spinoso_symbol/

inspect.rs

use core::fmt;
use core::iter::FusedIterator;

use scolapasta_string_escape::{ascii_char_with_escape, InvalidUtf8ByteSequence};

use crate::ident::IdentifierType;

/// An iterator that yields a debug representation of a `Symbol` and its byte
/// contents as a sequence of `char`s.
///
/// This struct is created by the [`inspect`] method on [`Symbol`]. See its
/// documentation for more.
///
/// To format a `Symbol` directly into a writer, see [`format_into`] or
/// [`write_into`].
///
/// # Examples
///
/// To inspect an empty byte string:
///
/// ```
/// # extern crate alloc;
/// # use alloc::string::String;
/// # use spinoso_symbol::Inspect;
/// let inspect = Inspect::default();
/// let debug = inspect.collect::<String>();
/// assert_eq!(debug, r#":"""#);
/// ```
///
/// To inspect a well-formed UTF-8 byte string:
///
/// ```
/// # extern crate alloc;
/// # use alloc::string::String;
/// # use spinoso_symbol::Inspect;
/// let inspect = Inspect::from("spinoso");
/// let debug = inspect.collect::<String>();
/// assert_eq!(debug, ":spinoso");
/// ```
///
/// To inspect a byte string with invalid UTF-8 bytes:
///
/// ```
/// # extern crate alloc;
/// # use alloc::string::String;
/// # use spinoso_symbol::Inspect;
/// let inspect = Inspect::from(&b"invalid-\xFF-utf8"[..]);
/// let debug = inspect.collect::<String>();
/// assert_eq!(debug, r#":"invalid-\xFF-utf8""#);
/// ```
///
/// [`inspect`]: crate::Symbol::inspect
/// [`Symbol`]: crate::Symbol
/// [`format_into`]: Self::format_into
/// [`write_into`]: Self::write_into
#[derive(Default, Debug, Clone)]
#[must_use = "this `Inspect` is an `Iterator`, which should be consumed if constructed"]
#[cfg_attr(docsrs, doc(cfg(feature = "inspect")))]
pub struct Inspect<'a>(State<'a>);

impl<'a> From<&'a str> for Inspect<'a> {
    #[inline]
    fn from(value: &'a str) -> Self {
        Self::from(value.as_bytes())
    }
}

impl<'a> From<&'a [u8]> for Inspect<'a> {
    #[inline]
    fn from(value: &'a [u8]) -> Self {
        match value {
            [] => Self::default(),
            value if IdentifierType::try_from(value).is_ok() => Self(State::ident(value)),
            value => Self(State::quoted(value)),
        }
    }
}

impl Iterator for Inspect<'_> {
    type Item = char;

    fn next(&mut self) -> Option<Self::Item> {
        self.0.next()
    }
}

impl FusedIterator for Inspect<'_> {}

impl Inspect<'_> {
    /// Write an `Inspect` iterator into the given destination using the debug
    /// representation of the interned byte slice associated with the symbol in
    /// the underlying interner.
    ///
    /// This formatter writes content like `:spinoso` and `:"invalid-\xFF-utf8"`.
    /// To see example output of the underlying iterator, see the `Inspect`
    /// documentation.
    ///
    /// To write binary output, use [`write_into`], which requires the **std**
    /// feature to be activated.
    ///
    /// # Errors
    ///
    /// If the given writer returns an error as it is being written to, that
    /// error is returned.
    ///
    /// # Examples
    ///
    /// ```
    /// # use core::fmt::Write;
    /// # use spinoso_symbol::Inspect;
    /// let mut buf = String::new();
    /// let iter = Inspect::from("spinoso");
    /// iter.format_into(&mut buf);
    /// assert_eq!(buf, ":spinoso");
    ///
    /// let mut buf = String::new();
    /// let iter = Inspect::from(&b"\xFF"[..]);
    /// iter.format_into(&mut buf);
    /// assert_eq!(buf, r#":"\xFF""#);
    /// ```
    ///
    /// [`write_into`]: Self::write_into
    #[inline]
    pub fn format_into<W>(self, mut dest: W) -> fmt::Result
    where
        W: fmt::Write,
    {
        for ch in self {
            dest.write_char(ch)?;
        }
        Ok(())
    }

