Sequence
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3bc608d4a7
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54
src/lib.rs
54
src/lib.rs
@ -28,7 +28,47 @@ where
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P: Parser<I, O1, E>,
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F: Fn(O1) -> O2,
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{
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move |input| parser.parse(input).map(|(result, rest)| (map_fn(result), rest))
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move |input| {
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parser
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.parse(input)
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.map(|(result, rest)| (map_fn(result), rest))
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}
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}
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fn seq<P1, P2, I, O1, O2, E>(parser1: P1, parser2: P2) -> impl Parser<I, (O1, O2), E>
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where
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P1: Parser<I, O1, E>,
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P2: Parser<I, O2, E>,
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{
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move |input| {
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parser1.parse(input).and_then(|(result1, rest1)| {
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parser2
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.parse(rest1)
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.map(|(result2, rest2)| ((result1, result2), rest2))
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})
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}
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}
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/// Parses a standard identifier in a programming language
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fn identifier(input: &str) -> ParseResult<&str, String, &str> {
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let mut chars = input.chars();
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let mut buf = String::new();
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match chars.next() {
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Some(ch) if ch.is_alphabetic() => buf.push(ch),
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_ => return Err(input),
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}
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while let Some(next) = chars.next() {
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if next.is_alphanumeric() {
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buf.push(next);
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} else {
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break;
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}
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}
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let next_index = buf.len();
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Ok((buf, &input[next_index..]))
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}
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#[cfg(test)]
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@ -42,10 +82,22 @@ mod tests {
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assert_matches!(output.unwrap(), ("a", " yolo"));
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}
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#[test]
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fn test_identifier() {
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assert_matches!(identifier("bongo1beans"), Ok((s, "")) if s == "bongo1beans");
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assert_matches!(identifier("2bongo1beans"), Err("2bongo1beans"));
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}
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#[test]
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fn test_map() {
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let lit_a = literal("a");
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let output = map(lit_a, |s| s.to_uppercase()).parse("a yolo");
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assert_matches!(output.unwrap(), (s, " yolo") if s == "A");
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}
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#[test]
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fn test_seq() {
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let p = seq(identifier, seq(literal(" "), literal("ruts")));
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assert_matches!(p.parse("fort1 ruts"), Ok((r, "")) if r.0 == "fort1" && r.1 == (" ", "ruts") );
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}
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}
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