Trait bpaf::Parser

source · [−]

pub trait Parser<T> {
Show 15 methods
    fn many(self) -> ParseMany<Self>
    where
        Self: Sized,
    { ... }
    fn some(self, message: &'static str) -> ParseSome<Self>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn optional(self) -> ParseOptional<Self>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn parse<F, R, E>(self, f: F) -> ParseWith<T, Self, F, E, R>
    where
        Self: Sized + Parser<T>,
        F: Fn(T) -> Result<R, E>,
        E: ToString,
    { ... }
    fn map<F, R>(self, map: F) -> ParseMap<T, Self, F, R>
    where
        Self: Sized + Parser<T>,
        F: Fn(T) -> R + 'static,
    { ... }
    fn guard<F>(self, check: F, message: &'static str) -> ParseGuard<Self, F>
    where
        Self: Sized + Parser<T>,
        F: Fn(&T) -> bool,
    { ... }
    fn fallback(self, value: T) -> ParseFallback<Self, T>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn fallback_with<F, E>(self, fallback: F) -> ParseFallbackWith<T, Self, F, E>
    where
        Self: Sized + Parser<T>,
        F: Fn() -> Result<T, E>,
        E: ToString,
    { ... }
    fn hide(self) -> ParseHide<Self>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn group_help(self, message: &'static str) -> ParseGroupHelp<Self>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn complete<M, F>(self, op: F) -> ParseComp<Self, F>
    where
        M: Into<String>,
        F: Fn(&T) -> Vec<(M, Option<M>)>,
        Self: Sized + Parser<T>,
    { ... }
    fn complete_style(self, style: CompleteDecor) -> ParseCompStyle<Self>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn adjacent(self) -> ParseAdjacent<Self>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn anywhere(self) -> ParseAnywhere<Self>
    where
        Self: Sized + Parser<T>,
    { ... }
    fn to_options(self) -> OptionParser<T>
    where
        Self: Sized + Parser<T> + 'static,
    { ... }
}

Expand description

Simple or composed argument parser

Overview

It’s best to think of an object implementing Parser trait as a container with a value inside that are composable with other Parser containers using construct! and the only way to extract this value is by transforming it to OptionParser with to_options and running it with run. At which point you either get your value out or bpaf would generate a message describing a problem (missing argument, validation failure, user requested help, etc) and the program would exit.

Values inside can be of any type for as long as they implement Debug, Clone and there’s no lifetimes other than static.

When consuming the values you can jump straight to a value that implements either FromOsStr or FromStr trait then transform into something that your program would actually use. Alternatively you can consume either String or OsString and parse that by hand. It’s better to perform as much parsing and validation inside the Parser as possible so the program itself gets strictly typed and correct value while user gets immediate feedback on what’s wrong with the arguments they pass.

For example suppose your program needs user to specify a dimensions of a rectangle, with sides being 1..20 units long and the total area must not exceed 200 units square. A parser that consumes it might look like this:

#[derive(Debug, Copy, Clone)]
struct Rectangle {
    width: u32,
    height: u32,
}

fn rectangle() -> impl Parser<Rectangle> {
    let invalid_size = "Sides of a rectangle must be 1..20 units long";
    let invalid_area = "Area of a rectangle must not exceed 200 units square";
    let width = long("width")
        .help("Width of the rectangle")
        .argument::<u32>("PX")
        .guard(|&x| 1 <= x && x <= 10, invalid_size);
    let height = long("height")
        .help("Height of the rectangle")
        .argument::<u32>("PX")
        .guard(|&x| 1 <= x && x <= 10, invalid_size);
    construct!(Rectangle { width, height })
        .guard(|&r| r.width * r.height <= 400, invalid_area)
}

Derive specific considerations

Every method defined on this trait belongs to the postprocessing section of the field annotation. bpaf_derive would try to figure out what chain to use for as long as there’s no options changing the type: you can use fallback, fallback_with, guard, hide and group_help but not the rest of them.

#[derive(Debug, Clone, Bpaf)]
struct Options {
    // no annotation at all - `bpaf_derive` inserts implicit `argument` and gets the right type
    number_1: u32,

    // fallback isn't changing the type so `bpaf_derive` still handles it
    #[bpaf(fallback(42))]
    number_2: u32,

    // `bpaf_derive` inserts implicit `argument`, `optional` and the right type
    number_3: Option<u32>,

    // fails to compile: you need to specify a consumer, `argument` or `argument_os`
    // #[bpaf(optional)]
    // number_4: Option<u32>

    // fails to compile: you also need to specify how to go from String to u32
    // #[bpaf(argument("N"), optional)]
    // number_5: Option<u32>,

    // explicit consumer and a full postprocessing chain
    #[bpaf(argument::<u32>("N"), optional)]
    number_6: Option<u32>,
}

Provided Methods

source

fn many(self) -> ParseMany<Self>where
Self: Sized,

Consume zero or more items from a command line and collect them into Vec

many preserves any parsing falures and propagates them outwards, with extra catch statement you can instead stop at the first value that failed to parse and ignore it and all the subsequent ones.

many only collects elements that only consume something from the argument list.

Combinatoric usage:

fn numbers() -> impl Parser<Vec<u32>> {
    short('n')
        .argument::<u32>("NUM")
        .many()
}

Derive usage:

bpaf would insert implicit many when resulting type is a vector

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(short, argument("NUM"))]
    numbers: Vec<u32>
}

But it’s also possible to specify it explicitly, both cases renerate the same code. Note, since using many resets the postprocessing chain - you also need to specify argument’s turbofish.

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(short, argument::<u32>("NUM"), many)]
    numbers: Vec<u32>
}

Example

$ app -n 1 -n 2 -n 3
// [1, 2, 3]

Examples found in repository ?

examples/at_least_two.rs (line 10)

fn main() {
    let opt = short('f')
        .req_flag(())
        .many()
        .guard(|x| x.len() >= 2, "at least two arguments are required")
        .to_options()
        .run();

    println!("{:?}", opt);
}

More examples

Hide additional examples

examples/derive_show_asm.rs (line 47)

fn verbosity() -> impl Parser<usize> {
    short('v')
        .long("verbose")
        .help("more verbose output, can be specified multiple times")
        .req_flag(())
        .many()
        .map(|v| v.len())
}

examples/ex_positional.rs (line 17)

fn main() {
    let value = long("value")
        .help("Mysterious value")
        .argument::<u32>("VAL")
        .fallback(42);
    let files = positional::<PathBuf>("FILE").many();
    let opts = construct!(Options { value, files }).to_options().run();

    println!("{:#?}", opts);
}

examples/top_to_bottom.rs (line 45)

≺ ≻↕

fn verbose() -> impl Parser<usize> {
    short('v')
        .long("verbose")
        .help("Increase the verbosity\nYou can specify it up to 3 times\neither as -v -v -v or as -vvv")
        .req_flag(())
        .many()
        .map(|xs| xs.len())
        .guard(|&x| x <= 3, "It doesn't get any more verbose than this")
}

// an argument, parsed and with default value
fn speed() -> impl Parser<f64> {
    short('s')
        .long("speed")
        .help("Set speed")
        .argument::<f64>("SPEED")
        .fallback(42.0)
}

fn output() -> impl Parser<PathBuf> {
    short('o')
        .long("output")
        .help("output file")
        .argument::<PathBuf>("OUTPUT")
}

// no magical name transmogrifications.
fn nb_cars() -> impl Parser<u32> {
    short('n').long("nb-cars").argument::<u32>("N")
}

fn files_to_process() -> impl Parser<Vec<PathBuf>> {
    short('f')
        .long("file")
        .help("File to process")
        .argument::<PathBuf>("FILE")
        .many()
}

examples/env_logger.rs (line 32)

↕

fn verbose() -> impl Parser<LevelFilter> {
    short('v')
        .help("Verbosity level, use multiple times for more verbosity")
        .req_flag(())
        .many()
        .map(|v| {
            use LevelFilter::*;
            *[Off, Error, Warn, Info, Debug, Trace]
                .get(v.len())
                .unwrap_or(&Trace)
        })
}

examples/derive.rs (line 33)

fn verbose() -> impl Parser<usize> {
    // number of occurrences of the v/verbose flag capped at 3
    short('v')
        .long("verbose")
        .help("Increase the verbosity\nYou can specify it up to 3 times\neither as -v -v -v or as -vvv")
        .req_flag(())
        .many()
        .map(|xs| xs.len())
        .guard(|&x| x <= 3, "It doesn't get any more verbose than this")
}

Additional examples can be found in:

source

fn some(self, message: &'static str) -> ParseSome<Self>where
Self: Sized + Parser<T>,

Consume one or more items from a command line

Takes a string used as an error message if there’s no specified parameters

some preserves any parsing falures and propagates them outwards, with extra catch statement you can instead stop at the first value that failed to parse and ignore it and all the subsequent ones.

some only collects elements that only consume something from the argument list.