    /// Write an `Inspect` iterator into the given destination using the debug
    /// representation of the interned byte slice associated with the symbol in
    /// the underlying interner.
    ///
    /// This formatter writes content like `:spinoso` and `:"invalid-\xFF-utf8"`.
    /// To see example output of the underlying iterator, see the `Inspect`
    /// documentation.
    ///
    /// To write to a [formatter], use [`format_into`].
    ///
    /// # Errors
    ///
    /// If the given writer returns an error as it is being written to, that
    /// error is returned.
    ///
    /// # Examples
    ///
    /// ```
    /// # use std::io::Write;
    /// # use spinoso_symbol::Inspect;
    /// let mut buf = Vec::new();
    /// let iter = Inspect::from("spinoso");
    /// iter.write_into(&mut buf);
    /// assert_eq!(buf, &b":spinoso"[..]);
    ///
    /// let mut buf = Vec::new();
    /// let iter = Inspect::from(&b"\xFF"[..]);
    /// iter.write_into(&mut buf);
    /// assert_eq!(buf, &[b':', b'"', b'\\', b'x', b'F', b'F', b'"']);
    /// ```
    ///
    /// [formatter]: fmt::Write
    /// [`format_into`]: Self::format_into
    #[inline]
    #[cfg(feature = "std")]
    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    pub fn write_into<W>(self, mut dest: W) -> std::io::Result<()>
    where
        W: std::io::Write,
    {
        let mut buf = [0; 4];
        for ch in self {
            let utf8 = ch.encode_utf8(&mut buf);
            dest.write_all(utf8.as_bytes())?;
        }
        Ok(())
    }
}

#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
struct Flags {
    bits: u8,
}

impl Flags {
    // Bit flags
    const IS_IDENT: Self = Self { bits: 0b1000_0000 };
    const EMIT_LEADING_COLON: Self = Self { bits: 0b0000_1000 };
    const EMIT_LEADING_QUOTE: Self = Self { bits: 0b0000_0001 };
    const EMIT_TRAILING_QUOTE: Self = Self { bits: 0b0000_0010 };

    // Initial states
    const IDENT: Self = Self {
        bits: Self::IS_IDENT.bits | Self::EMIT_LEADING_COLON.bits,
    };
    const QUOTED: Self = Self {
        bits: Self::EMIT_LEADING_COLON.bits | Self::EMIT_LEADING_QUOTE.bits | Self::EMIT_TRAILING_QUOTE.bits,
    };

    #[inline]
    fn emit_leading_colon(&mut self) -> Option<char> {
        if (self.bits & Self::EMIT_LEADING_COLON.bits) == Self::EMIT_LEADING_COLON.bits {
            self.bits &= !Self::EMIT_LEADING_COLON.bits;
            Some(':')
        } else {
            None
        }
    }

    #[inline]
    fn emit_leading_quote(&mut self) -> Option<char> {
        if (self.bits & Self::EMIT_LEADING_QUOTE.bits) == Self::EMIT_LEADING_QUOTE.bits {
            self.bits &= !Self::EMIT_LEADING_QUOTE.bits;
            Some('"')
        } else {
            None
        }
    }

    #[inline]
    fn emit_trailing_quote(&mut self) -> Option<char> {
        if (self.bits & Self::EMIT_TRAILING_QUOTE.bits) == Self::EMIT_TRAILING_QUOTE.bits {
            self.bits &= !Self::EMIT_TRAILING_QUOTE.bits;
            Some('"')
        } else {
            None
        }
    }

    #[inline]
    const fn is_ident(self) -> bool {
        (self.bits & Self::IS_IDENT.bits) == Self::IS_IDENT.bits
    }
}

