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//! Help message generation and rendering
#![allow(clippy::write_with_newline)]
use std::marker::PhantomData;
use crate::{
args::{Args, Conflict},
item::Item,
meta_help::render_help,
meta_usage::to_usage_meta,
params::short,
parsers::ParseCommand,
Meta, ParseFailure, Parser,
};
/// Unsuccessful command line parsing outcome, internal representation
#[derive(Debug)]
pub enum Error {
/// Terminate and print this to stdout
Stdout(String),
/// Terminate and print this to stderr
Stderr(String),
/// Expected one of those values
///
/// Used internally to generate better error messages
Missing(Vec<Item>),
}
impl Error {
#[must_use]
pub(crate) fn combine_with(self, other: Self) -> Self {
#[allow(clippy::match_same_arms)]
match (self, other) {
// help output takes priority
(a @ Error::Stdout(_), _) => a,
(_, b @ Error::Stdout(_)) => b,
// parsing failure takes priority
(a @ Error::Stderr(_), _) => a,
(_, b @ Error::Stderr(_)) => b,
// combine missing elements
(Error::Missing(mut a), Error::Missing(mut b)) => {
a.append(&mut b);
Error::Missing(a)
}
}
}
}
/// Information about the parser
///
/// No longer public, users are only interacting with it via [`OptionParser`]
#[derive(Debug, Clone, Default)]
#[doc(hidden)]
pub struct Info {
/// version field, see [`version`][Info::version]
pub version: Option<&'static str>,
/// Custom description field, see [`descr`][Info::descr]
pub descr: Option<&'static str>,
/// Custom header field, see [`header`][Info::header]
pub header: Option<&'static str>,
/// Custom footer field, see [`footer`][Info::footer]
pub footer: Option<&'static str>,
/// Custom usage field, see [`usage`][Info::usage]
pub usage: Option<&'static str>,
}
impl Info {
fn help_parser(&self) -> impl Parser<ExtraParams> {
ParseExtraParams {
version: self.version,
}
}
}
#[derive(Clone, Debug)]
enum ExtraParams {
Help,
Version(&'static str),
}
fn check_unexpected(args: &Args) -> Result<(), Error> {
match args.items_iter().next() {
None => Ok(()),
Some((ix, item)) => {
let mut msg = format!("{} is not expected in this context", item);
if let Some(Conflict::Conflicts(acc, rej)) = args.conflicts.get(&ix) {
use std::fmt::Write;
write!(msg, ": {} cannot be used at the same time as {}", rej, acc).unwrap();
}
Err(Error::Stderr(msg))
}
}
}
/// Ready to run [`Parser`] with additional information attached
///
/// Created with [`to_options`](Parser::to_options)
pub struct OptionParser<T> {
pub(crate) inner: Box<dyn Parser<T>>,
pub(crate) inner_type: PhantomData<T>,
pub(crate) info: Info,
}
impl<T> OptionParser<T> {
/// Execute the [`OptionParser`], extract a parsed value or print some diagnostic and exit
///
/// # Usage
/// ```no_run
/// # use bpaf::*;
/// /// Parses number of repetitions of `-v` on a command line
/// fn verbosity() -> OptionParser<usize> {
/// let parser = short('v')
/// .req_flag(())
/// .many()
/// .map(|xs|xs.len());
///
/// parser
/// .to_options()
/// .descr("Takes verbosity flag and does nothing else")
/// }
///
/// fn main() {
/// let verbosity: usize = verbosity().run();
/// }
/// ```
#[must_use]
pub fn run(self) -> T
where
Self: Sized,
{
match self.try_run() {
Ok(t) => t,
Err(ParseFailure::Stdout(msg)) => {
print!("{}", msg); // completions are sad otherwise
std::process::exit(0);
}
Err(ParseFailure::Stderr(msg)) => {
eprintln!("{}", msg);
std::process::exit(1);
}
}
}
/// Execute the [`OptionParser`], extract a parsed value or return a [`ParseFailure`]
///
/// In most cases using [`run`](OptionParser::run) is sufficient, you can use `try_run` if you
/// want to control the exit code or you need to perform a custom cleanup.
