FlatParse.Basic.Text

Parsers for textual data (UTF-8, ASCII).

UTF-8

char :: Char -> Q Exp

Parse a UTF-8 character literal. This is a template function, you can use it as $(char 'x'), for example, and the splice in this case has type Parser e ().

string :: String -> Q Exp

Parse a UTF-8 string literal. This is a template function, you can use it as $(string "foo"), for example, and the splice has type Parser e ().

anyChar :: ParserT st e Char

Parse any single Unicode character encoded using UTF-8 as a Char.

skipAnyChar :: ParserT st e ()

Skip any single Unicode character encoded using UTF-8.

satisfy :: (Char -> Bool) -> ParserT st e Char

Parse a UTF-8 Char for which a predicate holds.

skipSatisfy :: (Char -> Bool) -> ParserT st e ()

Skip a UTF-8 Char for which a predicate holds.

fusedSatisfy :: (Char -> Bool) -> (Char -> Bool) -> (Char -> Bool) -> (Char -> Bool) -> ParserT st e Char

This is a variant of satisfy which allows more optimization. We can pick four testing functions for the four cases for the possible number of bytes in the UTF-8 character. So in fusedSatisfy f1 f2 f3 f4, if we read a one-byte character, the result is scrutinized with f1, for two-bytes, with f2, and so on. This can result in dramatic lexing speedups.

For example, if we want to accept any letter, the naive solution would be to use isLetter, but this accesses a large lookup table of Unicode character classes. We can do better with fusedSatisfy isLatinLetter isLetter isLetter isLetter, since here the isLatinLetter is inlined into the UTF-8 decoding, and it probably handles a great majority of all cases without accessing the character table.

skipFusedSatisfy :: (Char -> Bool) -> (Char -> Bool) -> (Char -> Bool) -> (Char -> Bool) -> Parser e ()

Skipping variant of fusedSatisfy.

takeLine :: ParserT st e String

Parse the rest of the current line as a String. Assumes UTF-8 encoding, throws an error if the encoding is invalid.

takeRestString :: ParserT st e String

Take the rest of the input as a String. Assumes UTF-8 encoding.

ASCII

anyAsciiChar :: ParserT st e Char

Parse any single ASCII character (a single byte) as a Char.

More efficient than anyChar for ASCII-only input.

skipAnyAsciiChar :: ParserT st e ()

Skip any single ASCII character (a single byte).

More efficient than skipAnyChar for ASCII-only input.

satisfyAscii :: (Char -> Bool) -> ParserT st e Char

Parse an ASCII Char for which a predicate holds.

Assumption: the predicate must only return True for ASCII-range characters. Otherwise this function might read a 128-255 range byte, thereby breaking UTF-8 decoding.

skipSatisfyAscii :: (Char -> Bool) -> ParserT st e ()

Skip an ASCII Char for which a predicate holds. Assumption: the predicate must only return True for ASCII-range characters.

ASCII-encoded numbers

anyAsciiDecimalWord :: ParserT st e Word

Parse a non-empty ASCII decimal digit sequence as a Word. Fails on overflow.

anyAsciiDecimalInt :: ParserT st e Int

Parse a non-empty ASCII decimal digit sequence as a positive Int. Fails on overflow.

anyAsciiDecimalInteger :: ParserT st e Integer

Parse a non-empty ASCII decimal digit sequence as a positive Integer.

anyAsciiHexWord :: ParserT st e Word

Parse a non-empty, case-insensitive ASCII hexadecimal digit sequence as a Word. Fails on overflow.

anyAsciiHexInt :: ParserT st e Int

Parse a non-empty, case-insensitive ASCII hexadecimal digit sequence as a positive Int. Fails on overflow.

Debugging parsers

traceLine :: ParserT st e String

Parse the rest of the current line as a String, but restore the parsing state. Assumes UTF-8 encoding. This can be used for debugging.

traceRest :: ParserT st e String

Get the rest of the input as a String, but restore the parsing state. Assumes UTF-8 encoding. This can be used for debugging.