#[derive(Debug, Clone)]
#[must_use = "this `State` is an `Iterator`, which should be consumed if constructed"]
struct State<'a> {
    flags: Flags,
    escaped_bytes: &'static [u8],
    forward_byte_literal: InvalidUtf8ByteSequence,
    bytes: &'a [u8],
}

impl<'a> State<'a> {
    /// Construct a `State` that will not quote byte contents after the initial
    /// `:`.
    ///
    /// This constructor produces inspect contents like `:fred`.
    #[inline]
    fn ident(bytes: &'a [u8]) -> Self {
        Self {
            flags: Flags::IDENT,
            escaped_bytes: &[],
            forward_byte_literal: InvalidUtf8ByteSequence::new(),
            bytes,
        }
    }

    /// Construct a `State` that will quote byte contents after the initial `:`.
    ///
    /// This constructor produces inspect contents like `:"Spinoso Symbol"`.
    #[inline]
    fn quoted(bytes: &'a [u8]) -> Self {
        Self {
            flags: Flags::QUOTED,
            escaped_bytes: &[],
            forward_byte_literal: InvalidUtf8ByteSequence::new(),
            bytes,
        }
    }
}

impl Default for State<'_> {
    /// Construct a `State` that will render debug output for the empty slice.
    ///
    /// This constructor produces inspect contents like `:""`.
    #[inline]
    fn default() -> Self {
        Self::quoted(b"")
    }
}

impl Iterator for State<'_> {
    type Item = char;

    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        if let Some(ch) = self.flags.emit_leading_colon() {
            return Some(ch);
        }
        if let Some(ch) = self.flags.emit_leading_quote() {
            return Some(ch);
        }
        if let Some((&head, tail)) = self.escaped_bytes.split_first() {
            self.escaped_bytes = tail;
            return Some(head.into());
        }
        if let Some(ch) = self.forward_byte_literal.next() {
            return Some(ch);
        }
        let (ch, size) = bstr::decode_utf8(self.bytes);
        // SAFETY: bstr guarantees that the size is within the bounds of the slice.
        let (chunk, remainder) = unsafe { self.bytes.split_at_unchecked(size) };
        self.bytes = remainder;

        match ch {
            Some('"' | '\\') if self.flags.is_ident() => {
                return ch;
            }
            Some(ch) => {
                if let Some([head, tail @ ..]) = ascii_char_with_escape(ch).map(str::as_bytes) {
                    self.escaped_bytes = tail;
                    return Some(char::from(*head));
                }
                return Some(ch);
            }
            None if size == 0 => {}
            None => {
                // This conversion is safe to unwrap due to the documented
                // behavior of `bstr::decode_utf8` and `InvalidUtf8ByteSequence`
                // which indicate that `size` is always in the range of 0..=3.
                self.forward_byte_literal = InvalidUtf8ByteSequence::try_from(chunk).unwrap();
                return self.forward_byte_literal.next();
            }
        };
        if let Some(ch) = self.flags.emit_trailing_quote() {
            return Some(ch);
        }
        None
    }
}

impl FusedIterator for State<'_> {}

#[cfg(test)]
mod tests {
    use std::string::String;

    use super::Inspect;

    #[test]
    fn empty() {
        let inspect = Inspect::from("");
        let debug = inspect.collect::<String>();
        assert_eq!(debug, r#":"""#);
    }

    #[test]
    fn fred() {
        let inspect = Inspect::from("fred");
        let debug = inspect.collect::<String>();
        assert_eq!(debug, ":fred");
    }

    #[test]
    fn invalid_utf8_byte() {
        assert_eq!(Inspect::from(&b"\xFF"[..]).collect::<String>(), r#":"\xFF""#);
    }

    #[test]
    fn invalid_utf8() {
        let inspect = Inspect::from(&b"invalid-\xFF-utf8"[..]);
        let debug = inspect.collect::<String>();
        assert_eq!(debug, r#":"invalid-\xFF-utf8""#);
    }

