gen/cmd/src/app.rs

#[cfg(test)]
#[path = "test.rs"]
mod test;

use super::{Opt, Output};
use crate::cfg::{self, CfgValue};
use crate::gen::include::Include;
use crate::syntax::IncludeKind;
use clap::builder::{ArgAction, ValueParser};
use clap::{Arg, Command};
use std::collections::{BTreeMap as Map, BTreeSet as Set};
use std::path::PathBuf;
use std::process;
use std::sync::{Arc, Mutex, PoisonError};
use syn::parse::Parser;

const USAGE: &str = "\
    cxxbridge <input>.rs              Emit .cc file for bridge to stdout
    cxxbridge <input>.rs --header     Emit .h file for bridge to stdout
    cxxbridge --header                Emit \"rust/cxx.h\" header to stdout\
";

const TEMPLATE: &str = "\
{bin} {version}
David Tolnay <dtolnay@gmail.com>
https://github.com/dtolnay/cxx

{usage-heading}
    {usage}

{all-args}\
";

fn app() -> Command {
    let mut app = Command::new("cxxbridge")
        .override_usage(USAGE)
        .help_template(TEMPLATE)
        .next_line_help(true)
        .disable_help_flag(true)
        .disable_version_flag(true)
        .arg(arg_input())
        .arg(arg_cfg())
        .arg(arg_cxx_impl_annotations())
        .arg(arg_header())
        .arg(arg_help())
        .arg(arg_include())
        .arg(arg_output());
    if let Some(version) = option_env!("CARGO_PKG_VERSION") {
        app = app.arg(arg_version()).version(version);
    }
    app
}

const INPUT: &str = "input";
const CFG: &str = "cfg";
const CXX_IMPL_ANNOTATIONS: &str = "cxx-impl-annotations";
const HELP: &str = "help";
const HEADER: &str = "header";
const INCLUDE: &str = "include";
const OUTPUT: &str = "output";
const VERSION: &str = "version";

pub(super) fn from_args() -> Opt {
    let matches = app().get_matches();

    if matches.get_flag(HELP) {
        let _ = app().print_long_help();
        process::exit(0);
    }

    let input = matches.get_one::<PathBuf>(INPUT).cloned();
    let cxx_impl_annotations = matches
        .get_one::<String>(CXX_IMPL_ANNOTATIONS)
        .map(String::clone);
    let header = matches.get_flag(HEADER);
    let include = matches
        .get_many::<String>(INCLUDE)
        .unwrap_or_default()
        .map(|include| {
            if include.starts_with('<') && include.ends_with('>') {
                Include {
                    path: include[1..include.len() - 1].to_owned(),
                    kind: IncludeKind::Bracketed,
                }
            } else {
                Include {
                    path: include.clone(),
                    kind: IncludeKind::Quoted,
                }
            }
        })
        .collect();

    let mut outputs = Vec::new();
    for path in matches.get_many::<PathBuf>(OUTPUT).unwrap_or_default() {
        outputs.push(if path.as_os_str() == "-" {
            Output::Stdout
        } else {
            Output::File(path.clone())
        });
    }
    if outputs.is_empty() {
        outputs.push(Output::Stdout);
    }

    let mut cfg = Map::new();
    for arg in matches.get_many::<String>(CFG).unwrap_or_default() {
        let (name, value) = cfg::parse.parse_str(arg).unwrap();
        cfg.entry(name).or_insert_with(Set::new).insert(value);
    }

    Opt {
        input,
        header,
        cxx_impl_annotations,
        include,
        outputs,
        cfg,
    }
}

fn arg_input() -> Arg {
    Arg::new(INPUT)
        .help("Input Rust source file containing #[cxx::bridge].")
        .required_unless_present_any([HEADER, HELP])
        .value_parser(ValueParser::path_buf())
}

fn arg_cfg() -> Arg {
    const HELP: &str = "\
Compilation configuration matching what will be used to build
the Rust side of the bridge.";
    let bool_cfgs = Arc::new(Mutex::new(Map::<String, bool>::new()));
    Arg::new(CFG)
        .long(CFG)
        .num_args(1)
        .value_name("name=\"value\" | name[=true] | name=false")
        .action(ArgAction::Append)
        .value_parser(move |arg: &str| match cfg::parse.parse_str(arg) {
            Ok((_, CfgValue::Str(_))) => Ok(arg.to_owned()),
            Ok((name, CfgValue::Bool(value))) => {
                let mut bool_cfgs = bool_cfgs.lock().unwrap_or_else(PoisonError::into_inner);
                if let Some(&prev) = bool_cfgs.get(&name) {
                    if prev != value {
                        return Err(format!("cannot have both {0}=false and {0}=true", name));
                    }
                }
                bool_cfgs.insert(name, value);
                Ok(arg.to_owned())
            }
            Err(_) => Err("expected name=\"value\", name=true, or name=false".to_owned()),
        })
        .help(HELP)
}

fn arg_cxx_impl_annotations() -> Arg {
    const HELP: &str = "\
Optional annotation for implementations of C++ function wrappers
that may be exposed to Rust. You may for example need to provide
__declspec(dllexport) or __attribute__((visibility(\"default\")))
if Rust code from one shared object or executable depends on
these C++ functions in another.";
    Arg::new(CXX_IMPL_ANNOTATIONS)
        .long(CXX_IMPL_ANNOTATIONS)
        .num_args(1)
        .value_name("annotation")
        .value_parser(ValueParser::string())
        .help(HELP)
}

fn arg_header() -> Arg {
    const HELP: &str = "\
Emit header with declarations only. Optional if using `-o` with
a path ending in `.h`.";
    Arg::new(HEADER).long(HEADER).num_args(0).help(HELP)
}

fn arg_help() -> Arg {
    Arg::new(HELP)
        .long(HELP)
        .help("Print help information.")
        .num_args(0)
}

fn arg_include() -> Arg {
    const HELP: &str = "\
Any additional headers to #include. The cxxbridge tool does not
parse or even require the given paths to exist; they simply go
into the generated C++ code as #include lines.";
    Arg::new(INCLUDE)
        .long(INCLUDE)
        .short('i')
        .num_args(1)
        .action(ArgAction::Append)
        .value_parser(ValueParser::string())
        .help(HELP)
}

fn arg_output() -> Arg {
    const HELP: &str = "\
Path of file to write as output. Output goes to stdout if -o is
not specified.";
    Arg::new(OUTPUT)
        .long(OUTPUT)
        .short('o')
        .num_args(1)
        .action(ArgAction::Append)
        .value_parser(ValueParser::path_buf())
        .help(HELP)
}

fn arg_version() -> Arg {
    Arg::new(VERSION)
        .long(VERSION)
        .help("Print version information.")
        .action(ArgAction::Version)
}