Combinatoric usage:

let numbers
    = short('n')
    .argument::<u32>("NUM")
    .some("Need at least one number");

Derive usage

Since using some resets the postprocessing chain - you also might need to specify the type in turbofish:

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(short, argument::<u32>("NUM"), some("Need at least one number"))]
    numbers: Vec<u32>
}

Example

$ app
// fails with "Need at least one number"
$ app -n 1 -n 2 -n 3
// [1, 2, 3]

fn optional(self) -> ParseOptional<Self>where
Self: Sized + Parser<T>,

Turn a required argument into optional one

optional converts any missing items into is None and passes the remaining parsing failures untouched. With extra catch statement you can handle those failures too.

Combinatoric usage

fn number() -> impl Parser<Option<u32>> {
    short('n')
        .argument::<u32>("NUM")
        .optional()
}

Derive usage

By default bpaf_derive would automatically use optional for fields of type Option<T>, for as long as it’s not prevented from doing so by present postprocessing options

#[derive(Debug, Clone, Bpaf)]
struct Options {
   #[bpaf(short, argument("NUM"))]
   number: Option<u32>
}

But it’s also possible to specify it explicitly example.

#[derive(Debug, Clone, Bpaf)]
struct Options {
   #[bpaf(short, argument::<u32>("NUM"), optional)]
   number: Option<u32>
}

Example

$ app
// None
$ app -n 42
// Some(42)

Examples found in repository ?

examples/derive_commands.rs (line 36)

≺ ≻

fn feature_if() -> impl Parser<Option<String>> {
    positional::<String>("FEATURE")
        .guard(move |s| !is_version(s), "")
        .optional()
}

fn version_if() -> impl Parser<Option<String>> {
    positional::<String>("VERSION")
        .guard(move |s| is_version(s), "")
        .optional()
}

More examples

Hide additional examples

examples/find.rs (line 38)

≺ ≻↕

fn user() -> impl Parser<Option<String>> {
    let tag = any::<String>("TAG")
        .guard(|s| s == "-user", "not user")
        .hide();
    let value = positional::<String>("USER");
    construct!(tag, value)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

// parsers -exec xxx yyy zzz ;
fn exec() -> impl Parser<Option<Vec<OsString>>> {
    let tag = any::<String>("-exec")
        .help("-exec /path/to/command flags and options ;")
        .guard(|s| s == "-exec", "not find");
    let item = any::<OsString>("ITEM")
        .guard(|s| s != ";", "not word")
        .many()
        .catch()
        .hide();
    let endtag = any::<String>("END").guard(|s| s == ";", "not eot").hide();
    construct!(tag, item, endtag)
        .anywhere()
        .map(|triple| triple.1)
        .optional()
        .catch()
}

/// parses symbolic permissions `-perm -mode`, `-perm /mode` and `-perm mode`
fn perm() -> impl Parser<Option<Perm>> {
    fn parse_mode(input: &str) -> Result<Perms, String> {
        let mut perms = Perms::default();
        for c in input.chars() {
            match c {
                'r' => perms.read = true,
                'w' => perms.write = true,
                'x' => perms.exec = true,
                _ => return Err(format!("{} is not a valid permission string", input)),
            }
        }
        Ok(perms)
    }

    let tag = any::<String>("-mode").help("-mode (perm | -perm | /perm)");
    let mode = any::<String>("mode")
        .parse::<_, _, String>(|s| {
            if let Some(m) = s.strip_prefix('-') {
                Ok(Perm::All(parse_mode(m)?))
            } else if let Some(m) = s.strip_prefix('/') {
                Ok(Perm::Any(parse_mode(m)?))
            } else {
                Ok(Perm::Exact(parse_mode(&s)?))
            }
        })
        .hide();

    construct!(tag, mode)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

examples/numeric_prefix.rs (line 13)

pub fn options() -> OptionParser<Options> {
    let prefix = positional::<usize>("PREFIX")
        .help("Optional numeric command prefix")
        .optional()
        .catch();
    let command = positional::<String>("COMMAND").help("Required command name");

    construct!(Options { prefix, command }).to_options()
}

examples/enum_tuple.rs (line 20)

↕

fn main() {
    let bar = short('b')
        .long("bar")
        .help("some bar command")
        .argument::<String>("BAR")
        .optional();

    let bar_cmd = construct!(Foo { bar })
        .to_options()
        .descr("This command will try to do foo given a bar argument");

    let opt = command("foo", bar_cmd)
        .help("command for doing foo")
        .map(Command::Foo)
        .to_options()
        .run();

    println!("{:#?}", opt);
}

examples/cargo-cmd.rs (line 24)

↕

fn main() {
    // defining a parser in a usual way
    let width = short('w').argument::<usize>("WIDTH").fallback(10);
    let height = short('h').argument::<usize>("HEIGHT").fallback(10);
    let parser = construct!(Opts { width, height });

    let cmd = positional::<String>("")
        .guard(|s| s == "cmd", "")
        .optional()
        .hide();
    let combined_parser = construct!(cmd, parser).map(|x| x.1);

    let opts = combined_parser.to_options().run();

    println!("{:?}", opts);
}

examples/cat.rs (line 18)

↕

fn main() {
    let file = positional::<OsString>("FILE")
        .help("File name to concatenate, with no FILE or when FILE is -, read standard input")
        .optional()
        .parse::<_, Box<dyn Read>, std::io::Error>(|path| {
            Ok(if let Some(path) = path {
                if path == "-" {
                    Box::new(stdin())
                } else {
                    Box::new(File::open(path)?)
                }
            } else {
                Box::new(stdin())
            })
        })
        .to_options()
        .descr("Concatenate a file to standard output")
        .run();

    let reader = BufReader::new(file);

    for line in reader.lines() {
        println!("{}", line.unwrap());
    }
}

Additional examples can be found in:

source

fn parse<F, R, E>(self, f: F) -> ParseWith<T, Self, F, E, R>where
    Self: Sized + Parser<T>,
    F: Fn(T) -> Result<R, E>,
    E: ToString,

Apply a failing transformation to a contained value

Transformation preserves present/absent state of the value: to parse an optional value you can either first try to parse it and then mark as optional or first deal with the optionality and then parse a value wrapped in Option. In most cases former approach is more concise.

Similarly it is possible to parse multiple items with many or some by either parsing a single item first and then turning it into a Vec or collecting them into a Vec first and then parsing the whole vector. Former approach is more concise.

This is a most general of transforming parsers and you can express map and guard in terms of it.

Examples given here are a bit artificail, to parse a value from string you can specify the type directly in argument’s turbofish

Combinatoric usage:

fn number() -> impl Parser<u32> {
    short('n')
        .argument::<String>("NUM")
        .parse(|s| u32::from_str(&s))
}

Derive usage:

parse takes a single parameter: function name to call. Function type should match parameter F used by parse in combinatoric API.

fn read_number(s: String) -> Result<u32, ParseIntError> {
    u32::from_str(&s)
}

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(short, argument::<String>("NUM"), parse(read_number))]
    number: u32
}

Example

$ app -n 12
// 12
// fails with "Couldn't parse "pi": invalid numeric literal"

Examples found in repository ?

examples/derive_show_asm.rs (lines 55-63)

↕

fn parse_manifest_path() -> impl Parser<PathBuf> {
    long("manifest-path")
        .help("Path to Cargo.toml")
        .argument::<PathBuf>("PATH")
        .parse(|p| {
            if p.is_absolute() {
                Ok(p)
            } else {
                std::env::current_dir()
                    .map(|d| d.join(p))
                    .and_then(|full_path| full_path.canonicalize())
            }
        })
        .fallback_with(|| std::env::current_dir().map(|x| x.join("Cargo.toml")))
}

More examples

Hide additional examples

examples/dd.rs (lines 24-27)

↕

fn tag<T>(name: &'static str, meta: &'static str, help: &'static str) -> impl Parser<T>
where
    T: FromStr,
    <T as std::str::FromStr>::Err: std::fmt::Display,
{
    // it is possible to parse OsString here and strip the prefix with os_str_bytes or a similar
    // crate
    any::<String>(meta)
        .help(help)
        .parse::<_, _, String>(move |s| match s.strip_prefix(name) {
            None => Err("Wrong tag".to_string()),
            Some(body) => T::from_str(body).map_err(|e| e.to_string()),
        })
        .anywhere()
}

examples/xorg.rs (lines 14-27)