    #[test]
    fn quoted() {
        let mut inspect = Inspect::from(r#"a"b"#);
        assert_eq!(inspect.next(), Some(':'));
        assert_eq!(inspect.next(), Some('"'));
        assert_eq!(inspect.next(), Some('a'));
        assert_eq!(inspect.next(), Some('\\'));
        assert_eq!(inspect.next(), Some('"'));
        assert_eq!(inspect.next(), Some('b'));
        assert_eq!(inspect.next(), Some('"'));

        assert_eq!(Inspect::from(r#"a"b"#).collect::<String>(), r#":"a\"b""#);
    }

    #[test]
    fn emoji() {
        assert_eq!(Inspect::from("💎").collect::<String>(), ":💎");
        assert_eq!(Inspect::from("$💎").collect::<String>(), ":$💎");
        assert_eq!(Inspect::from("@💎").collect::<String>(), ":@💎");
        assert_eq!(Inspect::from("@@💎").collect::<String>(), ":@@💎");
    }

    #[test]
    fn unicode_replacement_char() {
        assert_eq!(Inspect::from("�").collect::<String>(), ":�");
        assert_eq!(Inspect::from("$�").collect::<String>(), ":$�");
        assert_eq!(Inspect::from("@�").collect::<String>(), ":@�");
        assert_eq!(Inspect::from("@@�").collect::<String>(), ":@@�");

        assert_eq!(Inspect::from("abc�").collect::<String>(), ":abc�");
        assert_eq!(Inspect::from("$abc�").collect::<String>(), ":$abc�");
        assert_eq!(Inspect::from("@abc�").collect::<String>(), ":@abc�");
        assert_eq!(Inspect::from("@@abc�").collect::<String>(), ":@@abc�");
    }

    #[test]
    fn escape_slash() {
        assert_eq!(Inspect::from("\\").collect::<String>(), r#":"\\""#);
        assert_eq!(Inspect::from("foo\\bar").collect::<String>(), r#":"foo\\bar""#);
    }

    #[test]
    fn nul() {
        assert_eq!(Inspect::from("\0").collect::<String>(), r#":"\x00""#);
    }

    #[test]
    fn del() {
        assert_eq!(Inspect::from("\x7F").collect::<String>(), r#":"\x7F""#);
    }

    #[test]
    fn ascii_control() {
        assert_eq!(Inspect::from("\0").collect::<String>(), r#":"\x00""#);
        assert_eq!(Inspect::from("\x01").collect::<String>(), r#":"\x01""#);
        assert_eq!(Inspect::from("\x02").collect::<String>(), r#":"\x02""#);
        assert_eq!(Inspect::from("\x03").collect::<String>(), r#":"\x03""#);
        assert_eq!(Inspect::from("\x04").collect::<String>(), r#":"\x04""#);
        assert_eq!(Inspect::from("\x05").collect::<String>(), r#":"\x05""#);
        assert_eq!(Inspect::from("\x06").collect::<String>(), r#":"\x06""#);
        assert_eq!(Inspect::from("\x07").collect::<String>(), r#":"\a""#);
        assert_eq!(Inspect::from("\x08").collect::<String>(), r#":"\b""#);
        assert_eq!(Inspect::from("\x09").collect::<String>(), r#":"\t""#);
        assert_eq!(Inspect::from("\x0A").collect::<String>(), r#":"\n""#);
        assert_eq!(Inspect::from("\x0B").collect::<String>(), r#":"\v""#);
        assert_eq!(Inspect::from("\x0C").collect::<String>(), r#":"\f""#);
        assert_eq!(Inspect::from("\x0D").collect::<String>(), r#":"\r""#);
        assert_eq!(Inspect::from("\x0E").collect::<String>(), r#":"\x0E""#);
        assert_eq!(Inspect::from("\x0F").collect::<String>(), r#":"\x0F""#);
        assert_eq!(Inspect::from("\x10").collect::<String>(), r#":"\x10""#);
        assert_eq!(Inspect::from("\x11").collect::<String>(), r#":"\x11""#);
        assert_eq!(Inspect::from("\x12").collect::<String>(), r#":"\x12""#);
        assert_eq!(Inspect::from("\x13").collect::<String>(), r#":"\x13""#);
        assert_eq!(Inspect::from("\x14").collect::<String>(), r#":"\x14""#);
        assert_eq!(Inspect::from("\x15").collect::<String>(), r#":"\x15""#);
        assert_eq!(Inspect::from("\x16").collect::<String>(), r#":"\x16""#);
        assert_eq!(Inspect::from("\x17").collect::<String>(), r#":"\x17""#);
        assert_eq!(Inspect::from("\x18").collect::<String>(), r#":"\x18""#);
        assert_eq!(Inspect::from("\x19").collect::<String>(), r#":"\x19""#);
        assert_eq!(Inspect::from("\x1A").collect::<String>(), r#":"\x1A""#);
        assert_eq!(Inspect::from("\x1B").collect::<String>(), r#":"\e""#);
        assert_eq!(Inspect::from("\x1C").collect::<String>(), r#":"\x1C""#);
        assert_eq!(Inspect::from("\x1D").collect::<String>(), r#":"\x1D""#);
        assert_eq!(Inspect::from("\x1E").collect::<String>(), r#":"\x1E""#);
        assert_eq!(Inspect::from("\x1F").collect::<String>(), r#":"\x1F""#);
        assert_eq!(Inspect::from("\x20").collect::<String>(), r#":" ""#);
    }