///
/// # Usage
/// ```no_run
/// # use bpaf::*;
/// /// Parses number of repetitions of `-v` on a command line
/// fn verbosity() -> OptionParser<usize> {
/// let parser = short('v')
/// .req_flag(())
/// .many()
/// .map(|xs|xs.len());
///
/// parser
/// .to_options()
/// .descr("Takes verbosity flag and does nothing else")
/// }
///
/// fn main() {
/// let verbosity: Option<usize> = match verbosity().try_run() {
/// Ok(v) => Some(v),
/// Err(ParseFailure::Stdout(msg)) => {
/// print!("{}", msg); // completions are sad otherwise
/// None
/// }
/// Err(ParseFailure::Stderr(msg)) => {
/// eprintln!("{}", msg);
/// None
/// }
/// };
///
/// // Run cleanup tasks
/// }
/// ```
///
/// # Errors
///
/// [`ParseFailure`] represents parsing errors, autocomplete results and generated `--help`
/// output.
pub fn try_run(self) -> Result<T, ParseFailure>
where
Self: Sized,
{
let mut arg_vec = Vec::new();
#[cfg(feature = "autocomplete")]
let mut complete_vec = Vec::new();
let mut args = std::env::args_os();
#[allow(unused_variables)]
let name = args.next().expect("no command name from args_os?");
#[cfg(feature = "autocomplete")]
for arg in args {
if arg
.to_str()
.map_or(false, |s| s.starts_with("--bpaf-complete-"))
{
complete_vec.push(arg);
} else {
arg_vec.push(arg);
}
}
#[cfg(not(feature = "autocomplete"))]
arg_vec.extend(args);
#[cfg(feature = "autocomplete")]
let args = crate::complete_run::args_with_complete(name, &arg_vec, &complete_vec);
#[cfg(not(feature = "autocomplete"))]
let args = Args::from(arg_vec.as_slice());
self.run_inner(args)
}
/// Execute the [`OptionParser`] and produce a values for unit tests or manual processing
///
/// ```rust
/// # use bpaf::*;
/// # /*
/// #[test]
/// fn positional_argument() {
/// # */
/// let parser =
/// positional::<String>("FILE")
/// .help("File to process")
/// .to_options();
///
/// let help = parser
/// .run_inner(Args::from(&["--help"]))
/// .unwrap_err()
/// .unwrap_stdout();
/// let expected_help = "\
/// Usage: <FILE>
///
/// Available positional items:
/// <FILE> File to process
///
/// Available options:
/// -h, --help Prints help information
/// ";
/// assert_eq!(expected_help, help);
/// # /*
/// }
/// # */
/// ```
///
/// See also [`Args`] and it's `From` impls to produce input and
/// [`ParseFailure::unwrap_stderr`] / [`ParseFailure::unwrap_stdout`] for processing results.
///
/// # Errors
///
/// If parser can't produce desired result `run_inner` returns [`ParseFailure`]
/// which represents runtime behavior: one branch to print something to stdout and exit with
/// success and the other branch to print something to stderr and exit with failure.
///
/// `bpaf` generates contents of this `ParseFailure` using expected textual output from
/// [`parse`](Parser::parse), stdout/stderr isn't actually captured.
///
/// Exact string reperentations may change between versions including minor releases.
pub fn run_inner(&self, mut args: Args) -> Result<T, ParseFailure>
where
Self: Sized,
{
let mut avail_flags = Vec::new();
let mut avail_args = Vec::new();
self.inner
.meta()
.collect_shorts(&mut avail_flags, &mut avail_args);
args.disambiguate(&avail_flags, &avail_args)?;
match self.run_subparser(&mut args) {
Ok(t) if args.is_empty() => Ok(t),
Ok(_) => Err(ParseFailure::Stderr(format!("unexpected {:?}", args))),
Err(err) => match report_missing_items(err) {
Error::Stdout(msg) => Err(ParseFailure::Stdout(msg)),
Error::Stderr(msg) => Err(ParseFailure::Stderr(msg)),
Error::Missing(_) => unreachable!(),
},
}
}
/// Run subparser, implementation detail
pub(crate) fn run_subparser(&self, args: &mut Args) -> Result<T, Error> {
let depth = args.depth;
let res = self.inner.eval(args);
if let Err(Error::Stdout(_)) = &res {
return res;
}
#[cfg(feature = "autocomplete")]
args.check_complete()?;
let err = match res {
Ok(r) => {
if let Err(err) = check_unexpected(args) {
err
} else {
return Ok(r);
}
}
// Stderr means nested parser couldn't parse something, store it,
// report it if parsing --help and --version also fails
Err(Error::Stderr(e)) => Error::Stderr(e),
// Stdout usually means a happy path such as calling --help or --version on one of
// the nested commands
Err(Error::Stdout(e)) => return Err(Error::Stdout(e)),
Err(err) => err,
};
match self.info.help_parser().eval(args) {
Ok(ExtraParams::Help) => {
let msg = render_help(
&self.info,
&self.inner.meta(),
&self.info.help_parser().meta(),
)
.expect("Couldn't render help");
return Err(Error::Stdout(msg));
}
Ok(ExtraParams::Version(v)) => {
return Err(Error::Stdout(format!("Version: {}\n", v)));
}
Err(_) => {}
}
if crate::meta_youmean::should_suggest(&err) && args.depth == depth {
crate::meta_youmean::suggest(args, &self.inner.meta())?;
}
Err(report_missing_items(err))
}
/// Get first line of description if Available
///
/// Used internally to avoid duplicating description for [`command`].
