS, Mode::with_env(env), args)?;
+
+    // `type` is equivalent to `command -V`, so add the `-V` option and delegate
+    // to the `command` built-in.
+    let spec = OptionSpec::new().short('V').long("verbose-identify");
+    let location = env.stack.current_builtin().map_or_else(
+        || Location::dummy(""),
+        |builtin| builtin.name.origin.clone(),
+    );
+    options.push(OptionOccurrence {
+        spec: &spec,
+        location,
+        argument: None,
+    });
+
+    interpret(options, operands)
+}
+
+/// Entry point of the `type` built-in
+pub async fn main(env: &mut Env, args: Vec<Field>) -> crate::Result {
+    match parse(env, args) {
+        Ok(command) => command.execute(env).await,
+        Err(error) => report_error(env, &error).await,
+    }
+}