Data.Text.Format.Heavy.Parse

This module contains parsers for formatting strings. We have to deal with two kinds of strings:

• String formats. This is the whole construct like "Hello, {}! Your account balance is {1:+8.4}.".
• Variable formats. This is only part after colon in braces, i.e. the +8.4 thing in previous example.

The string format syntax is supposed to be very stable and simple. It is basically defined by phrase "any part in braces is variable substitution".

Variable formats syntax depends on type of data which we are going to format. These formats can be pretty complex, for example they can include alignment, rounding, and so on.

Parse functions

parseFormat :: Text -> Either ParseError Format

Parse string format definition.

parseFormat' :: Text -> Format

Version of parseFormat which throws error in case of syntax error in the formatting string.

parseGenericFormat :: Text -> Either ParseError GenericFormat

Parse generic variable format.

Syntax is:

[[fill]align][sign][#][width][.precision][radix]

where:

• fill - padding character (space by default)
• align - alignment indicator (<, >, or ^)
• sign - when to show number's sign (+, -, or space)
• # - if specified, then for hexadecimal numbers the leading 0x will be added
• width - minimum length of the field
• precision - number of decimal places after point, for floatting-point numbers
• radix - h or x for hexadecimal, d for decimal (default).

parseBoolFormat :: Text -> Either ParseError BoolFormat

Parse Bool format.

Syntax is:

TRUE:FALSE

Colon can be replaced with comma or semicolon.

For example, valid format specifications are true:false (the default one), True:False, yes:no, and so on.

parseMaybeFormat :: Text -> Maybe (Text, Text)

Try to parse format for Maybe x type. The syntax is:

someformat|nothing

where someformat is format for the x type, and nothing is the string to be substituted for Nothing value.

Returns Nothing, if format does not contain |. Otherwise, returns Just (someformat, nothing).

Parsec functions

pFormat :: Parser Format

Parsec parser for string format.

pGenericFormat :: Parsec Text st GenericFormat

Parsec parser for generic (Python-like) variable format.

pBoolFormat :: Parsec Text st BoolFormat

Parsec parser for Bool format

Utility types

type Parser a = Parsec Text ParserState a

data ParserState

Constructors

ParserState

Fields

• psNextIndex :: Int

Instances

Eq ParserState

Methods

(==) :: ParserState -> ParserState -> Bool

(/=) :: ParserState -> ParserState -> Bool

Show ParserState

Methods

showsPrec :: Int -> ParserState -> ShowS

show :: ParserState -> String

showList :: [ParserState] -> ShowS

initParserState :: ParserState