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    // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
    // file at the top-level directory of this distribution and at
    // http://rust-lang.org/COPYRIGHT.
    //
    // 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.

    //! Determine displayed width of `char` and `str` types according to
    //! [Unicode Standard Annex #11](http://www.unicode.org/reports/tr11/)
    //! rules.
    //!
    //! ```rust
    //! extern crate unicode_width;
    //!
    //! use unicode_width::UnicodeWidthStr;
    //!
    //! fn main() {
    //!     let teststr = "Ｈｅｌｌｏ, ｗｏｒｌｄ!";
    //!     let width = UnicodeWidthStr::width(teststr);
    //!     println!("{}", teststr);
    //!     println!("The above string is {} columns wide.", width);
    //!     let width = teststr.width_cjk();
    //!     println!("The above string is {} columns wide (CJK).", width);
    //! }
    //! ```
    //!
    //! # features
    //!
    //! unicode-width supports a `no_std` feature. This eliminates dependence
    //! on std, and instead uses equivalent functions from core.
    //!
    //! # crates.io
    //!
    //! You can use this package in your project by adding the following
    //! to your `Cargo.toml`:
    //!
    //! ```toml
    //! [dependencies]
    //! unicode-width = "0.1.1"
    //! ```

    #![deny(missing_docs, unsafe_code)]
    #![doc(html_logo_url = "https://unicode-rs.github.io/unicode-rs_sm.png",
           html_favicon_url = "https://unicode-rs.github.io/unicode-rs_sm.png")]

    #![cfg_attr(feature = "no_std", no_std)]
    #![cfg_attr(feature = "no_std", feature(no_std, core_slice_ext, core_str_ext))]

    #![cfg_attr(test, feature(test))]

    #[cfg(all(test, feature = "no_std"))]
    #[macro_use]
    extern crate std;

    #[cfg(test)]
    extern crate test;

    use tables::charwidth as cw;
    pub use tables::UNICODE_VERSION;

    #[cfg(feature = "no_std")]
    use core::ops::Add;
    #[cfg(not(feature = "no_std"))]
    use std::ops::Add;

    mod tables;

    #[cfg(test)]
    mod tests;

    /// Methods for determining displayed width of Unicode characters.
    pub trait UnicodeWidthChar {
        /// Returns the character's displayed width in columns, or `None` if the
        /// character is a control character other than `'\x00'`.
        ///
        /// This function treats characters in the Ambiguous category according
        /// to [Unicode Standard Annex #11](http://www.unicode.org/reports/tr11/)
        /// as 1 column wide. This is consistent with the recommendations for non-CJK
        /// contexts, or when the context cannot be reliably determined.
        fn width(self) -> Option<usize>;

        /// Returns the character's displayed width in columns, or `None` if the
        /// character is a control character other than `'\x00'`.
        ///
        /// This function treats characters in the Ambiguous category according
        /// to [Unicode Standard Annex #11](http://www.unicode.org/reports/tr11/)
        /// as 2 columns wide. This is consistent with the recommendations for
        /// CJK contexts.
        fn width_cjk(self) -> Option<usize>;
    }

    impl UnicodeWidthChar for char {
        #[inline]
        fn width(self) -> Option<usize> { cw::width(self, false) }

        #[inline]
        fn width_cjk(self) -> Option<usize> { cw::width(self, true) }
    }

    /// Methods for determining displayed width of Unicode strings.
    pub trait UnicodeWidthStr {
        /// Returns the string's displayed width in columns.
        ///
        /// Control characters are treated as having zero width.
        ///
        /// This function treats characters in the Ambiguous category according
        /// to [Unicode Standard Annex #11](http://www.unicode.org/reports/tr11/)
        /// as 1 column wide. This is consistent with the recommendations for
        /// non-CJK contexts, or when the context cannot be reliably determined.
        fn width<'a>(&'a self) -> usize;

        /// Returns the string's displayed width in columns.
        ///
        /// Control characters are treated as having zero width.
        ///
        /// This function treats characters in the Ambiguous category according
        /// to [Unicode Standard Annex #11](http://www.unicode.org/reports/tr11/)
        /// as 2 column wide. This is consistent with the recommendations for
        /// CJK contexts.
        fn width_cjk<'a>(&'a self) -> usize;
    }

    impl UnicodeWidthStr for str {
        #[inline]
        fn width(&self) -> usize {
            self.chars().map(|c| cw::width(c, false).unwrap_or(0)).fold(0, Add::add)
        }

        #[inline]
        fn width_cjk(&self) -> usize {
            self.chars().map(|c| cw::width(c, true).unwrap_or(0)).fold(0, Add::add)
        }
    }

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