≺ ≻↕

fn toggle_options(name: &'static str, help: &'static str) -> impl Parser<bool> {
    any::<String>(name)
        .help(help)
        .parse(move |s| {
            let (state, cur_name) = if let Some(rest) = s.strip_prefix('+') {
                (true, rest)
            } else if let Some(rest) = s.strip_prefix('-') {
                (false, rest)
            } else {
                return Err(format!("{} is not a toggle option", s));
            };
            if cur_name != name {
                Err(format!("{} is not a known toggle option name", cur_name))
            } else {
                Ok(state)
            }
        })
        .anywhere()
}

fn extension() -> impl Parser<(String, bool)> {
    let on = any::<String>("+ext")
        .help("enable ext <EXT>")
        .parse::<_, _, String>(|s| {
            if s == "+ext" {
                Ok(true)
            } else {
                Err(String::new())
            }
        });
    let off = any::<String>("-ext")
        .help("disable ext <EXT>")
        .parse::<_, _, String>(|s| {
            if s == "-ext" {
                Ok(false)
            } else {
                Err(String::new())
            }
        });

    let state = construct!([on, off]);
    let name = positional::<String>("EXT").hide();
    construct!(state, name).map(|(a, b)| (b, a)).anywhere()
}

examples/cat.rs (lines 19-29)

↕

fn main() {
    let file = positional::<OsString>("FILE")
        .help("File name to concatenate, with no FILE or when FILE is -, read standard input")
        .optional()
        .parse::<_, Box<dyn Read>, std::io::Error>(|path| {
            Ok(if let Some(path) = path {
                if path == "-" {
                    Box::new(stdin())
                } else {
                    Box::new(File::open(path)?)
                }
            } else {
                Box::new(stdin())
            })
        })
        .to_options()
        .descr("Concatenate a file to standard output")
        .run();

    let reader = BufReader::new(file);

    for line in reader.lines() {
        println!("{}", line.unwrap());
    }
}

examples/find.rs (lines 77-85)

↕

fn perm() -> impl Parser<Option<Perm>> {
    fn parse_mode(input: &str) -> Result<Perms, String> {
        let mut perms = Perms::default();
        for c in input.chars() {
            match c {
                'r' => perms.read = true,
                'w' => perms.write = true,
                'x' => perms.exec = true,
                _ => return Err(format!("{} is not a valid permission string", input)),
            }
        }
        Ok(perms)
    }

    let tag = any::<String>("-mode").help("-mode (perm | -perm | /perm)");
    let mode = any::<String>("mode")
        .parse::<_, _, String>(|s| {
            if let Some(m) = s.strip_prefix('-') {
                Ok(Perm::All(parse_mode(m)?))
            } else if let Some(m) = s.strip_prefix('/') {
                Ok(Perm::Any(parse_mode(m)?))
            } else {
                Ok(Perm::Exact(parse_mode(&s)?))
            }
        })
        .hide();

    construct!(tag, mode)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

examples/confusing.rs (lines 61-71)

↕

fn main() {
    let token = long("token")
        .help("Token used for complex commands")
        .argument::<String>("TOKEN")
        .optional();

    // start with defining 3 commands: simple, complex1 and complex2
    let simple_parser = pure(PreCommand::Simple).to_options();
    let simple = command("simple", simple_parser);

    let complex1_parser = positional::<i32>("ARG");
    let complex1 = command(
        "complex1",
        construct!(PreCommand::Complex1(complex1_parser))
            .to_options()
            .descr("This is complex command 1"),
    );

    let complex2_parser = positional::<i16>("ARG");
    let complex2 = command(
        "complex1",
        construct!(PreCommand::Complex2(complex2_parser))
            .to_options()
            .descr("This is complex command 2"),
    );

    // compose then to accept any of those
    let preparser = construct!([simple, complex1, complex2]);

    // make a parser that accepts optional token and one of incomplete commands
    // then create complete command or fail
    let parser = construct!(token, preparser).parse(|(token, cmd)| match cmd {
        PreCommand::Simple => Ok(Command::Simple),
        PreCommand::Complex1(a) => match token {
            Some(token) => Ok(Command::Complex1(token, a)),
            None => Err("You must specify token to use with --token"),
        },
        PreCommand::Complex2(a) => match token {
            Some(token) => Ok(Command::Complex2(token, a)),
            None => Err("You must specify token to use with --token"),
        },
    });

    let cmd = parser.to_options().run();
    println!("{:?}", cmd);
}

source

fn map<F, R>(self, map: F) -> ParseMap<T, Self, F, R>where
Self: Sized + Parser<T>,
F: Fn(T) -> R + 'static,

Apply a pure transformation to a contained value

A common case of parse method, exists mostly for convenience.

Combinatoric usage

fn number() -> impl Parser<u32> {
    short('n')
        .argument::<u32>("NUM")
        .map(|v| v * 2)
}

Derive usage

fn double(num: u32) -> u32 {
    num * 2
}

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(short, argument::<u32>("NUM"), map(double))]
    number: u32,
}

Example

$ app -n 21
// 42

Examples found in repository ?

examples/derive_show_asm.rs (line 48)

fn verbosity() -> impl Parser<usize> {
    short('v')
        .long("verbose")
        .help("more verbose output, can be specified multiple times")
        .req_flag(())
        .many()
        .map(|v| v.len())
}

More examples

Hide additional examples

examples/find.rs (line 37)

≺ ≻↕

fn user() -> impl Parser<Option<String>> {
    let tag = any::<String>("TAG")
        .guard(|s| s == "-user", "not user")
        .hide();
    let value = positional::<String>("USER");
    construct!(tag, value)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

// parsers -exec xxx yyy zzz ;
fn exec() -> impl Parser<Option<Vec<OsString>>> {
    let tag = any::<String>("-exec")
        .help("-exec /path/to/command flags and options ;")
        .guard(|s| s == "-exec", "not find");
    let item = any::<OsString>("ITEM")
        .guard(|s| s != ";", "not word")
        .many()
        .catch()
        .hide();
    let endtag = any::<String>("END").guard(|s| s == ";", "not eot").hide();
    construct!(tag, item, endtag)
        .anywhere()
        .map(|triple| triple.1)
        .optional()
        .catch()
}

/// parses symbolic permissions `-perm -mode`, `-perm /mode` and `-perm mode`
fn perm() -> impl Parser<Option<Perm>> {
    fn parse_mode(input: &str) -> Result<Perms, String> {
        let mut perms = Perms::default();
        for c in input.chars() {
            match c {
                'r' => perms.read = true,
                'w' => perms.write = true,
                'x' => perms.exec = true,
                _ => return Err(format!("{} is not a valid permission string", input)),
            }
        }
        Ok(perms)
    }

    let tag = any::<String>("-mode").help("-mode (perm | -perm | /perm)");
    let mode = any::<String>("mode")
        .parse::<_, _, String>(|s| {
            if let Some(m) = s.strip_prefix('-') {
                Ok(Perm::All(parse_mode(m)?))
            } else if let Some(m) = s.strip_prefix('/') {
                Ok(Perm::Any(parse_mode(m)?))
            } else {
                Ok(Perm::Exact(parse_mode(&s)?))
            }
        })
        .hide();

    construct!(tag, mode)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

examples/top_to_bottom.rs (line 46)

fn verbose() -> impl Parser<usize> {
    short('v')
        .long("verbose")
        .help("Increase the verbosity\nYou can specify it up to 3 times\neither as -v -v -v or as -vvv")
        .req_flag(())
        .many()
        .map(|xs| xs.len())
        .guard(|&x| x <= 3, "It doesn't get any more verbose than this")
}

examples/env_logger.rs (lines 33-38)

↕

fn verbose() -> impl Parser<LevelFilter> {
    short('v')
        .help("Verbosity level, use multiple times for more verbosity")
        .req_flag(())
        .many()
        .map(|v| {
            use LevelFilter::*;
            *[Off, Error, Warn, Info, Debug, Trace]
                .get(v.len())
                .unwrap_or(&Trace)
        })
}

examples/derive.rs (line 34)

fn verbose() -> impl Parser<usize> {
    // number of occurrences of the v/verbose flag capped at 3
    short('v')
        .long("verbose")
        .help("Increase the verbosity\nYou can specify it up to 3 times\neither as -v -v -v or as -vvv")
        .req_flag(())
        .many()
        .map(|xs| xs.len())
        .guard(|&x| x <= 3, "It doesn't get any more verbose than this")
}

examples/enum_tuple.rs (line 28)

↕

fn main() {
    let bar = short('b')
        .long("bar")
        .help("some bar command")
        .argument::<String>("BAR")
        .optional();

    let bar_cmd = construct!(Foo { bar })
        .to_options()
        .descr("This command will try to do foo given a bar argument");

    let opt = command("foo", bar_cmd)
        .help("command for doing foo")
        .map(Command::Foo)
        .to_options()
        .run();

    println!("{:#?}", opt);
}

Additional examples can be found in:

source

fn guard<F>(self, check: F, message: &'static str) -> ParseGuard<Self, F>where
Self: Sized + Parser<T>,
F: Fn(&T) -> bool,

Validate or fail with a message

If value doesn’t satisfy the constraint - parser fails with the specified error message.

