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// Copyright 2018 Guillaume Pinot (@TeXitoi) <texitoi@texitoi.eu> // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![deny(missing_docs)] //! This crate defines the `StructOpt` trait and its custom derive. //! //! ## Features //! //! If you want to disable all the `clap` features (colors, //! suggestions, ..) add `default-features = false` to the `structopt` //! dependency: //! //! ```toml //! [dependencies] //! structopt = { version = "0.2", default-features = false } //! ``` //! //! //! Support for [`paw`](https://github.com/rust-cli/paw) (the //! `Command line argument paw-rser abstraction for main`) is disabled //! by default, but can be enabled in the `structopt` dependency //! with the feature `paw`: //! //! ```toml //! [dependencies] //! structopt = { version = "0.2", features = [ "paw" ] } //! paw = "1.0" //! ``` //! //! ## How to `derive(StructOpt)` //! //! First, let's look at an example: //! //! ```should_panic //! #[macro_use] //! extern crate structopt; //! //! use std::path::PathBuf; //! use structopt::StructOpt; //! //! #[derive(Debug, StructOpt)] //! #[structopt(name = "example", about = "An example of StructOpt usage.")] //! struct Opt { //! /// Activate debug mode //! #[structopt(short = "d", long = "debug")] //! debug: bool, //! /// Set speed //! #[structopt(short = "s", long = "speed", default_value = "42")] //! speed: f64, //! /// Input file //! #[structopt(parse(from_os_str))] //! input: PathBuf, //! /// Output file, stdout if not present //! #[structopt(parse(from_os_str))] //! output: Option<PathBuf>, //! } //! //! fn main() { //! let opt = Opt::from_args(); //! println!("{:?}", opt); //! } //! ``` //! //! So `derive(StructOpt)` tells Rust to generate a command line parser, //! and the various `structopt` attributes are simply //! used for additional parameters. //! //! First, define a struct, whatever its name. This structure will //! correspond to a `clap::App`. Every method of `clap::App` in the //! form of `fn function_name(self, &str)` can be used through attributes //! placed on the struct. In our example above, the `about` attribute //! will become an `.about("An example of StructOpt usage.")` call on the //! generated `clap::App`. There are a few attributes that will default //! if not specified: //! //! - `name`: The binary name displayed in help messages. Defaults //! to the crate name given by Cargo. //! - `version`: Defaults to the crate version given by Cargo. //! - `author`: Defaults to the crate author name given by Cargo. //! - `about`: Defaults to the crate description given by Cargo. //! //! Methods from `clap::App` that don't take an `&str` can be called by //! wrapping them in `raw()`, e.g. to activate colored help text: //! //! ``` //! #[macro_use] //! extern crate structopt; //! //! use structopt::StructOpt; //! //! #[derive(StructOpt, Debug)] //! #[structopt(raw(setting = "structopt::clap::AppSettings::ColoredHelp"))] //! struct Opt { //! #[structopt(short = "s")] //! speed: bool, //! #[structopt(short = "d")] //! debug: bool, //! } //! # fn main() {} //! ``` //! //! Then, each field of the struct not marked as a subcommand corresponds //! to a `clap::Arg`. As with the struct attributes, every method of //! `clap::Arg` in the form of `fn function_name(self, &str)` can be used //! through specifying it as an attribute. The `name` attribute can be used //! to customize the `Arg::with_name()` call (defaults to the field name in //! kebab-case). //! For functions that do not take a `&str` as argument, the attribute can be //! wrapped in `raw()`, e. g. `raw(aliases = r#"&["alias"]"#, next_line_help = "true")`. //! //! The type of the field gives the kind of argument: //! //! Type | Effect | Added method call to `clap::Arg` //! -----------------------------|---------------------------------------------------|-------------------------------------- //! `bool` | `true` if the flag is present | `.takes_value(false).multiple(false)` //! `Option<T: FromStr>` | optional positional argument or option | `.takes_value(true).multiple(false)` //! `Option<Option<T: FromStr>>` | optional option with optional value | `.takes_value(true).multiple(false).min_values(0).max_values(1)` //! `Vec<T: FromStr>` | list of options or the other positional arguments | `.takes_value(true).multiple(true)` //! `T: FromStr` | required option or positional argument | `.takes_value(true).multiple(false).required(!has_default)` //! //! The `FromStr` trait is used to convert the argument to the given //! type, and the `Arg::validator` method is set to a method using //! `to_string()` (`FromStr::Err` must implement `std::fmt::Display`). //! If you would like to use a custom string parser other than `FromStr`, see //! the [same titled section](#custom-string-parsers) below. //! //! Thus, the `speed` argument is generated as: //! //! ``` //! # extern crate clap; //! # fn parse_validator<T>(_: String) -> Result<(), String> { unimplemented!