gettext-parser

Parse and compile gettext po and mo files with node.js, nothing more, nothing less.

Please note: starting with version 3 only latest LTS and latest stable node versions are supported. Use version 2 with older node versions.

Usage

Include the library:

import gettextParser from "gettext-parser";

Parse PO files

Parse a PO file with

gettextParser.po.parse(input[, options]) → Object

Where

• input is a po file as a Buffer or an unicode string. Charset is converted to unicode from other encodings only if the input is a Buffer, otherwise the charset information is discarded
• options is an optional object with the following optional properties:

  • defaultCharset is the charset to use if charset is not defined or is the default "CHARSET" (applies only if input is a Buffer)

  • validation is a flag to turn on PO source file validation. The validation makes sure that:

    • there is exactly zero or one msgid_plural definition per translation entry; a Multiple msgid_plural error error gets thrown otherwise.
    • there are no duplicate entries with exact msgid values; a Duplicate msgid error error gets thrown otherwise.
    • the number of plural forms matches exactly the number from nplurals defined in Plural-Forms header for entries that have plural forms; a Plural forms range error error gets thrown otherwise.
    • the number of msgstr matches exacty the one (if msgid_plural is not defined) or the number from nplurals (if msgid_plural is defined); a Translation string range error error gets thrown otherwise.
    • strings end on the same line they start on, with line breaks encoded as \n (matching GNU gettext, which rejects strings spanning multiple lines); an End-of-line within string error gets thrown otherwise.
    • the file does not end in the middle of a string; an End-of-file within string error gets thrown otherwise.

Method returns gettext-parser specific translation object (see below)

Example

import { readFileSync } from 'node:fs';
var input = readFileSync('en.po');
var po = gettextParser.po.parse(input);
console.log(po.translations['']); // output translations for the default context

Parse PO as a Stream

PO files can also be parsed from a stream source. After all input is processed the parser emits a single 'data' event which contains the parsed translation object.

gettextParser.po.createParseStream([options][, transformOptions]) → Transform Stream

Where

• options is an optional object, same as in parse. See Parse PO files section for details.
• transformOptions are the standard stream options.

Example

import { createReadStream } from 'node:fs';
var input = createReadStream('en.po');
var po = gettextParser.po.createParseStream();
input.pipe(po);
po.on('data', function(data){
    console.log(data.translations['']); // output translations for the default context
});

Compile PO from a translation object

If you have a translation object you can convert this to a valid PO file with

gettextParser.po.compile(data[, options]) → Buffer

Where

• data is a translation object either got from parsing a PO/MO file or composed by other means
• options is a configuration object with possible values
  • foldLength is the length at which to fold message strings into newlines (default: 76). Set to 0 or false to disable folding.
  • sort (boolean|Function) - (default false) if true, entries will be sorted by msgid in the resulting .po(.pot) file. If a comparator function is provided, that function will be used to sort entries in the output. The function is called with two arguments, each of which is a single message entry with the structure described below. The function should follow the standard rules for functions passed to Array.sort(): return 0 if the entries are interchangeable in sort order; return a number less than 0 if the first entry should come before the second one; and return a number greater than 0 if the second entry should come before the first one.
  • escapeCharacters (boolean) - (default true) if false, will skip escape newlines and quotes characters functionality.

Example

import { writeFileSync } from 'node:fs';
var data = {
    ...
};
var output = gettextParser.po.compile(data);
writeFileSync('filename.po', output);

Parse MO files

Parse a MO file with

gettextParser.mo.parse(input[, defaultCharset]) → Object

Where

• input is a mo file as a Buffer
• defaultCharset is the charset to use if charset is not defined or is the default "CHARSET"

Method returns gettext-parser specific translation object (see below)

Example

import { readFileSync } from 'node:fs';
var input = readFileSync('en.mo');
var mo = gettextParser.mo.parse(input);
console.log(mo.translations['']); // output translations for the default context

Compile MO from a translation object

If you have a translation object you can convert this to a valid MO file with

gettextParser.mo.compile(data) → Buffer

Where

• data is a translation object either got from parsing a PO/MO file or composed by other means

Example

import { writeFileSync } from 'node:fs';
var data = {
    ...
};
var output = gettextParser.mo.compile(data);
writeFileSync('filename.mo', output);

Notes

Overriding charset

If you are compiling a previously parsed translation object, you can override the output charset with the charset property (applies both for compiling mo and po files).

var obj = gettextParser.po.parse(inputBuf);
obj.charset = "windows-1257";
outputBuf = gettextParser.po.compile(obj);

Headers for the output are modified to match the updated charset.

ICONV support

By default gettext-parser uses pure JS iconv-lite for encoding and decoding non UTF-8 charsets. If you need to support more complex encodings that are not supported by iconv-lite, you need to add iconv as an additional dependency for your project (gettext-parser will detect if it is available and tries to use it instead of iconv-lite).

Data structure of parsed mo/po files

Character set

Parsed data is always in unicode but the original charset of the file can be found from the charset property. This value is also used when compiling translations to a mo or po file.

Headers

Headers can be found from the headers object and the value for a key is a string. This value will also be used when compiling.

Key casing isn't lowercased: the ~10 standard gettext headers (Language, Plural-Forms, Content-Type, ...) are recognized case-insensitively and normalized to their canonical name, while any other header (e.g. a tool-specific X-Poedit-* header) keeps whatever casing the source file used, unchanged (see #52).

Translations

Translations can be found from the translations object which in turn holds context objects for msgctxt. Default context can be found from translations[""].

Context objects include all the translations, where msgid value is the key. The value is an object with the following possible properties:

• msgctxt context for this translation, if not present the default context applies
• msgid string to be translated
• msgid_plural the plural form of the original string (might not be present)
• msgstr an array of translations
• comments an object with the following properties: translator, reference, extracted, flag, previous.

Example

{
  "charset": "iso-8859-1",

  "headers": {
    "content-type": "text/plain; charset=iso-8859-1",
    "plural-forms": "nplurals=2; plural=(n!=1);"
  },

  "translations": {
    "": {
      "": {
        "msgid": "",
        "msgstr": ["Content-Type: text/plain; charset=iso-8859-1\n..."]
      }
    },
    "another context": {
      "%s example": {
        "msgctxt": "another context",
        "msgid": "%s example",
        "msgid_plural": "%s examples",
        "msgstr": ["% näide", "%s näidet"],
        "comments": {
          "translator": "This is regular comment",
          "reference": "/path/to/file:123"
        }
      }
    }
  }
}

Notice that the structure has both a headers object and a "" translation with the header string. When compiling the structure to a mo or a po file, the headers object is used to define the header. Header string in the "" translation is just for reference (includes the original unmodified data) but will not be used when compiling. So if you need to add or alter header values, use only the headers object.

If you need to convert gettext-parser formatted translation object to something else, eg. for jed, check out po2json.

License

MIT