Combinatoric usage

fn number() -> impl Parser<u32> {
    short('n')
        .argument::<u32>("NUM")
        .guard(|n| *n <= 10, "Values greater than 10 are only available in the DLC pack!")
}

Derive usage

Unlike combinator counterpart, derive variant of guard takes a function name instead of a closure, mostly to keep things clean. Second argument can be either a string literal or a constant name for a static str.

fn dlc_check(number: &u32) -> bool {
    *number <= 10
}

const DLC_NEEDED: &str = "Values greater than 10 are only available in the DLC pack!";

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(short, argument("NUM"), guard(dlc_check, DLC_NEEDED))]
    number: u32,
}

Example

$ app -n 100
// fails with "Values greater than 10 are only available in the DLC pack!"
$ app -n 5
// 5

Examples found in repository ?

examples/derive_commands.rs (line 35)

≺ ≻

fn feature_if() -> impl Parser<Option<String>> {
    positional::<String>("FEATURE")
        .guard(move |s| !is_version(s), "")
        .optional()
}

fn version_if() -> impl Parser<Option<String>> {
    positional::<String>("VERSION")
        .guard(move |s| is_version(s), "")
        .optional()
}

More examples

Hide additional examples

examples/at_least_two.rs (line 11)

fn main() {
    let opt = short('f')
        .req_flag(())
        .many()
        .guard(|x| x.len() >= 2, "at least two arguments are required")
        .to_options()
        .run();

    println!("{:?}", opt);
}

examples/find.rs (line 32)

≺ ≻↕

fn user() -> impl Parser<Option<String>> {
    let tag = any::<String>("TAG")
        .guard(|s| s == "-user", "not user")
        .hide();
    let value = positional::<String>("USER");
    construct!(tag, value)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

// parsers -exec xxx yyy zzz ;
fn exec() -> impl Parser<Option<Vec<OsString>>> {
    let tag = any::<String>("-exec")
        .help("-exec /path/to/command flags and options ;")
        .guard(|s| s == "-exec", "not find");
    let item = any::<OsString>("ITEM")
        .guard(|s| s != ";", "not word")
        .many()
        .catch()
        .hide();
    let endtag = any::<String>("END").guard(|s| s == ";", "not eot").hide();
    construct!(tag, item, endtag)
        .anywhere()
        .map(|triple| triple.1)
        .optional()
        .catch()
}

examples/top_to_bottom.rs (line 47)

fn verbose() -> impl Parser<usize> {
    short('v')
        .long("verbose")
        .help("Increase the verbosity\nYou can specify it up to 3 times\neither as -v -v -v or as -vvv")
        .req_flag(())
        .many()
        .map(|xs| xs.len())
        .guard(|&x| x <= 3, "It doesn't get any more verbose than this")
}

examples/derive.rs (line 35)

fn verbose() -> impl Parser<usize> {
    // number of occurrences of the v/verbose flag capped at 3
    short('v')
        .long("verbose")
        .help("Increase the verbosity\nYou can specify it up to 3 times\neither as -v -v -v or as -vvv")
        .req_flag(())
        .many()
        .map(|xs| xs.len())
        .guard(|&x| x <= 3, "It doesn't get any more verbose than this")
}

examples/cargo-cmd.rs (line 23)

↕

fn main() {
    // defining a parser in a usual way
    let width = short('w').argument::<usize>("WIDTH").fallback(10);
    let height = short('h').argument::<usize>("HEIGHT").fallback(10);
    let parser = construct!(Opts { width, height });

    let cmd = positional::<String>("")
        .guard(|s| s == "cmd", "")
        .optional()
        .hide();
    let combined_parser = construct!(cmd, parser).map(|x| x.1);

    let opts = combined_parser.to_options().run();

    println!("{:?}", opts);
}

Additional examples can be found in:

source

fn fallback(self, value: T) -> ParseFallback<Self, T>where
Self: Sized + Parser<T>,

Use this value as default if value isn’t present on a command line

Parser would still fail if value is present but failure comes from some transformation

Combinatoric usage

fn number() -> impl Parser<u32> {
    short('n')
        .argument::<u32>("NUM")
        .fallback(42)
}

Derive usage

Expression in parens should have the right type, this example uses u32 literal, but it can also be your own type if that’s what you are parsing, it can also be a function call.

#[derive(Debug, Clone, Bpaf)]
struct Options {
   #[bpaf(short, argument("NUM"), fallback(42))]
   number: u32
}

Example

$ app -n 100
// 10
$ app
// 42
$ app -n pi
// fails with "Couldn't parse "pi": invalid numeric literal"

Examples found in repository ?

examples/dd.rs (line 32)

≺ ≻↕

fn in_file() -> impl Parser<String> {
    tag::<String>("if=", "if=FILE", "read from FILE instead of stdin").fallback(String::from("-"))
}

fn out_file() -> impl Parser<String> {
    tag::<String>("of=", "of=FILE", "write to FILE instead of stdout").fallback(String::from("-"))
}

fn block_size() -> impl Parser<usize> {
    // it is possible to parse notation used by dd itself as well, using only ints for simplicity
    tag::<usize>(
        "bs=",
        "bs=SIZE",
        "read/write SIZE blocks at once instead of 512",
    )
    .fallback(512)
}

More examples

Hide additional examples

examples/top_to_bottom.rs (line 56)

fn speed() -> impl Parser<f64> {
    short('s')
        .long("speed")
        .help("Set speed")
        .argument::<f64>("SPEED")
        .fallback(42.0)
}

examples/ex_positional.rs (line 16)

fn main() {
    let value = long("value")
        .help("Mysterious value")
        .argument::<u32>("VAL")
        .fallback(42);
    let files = positional::<PathBuf>("FILE").many();
    let opts = construct!(Options { value, files }).to_options().run();

    println!("{:#?}", opts);
}

examples/xorg.rs (line 57)

≺ ≻↕

pub fn options() -> OptionParser<Options> {
    let backing = toggle_options("backing", "Backing status").fallback(false);
    let xinerama = toggle_options("xinerama", "Xinerama status").fallback(true);
    let turbo = short('t')
        .long("turbo")
        .help("Engage the turbo mode")
        .switch();
    let extensions = extension().many();
    construct!(Options {
        turbo,
        backing,
        xinerama,
        extensions,
    })
    .to_options()
}

examples/cargo-cmd.rs (line 18)

≺ ≻↕

fn main() {
    // defining a parser in a usual way
    let width = short('w').argument::<usize>("WIDTH").fallback(10);
    let height = short('h').argument::<usize>("HEIGHT").fallback(10);
    let parser = construct!(Opts { width, height });

    let cmd = positional::<String>("")
        .guard(|s| s == "cmd", "")
        .optional()
        .hide();
    let combined_parser = construct!(cmd, parser).map(|x| x.1);

    let opts = combined_parser.to_options().run();

    println!("{:?}", opts);
}

examples/no_import.rs (lines 18-24)

↕

fn main() {
    // A flag, true if used in the command line. Can be required, this one is optional
    let debug = bpaf::short('d')
        .long("debug")
        .help("Activate debug mode")
        .switch();

    // an argument, parsed and with default value
    let speed = bpaf::Parser::fallback(
        bpaf::short('s')
            .long("speed")
            .help("Set speed")
            .argument::<f64>("SPEED"),
        42.0,
    );

    // packing things in a struct assumes parser for each field is in scope.
    let opt = bpaf::Parser::to_options(bpaf::construct!(Out { debug, speed })).run();

    println!("{:#?}", opt);
}

Additional examples can be found in:

source

fn fallback_with<F, E>(self, fallback: F) -> ParseFallbackWith<T, Self, F, E>where
    Self: Sized + Parser<T>,
    F: Fn() -> Result<T, E>,
    E: ToString,

Use value produced by this function as default if value isn’t present

Would still fail if value is present but failure comes from some earlier transformation

Combinatoric usage

fn username() -> impl Parser<String> {
    long("user")
        .argument::<String>("USER")
        .fallback_with::<_, Box<dyn std::error::Error>>(||{
            let output = std::process::Command::new("whoami")
                .stdout(std::process::Stdio::piped())
                .spawn()?
                .wait_with_output()?
                .stdout;
            Ok(std::str::from_utf8(&output)?.to_owned())
        })
}

Derive usage

fn get_current_user() -> Result<String, Box<dyn std::error::Error>> {
    let output = std::process::Command::new("whoami")
        .stdout(std::process::Stdio::piped())
        .spawn()?
        .wait_with_output()?
        .stdout;
    Ok(std::str::from_utf8(&output)?.to_owned())
}