() } //! # fn main() { //! clap::Arg::with_name("speed") //! .takes_value(true) //! .multiple(false) //! .required(false) //! .validator(parse_validator::<f64>) //! .short("s") //! .long("speed") //! .help("Set speed") //! .default_value("42"); //! # } //! ``` //! //! ## Specifying argument types //! //! There are three types of arguments that can be supplied to each //! (sub-)command: //! //! - short (e.g. `-h`), //! - long (e.g. `--help`) //! - and positional. //! //! Like clap, structopt defaults to creating positional arguments. //! //! If you want to generate a long argument you can specify either //! `long = $NAME`, or just `long` to get a long flag generated using //! the field name. The generated casing style can be modified using //! the `rename_all` attribute. See the `rename_all` example for more. //! //! For short arguments, `short` will use the first letter of the //! field name by default, but just like the long option it's also //! possible to use a custom letter through `short = $LETTER`. //! //! If an argument is renamed using `name = $NAME` any following call to //! `short` or `long` will use the new name. //! //! ``` //! #[macro_use] //! extern crate structopt; //! //! use structopt::StructOpt; //! //! #[derive(StructOpt)] //! #[structopt(rename_all = "kebab-case")] //! struct Opt { //! /// This option can be specified with something like `--foo-option //! /// value` or `--foo-option=value` //! #[structopt(long)] //! foo_option: String, //! //! /// This option can be specified with something like `-b value` (but //! /// not `--bar-option value`). //! #[structopt(short)] //! bar_option: String, //! //! /// This option can be specified either `--baz value` or `-z value`. //! #[structopt(short = "z", long = "baz")] //! baz_option: String, //! //! /// This option can be specified either by `--custom value` or //! /// `-c value`. //! #[structopt(name = "custom", long, short)] //! custom_option: String, //! //! /// This option is positional, meaning it is the first unadorned string //! /// you provide (multiple others could follow). //! my_positional: String, //! } //! //! # fn main() { //! # Opt::from_clap(&Opt::clap().get_matches_from( //! # &["test", "--foo-option", "", "-b", "", "--baz", "", "--custom", "", "positional"])); //! # } //! ``` //! //! ## Help messages //! //! Help messages for the whole binary or individual arguments can be //! specified using the `about` attribute on the struct and the `help` //! attribute on the field, as we've already seen. For convenience, //! they can also be specified using doc comments. For example: //! //! ``` //! # #[macro_use] extern crate structopt; //! #[derive(StructOpt)] //! #[structopt(name = "foo")] //! /// The help message that will be displayed when passing `--help`. //! struct Foo { //! #[structopt(short = "b")] //! /// The description for the arg that will be displayed when passing `--help`. //! bar: String //! } //! # fn main() {} //! ``` //! //! If it is necessary or wanted to provide a more complex help message then the //! previous used ones, it could still be a good idea to distinguish between the //! actual help message a short summary. In this case `about` and `help` should //! only contain the short and concise form while the two additional arguments //! `long_about` and `long_help` can be used to store a descriptive and more in //! depth message. //! //! If both - the short and the long version of the argument - are present, //! the user can later chose between the short summary (`-h`) and the long //! descriptive version (`--help`) of the help message. Also in case //! of subcommands the short help message will automatically be used for the //! command description inside the parents help message and the long version //! as command description if help is requested on the actual subcommand. //! //! This feature can also be used with doc comments instead of arguments through //! proper comment formatting. To be activated it requires, that the first line //! of the comment is separated from the rest of the comment through an empty line. //! In this case the first line is used as summary and the whole comment represents //! the long descriptive message. //! //! ``` //! # #[macro_use] extern crate