    #[test]
    fn special_escapes() {
        // double quote
        assert_eq!(Inspect::from("\x22").collect::<String>(), r#":"\"""#);
        assert_eq!(Inspect::from("\"").collect::<String>(), r#":"\"""#);
        // backslash
        assert_eq!(Inspect::from("\x5C").collect::<String>(), r#":"\\""#);
        assert_eq!(Inspect::from("\\").collect::<String>(), r#":"\\""#);
    }

    #[test]
    fn invalid_utf8_special_global() {
        assert_eq!(Inspect::from(&b"$-\xFF"[..]).collect::<String>(), r#":"$-\xFF""#);
    }

    #[test]
    fn replacement_char_special_global() {
        assert_eq!(Inspect::from("$-�").collect::<String>(), ":$-�");
        assert_eq!(Inspect::from("$-�a").collect::<String>(), r#":"$-�a""#);
        assert_eq!(Inspect::from("$-��").collect::<String>(), r#":"$-��""#);
    }
}

#[cfg(test)]
mod specs {
    use std::string::String;

    use super::{Flags, Inspect};

    #[test]
    fn flags_ident() {
        let mut flags = Flags::IDENT;
        assert!(flags.is_ident());
        assert_eq!(flags.emit_leading_colon(), Some(':'));
        assert!(flags.is_ident());
        assert_eq!(flags.emit_leading_colon(), None);
        assert!(flags.is_ident());

        assert_eq!(flags.emit_leading_quote(), None);
        assert!(flags.is_ident());

        assert_eq!(flags.emit_trailing_quote(), None);
        assert!(flags.is_ident());
    }

    #[test]
    fn flags_quoted() {
        let mut flags = Flags::QUOTED;
        assert!(!flags.is_ident());
        assert_eq!(flags.emit_leading_colon(), Some(':'));
        assert!(!flags.is_ident());
        assert_eq!(flags.emit_leading_colon(), None);
        assert!(!flags.is_ident());

        assert_eq!(flags.emit_leading_quote(), Some('"'));
        assert!(!flags.is_ident());
        assert_eq!(flags.emit_leading_quote(), None);
        assert!(!flags.is_ident());

        assert_eq!(flags.emit_trailing_quote(), Some('"'));
        assert!(!flags.is_ident());
        assert_eq!(flags.emit_trailing_quote(), None);
        assert!(!flags.is_ident());
    }

