1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170

/*
 * mini-haskell: light-weight Haskell for fun
 * Copyright (C) 2020  Xie Ruifeng
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

//! chars and strings: see "Haskell 2010 Report: 2.6 Character and String Literals".

use std::convert::identity;
use num_bigint::BigInt;
use num_traits::ToPrimitive;

use super::{Scanner, Result, basic::*};
use crate::utils::char::{Stream, CharPredicate, Ascii};
use crate::error::Diagnostic;
use crate::error::DiagnosticMessage::Error;
use crate::error::Error::CharOutOfBound;
use crate::lexeme::Lexeme::{self, CharLiteral, StringLiteral};

impl<I: std::io::Read> Scanner<I> {
    /// Character literals or string literals.
    pub fn char_or_string(&mut self) -> Result<Lexeme> {
        alt!(self, Self::char, Self::string);
        Self::keep_trying()
    }

    fn char(&mut self) -> Option<Lexeme> {
        // char     -> ' ( graphic<’ | \> | space | escape<\&> ) '
        analyse!(self, '\'');
        let c = simple_alt!(self, choice!(c; c: all!(Graphic, not!("'\\"))), Self::escape)?;
        analyse!(self, '\'');
        Some(CharLiteral(c))
    }

    fn string(&mut self) -> Option<Lexeme> {
        // string   -> " {graphic<" | \>  | space | escape | gap} "
        analyse!(self, '"');
        let s = identity::<Option<_>>(self.many(
            |this| {
                alt!(this, seq!("\\&" => None),
                           choice!(Some(c); c: any!(all!(Graphic, not!("\"\\")), ' ')),
                           |this| this.escape().map(Some),
                           |this| this.gap().map(|_| None));
                None
            },
            String::new(),
            |res: &mut String, c| if let Some(c) = c { res.push(c) }))?;
        analyse!(self, '"');
        Some(StringLiteral(s))
    }

    fn escape(&mut self) -> Option<char> {
        // escape   -> \ ( charesc | ascii | decimal | o octal | x hexadecimal )
        analyse!(self, '\\');
        simple_alt!(self,
            Self::char_esc,
            Self::ascii,
            |this| this.numeric_escape(10),
            |this| { analyse!(this, 'o'); this.numeric_escape(8) },
            |this| { analyse!(this, 'x'); this.numeric_escape(16) })
    }

    fn numeric_escape(&mut self, base: u32) -> Option<char> {
        let start_loc = self.location;
        analyse!(self, d: {BigInt::from(0)}{Self::app_int(base)} +Digit);
        Some(d.to_u32().and_then(std::char::from_u32).unwrap_or_else(|| {
            Diagnostic::new(self.location, Error(CharOutOfBound(d)))
                .within(start_loc, self.location)
                .report(&mut self.diagnostics);
            '�'
        }))
    }

    fn char_esc(&mut self) -> Option<char> {
        // charesc  -> a | b | f | n | r | t | v | \ | " | ’ | &
        // Note: '\&' produces no character at all, so should be specially handled.
        Some(match self.next()? {
            'a' => '\u{7}',
            'b' => '\u{8}',
            'f' => '\u{C}',
            'n' => '\n',
            'r' => '\r',
            't' => '\t',
            'v' => '\u{B}',
            '\\' => '\\',
            '"' => '"',
            '\'' => '\'',
            _ => return None,
        })
    }

    fn gap(&mut self) -> Option<()> {
        // gap      -> \ whitechar {whitechar} \
        analyse!(self, '\\');
        identity::<Option<_>>(self.some_(Self::whitechar))?;
        analyse!(self, '\\');
        Some(())
    }

    fn ascii(&mut self) -> Option<char> {
        simple_alt!(self, Self::ascii_control, Self::ascii_rest)
    }

    fn ascii_control(&mut self) -> Option<char> {
        // cntrl    -> ascLarge | @ | [ | \ | ] | ˆ | _
        analyse!(self, '^');
        simple_alt!(self,
            choice!(char::from(c as u8 - b'A' + 1); c: Ascii::Upper),
            choice!('\0'; '@'),
            choice!(char::from(27); '['),
            choice!(char::from(28); '\\'),
            choice!(char::from(29); ']'),
            choice!(char::from(30); '^'),
            choice!(char::from(31); '_'))
    }

    fn ascii_rest(&mut self) -> Option<char> {
        // ascii    -> ˆcntrl | NUL | SOH | STX | ETX | EOT | ENQ | ACK
        //           | BEL | BS | HT | LF | VT | FF | CR | SO | SI | DLE
        //           | DC1 | DC2 | DC3 | DC4 | NAK | SYN | ETB | CAN
        //           | EM | SUB | ESC | FS | GS | RS | US | SP | DEL
        let names = ["NUL", "SOH", "STX", "ETX", "EOT", "ENQ", "ACK",
            "BEL", "BS", "HT", "LF", "VT", "FF", "CR", "SO", "SI", "DLE",
            "DC1", "DC2", "DC3", "DC4", "NAK", "SYN", "ETB", "CAN",
            "EM", "SUB", "ESC", "FS", "GS", "RS", "US", "SP", "DEL"];
        for (k, nm) in names.iter().copied().enumerate() {
            if let Some(r) = self.anchored(seq!(nm => k)) {
                return Some(char::from(r as u8));
            }
        }
        None
    }
}

#[cfg(test)]
mod tests {
    use crate::scanner::test_scanner_on;
    use crate::utils::setup_logger;
    use crate::utils::Result3::Success;
    use crate::lexeme::Lexeme::{self, CharLiteral, StringLiteral};

    #[test]
    fn test_char_string() {
        setup_logger();
        fn test(input: &str, res: Lexeme) {
            trace!(scanner, "test on {:?} ...", input);
            test_scanner_on(input, method!(char_or_string), Success(res), None);
        }
        test("'A'", CharLiteral('A'));
        test(r"'\r'", CharLiteral('\r'));
        test(r"'\ESC'", CharLiteral('\x1b'));
        test(r"'\^X'", CharLiteral('\x18'));
        test(r#""A\r\ESC\^X""#, StringLiteral("A\r\x1b\x18".to_string()));
        test(r#""\SO\&H\SOH\4\&2\
                      \Some\&Other\nText""#,
             StringLiteral("\x0eH\x01\x042SomeOther\nText".to_string()));
    }
}