structopt; //! #[derive(StructOpt)] //! #[structopt(name = "foo")] //! /// The help message that will be displayed when passing `--help`. //! struct Foo { //! #[structopt(short = "b")] //! /// Only this summary is visible when passing `-h`. //! /// //! /// But the whole comment will be displayed when passing `--help`. //! /// This could be quite useful to provide further hints are usage //! /// examples. //! bar: String //! } //! # fn main() {} //! ``` //! //! ## Subcommands //! //! Some applications, especially large ones, split their functionality //! through the use of "subcommands". Each of these act somewhat like a separate //! command, but is part of the larger group. //! One example is `git`, which has subcommands such as `add`, `commit`, //! and `clone`, to mention just a few. //! //! `clap` has this functionality, and `structopt` supports it through enums: //! //! ``` //! # #[macro_use] extern crate structopt; //! # use std::path::PathBuf; //! #[derive(StructOpt)] //! #[structopt(name = "git", about = "the stupid content tracker")] //! enum Git { //! #[structopt(name = "add")] //! Add { //! #[structopt(short = "i")] //! interactive: bool, //! #[structopt(short = "p")] //! patch: bool, //! #[structopt(parse(from_os_str))] //! files: Vec<PathBuf> //! }, //! #[structopt(name = "fetch")] //! Fetch { //! #[structopt(long = "dry-run")] //! dry_run: bool, //! #[structopt(long = "all")] //! all: bool, //! repository: Option<String> //! }, //! #[structopt(name = "commit")] //! Commit { //! #[structopt(short = "m")] //! message: Option<String>, //! #[structopt(short = "a")] //! all: bool //! } //! } //! # fn main() {} //! ``` //! //! Using `derive(StructOpt)` on an enum instead of a struct will produce //! a `clap::App` that only takes subcommands. So `git add`, `git fetch`, //! and `git commit` would be commands allowed for the above example. //! //! `structopt` also provides support for applications where certain flags //! need to apply to all subcommands, as well as nested subcommands: //! //! ``` //! # #[macro_use] extern crate structopt; //! # fn main() {} //! #[derive(StructOpt)] //! #[structopt(name = "make-cookie")] //! struct MakeCookie { //! #[structopt(name = "supervisor", default_value = "Puck", long = "supervisor")] //! supervising_faerie: String, //! #[structopt(name = "tree")] //! /// The faerie tree this cookie is being made in. //! tree: Option<String>, //! #[structopt(subcommand)] // Note that we mark a field as a subcommand //! cmd: Command //! } //! //! #[derive(StructOpt)] //! enum Command { //! #[structopt(name = "pound")] //! /// Pound acorns into flour for cookie dough. //! Pound { //! acorns: u32 //! }, //! #[structopt(name = "sparkle")] //! /// Add magical sparkles -- the secret ingredient! //! Sparkle { //! #[structopt(short = "m", parse(from_occurrences))] //! magicality: u64, //! #[structopt(short = "c")] //! color: String //! }, //! #[structopt(name = "finish")] //! Finish(Finish), //! } //! //! // Subcommand can also be externalized by using a 1-uple enum variant //! #[derive(StructOpt)] //! struct Finish { //! #[structopt(short = "t")] //! time: u32, //! #[structopt(subcommand)] // Note that we mark a field as a subcommand //! finish_type: FinishType //! } //! //! // subsubcommand! //! #[derive(StructOpt)] //! enum FinishType { //! #[structopt(name = "glaze")] //! Glaze { //! applications: u32 //! }, //! #[structopt(name = "powder")] //! Powder { //! flavor: String, //! dips: u32 //! } //! } //! ``` //! //! Marking a field with `structopt(subcommand)` will add the subcommands of the //! designated enum to the current `clap::App`. The designated enum *must* also //! be derived `StructOpt`. So the above example would take the following //! commands: //! //! + `make-cookie pound 50` //! + `make-cookie sparkle -mmm --color "green"` //! + `make-cookie finish 130 glaze 3` //! //! ### Optional subcommands //! //! A nested subcommand can be marked optional: //! //! ``` //! # #[macro_use] extern crate structopt; //! # fn main() {} //! #[derive(StructOpt)] //! #[structopt(name = "foo")] //! struct Foo { //! file: String, //! #[structopt(subcommand)] //! cmd: Option<Command> //! } //! //! #[derive(StructOpt)] //! enum Command { //! Bar, //! Baz, //! Quux //! } //! ``` //! //! ## Flattening //! //! It can sometimes be useful to group related arguments in a substruct, //! while keeping the command-line interface flat. In these cases you can mark //! a field as `flatten` and give it another type that derives `StructOpt`: //! //! ``` //! # #[macro_use] extern crate structopt; //! # use structopt::StructOpt; //! # fn