    // From `spec/core/symbol/inspect_spec.rb`:
    //
    // ```ruby
    // symbols = {
    //   fred:         ":fred",
    //   :fred?     => ":fred?",
    //   :fred!     => ":fred!",
    //   :$ruby     => ":$ruby",
    //   :@ruby     => ":@ruby",
    //   :@@ruby    => ":@@ruby",
    //   :"$ruby!"  => ":\"$ruby!\"",
    //   :"$ruby?"  => ":\"$ruby?\"",
    //   :"@ruby!"  => ":\"@ruby!\"",
    //   :"@ruby?"  => ":\"@ruby?\"",
    //   :"@@ruby!" => ":\"@@ruby!\"",
    //   :"@@ruby?" => ":\"@@ruby?\"",
    //
    //   :$-w       => ":$-w",
    //   :"$-ww"    => ":\"$-ww\"",
    //   :"$+"      => ":$+",
    //   :"$~"      => ":$~",
    //   :"$:"      => ":$:",
    //   :"$?"      => ":$?",
    //   :"$<"      => ":$<",
    //   :"$_"      => ":$_",
    //   :"$/"      => ":$/",
    //   :"$'"      => ":$'",
    //   :"$\""     => ":$\"",
    //   :"$$"      => ":$$",
    //   :"$."      => ":$.",
    //   :"$,"      => ":$,",
    //   :"$`"      => ":$`",
    //   :"$!"      => ":$!",
    //   :"$;"      => ":$;",
    //   :"$\\"     => ":$\\",
    //   :"$="      => ":$=",
    //   :"$*"      => ":$*",
    //   :"$>"      => ":$>",
    //   :"$&"      => ":$&",
    //   :"$@"      => ":$@",
    //   :"$1234"   => ":$1234",
    //
    //   :-@        => ":-@",
    //   :+@        => ":+@",
    //   :%         => ":%",
    //   :&         => ":&",
    //   :*         => ":*",
    //   :**        => ":**",
    //   :"/"       => ":/",     # lhs quoted for emacs happiness
    //   :<         => ":<",
    //   :<=        => ":<=",
    //   :<=>       => ":<=>",
    //   :==        => ":==",
    //   :===       => ":===",
    //   :=~        => ":=~",
    //   :>         => ":>",
    //   :>=        => ":>=",
    //   :>>        => ":>>",
    //   :[]        => ":[]",
    //   :[]=       => ":[]=",
    //   :"\<\<"    => ":\<\<",
    //   :^         => ":^",
    //   :"`"       => ":`",     # for emacs, and justice!
    //   :~         => ":~",
    //   :|         => ":|",
    //
    //   :"!"       => [":\"!\"",  ":!" ],
    //   :"!="      => [":\"!=\"", ":!="],
    //   :"!~"      => [":\"!~\"", ":!~"],
    //   :"\$"      => ":\"$\"", # for justice!
    //   :"&&"      => ":\"&&\"",
    //   :"'"       => ":\"\'\"",
    //   :","       => ":\",\"",
    //   :"."       => ":\".\"",
    //   :".."      => ":\"..\"",
    //   :"..."     => ":\"...\"",
    //   :":"       => ":\":\"",
    //   :"::"      => ":\"::\"",
    //   :";"       => ":\";\"",
    //   :"="       => ":\"=\"",
    //   :"=>"      => ":\"=>\"",
    //   :"\?"      => ":\"?\"", # rawr!
    //   :"@"       => ":\"@\"",
    //   :"||"      => ":\"||\"",
    //   :"|||"     => ":\"|||\"",
    //   :"++"      => ":\"++\"",
    //
    //   :"\""      => ":\"\\\"\"",
    //   :"\"\""    => ":\"\\\"\\\"\"",
    //
    //   :"9"       => ":\"9\"",
    //   :"foo bar" => ":\"foo bar\"",
    //   :"*foo"    => ":\"*foo\"",
    //   :"foo "    => ":\"foo \"",
    //   :" foo"    => ":\" foo\"",
    //   :" "       => ":\" \"",
    // }
    // ```

    #[test]
    fn specs() {
        // idents
        assert_eq!(Inspect::from("fred").collect::<String>(), ":fred");
        assert_eq!(Inspect::from("fred?").collect::<String>(), ":fred?");
        assert_eq!(Inspect::from("fred!").collect::<String>(), ":fred!");
        assert_eq!(Inspect::from("$ruby").collect::<String>(), ":$ruby");
        assert_eq!(Inspect::from("@ruby").collect::<String>(), ":@ruby");
        assert_eq!(Inspect::from("@@ruby").collect::<String>(), ":@@ruby");

