std/encodings

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Routines for converting between different character encodings. On UNIX, this uses the iconv library, on Windows the Windows API.

The following example shows how to change character encodings.

Example:

import std/encodings
when defined(windows):
  let
    orig = "öäüß"
    # convert `orig` from "UTF-8" to "CP1252"
    cp1252 = convert(orig, "CP1252", "UTF-8")
    # convert `cp1252` from "CP1252" to "ibm850"
    ibm850 = convert(cp1252, "ibm850", "CP1252")
    current = getCurrentEncoding()
  assert orig == "\195\182\195\164\195\188\195\159"
  assert ibm850 == "\148\132\129\225"
  assert convert(ibm850, current, "ibm850") == orig

The example below uses a reuseable EncodingConverter object which is created by open with destEncoding and srcEncoding specified. You can use convert on this object multiple times.

Example:

import std/encodings
when defined(windows):
  var fromGB2312 = open("utf-8", "gb2312")
  let first = "\203\173\197\194\163\191\210\187" &
      "\203\242\209\204\211\234\200\206\198\189\201\250"
  assert fromGB2312.convert(first) == "谁怕？一蓑烟雨任平生"

  let second = "\211\208\176\215\205\183\200\231" &
      "\208\194\163\172\199\227\184\199\200\231\185\202"
  assert fromGB2312.convert(second) == "有白头如新，倾盖如故"

Imports

os, parseutils, strutils

Types

EncodingConverter = object

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EncodingError = object of ValueError

Exception that is raised for encoding errors. Source Edit

Procs

proc close(c: EncodingConverter) {....raises: [], tags: [], forbids: [].}

Frees the resources the converter c holds. Source Edit

proc codePageToName(c: CodePage): string {....raises: [], tags: [], forbids: [].}

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proc convert(c: EncodingConverter; s: string): string {.
    ...raises: [EncodingError, OSError], tags: [], forbids: [].}

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proc convert(s: string; destEncoding = "UTF-8"; srcEncoding = "CP1252"): string {.
    ...raises: [ValueError, EncodingError, EncodingError, OSError], tags: [],
    forbids: [].}

Converts s to destEncoding. It assumed that s is in srcEncoding. This opens a converter, uses it and closes it again and is thus more convenient but also likely less efficient than re-using a converter.

Warning: UTF-16BE and UTF-32 conversions are not supported on Windows.

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proc getCurrentEncoding(uiApp = false): string {....raises: [], tags: [],
    forbids: [].}

Retrieves the current encoding. On Unix, "UTF-8" is always returned. The uiApp parameter is Windows specific. If true, the UI's code-page is returned, if false, the Console's code-page is returned. Source Edit

proc nameToCodePage(name: string): CodePage {....raises: [ValueError], tags: [],
    forbids: [].}

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proc open(destEncoding = "UTF-8"; srcEncoding = "CP1252"): EncodingConverter {.
    ...raises: [ValueError, EncodingError], tags: [], forbids: [].}

Opens a converter that can convert from srcEncoding to destEncoding. Raises EncodingError if it cannot fulfill the request. Source Edit