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Current File : //usr/share/doc/re2c/examples/rust/reuse/usedir.re

// re2rust $INPUT -o $OUTPUT

// This example shows how to combine reusable re2c blocks: two blocks
// ('colors' and 'fish') are merged into one. The 'salmon' rule occurs
// in both blocks; the 'fish' block takes priority because it is used
// earlier. Default rule * occurs in all three blocks; the local (not
// inherited) definition takes priority.

#[derive(Debug, PartialEq)]
enum Ans { Color, Fish, Dunno }

/*!rules:re2c:colors
    *                            { panic!("ah"); }
    "red" | "salmon" | "magenta" { return Ans::Color; }
*/

/*!rules:re2c:fish
    *                            { panic!("oh"); }
    "haddock" | "salmon" | "eel" { return Ans::Fish; }
*/

fn lex(str: &[u8]) -> Ans {
    let (mut cur, mut mar) = (0, 0);
    /*!re2c
        re2c:yyfill:enable = 0;
        re2c:define:YYCTYPE   = u8;
        re2c:define:YYPEEK    = "*str.get_unchecked(cur)";
        re2c:define:YYSKIP    = "cur += 1;";
        re2c:define:YYBACKUP  = "mar = cur;";
        re2c:define:YYRESTORE = "cur = mar;";

        !use:fish;
        !use:colors;
        * { return Ans::Dunno; }  // overrides inherited '*' rules
    */
}

fn main() {
    assert_eq!(lex(b"salmon"), Ans::Fish);
    assert_eq!(lex(b"what?"), Ans::Dunno);
}

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