        // idents can't end in bang or question
        assert_eq!(Inspect::from("$ruby!").collect::<String>(), r#":"$ruby!""#);
        assert_eq!(Inspect::from("$ruby?").collect::<String>(), r#":"$ruby?""#);
        assert_eq!(Inspect::from("@ruby!").collect::<String>(), r#":"@ruby!""#);
        assert_eq!(Inspect::from("@ruby?").collect::<String>(), r#":"@ruby?""#);
        assert_eq!(Inspect::from("@@ruby!").collect::<String>(), r#":"@@ruby!""#);
        assert_eq!(Inspect::from("@@ruby?").collect::<String>(), r#":"@@ruby?""#);

        // globals
        assert_eq!(Inspect::from("$-w").collect::<String>(), ":$-w");
        assert_eq!(Inspect::from("$-ww").collect::<String>(), r#":"$-ww""#);
        assert_eq!(Inspect::from("$+").collect::<String>(), ":$+");
        assert_eq!(Inspect::from("$~").collect::<String>(), ":$~");
        assert_eq!(Inspect::from("$:").collect::<String>(), ":$:");
        assert_eq!(Inspect::from("$?").collect::<String>(), ":$?");
        assert_eq!(Inspect::from("$<").collect::<String>(), ":$<");
        assert_eq!(Inspect::from("$_").collect::<String>(), ":$_");
        assert_eq!(Inspect::from("$/").collect::<String>(), ":$/");
        assert_eq!(Inspect::from("$\"").collect::<String>(), ":$\"");
        assert_eq!(Inspect::from("$$").collect::<String>(), ":$$");
        assert_eq!(Inspect::from("$.").collect::<String>(), ":$.");
        assert_eq!(Inspect::from("$,").collect::<String>(), ":$,");
        assert_eq!(Inspect::from("$`").collect::<String>(), ":$`");
        assert_eq!(Inspect::from("$!").collect::<String>(), ":$!");
        assert_eq!(Inspect::from("$;").collect::<String>(), ":$;");
        assert_eq!(Inspect::from("$\\").collect::<String>(), ":$\\");
        assert_eq!(Inspect::from("$=").collect::<String>(), ":$=");
        assert_eq!(Inspect::from("$*").collect::<String>(), ":$*");
        assert_eq!(Inspect::from("$>").collect::<String>(), ":$>");
        assert_eq!(Inspect::from("$&").collect::<String>(), ":$&");
        assert_eq!(Inspect::from("$@").collect::<String>(), ":$@");
        assert_eq!(Inspect::from("$1234").collect::<String>(), ":$1234");

        // symbolic methods
        assert_eq!(Inspect::from("-@").collect::<String>(), ":-@");
        assert_eq!(Inspect::from("+@").collect::<String>(), ":+@");
        assert_eq!(Inspect::from("%").collect::<String>(), ":%");
        assert_eq!(Inspect::from("&").collect::<String>(), ":&");
        assert_eq!(Inspect::from("*").collect::<String>(), ":*");
        assert_eq!(Inspect::from("**").collect::<String>(), ":**");
        assert_eq!(Inspect::from("/").collect::<String>(), ":/");
        assert_eq!(Inspect::from("<").collect::<String>(), ":<");
        assert_eq!(Inspect::from("<=").collect::<String>(), ":<=");
        assert_eq!(Inspect::from("<=>").collect::<String>(), ":<=>");
        assert_eq!(Inspect::from("==").collect::<String>(), ":==");
        assert_eq!(Inspect::from("===").collect::<String>(), ":===");
        assert_eq!(Inspect::from("=~").collect::<String>(), ":=~");
        assert_eq!(Inspect::from(">").collect::<String>(), ":>");
        assert_eq!(Inspect::from(">=").collect::<String>(), ":>=");
        assert_eq!(Inspect::from(">>").collect::<String>(), ":>>");
        assert_eq!(Inspect::from("[]").collect::<String>(), ":[]");
        assert_eq!(Inspect::from("[]=").collect::<String>(), ":[]=");
        assert_eq!(Inspect::from("<<").collect::<String>(), ":<<");
        assert_eq!(Inspect::from("^").collect::<String>(), ":^");
        assert_eq!(Inspect::from("`").collect::<String>(), ":`");
        assert_eq!(Inspect::from("~").collect::<String>(), ":~");
        assert_eq!(Inspect::from("|").collect::<String>(), ":|");