#[must_use]
pub(crate) fn short_descr(&self) -> Option<&'static str> {
self.info.descr.and_then(|descr| descr.lines().next())
}
/// Set the version field.
///
/// By default `bpaf` won't include any version info and won't accept `--version` switch.
///
/// # Combinatoric usage
///
/// ```rust
/// use bpaf::*;
/// fn options() -> OptionParser<bool> {
/// short('s')
/// .switch()
/// .to_options()
/// .version(env!("CARGO_PKG_VERSION"))
/// }
/// ```
///
/// # Derive usage
///
/// `version` annotation is available after `options` and `command` annotations, takes
/// an optional argument - version value to use, otherwise `bpaf_derive` would use value from cargo.
///
/// ```rust
/// # use bpaf::*;
/// #[derive(Debug, Clone, Bpaf)]
/// #[bpaf(options, version)]
/// struct Options {
/// #[bpaf(short)]
/// switch: bool
/// }
/// ```
///
/// # Example
/// ```console
/// $ app --version
/// Version: 0.5.0
/// ```
#[must_use]
pub fn version(mut self, version: &'static str) -> Self {
self.info.version = Some(version);
self
}
/// Set the description field
///
/// Description field should be 1-2 lines long briefly explaining program purpose. If
/// description field is present `bpaf` would print it right before the usage line.
///
/// # Combinatoric usage
/// ```rust
/// # use bpaf::*;
/// fn options() -> OptionParser<bool> {
/// short('s')
/// .switch()
/// .to_options()
/// .descr("This is a description")
/// .header("This is a header")
/// .footer("This is a footer")
/// }
/// ```
///
/// # Derive usage
///
/// `bpaf_derive` uses doc comments on the `struct` / `enum` to derive description, it skips single empty
/// lines and uses double empty lines break it into blocks. `bpaf_derive` would use first block as the
/// description, second block - header, third block - footer.
///
/// ```rust
/// # use bpaf::*;
/// #[derive(Debug, Clone, Bpaf)]
/// #[bpaf(options, version)]
/// /// This is a description
/// ///
/// ///
/// /// This is a header
/// ///
/// ///
/// /// This is a footer
/// ///
/// ///
/// /// This is just a comment
/// struct Options {
/// #[bpaf(short)]
/// switch: bool
/// }
/// ```
///
/// # Example
///
/// ```console
/// This is a description
///
/// Usage: [-s]
///
/// This is a header
///
/// Available options:
/// -s
/// -h, --help Prints help information
/// -V, --version Prints version information
///
/// This is a footer
/// ```
#[must_use]
pub fn descr(mut self, descr: &'static str) -> Self {
self.info.descr = Some(descr);
self
}
/// Set the header field
///
/// `bpaf` displays the header between the usage line and a list of the available options in `--help` output
///
/// # Combinatoric usage
/// ```rust
/// # use bpaf::*;
/// fn options() -> OptionParser<bool> {
/// short('s')
/// .switch()
/// .to_options()
/// .descr("This is a description")
/// .header("This is a header")
/// .footer("This is a footer")
/// }
/// ```
///
/// # Derive usage
///
/// `bpaf_derive` uses doc comments on the `struct` / `enum` to derive description, it skips single empty
/// lines and uses double empty lines break it into blocks. `bpaf_derive` would use first block as the
/// description, second block - header, third block - footer.
///
/// ```rust
/// # use bpaf::*;
/// #[derive(Debug, Clone, Bpaf)]
/// #[bpaf(options, version)]
/// /// This is a description
/// ///
/// ///
/// /// This is a header
/// ///
/// ///
/// /// This is a footer
/// ///
/// ///
/// /// This is just a comment
/// struct Options {
/// #[bpaf(short)]
/// switch: bool
/// }
/// ```
///
/// # Example
///
/// ```console
/// This is a description
///
/// Usage: [-s]
///
/// This is a header
///
/// Available options:
/// -s
/// -h, --help Prints help information
/// -V, --version Prints version information
///
/// This is a footer
/// ```
#[must_use]
pub fn header(mut self, header: &'static str) -> Self {
self.info.header = Some(header);
self
}
/// Set the footer field
///
/// `bpaf` displays the footer after list of the available options in `--help` output
///
/// # Combinatoric usage
/// ```rust
/// # use bpaf::*;
/// fn options() -> OptionParser<bool> {
/// short('s')
/// .switch()
/// .to_options()
/// .descr("This is a description")
/// .header("This is a header")
/// .footer("This is a footer")
/// }
/// ```
///
/// # Derive usage
///
/// `bpaf_derive` uses doc comments on the `struct` / `enum` to derive description, it skips single empty
/// lines and uses double empty lines break it into blocks. `bpaf_derive` would use first block as the
/// description, second block - header, third block - footer.