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(long, argument("USER"), fallback_with(get_current_user))]
    user: String,
}

Example

$ app --user bobert
// "bobert"
$ app
// "pacak"

Examples found in repository ?

examples/derive_show_asm.rs (line 64)

≺ ≻↕

fn parse_manifest_path() -> impl Parser<PathBuf> {
    long("manifest-path")
        .help("Path to Cargo.toml")
        .argument::<PathBuf>("PATH")
        .parse(|p| {
            if p.is_absolute() {
                Ok(p)
            } else {
                std::env::current_dir()
                    .map(|d| d.join(p))
                    .and_then(|full_path| full_path.canonicalize())
            }
        })
        .fallback_with(|| std::env::current_dir().map(|x| x.join("Cargo.toml")))
}

#[derive(Debug, Clone, Bpaf)]
pub struct Format {
    /// Print interleaved Rust code
    pub rust: bool,

    #[bpaf(external(color_detection))]
    pub color: bool,

    /// include full demangled name instead of just prefix
    pub full_name: bool,
}

#[derive(Debug, Clone, Bpaf)]
pub enum Syntax {
    /// Generate assembly using Intel style
    Intel,
    /// Generate assembly using AT&T style
    Att,
}

impl ToString for Syntax {
    fn to_string(&self) -> String {
        match self {
            Syntax::Intel => String::from("llvm-args=-x86-asm-syntax=intel"),
            Syntax::Att => String::from("llvm-args=-x86-asm-syntax=att"),
        }
    }
}

fn color_detection() -> impl Parser<bool> {
    let yes = long("color")
        .help("Enable color highlighting")
        .req_flag(true);
    let no = long("no-color")
        .help("Disable color highlighting")
        .req_flag(false);
    construct!([yes, no]).fallback_with::<_, &str>(|| Ok(true))
}

source

fn hide(self) -> ParseHide<Self>where
Self: Sized + Parser<T>,

Ignore this parser during any sort of help generation

Best used for optional parsers or parsers with a defined fallback, usually for implementing backward compatibility or hidden aliases

Combinatoric usage

/// bpaf would accept both `-W` and `-H` flags, but the help message
/// would contain only `-H`
fn rectangle() -> impl Parser<(u32, u32)> {
    let width = short('W')
        .argument::<u32>("PX")
        .fallback(10)
        .hide();
    let height = short('H')
        .argument::<u32>("PX")
        .fallback(10)
        .hide();
    construct!(width, height)
}

Example

$ app -W 12 -H 15
// (12, 15)
$ app -H 333
// (10, 333)
$ app --help
// contains -H but not -W

Derive usage

#[derive(Debug, Clone, Bpaf)]
struct Rectangle {
    #[bpaf(short('W'), argument("PX"), fallback(10), hide)]
    width: u32,
    #[bpaf(short('H'), argument("PX"))]
    height: u32,
}

Example

$ app -W 12 -H 15
// Rectangle { width: 12, height: 15 }
$ app -H 333
// Rectangle { width: 10, height: 333 }
$ app --help
// contains -H but not -W

Examples found in repository ?

examples/find.rs (line 33)

≺ ≻↕

fn user() -> impl Parser<Option<String>> {
    let tag = any::<String>("TAG")
        .guard(|s| s == "-user", "not user")
        .hide();
    let value = positional::<String>("USER");
    construct!(tag, value)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

// parsers -exec xxx yyy zzz ;
fn exec() -> impl Parser<Option<Vec<OsString>>> {
    let tag = any::<String>("-exec")
        .help("-exec /path/to/command flags and options ;")
        .guard(|s| s == "-exec", "not find");
    let item = any::<OsString>("ITEM")
        .guard(|s| s != ";", "not word")
        .many()
        .catch()
        .hide();
    let endtag = any::<String>("END").guard(|s| s == ";", "not eot").hide();
    construct!(tag, item, endtag)
        .anywhere()
        .map(|triple| triple.1)
        .optional()
        .catch()
}

/// parses symbolic permissions `-perm -mode`, `-perm /mode` and `-perm mode`
fn perm() -> impl Parser<Option<Perm>> {
    fn parse_mode(input: &str) -> Result<Perms, String> {
        let mut perms = Perms::default();
        for c in input.chars() {
            match c {
                'r' => perms.read = true,
                'w' => perms.write = true,
                'x' => perms.exec = true,
                _ => return Err(format!("{} is not a valid permission string", input)),
            }
        }
        Ok(perms)
    }

    let tag = any::<String>("-mode").help("-mode (perm | -perm | /perm)");
    let mode = any::<String>("mode")
        .parse::<_, _, String>(|s| {
            if let Some(m) = s.strip_prefix('-') {
                Ok(Perm::All(parse_mode(m)?))
            } else if let Some(m) = s.strip_prefix('/') {
                Ok(Perm::Any(parse_mode(m)?))
            } else {
                Ok(Perm::Exact(parse_mode(&s)?))
            }
        })
        .hide();

    construct!(tag, mode)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

More examples

Hide additional examples

examples/cargo-cmd.rs (line 25)

↕

fn main() {
    // defining a parser in a usual way
    let width = short('w').argument::<usize>("WIDTH").fallback(10);
    let height = short('h').argument::<usize>("HEIGHT").fallback(10);
    let parser = construct!(Opts { width, height });

    let cmd = positional::<String>("")
        .guard(|s| s == "cmd", "")
        .optional()
        .hide();
    let combined_parser = construct!(cmd, parser).map(|x| x.1);

    let opts = combined_parser.to_options().run();

    println!("{:?}", opts);
}

examples/xorg.rs (line 52)

↕

fn extension() -> impl Parser<(String, bool)> {
    let on = any::<String>("+ext")
        .help("enable ext <EXT>")
        .parse::<_, _, String>(|s| {
            if s == "+ext" {
                Ok(true)
            } else {
                Err(String::new())
            }
        });
    let off = any::<String>("-ext")
        .help("disable ext <EXT>")
        .parse::<_, _, String>(|s| {
            if s == "-ext" {
                Ok(false)
            } else {
                Err(String::new())
            }
        });

    let state = construct!([on, off]);
    let name = positional::<String>("EXT").hide();
    construct!(state, name).map(|(a, b)| (b, a)).anywhere()
}

source

fn group_help(self, message: &'static str) -> ParseGroupHelp<Self>where
Self: Sized + Parser<T>,

Attach help message to a complex parser

bpaf inserts the group help message before the block with all the fields from the inner parser and an empty line after the block.

Combinatoric usage

fn rectangle() -> impl Parser<(u32, u32)> {
    let width = short('w')
        .argument::<u32>("PX");
    let height = short('h')
        .argument::<u32>("PX");
    construct!(width, height)
        .group_help("Takes a rectangle")
}

Example

$ app --help
<skip>
            Takes a rectangle
   -w <PX>  Width of the rectangle
   -h <PX>  Height of the rectangle

<skip>

Derive usage

#[derive(Debug, Clone, Bpaf)]
struct Rectangle {
    width: u32,
    height: u32,
}

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(external, group_help("Takes a rectangle"))]
    rectangle: Rectangle
}

Examples found in repository ?

examples/rectangle.rs (line 31)

↕

fn main() {
    let width = short('w')
        .long("width")
        .help("Width of the rectangle")
        .argument::<usize>("PX");

    let height = short('h')
        .long("height")
        .help("Height of the rectangle")
        .argument::<usize>("PX");

    let rect = construct!(Rect { width, height })
        .group_help("Rectangle is defined by width and height in meters")
        .optional();

    let verbose = short('v')
        .long("verbose")
        .help("Print computation steps")
        .switch();

    let opt = construct!(Out { verbose, rect })
        .to_options()
        .descr("This program calculates rectangle's area")
        .header("vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv")
        .footer("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^")
        .run();
    println!("{:#?}", opt);
}

source

fn complete<M, F>(self, op: F) -> ParseComp<Self, F>where
    M: Into<String>,
    F: Fn(&T) -> Vec<(M, Option<M>)>,
    Self: Sized + Parser<T>,

Dynamic shell completion

Allows to generate autocompletion information for shell. Completer places generated input in place of metavar placeholders, so running completer on something that doesn’t have a positional or an argument (or their _os variants) doesn’t make much sense.

Takes a function as a parameter that tries to complete partial input to a full one with optional description. bpaf would substitute current positional item or an argument an empty string if a value isn’t available yet so it’s best to run complete where parsing can’t fail: right after argument or positional, but this isn’t enforced.

bpaf doesn’t support generating OsString completions: bpaf must print completions to console and for non-string values it’s not possible (accurately).

