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// Copyright 2015 Will Lentz.
// Licensed under the MIT license.

//! This crate provides a simple sscanf()-like interface to extract
//! data from strings and stdin.
//!
//! To use this crate, do:
//!
//! ```ignore
//! #[macro_use] extern crate scan_fmt;
//! ```
//!
//! Example to read from a string:
//!
//! ```rust
//! # #[macro_use] extern crate scan_fmt;
//! # fn main() {
//!   let (a,b,c) = scan_fmt!( "hello 12 345 bye", // input string
//!                            "hello {} {d} {}",  // format
//!                            u8, i32, String);   // type of a-c Options
//!   assert_eq!( a.unwrap(), 12 ) ;
//!   assert_eq!( b.unwrap(), 345 ) ;
//!   assert_eq!( c.unwrap(), "bye" ) ;
//! # }
//! ```
//!
//! Special format_string tokens:
//! <pre class="rust">
//!   {{ = escape for '{'
//!   }} = escape for '}'
//!   {} = return any value (until next whitespace)
//!   {d} = return base-10 decimal
//!   {x} = return hex (0xab or ab)
//!   {f} = return float
//!   {*d} = "*" as the first character means "match but don't return"
//!   {[...]} = return pattern.
//!     ^ inverts if it is the first character
//!     - is for ranges.  For a literal - put it at the start or end.
//!     To add a literal ] do "[]abc]"
//!   Examples:
//!     {[0-9ab]} = match 0-9 or a or b
//!     {[^,.]} = match anything but , or .
//!   {/.../} = return regex inside of `//`.
//!     If there is a single capture group inside of the slashes then
//!     that group will make up the pattern.
//!   Examples:
//!     {/[0-9ab]/} = same as {[0-9]ab}, above
//!     {/a+/} = matches at least one `a`, greedily
//!     {/jj(a*)jj/} = matches any number of `a`s, but only if
//!       they're surrounded by two `j`s
//! </pre>
//!
//! Example to read from stdin:
//!
//! ```rust
//! # #[macro_use] extern crate scan_fmt;
//! # fn main() {
//!   let (a,b) = scanln_fmt!( "{}-{}",   // format
//!                            u16, u8);    // type of a&b Options
//!   match (a,b) {
//!     (Some(aa),Some(bb)) => println!("Got {} and {}",aa,bb),
//!     _ => println!("input error")
//!   }
//! # }
//! ```
//!
//! ## LIMITATIONS:
//! There are no compile-time checks to make sure the format
//! strings matches the number of return arguments.  Extra
//! return values will be None.
//!
//! Like sscanf(), whitespace (including \n) is largely ignored.
//!
//! Conversion to output values is done using parse::<T>().

extern crate regex;

pub mod parse;

/// (a,+) = scan_fmt!( input_string, format_string, types,+ )
#[macro_export]
macro_rules! scan_fmt {
    ( $instr:expr, $fmt:expr, $arg1:ty, $($arg2:ty),* ) => {
        {
            let mut res = $crate::parse::scan( $instr, $fmt ) ;
            ( match res.next() {
                Some(item) => item.parse::<$arg1>().ok(),
                _ => None
            }
              $( , match res.next() {
                  Some(item) => item.parse::<$arg2>().ok(),
                  _ => None
              }
                   )*
              )
        }
    };
    ( $instr:expr, $fmt:expr, $arg1:ty ) => {
        {
            let mut res = $crate::parse::scan( $instr, $fmt ) ;
            ( match res.next() {
                Some(item) => item.parse::<$arg1>().ok(),
                _ => None
            } )
        }
    };
}

pub fn get_input_unwrap() -> String {
    let mut input = String::new();
    std::io::stdin().read_line(&mut input).unwrap();
    input
}

/// (a,+) = scanln_fmt!( format_string, types,+ )
/// <p>Same as scan_fmt!(), but reads input string from stdin.</p>
#[macro_export]
macro_rules! scanln_fmt {
    ($($arg:tt)*) => {{ scan_fmt!(&$crate::get_input_unwrap(), $($arg)*) }}
}

#[cfg(test)]
macro_rules! assert_flt_eq {
    ($t:ident, $v1:expr, $v2:expr) =>
    {{ assert!( ($v1 - $v2).abs() <= 2.0*std::$t::EPSILON ); }};
}

#[test]
fn test_plus_sign() {
    let a = scan_fmt!("+42", "{d}", i32);
    assert_eq!(a, Some(42));
    let a = scan_fmt!("+42.0", "{f}", f64);
    assert_flt_eq!(f64, a.unwrap(), 42.0);
}

#[test]
fn test_limited_data_range() {
    let (a, b, c) = scan_fmt!(
        "test{\t 1e9 \n bye 257} hi  22.7e-1",
        "test{{ {} bye {d}}} hi {f}",
        f64,
        u8,
        f32
    );
    assert_flt_eq!(f64, a.unwrap(), 1e9);
    assert_eq!(b, None); // 257 doesn't fit into a u8
    assert_flt_eq!(f32, c.unwrap(), 2.27);
}

#[test]
fn test_too_many_outputs() {
    let (a, b, c, d) = scan_fmt!("a_aa bb_b c", "{} {s} {}", String, String, String, String);
    assert_eq!(a.unwrap(), "a_aa");
    assert_eq!(b.unwrap(), "bb_b");
    assert_eq!(c.unwrap(), "c");
    assert_eq!(d, None);
}

#[test]
fn test_skip_assign() {
    let (a, b) = scan_fmt!("1 2 3, 4 5, 6 7", "{[^,]},{*[^,]},{[^,]}", String, String);
    assert_eq!(a.unwrap(), "1 2 3");
    assert_eq!(b.unwrap(), "6 7");
}