///
/// ```rust
/// # use bpaf::*;
/// #[derive(Debug, Clone, Bpaf)]
/// #[bpaf(options, version)]
/// /// This is a description
/// ///
/// ///
/// /// This is a header
/// ///
/// ///
/// /// This is a footer
/// ///
/// ///
/// /// This is just a comment
/// struct Options {
/// #[bpaf(short)]
/// switch: bool
/// }
/// ```
///
/// # Example
///
/// ```console
/// This is a description
///
/// Usage: [-s]
///
/// This is a header
///
/// Available options:
/// -s
/// -h, --help Prints help information
/// -V, --version Prints version information
///
/// This is a footer
/// ```
#[must_use]
pub fn footer(mut self, footer: &'static str) -> Self {
self.info.footer = Some(footer);
self
}
/// Set custom usage field
///
/// Custom usage field to use instead of one derived by `bpaf`. Custom message should contain
/// `"Usage: "` prefix if you want to display one.
///
/// Before using it `bpaf` would replace `"{usage}"` tokens inside a custom usage string with
/// automatically generated usage.
///
/// # Combinatoric usage
/// ```rust
/// # use bpaf::*;
/// fn options() -> OptionParser<bool> {
/// short('s')
/// .switch()
/// .to_options()
/// .usage("Usage: my_program: {usage}")
/// }
/// ```
///
/// # Derive usage
///
/// Not available directly, but you can call `usage` on generated [`OptionParser`].
#[must_use]
pub fn usage(mut self, usage: &'static str) -> Self {
self.info.usage = Some(usage);
self
}
/// Turn `OptionParser` into subcommand parser
///
/// This is identical to [`command`](crate::params::command)
#[must_use]
pub fn command(self, name: &'static str) -> ParseCommand<T>
where
T: 'static,
{
crate::params::command(name, self)
}
/// Check the invariants `bpaf` relies on for normal operations
///
/// Takes a parameter whether to check for cosmetic invariants or not
/// (max help width exceeding 120 symbols, etc), currently not in use
///
/// Best used as part of your test suite:
/// ```no_run
/// # use bpaf::*;
/// #[test]
/// fn check_options() {
/// # let options = || short('p').switch().to_options();
/// options().check_invariants(false)
/// }
/// ```
///
/// # Panics
///
/// `check_invariants` indicates problems with panic
pub fn check_invariants(&self, _cosmetic: bool) {
perform_invariant_check(&self.inner.meta(), true);
}
}
fn report_missing_items(err: Error) -> Error {
match err {
Error::Stdout(_) | Error::Stderr(_) => err,
Error::Missing(items) => Error::Stderr(format!(
"Expected {}, pass --help for usage information",
Meta::Or(items.into_iter().map(Meta::Item).collect::<Vec<_>>())
)),
}
}
fn perform_invariant_check(meta: &Meta, fresh: bool) {
if fresh {
println!("Checking\n{:#?}", meta);
to_usage_meta(meta);
}
match meta {
Meta::And(xs) | Meta::Or(xs) => {
for i in xs.iter() {
perform_invariant_check(i, false);
}
}
Meta::HideUsage(x) | Meta::Optional(x) | Meta::Many(x) | Meta::Decorated(x, _) => {
perform_invariant_check(x, false);
}
Meta::Item(i) => match i {
Item::Command { meta, .. } => perform_invariant_check(meta, true),
Item::Positional { .. } | Item::Flag { .. } | Item::Argument { .. } => {}
},
Meta::Skip => {}
}
}
struct ParseExtraParams {
version: Option<&'static str>,
}
impl Parser<ExtraParams> for ParseExtraParams {
fn eval(&self, args: &mut Args) -> Result<ExtraParams, Error> {
if let Ok(ok) = ParseExtraParams::help().eval(args) {
return Ok(ok);
}
match self.version {
Some(ver) => Self::ver(ver).eval(args),
None => Err(Error::Stderr(String::from("Not a version or help flag"))),
}
}
fn meta(&self) -> Meta {
match self.version {
Some(ver) => Meta::And(vec![Self::help().meta(), Self::ver(ver).meta()]),
None => Self::help().meta(),
}
}
}
impl ParseExtraParams {
#[inline(never)]
fn help() -> impl Parser<ExtraParams> {
short('h')
.long("help")
.help("Prints help information")
.req_flag(ExtraParams::Help)
}
#[inline(never)]
fn ver(version: &'static str) -> impl Parser<ExtraParams> {
short('V')
.long("version")
.help("Prints version information")
.req_flag(ExtraParams::Version(version))
}
}