Using this function requires enabling "autocomplete" feature, not enabled by default.

Example

$ app --name L<TAB>
$ app --name Lupusregina _

Combinatoric usage

fn completer(input: &String) -> Vec<(&'static str, Option<&'static str>)> {
    let names = ["Yuri", "Lupusregina", "Solution", "Shizu", "Entoma"];
    names
        .iter()
        .filter(|name| name.starts_with(input))
        .map(|name| (*name, None))
        .collect::<Vec<_>>()
}

fn name() -> impl Parser<String> {
    short('n')
        .long("name")
        .help("Specify character's name")
        .argument::<String>("Name")
        .complete(completer)
}

Derive usage

fn completer(input: &String) -> Vec<(&'static str, Option<&'static str>)> {
    let names = ["Yuri", "Lupusregina", "Solution", "Shizu", "Entoma"];
    names
        .iter()
        .filter(|name| name.starts_with(input))
        .map(|name| (*name, None))
        .collect::<Vec<_>>()
}

#[derive(Debug, Clone, Bpaf)]
struct Options {
    #[bpaf(argument("NAME"), complete(completer))]
    name: String,
}

Examples found in repository ?

examples/csample.rs (line 19)

↕

fn main() {
    use bpaf::*;

    let a = short('a').long("avocado").help("Use avocado").switch();
    let b = short('b').long("banana").help("Use banana").switch();
    let bb = long("bananananana").help("I'm Batman").switch();
    let c = long("calculator")
        .help("calculator expression")
        .argument::<String>("EXPR")
        .complete(complete_calculator);
    let parser = construct!(a, b, bb, c)
        .to_options()
        .descr("Dynamic autocomplete example")
        .footer(
            "\
    bpaf supports dynamic autocompletion for a few shells, make sure your binary is in $PATH
    and try using one of those this output should go into a file that depends on your shell:
    $ csample --bpaf-complete-style-bash
    $ csample --bpaf-complete-style-zsh
    $ csample --bpaf-complete-style-fish
    $ csample --bpaf-complete-style-elvish",
        );

    println!("{:?}", parser.run());
}

source

fn complete_style(self, style: CompleteDecor) -> ParseCompStyle<Self>where
Self: Sized + Parser<T>,

Add extra annotations to completion information

Not all information is gets supported by all the shells

Combinatoric usage

fn opts() -> impl Parser<(bool, bool)> {
    let a = short('a').switch();
    let b = short('b').switch();
    let c = short('c').switch();
    let d = short('d').switch();
    let ab = construct!(a, b).complete_style(CompleteDecor::VisibleGroup("a and b"));
    let cd = construct!(c, d).complete_style(CompleteDecor::VisibleGroup("c and d"));
    construct!([ab, cd])
}

source

fn adjacent(self) -> ParseAdjacent<Self>where
Self: Sized + Parser<T>,

Automagically restrict the inner parser scope to accept adjacent values only

adjacent can solve surprisingly wide variety of problems: sequential command chaining, multi-value arguments, option-structs to name a few. If you want to run a parser on a sequential subset of arguments - adjacent might be able to help you. Check the examples for better intuition.

Multi-value arguments

Parsing things like --foo ARG1 ARG2 ARG3

Combinatoric usage

#[derive(Debug, Clone)]
pub struct Options {
    multi: Vec<Multi>,
    switch: bool,
}

#[derive(Debug, Clone)]
struct Multi {
    m: (),
    val_1: usize,
    val_2: usize,
    val_3: f64,
}

fn multi() -> impl Parser<Multi> {
    let m = short('m').req_flag(());
    let val_1 = positional::<usize>("V1");
    let val_2 = positional::<usize>("V2");
    let val_3 = positional::<f64>("V3");
    construct!(Multi {
        m,
        val_1,
        val_2,
        val_3
    })
    .adjacent()
}

pub fn options() -> OptionParser<Options> {
    let switch = short('s').switch();
    let multi = multi().many();
    construct!(Options { multi, switch }).to_options()
}

Derive usage

#[derive(Debug, Clone, Bpaf)]
#[bpaf(options)]
pub struct Options {
    #[bpaf(external, many)]
    multi: Vec<Multi>,
    #[bpaf(short)]
    switch: bool,
}

#[derive(Debug, Clone, Bpaf)]
#[bpaf(adjacent)]
struct Multi {
    m: (),
    #[bpaf(positional("V1"))]
    val_1: usize,
    #[bpaf(positional("V2"))]
    val_2: usize,
    #[bpaf(positional("V3"))]
    val_3: f64,
}

Examples

short flag -m takes 3 positional arguments: two integers and one floating point, order is important, switch -s can go on either side of it

% app -s -m 10 20 3.1415
Options { multi: [Multi { m: (), val_1: 10, val_2: 20, val_3: 3.1415 }], switch: true }

parser accepts multiple groups of -m - they must not interleave

% app -s -m 10 20 3.1415 -m 1 2 0.0
Options { multi: [Multi { m: (), val_1: 10, val_2: 20, val_3: 3.1415 }, Multi { m: (), val_1: 1, val_2: 2, val_3: 0.0 }], switch: true }

-s can’t go in the middle

% app -m 10 20 -s 3.1415
-m is not expected in this context

Structure groups

Parsing things like --foo --foo-1 ARG1 --foo-2 ARG2 --foo-3 ARG3

Combinatoric usage

#[derive(Debug, Clone)]
pub struct Options {
    switch: bool,
    multi: Vec<Rect>,
}

#[derive(Debug, Clone)]
struct Rect {
    item: (),
    width: usize,
    height: usize,
    painted: bool,
}

fn multi() -> impl Parser<Rect> {
    let item = long("rect").req_flag(());
    let width = long("width").argument::<usize>("PX");
    let height = long("height").argument::<usize>("PX");
    let painted = long("painted").switch();
    construct!(Rect {
        item,
        width,
        height,
        painted,
    })
    .adjacent()
}

pub fn options() -> OptionParser<Options> {
    let switch = short('s').switch();
    let multi = multi().many();
    construct!(Options { multi, switch }).to_options()
}

Examples

Order of items within the rectangle is not significant and you can have several of them

% app --rect --width 10 --height 10 --rect --height 10 --width 10
Options { switch: false, multi: [Rect { item: (), width: 10, height: 10, painted: false }, Rect { item: (), width: 10, height: 10, painted: false }] }

You can have optional values that belong to the group inside and outer flags in the middle

% app --rect --width 10 --painted --height 10 -s --rect --height 10 --width 10
Options { switch: true, multi: [Rect { item: (), width: 10, height: 10, painted: true }, Rect { item: (), width: 10, height: 10, painted: false }] }

But with adjacent they cannot interleave

% app --rect --rect --width 10 --painted --height 10 --height 10 --width 10
--rect is not expected in this context

Chaining commands

Parsing things like cmd1 --arg1 cmd2 --arg2 --arg3 cmd3 --flag

Combinatoric usage

#[derive(Debug, Clone)]
pub struct Options {
    switch: bool,
    commands: Vec<Cmd>,
}

#[derive(Debug, Clone)]
enum Cmd {
    Eat(String),
    Drink(bool),
    Sleep(usize),
}

fn cmd() -> impl Parser<Cmd> {
    let eat = positional::<String>("FOOD")
        .to_options()
        .command("eat")
        .adjacent()
        .map(Cmd::Eat);

    let drink = long("coffee")
        .switch()
        .to_options()
        .command("drink")
        .adjacent()
        .map(Cmd::Drink);

    let sleep = long("time")
        .argument::<usize>("HOURS")
        .to_options()
        .command("sleep")
        .adjacent()
        .map(Cmd::Sleep);

    construct!([eat, drink, sleep])
}

pub fn options() -> OptionParser<Options> {
    let switch = short('s').switch();
    let commands = cmd().many();
    construct!(Options { commands, switch }).to_options()
}

Examples

You can chain one or more commands, commands can be arbitrarily nested too

% app eat fastfood drink --coffee sleep --time=5
Options { switch: false, commands: [Eat("fastfood"), Drink(true), Sleep(5)] }

You can pass other flags after all the commands but not in between them since commands are treated as positionals. It should be possible to consume items before and between commands as well if they are consumed before the commands like this: construct!(Options { switch, commands }) but in that case you need to be careful about not consuming anything from the command themselves.

