Data.Text.ICU.Convert

text-icu-0.7.0.1: Bindings to the ICU library

Copyright | (c) 2009, 2010 Bryan O'Sullivan
License | BSD-style
Maintainer | bos@serpentine.com
Stability | experimental
Portability | GHC
Safe Haskell | None
Language | Haskell98

Data.Text.ICU.Convert

Contents

- Character set conversion
  - Basic functions
  - Converter metadata
- Functions for controlling global behavior
- Miscellaneous functions
- Metadata

Description

Character set conversion functions for Unicode, implemented as bindings to the International Components for Unicode (ICU) libraries.

Synopsis

- data Converter
- open :: String -> Maybe Bool -> IO Converter
- fromUnicode :: Converter -> Text -> ByteString
- toUnicode :: Converter -> ByteString -> Text
- getName :: Converter -> String
- usesFallback :: Converter -> Bool
- isAmbiguous :: Converter -> Bool
- getDefaultName :: IO String
- setDefaultName :: String -> IO ()
- compareNames :: String -> String -> Ordering
- aliases :: String -> [String]
- converterNames :: [String]
- standardNames :: [String]

# Character set conversion

data Converter #

Character set converter type. Note: this structure is not thread safe. It is not safe to use value of this type simultaneously from multiple threads.

Instances

Eq Converter # |
Methods (==) :: Converter -> Converter -> Bool # (/=) :: Converter -> Converter -> Bool #
Show Converter # |
Methods showsPrec :: Int -> Converter -> ShowS # show :: Converter -> String # showList :: [Converter] -> ShowS #

## Basic functions

open #

Arguments

:: String | Name of the converter to use.
-> Maybe Bool | Whether to use fallback mappings (see `usesFallback` for details).
-> IO Converter |

Create a `Converter` with the name of a coded character set specified as a string. The actual name will be resolved with the alias file using a case-insensitive string comparison that ignores leading zeroes and all non-alphanumeric characters. E.g., the names `"UTF8"`, `"utf-8"`, `"u*T@f08"` and `"Utf 8"` are all equivalent (see also `compareNames`). If an empty string is passed for the converter name, it will create one with the `getDefaultName` return value.

A converter name may contain options like a locale specification to control the specific behavior of the newly instantiated converter. The meaning of the options depends on the particular converter. If an option is not defined for or recognized by a given converter, then it is ignored.

Options are appended to the converter name string, with a comma between the name and the first option and also between adjacent options.

If the alias is ambiguous, then the preferred converter is used.

The conversion behavior and names can vary between platforms. ICU may convert some characters differently from other platforms. Details on this topic are in the ICU User's Guide at http://icu-project.org/userguide/conversion.html. Aliases starting with a `"cp"` prefix have no specific meaning other than its an alias starting with the letters `"cp"`. Please do not associate any meaning to these aliases.

fromUnicode :: Converter -> Text -> ByteString #

Encode a Unicode string into a codepage string using the given converter.

toUnicode :: Converter -> ByteString -> Text #

Decode an encoded string into a Unicode string using the given converter.

## Converter metadata

getName :: Converter -> String #

Gets the internal, canonical name of the converter.

usesFallback :: Converter -> Bool #

Determines whether the converter uses fallback mappings or not. This flag has restrictions. Regardless of this flag, the converter will always use fallbacks from Unicode Private Use code points, as well as reverse fallbacks (to Unicode). For details see ".ucm File Format" in the Conversion Data chapter of the ICU User Guide: http://www.icu-project.org/userguide/conversion-data.html#ucmformat

isAmbiguous :: Converter -> Bool #

Indicates whether the converter contains ambiguous mappings of the same character or not.

# Functions for controlling global behavior

getDefaultName :: IO String #

Returns the current default converter name. If you want to `open` a default converter, you do not need to use this function. It is faster to pass the empty string to `open` the default converter.

setDefaultName :: String -> IO () #

Sets the current default converter name. If this function needs to be called, it should be called during application initialization. Most of the time, the results from `getDefaultName` or `open` with an empty string argument is sufficient for your application.

Note: this function is not thread safe. Do not call this function when any ICU function is being used from more than one thread!

# Miscellaneous functions

compareNames :: String -> String -> Ordering #

Do a fuzzy compare of two converter/alias names. The comparison is case-insensitive, ignores leading zeroes if they are not followed by further digits, and ignores all but letters and digits. Thus the strings `"UTF-8"`, `"utf_8"`, `"u*T@f08"` and `"Utf 8"` are exactly equivalent. See section 1.4, Charset Alias Matching in Unicode Technical Standard #22 at http://www.unicode.org/reports/tr22/

aliases :: String -> [String] #

Return the aliases for a given converter or alias name.

# Metadata

converterNames :: [String] #

A list of the canonical names of all available converters.

standardNames :: [String] #

The list of supported standard names.