        // non-symbol symbolics
        assert_eq!(Inspect::from("!").collect::<String>(), ":!");
        assert_eq!(Inspect::from("!=").collect::<String>(), ":!=");
        assert_eq!(Inspect::from("!~").collect::<String>(), ":!~");
        assert_eq!(Inspect::from("$").collect::<String>(), r#":"$""#);
        assert_eq!(Inspect::from("&&").collect::<String>(), r#":"&&""#);
        assert_eq!(Inspect::from("'").collect::<String>(), r#":"'""#);
        assert_eq!(Inspect::from(",").collect::<String>(), r#":",""#);
        assert_eq!(Inspect::from(".").collect::<String>(), r#":".""#);
        assert_eq!(Inspect::from("..").collect::<String>(), r#":"..""#);
        assert_eq!(Inspect::from("...").collect::<String>(), r#":"...""#);
        assert_eq!(Inspect::from(":").collect::<String>(), r#":":""#);
        assert_eq!(Inspect::from("::").collect::<String>(), r#":"::""#);
        assert_eq!(Inspect::from(";").collect::<String>(), r#":";""#);
        assert_eq!(Inspect::from("=").collect::<String>(), r#":"=""#);
        assert_eq!(Inspect::from("=>").collect::<String>(), r#":"=>""#);
        assert_eq!(Inspect::from("?").collect::<String>(), r#":"?""#);
        assert_eq!(Inspect::from("@").collect::<String>(), r#":"@""#);
        assert_eq!(Inspect::from("||").collect::<String>(), r#":"||""#);
        assert_eq!(Inspect::from("|||").collect::<String>(), r#":"|||""#);
        assert_eq!(Inspect::from("++").collect::<String>(), r#":"++""#);

        // quotes
        assert_eq!(Inspect::from(r#"""#).collect::<String>(), r#":"\"""#);
        assert_eq!(Inspect::from(r#""""#).collect::<String>(), r#":"\"\"""#);

        assert_eq!(Inspect::from("9").collect::<String>(), r#":"9""#);
        assert_eq!(Inspect::from("foo bar").collect::<String>(), r#":"foo bar""#);
        assert_eq!(Inspect::from("*foo").collect::<String>(), r#":"*foo""#);
        assert_eq!(Inspect::from("foo ").collect::<String>(), r#":"foo ""#);
        assert_eq!(Inspect::from(" foo").collect::<String>(), r#":" foo""#);
        assert_eq!(Inspect::from(" ").collect::<String>(), r#":" ""#);
    }
}

/// Tests generated from symbols loaded at MRI interpreter boot.
///
/// # Generation
///
/// ```shell
/// cat <<EOF | ruby --disable-gems --disable-did_you_mean
/// def boot_identifier_symbols
///   syms = Symbol.all_symbols.map(&:inspect)
///   # remove symbols that must be debug wrapped in quotes
///   syms = syms.reject { |s| s[0..1] == ':"' }
///
///   fixture = syms.map { |s| "r##\"#{s}\"##" }
///   puts fixture.join(",\n")
/// end
///
/// boot_identifier_symbols
/// EOF
/// ```
#[cfg(test)]
mod functionals {
    use std::string::String;

    use super::Inspect;
    use crate::fixtures::{IDENTS, IDENT_INSPECTS};

    #[test]
    fn mri_symbol_idents() {
        let pairs = IDENTS.iter().copied().zip(IDENT_INSPECTS.iter().copied());
        for (sym, expected) in pairs {
            let inspect = Inspect::from(sym).collect::<String>();
            assert_eq!(
                inspect, expected,
                "Expected '{expected}', to be the result of '{sym}'.inspect; got '{inspect}'",
            );
        }
    }
}