% app sleep --time 10 eat "Bak Kut Teh" drink -s
Options { switch: true, commands: [Sleep(10), Eat("Bak Kut Teh"), Drink(false)] }

Start and end markers

Parsing things like find . --exec foo {} -bar ; --more

Combinatoric usage

#[derive(Debug, Clone)]
pub struct Options {
    switch: bool,
    exec: Vec<OsString>,
}

fn exec() -> impl Parser<Vec<OsString>> {
    let start = long("exec").req_flag(());
    let body = any::<OsString>("EXEC")
        .guard(|s| s != ";", "end marker")
        .many()
        .catch();
    let end = any::<OsString>("TAIL").guard(|s| s == ";", "end marker");
    construct!(start, body, end).adjacent().map(|x| x.1)
}

pub fn options() -> OptionParser<Options> {
    let switch = short('s').switch();
    let exec = exec();
    construct!(Options { exec, switch }).to_options()
}

Examples

You can have as many items between --exec and ; as you want, they all will be captured inside the exec vector. Extra options can go either before or after the block.

% app --exec foo --bar ; -s
Options { switch: true, exec: ["foo", "--bar"] }

Multi-value arguments with optional flags

Parsing things like --foo ARG1 --flag --inner ARG2

So you can parse things while parsing things. Not sure why you might need this, but you can :)

Combinatoric usage

#[derive(Debug, Clone)]
pub struct Options {
    multi: Vec<Multi>,
    switch: bool,
}

#[derive(Debug, Clone)]
struct Multi {
    m: (),
    pos: usize,
    flag: bool,
    arg: Option<usize>,
}

/// You can mix all sorts of things inside the adjacent group
fn multi() -> impl Parser<Multi> {
    let m = short('m').req_flag(());
    let pos = positional::<usize>("POS");
    let arg = long("arg").argument::<usize>("ARG").optional();
    let flag = long("flag").switch();
    construct!(Multi { m, arg, flag, pos }).adjacent()
}

pub fn options() -> OptionParser<Options> {
    let switch = short('s').switch();
    let multi = multi().many();
    construct!(Options { multi, switch }).to_options()
}

Examples

Let’s start simple - a single flag accepts a bunch of stuff, and eveything is present

% app -m 330 --arg 10 --flag
Options { multi: [Multi { m: (), pos: 330, flag: true, arg: Some(10) }], switch: false }

You can omit some parts, but also have multiple groups thank to many

% app -m 100 --flag    -m 30 --arg 10    -m 50
Options { multi: [Multi { m: (), pos: 100, flag: true, arg: None }, Multi { m: (), pos: 30, flag: false, arg: Some(10) }, Multi { m: (), pos: 50, flag: false, arg: None }], switch: false }

Performance and other considerations

bpaf can run adjacently restricted parsers multiple times to refine the guesses. It’s best not to have complex inter-fields verification since they might trip up the detection logic: instead of destricting, for example “sum of two fields to be 5 or greater” inside the adjacent parser, you can restrict it outside, once adjacent done the parsing.

adjacent is available on a trait for better discoverability, it doesn’t make much sense to use it on something other than command or construct! encasing several fields.

There’s also similar method adjacent that allows to restrict argument parser to work only for arguments where both key and a value are in the same shell word: -f=bar or -fbar, but not -f bar.

Examples found in repository ?

examples/sensors.rs (line 49)

↕

fn opts() -> Opts {
    let sensor = long("sensor").req_flag(());
    let device = long("sensor-device").argument::<String>("DEVICE");
    let name = long("sensor-name").argument::<String>("NAME");

    // from_str needs to be replaced with `parse` that can deal with hex digits
    let bus_id = long("sensor-i2c-bus").argument::<usize>("BUS");
    let address = long("sensor-i2c-address").argument::<usize>("ADDRESS");
    let sensors = construct!(Sensor {
        sensor,
        device,
        name,
        bus_id,
        address
    })
    .adjacent()
    .many();
    construct!(Opts { sensors }).to_options().run()
}

source

fn anywhere(self) -> ParseAnywhere<Self>where
Self: Sized + Parser<T>,

Parse anywhere

Most generic escape hatch available, in combination with any allows to parse anything anywhere, works by repeatedly trying to run the inner parser on each subsequent context. Can be expensive performance wise especially if parser contains complex logic.

Combinatoric usage

#[derive(Debug, Clone)]
pub struct Options {
    turbo: bool,
    backing: bool,
    xinerama: bool,
}

fn toggle_options(name: &'static str, help: &'static str) -> impl Parser<bool> {
    any::<String>(name)
        .help(help)
        .parse(move |s| {
            let (state, cur_name) = if let Some(rest) = s.strip_prefix('+') {
                (true, rest)
            } else if let Some(rest) = s.strip_prefix('-') {
                (false, rest)
            } else {
                return Err(format!("{} is not a toggle option", s));
            };
            if cur_name != name {
                Err(format!("{} is not a known toggle option name", cur_name))
            } else {
                Ok(state)
            }
        })
        .anywhere()
}

pub fn options() -> OptionParser<Options> {
    let backing = toggle_options("backing", "Backing status").fallback(false);
    let xinerama = toggle_options("xinerama", "Xinerama status").fallback(true);
    let turbo = short('t')
        .long("turbo")
        .help("Engage the turbo mode")
        .switch();
    construct!(Options {
        turbo,
        backing,
        xinerama,
    })
    .to_options()
}

Examples

This example shows how to parse some very unusual options, same style as used by Xorg -backing disables backing +backing enables it, usual restrictions and combinations apply: fails if present more than once, can be further transformed with combinators. By default xinerama is enabled, anything else is disabled

% app 
Options { turbo: false, backing: false, xinerama: true }

Strange things we added can be mixed with the regular options

% app --turbo +backing -xinerama
Options { turbo: true, backing: true, xinerama: false }

As expected - order doesn’t matter

% app +backing --turbo
Options { turbo: true, backing: true, xinerama: true }

–help will try to render it but you can always .hide it and add your own lines with .header or .footer methods on OptionParser.

% app --help
Usage: [-t] [<backing>] [<xinerama>]

Available positional items:
    <backing>   Backing status
    <xinerama>  Xinerama status

Available options:
    -t, --turbo  Engage the turbo mode
    -h, --help   Prints help information

Examples found in repository ?

examples/find.rs (line 36)

≺ ≻↕

fn user() -> impl Parser<Option<String>> {
    let tag = any::<String>("TAG")
        .guard(|s| s == "-user", "not user")
        .hide();
    let value = positional::<String>("USER");
    construct!(tag, value)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

// parsers -exec xxx yyy zzz ;
fn exec() -> impl Parser<Option<Vec<OsString>>> {
    let tag = any::<String>("-exec")
        .help("-exec /path/to/command flags and options ;")
        .guard(|s| s == "-exec", "not find");
    let item = any::<OsString>("ITEM")
        .guard(|s| s != ";", "not word")
        .many()
        .catch()
        .hide();
    let endtag = any::<String>("END").guard(|s| s == ";", "not eot").hide();
    construct!(tag, item, endtag)
        .anywhere()
        .map(|triple| triple.1)
        .optional()
        .catch()
}

/// parses symbolic permissions `-perm -mode`, `-perm /mode` and `-perm mode`
fn perm() -> impl Parser<Option<Perm>> {
    fn parse_mode(input: &str) -> Result<Perms, String> {
        let mut perms = Perms::default();
        for c in input.chars() {
            match c {
                'r' => perms.read = true,
                'w' => perms.write = true,
                'x' => perms.exec = true,
                _ => return Err(format!("{} is not a valid permission string", input)),
            }
        }
        Ok(perms)
    }

    let tag = any::<String>("-mode").help("-mode (perm | -perm | /perm)");
    let mode = any::<String>("mode")
        .parse::<_, _, String>(|s| {
            if let Some(m) = s.strip_prefix('-') {
                Ok(Perm::All(parse_mode(m)?))
            } else if let Some(m) = s.strip_prefix('/') {
                Ok(Perm::Any(parse_mode(m)?))
            } else {
                Ok(Perm::Exact(parse_mode(&s)?))
            }
        })
        .hide();

    construct!(tag, mode)
        .anywhere()
        .map(|pair| pair.1)
        .optional()
        .catch()
}

More examples

Hide additional examples

examples/dd.rs (line 28)

↕

fn tag<T>(name: &'static str, meta: &'static str, help: &'static str) -> impl Parser<T>
where
    T: FromStr,
    <T as std::str::FromStr>::Err: std::fmt::Display,
{
    // it is possible to parse OsString here and strip the prefix with os_str_bytes or a similar
    // crate
    any::<String>(meta)
        .help(help)
        .parse::<_, _, String>(move |s| match s.strip_prefix(name) {
            None => Err("Wrong tag".to_string()),
            Some(body) => T::from_str(body).map_err(|e| e.to_string()),
        })
        .anywhere()
}

examples/xorg.rs (line 28)

