clap 3.0.0-rc.4

#[cfg(feature = "yaml")]
macro_rules! yaml_tuple2 {
    ($a:ident, $v:ident, $c:ident) => {{
        if let Some(vec) = $v.as_vec() {
            for ys in vec {
                if let Some(tup) = ys.as_vec() {
                    debug_assert_eq!(2, tup.len());
                    $a = $a.$c(yaml_str!(tup[0]), yaml_str!(tup[1]));
                } else {
                    panic!("Failed to convert YAML value to vec");
                }
            }
        } else {
            panic!("Failed to convert YAML value to vec");
        }
        $a
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_tuple3 {
    ($a:ident, $v:ident, $c:ident) => {{
        if let Some(vec) = $v.as_vec() {
            for ys in vec {
                if let Some(tup) = ys.as_vec() {
                    debug_assert_eq!(3, tup.len());
                    $a = $a.$c(
                        yaml_str!(tup[0]),
                        yaml_opt_str!(tup[1]),
                        yaml_opt_str!(tup[2]),
                    );
                } else {
                    panic!("Failed to convert YAML value to vec");
                }
            }
        } else {
            panic!("Failed to convert YAML value to vec");
        }
        $a
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_vec_or_str {
    ($a:ident, $v:ident, $c:ident) => {{
        let maybe_vec = $v.as_vec();
        if let Some(vec) = maybe_vec {
            for ys in vec {
                if let Some(s) = ys.as_str() {
                    $a = $a.$c(s);
                } else {
                    panic!("Failed to convert YAML value {:?} to a string", ys);
                }
            }
        } else {
            if let Some(s) = $v.as_str() {
                $a = $a.$c(s);
            } else {
                panic!(
                    "Failed to convert YAML value {:?} to either a vec or string",
                    $v
                );
            }
        }
        $a
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_vec {
    ($a:ident, $v:ident, $c:ident) => {{
        let maybe_vec = $v.as_vec();
        if let Some(vec) = maybe_vec {
            let content = vec.into_iter().map(|ys| {
                if let Some(s) = ys.as_str() {
                    s
                } else {
                    panic!("Failed to convert YAML value {:?} to a string", ys);
                }
            });
            $a = $a.$c(content)
        } else {
            panic!("Failed to convert YAML value {:?} to a vec", $v);
        }
        $a
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_opt_str {
    ($v:expr) => {{
        if !$v.is_null() {
            Some(
                $v.as_str()
                    .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", $v)),
            )
        } else {
            None
        }
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_char {
    ($v:expr) => {{
        $v.as_str()
            .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", $v))
            .chars()
            .next()
            .unwrap_or_else(|| panic!("Expected char"))
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_str {
    ($v:expr) => {{
        $v.as_str()
            .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", $v))
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_to_char {
    ($a:ident, $v:ident, $c:ident) => {{
        $a.$c(yaml_char!($v))
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_to_str {
    ($a:ident, $v:ident, $c:ident) => {{
        $a.$c(yaml_str!($v))
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_to_bool {
    ($a:ident, $v:ident, $c:ident) => {{
        $a.$c($v
            .as_bool()
            .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", $v)))
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_to_usize {
    ($a:ident, $v:ident, $c:ident) => {{
        $a.$c($v
            .as_i64()
            .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", $v))
            as usize)
    }};
}

#[cfg(feature = "yaml")]
macro_rules! yaml_to_setting {
    ($a:ident, $v:ident, $c:ident, $s:ident, $t:literal, $n:expr) => {{
        if let Some(v) = $v.as_vec() {
            for ys in v {
                if let Some(s) = ys.as_str() {
                    $a = $a.$c(s.parse::<$s>().unwrap_or_else(|_| {
                        panic!("Unknown {} '{}' found in YAML file for {}", $t, s, $n)
                    }));
                } else {
                    panic!(
                        "Failed to convert YAML {:?} value to an array of strings",
                        $v
                    );
                }
            }
        } else if let Some(v) = $v.as_str() {
            $a = $a.$c(v
                .parse::<$s>()
                .unwrap_or_else(|_| panic!("Unknown {} '{}' found in YAML file for {}", $t, v, $n)))
        } else {
            panic!("Failed to convert YAML {:?} value to a string", $v);
        }
        $a
    }};
}