serde_graphql_input 0.1.2

use std::io;

mod compact;
mod pretty;

pub use compact::*;
pub use pretty::*;

pub(crate) fn format_key<W, F>(writer: &mut W, formatter: &mut F, value: &str) -> io::Result<()>
where
    W: io::Write,
    F: Formatter,
{
    formatter.write_string(writer, value)
}

pub(crate) fn format_escaped_str<W, F>(
    writer: &mut W,
    formatter: &mut F,
    value: &str,
) -> io::Result<()>
where
    W: io::Write,
    F: Formatter,
{
    formatter.begin_string(writer)?;
    format_escaped_str_contents(writer, formatter, value)?;
    formatter.end_string(writer)
}

fn format_escaped_str_contents<W, F>(
    writer: &mut W,
    formatter: &mut F,
    value: &str,
) -> io::Result<()>
where
    W: io::Write,
    F: Formatter,
{
    let bytes = value.as_bytes();

    let mut start = 0;

    for (i, &byte) in bytes.iter().enumerate() {
        let escape = ESCAPE[byte as usize];
        if escape == 0 {
            continue;
        }

        if start < i {
            formatter.write_string_fragment(writer, &value[start..i])?;
        }

        let char_escape = CharEscape::from_escape_table(escape, byte);
        formatter.write_char_escape(writer, char_escape)?;

        start = i + 1;
    }

    if start == bytes.len() {
        return Ok(());
    }

    formatter.write_string_fragment(writer, &value[start..])
}

const BB: u8 = b'b'; // \x08
const TT: u8 = b't'; // \x09
const NN: u8 = b'n'; // \x0A
const FF: u8 = b'f'; // \x0C
const RR: u8 = b'r'; // \x0D
const QU: u8 = b'"'; // \x22
const BS: u8 = b'\\'; // \x5C
const UU: u8 = b'u'; // \x00...\x1F except the ones above
const __: u8 = 0;

// Lookup table of escape sequences. A value of b'x' at index i means that byte
// i is escaped as "\x" in JSON. A value of 0 means that byte i is not escaped.
static ESCAPE: [u8; 256] = [
    //   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
    UU, UU, UU, UU, UU, UU, UU, UU, BB, TT, NN, UU, FF, RR, UU, UU, // 0
    UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, // 1
    __, __, QU, __, __, __, __, __, __, __, __, __, __, __, __, __, // 2
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 3
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 4
    __, __, __, __, __, __, __, __, __, __, __, __, BS, __, __, __, // 5
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 6
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 7
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 8
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 9
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // A
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // B
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // C
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // D
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // E
    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // F
];

/// Represents a character escape code in a type-safe manner.
pub enum CharEscape {
    /// An escaped quote `"`
    Quote,
    /// An escaped reverse solidus `\`
    ReverseSolidus,
    /// An escaped solidus `/`
    Solidus,
    /// An escaped backspace character (usually escaped as `\b`)
    Backspace,
    /// An escaped form feed character (usually escaped as `\f`)
    FormFeed,
    /// An escaped line feed character (usually escaped as `\n`)
    LineFeed,
    /// An escaped carriage return character (usually escaped as `\r`)
    CarriageReturn,
    /// An escaped tab character (usually escaped as `\t`)
    Tab,
    /// An escaped ASCII plane control character (usually escaped as
    /// `\u00XX` where `XX` are two hex characters)
    AsciiControl(u8),
}

impl CharEscape {
    #[inline]
    fn from_escape_table(escape: u8, byte: u8) -> CharEscape {
        match escape {
            self::BB => CharEscape::Backspace,
            self::TT => CharEscape::Tab,
            self::NN => CharEscape::LineFeed,
            self::FF => CharEscape::FormFeed,
            self::RR => CharEscape::CarriageReturn,
            self::QU => CharEscape::Quote,
            self::BS => CharEscape::ReverseSolidus,
            self::UU => CharEscape::AsciiControl(byte),
            _ => unreachable!(),
        }
    }
}

pub trait Formatter {
    fn write_i8<W>(&mut self, writer: &mut W, value: i8) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_i16<W>(&mut self, writer: &mut W, value: i16) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_i32<W>(&mut self, writer: &mut W, value: i32) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_i64<W>(&mut self, writer: &mut W, value: i64) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_u8<W>(&mut self, writer: &mut W, value: u8) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_u16<W>(&mut self, writer: &mut W, value: u16) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_u32<W>(&mut self, writer: &mut W, value: u32) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_u64<W>(&mut self, writer: &mut W, value: u64) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let mut buffer = itoa::Buffer::new();
        let s = buffer.format(value);
        writer.write_all(s.as_bytes())
    }

    fn write_f32<W>(&mut self, writer: &mut W, value: f32) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(format!("{value}").as_bytes())
    }

    fn write_f64<W>(&mut self, writer: &mut W, value: f64) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(format!("{value}").as_bytes())
    }

    fn write_bool<W>(&mut self, writer: &mut W, value: bool) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        let output = if value { b"true" as &[u8] } else { b"false" };

        writer.write_all(output)
    }

    fn write_null<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b"null")
    }

    fn write_char<W>(&mut self, writer: &mut W, value: char) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(format!(r#"'{}'"#, value).as_bytes())
    }

    fn begin_object<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b"{")
    }

    fn end_object<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b"}")
    }

    fn begin_array<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b"[")
    }

    fn end_array<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b"]")
    }

    fn begin_string<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b"\"")
    }

    fn write_string<W>(&mut self, writer: &mut W, value: &str) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(value.as_bytes())
    }

    fn end_string<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b"\"")
    }

    fn begin_object_key<W>(&mut self, writer: &mut W, first: bool) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        if !first {
            writer.write_all(b",")
        } else {
            Ok(())
        }
    }

    fn end_object_key<W>(&mut self, _writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        Ok(())
    }

    fn begin_object_value<W>(&mut self, writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(b":")
    }

    fn end_object_value<W>(&mut self, _writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        Ok(())
    }
    fn begin_array_value<W>(&mut self, writer: &mut W, first: bool) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        if first {
            Ok(())
        } else {
            writer.write_all(b",")
        }
    }

    fn end_array_value<W>(&mut self, _writer: &mut W) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        Ok(())
    }

    #[inline]
    fn write_string_fragment<W>(&mut self, writer: &mut W, fragment: &str) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        writer.write_all(fragment.as_bytes())
    }

    /// Writes a character escape code to the specified writer.
    #[inline]
    fn write_char_escape<W>(&mut self, writer: &mut W, char_escape: CharEscape) -> io::Result<()>
    where
        W: ?Sized + io::Write,
    {
        use self::CharEscape::*;

        let s = match char_escape {
            Quote => b"\\\"",
            ReverseSolidus => b"\\\\",
            Solidus => b"\\/",
            Backspace => b"\\b",
            FormFeed => b"\\f",
            LineFeed => b"\\n",
            CarriageReturn => b"\\r",
            Tab => b"\\t",
            AsciiControl(byte) => {
                static HEX_DIGITS: [u8; 16] = *b"0123456789abcdef";
                let bytes = &[
                    b'\\',
                    b'u',
                    b'0',
                    b'0',
                    HEX_DIGITS[(byte >> 4) as usize],
                    HEX_DIGITS[(byte & 0xF) as usize],
                ];
                return writer.write_all(bytes);
            }
        };

        writer.write_all(s)
    }
}