≺ ≻↕

fn toggle_options(name: &'static str, help: &'static str) -> impl Parser<bool> {
    any::<String>(name)
        .help(help)
        .parse(move |s| {
            let (state, cur_name) = if let Some(rest) = s.strip_prefix('+') {
                (true, rest)
            } else if let Some(rest) = s.strip_prefix('-') {
                (false, rest)
            } else {
                return Err(format!("{} is not a toggle option", s));
            };
            if cur_name != name {
                Err(format!("{} is not a known toggle option name", cur_name))
            } else {
                Ok(state)
            }
        })
        .anywhere()
}

fn extension() -> impl Parser<(String, bool)> {
    let on = any::<String>("+ext")
        .help("enable ext <EXT>")
        .parse::<_, _, String>(|s| {
            if s == "+ext" {
                Ok(true)
            } else {
                Err(String::new())
            }
        });
    let off = any::<String>("-ext")
        .help("disable ext <EXT>")
        .parse::<_, _, String>(|s| {
            if s == "-ext" {
                Ok(false)
            } else {
                Err(String::new())
            }
        });

    let state = construct!([on, off]);
    let name = positional::<String>("EXT").hide();
    construct!(state, name).map(|(a, b)| (b, a)).anywhere()
}

source

fn to_options(self) -> OptionParser<T>where
Self: Sized + Parser<T> + 'static,

Transform Parser into OptionParser to attach metadata and run

Combinatoric usage

fn parser() -> impl Parser<u32> {
    short('i')
        .argument::<u32>("ARG")
}

fn option_parser() -> OptionParser<u32> {
    parser()
        .to_options()
        .version("3.1415")
        .descr("This is a description")
}

See OptionParser for more methods available after conversion.

Derive usage

Add a top level options annotation to generate OptionParser instead of default Parser.

In addition to options annotation you can also specify either version or version(value) annotation. Former uses version from cargo, later uses the specified value which should be an expression of type &'static str, see version.

#[derive(Debug, Clone, Bpaf)]
#[bpaf(options, version("3.1415"))]
/// This is a description
struct Options {
   verbose: bool,
}

Example

$ app --version
// Version: 3.1415
$ app --help
<skip>
This is a description
<skip>

Examples found in repository ?

examples/enum_in_args.rs (line 34)

fn main() {
    let opt = long("baz")
        .short('b')
        .help("choose between foo, bar or foobar")
        .argument::<Baz>("CMD")
        .to_options()
        .run();

    println!("{:#?}", opt);
}

More examples

Hide additional examples

examples/dd.rs (line 57)

pub fn options() -> OptionParser<Options> {
    let magic = long("magic").switch();
    construct!(Options {
        magic,
        in_file(),
        out_file(),
        block_size(),
    })
    .to_options()
}

examples/find.rs (line 104)

pub fn options() -> OptionParser<Options> {
    let paths = positional::<PathBuf>("PATH").many();

    construct!(Options {
        exec(),
        user(),
        perm(),
        paths,
    })
    .to_options()
}

examples/at_least_two.rs (line 12)

fn main() {
    let opt = short('f')
        .req_flag(())
        .many()
        .guard(|x| x.len() >= 2, "at least two arguments are required")
        .to_options()
        .run();

    println!("{:?}", opt);
}

examples/env_variable.rs (line 17)

pub fn main() {
    let key = long("key")
        .env("ACCESS_KEY")
        .help("access key to use")
        .argument::<String>("KEY");

    let opts = construct!(Opts { key }).to_options().run();

    println!("{:?}", opts);
}

examples/ex_positional.rs (line 18)

fn main() {
    let value = long("value")
        .help("Mysterious value")
        .argument::<u32>("VAL")
        .fallback(42);
    let files = positional::<PathBuf>("FILE").many();
    let opts = construct!(Options { value, files }).to_options().run();

    println!("{:#?}", opts);
}

Additional examples can be found in:

Implementors

source

Trait bpaf::Parser

Provided Methods

fn many(self) -> ParseMany<Self>where Self: Sized,

fn some(self, message: &'static str) -> ParseSome<Self>where Self: Sized + Parser<T>,

fn optional(self) -> ParseOptional<Self>where Self: Sized + Parser<T>,

fn parse<F, R, E>(self, f: F) -> ParseWith<T, Self, F, E, R>where Self: Sized + Parser<T>, F: Fn(T) -> Result<R, E>, E: ToString,

fn map<F, R>(self, map: F) -> ParseMap<T, Self, F, R>where Self: Sized + Parser<T>, F: Fn(T) -> R + 'static,

fn guard<F>(self, check: F, message: &'static str) -> ParseGuard<Self, F>where Self: Sized + Parser<T>, F: Fn(&T) -> bool,

fn fallback(self, value: T) -> ParseFallback<Self, T>where Self: Sized + Parser<T>,

fn fallback_with<F, E>(self, fallback: F) -> ParseFallbackWith<T, Self, F, E>where Self: Sized + Parser<T>, F: Fn() -> Result<T, E>, E: ToString,

fn hide(self) -> ParseHide<Self>where Self: Sized + Parser<T>,

fn group_help(self, message: &'static str) -> ParseGroupHelp<Self>where Self: Sized + Parser<T>,

fn complete<M, F>(self, op: F) -> ParseComp<Self, F>where M: Into<String>, F: Fn(&T) -> Vec<(M, Option<M>)>, Self: Sized + Parser<T>,

fn complete_style(self, style: CompleteDecor) -> ParseCompStyle<Self>where Self: Sized + Parser<T>,

fn adjacent(self) -> ParseAdjacent<Self>where Self: Sized + Parser<T>,

fn anywhere(self) -> ParseAnywhere<Self>where Self: Sized + Parser<T>,

fn to_options(self) -> OptionParser<T>where Self: Sized + Parser<T> + 'static,

Implementors

impl<O, T> Parser<O> for ParseArgument<T>where T: FromOsStr<Out = O>,

impl<O, T> Parser<O> for ParsePositional<T>where T: FromOsStr<Out = O>,

impl<T> Parser<T> for ParseCommand<T>

impl<T> Parser<T> for ParseBox<T>

impl<T, O> Parser<O> for ParseAny<T>where T: FromOsStr<Out = O>,

impl<T, P> Parser<Option<T>> for ParseOptional<P>where P: Parser<T>,

impl<T, P> Parser<Vec<T, Global>> for ParseMany<P>where P: Parser<T>,

impl<T, P> Parser<Vec<T, Global>> for ParseSome<P>where P: Parser<T>,

fn many(self) -> ParseMany<Self>where
Self: Sized,

fn some(self, message: &'static str) -> ParseSome<Self>where
Self: Sized + Parser<T>,

fn optional(self) -> ParseOptional<Self>where
Self: Sized + Parser<T>,

fn parse<F, R, E>(self, f: F) -> ParseWith<T, Self, F, E, R>where
Self: Sized + Parser<T>,
F: Fn(T) -> Result<R, E>,
E: ToString,

fn map<F, R>(self, map: F) -> ParseMap<T, Self, F, R>where
Self: Sized + Parser<T>,
F: Fn(T) -> R + 'static,

fn guard<F>(self, check: F, message: &'static str) -> ParseGuard<Self, F>where
Self: Sized + Parser<T>,
F: Fn(&T) -> bool,

fn fallback(self, value: T) -> ParseFallback<Self, T>where
Self: Sized + Parser<T>,

fn fallback_with<F, E>(self, fallback: F) -> ParseFallbackWith<T, Self, F, E>where
Self: Sized + Parser<T>,
F: Fn() -> Result<T, E>,
E: ToString,

fn hide(self) -> ParseHide<Self>where
Self: Sized + Parser<T>,

fn group_help(self, message: &'static str) -> ParseGroupHelp<Self>where
Self: Sized + Parser<T>,

fn complete<M, F>(self, op: F) -> ParseComp<Self, F>where
M: Into<String>,
F: Fn(&T) -> Vec<(M, Option<M>)>,
Self: Sized + Parser<T>,

fn complete_style(self, style: CompleteDecor) -> ParseCompStyle<Self>where
Self: Sized + Parser<T>,

fn adjacent(self) -> ParseAdjacent<Self>where
Self: Sized + Parser<T>,

fn anywhere(self) -> ParseAnywhere<Self>where
Self: Sized + Parser<T>,

fn to_options(self) -> OptionParser<T>where
Self: Sized + Parser<T> + 'static,

impl<O, T> Parser<O> for ParseArgument<T>where
T: FromOsStr<Out = O>,

impl<O, T> Parser<O> for ParsePositional<T>where
T: FromOsStr<Out = O>,

impl<T, O> Parser<O> for ParseAny<T>where
T: FromOsStr<Out = O>,

impl<T, P> Parser<Option<T>> for ParseOptional<P>where
P: Parser<T>,

impl<T, P> Parser<Vec<T, Global>> for ParseMany<P>where
P: Parser<T>,

impl<T, P> Parser<Vec<T, Global>> for ParseSome<P>where
P: Parser<T>,