main() {} //! #[derive(StructOpt)] //! struct Cmdline { //! #[structopt(short = "v", help = "switch on verbosity")] //! verbose: bool, //! #[structopt(flatten)] //! daemon_opts: DaemonOpts, //! } //! //! #[derive(StructOpt)] //! struct DaemonOpts { //! #[structopt(short = "u", help = "daemon user")] //! user: String, //! #[structopt(short = "g", help = "daemon group")] //! group: String, //! } //! ``` //! //! In this example, the derived `Cmdline` parser will support the options `-v`, //! `-u` and `-g`. //! //! This feature also makes it possible to define a `StructOpt` struct in a //! library, parse the corresponding arguments in the main argument parser, and //! pass off this struct to a handler provided by that library. //! //! ## Custom string parsers //! //! If the field type does not have a `FromStr` implementation, or you would //! like to provide a custom parsing scheme other than `FromStr`, you may //! provide a custom string parser using `parse(...)` like this: //! //! ``` //! # #[macro_use] extern crate structopt; //! # fn main() {} //! use std::num::ParseIntError; //! use std::path::PathBuf; //! //! fn parse_hex(src: &str) -> Result<u32, ParseIntError> { //! u32::from_str_radix(src, 16) //! } //! //! #[derive(StructOpt)] //! struct HexReader { //! #[structopt(short = "n", parse(try_from_str = "parse_hex"))] //! number: u32, //! #[structopt(short = "o", parse(from_os_str))] //! output: PathBuf, //! } //! ``` //! //! There are five kinds of custom parsers: //! //! | Kind | Signature | Default | //! |-------------------|---------------------------------------|---------------------------------| //! | `from_str` | `fn(&str) -> T` | `::std::convert::From::from` | //! | `try_from_str` | `fn(&str) -> Result<T, E>` | `::std::str::FromStr::from_str` | //! | `from_os_str` | `fn(&OsStr) -> T` | `::std::convert::From::from` | //! | `try_from_os_str` | `fn(&OsStr) -> Result<T, OsString>` | (no default function) | //! | `from_occurrences`| `fn(u64) -> T` | `value as T` | //! //! The `from_occurrences` parser is special. Using `parse(from_occurrences)` //! results in the _number of flags occurrences_ being stored in the relevant //! field or being passed to the supplied function. In other words, it converts //! something like `-vvv` to `3`. This is equivalent to //! `.takes_value(false).multiple(true)`. Note that the default parser can only //! be used with fields of integer types (`u8`, `usize`, `i64`, etc.). //! //! When supplying a custom string parser, `bool` will not be treated specially: //! //! Type | Effect | Added method call to `clap::Arg` //! ------------|-------------------|-------------------------------------- //! `Option<T>` | optional argument | `.takes_value(true).multiple(false)` //! `Vec<T>` | list of arguments | `.takes_value(true).multiple(true)` //! `T` | required argument | `.takes_value(true).multiple(false).required(!has_default)` //! //! In the `try_from_*` variants, the function will run twice on valid input: //! once to validate, and once to parse. Hence, make sure the function is //! side-effect-free. extern crate clap as _clap; #[allow(unused_imports)] #[macro_use] extern crate structopt_derive; #[doc(hidden)] pub use structopt_derive::*; use std::ffi::OsString; /// Re-export of clap pub mod clap { pub use _clap::*; } /// A struct that is converted from command line arguments. pub trait StructOpt { /// Returns the corresponding `clap::App`. fn clap<'a, 'b>() -> clap::App<'a, 'b>; /// Creates the struct from `clap::ArgMatches`. It cannot fail /// with a parameter generated by `clap` by construction. fn from_clap(&clap::ArgMatches) -> Self; /// Gets the struct from the command line arguments. Print the /// error message and quit the program in case of failure. fn from_args() -> Self where Self: Sized, { Self::from_clap(&Self::clap().get_matches()) } /// Gets the struct from any iterator such as a `Vec` of your making. /// Print the error message and quit the program in case of failure. fn from_iter<I>(iter: I) -> Self where Self: Sized, I: IntoIterator, I::Item: Into<OsString> + Clone, { Self::from_clap(&Self::clap().get_matches_from(iter)) } /// Gets the struct from any iterator such as a `Vec` of your making. /// /// Returns a `clap::Error` in case of failure. This does *not* exit in the /// case of `--help` or `--version`, to achieve the same behavior as /// `from_iter()` you must call `.exit()` on the error value. fn from_iter_safe<I>(iter: I) -> Result<Self, clap::Error> where Self: Sized, I: IntoIterator, I::Item: Into<OsString> + Clone, { Ok(Self::from_clap(&Self::clap().get_matches_from_safe(iter)?)) } }