Reads and writes MO (Machine Object) binary translation files — the compiled format used by gettext at runtime.

Source: wp-includes/pomo/mo.php Since: 2.8.0 Extends: Gettext_Translations

Properties

Methods

get_filename()

Returns the path of the loaded MO file.

Returns: string

import_from_file( $filename )

Loads translation entries from an MO file.

Parameters:

Returns: bool — true on success, false on failure.

Behavior: Opens the file with POMO_FileReader, stores the filename, and delegates to import_from_reader().

import_from_reader( $reader )

Parses an MO file from a POMO_FileReader.

Parameters:

Returns: bool — true on success, false on failure.

Behavior:

1. Reads magic number (first 4 bytes) to determine byte order via get_byteorder()
2. Reads 24-byte header: revision, total strings, originals table offset, translations table offset, hash length, hash address
3. Validates: only revision 0 is supported; table sizes must match total * 8
4. Reads originals and translations length/offset tables
5. Skips hash table, reads all string data
6. For each entry:
   • Empty original → parsed as headers via make_headers()
   • Non-empty → parsed via make_entry() into Translation_Entry

export()

Exports the MO data as a binary string.

Returns: string|false — The binary MO data, or false on failure.

Uses php://temp stream internally.

export_to_file( $filename )

Writes the MO data to a file.

Returns: bool

export_to_file_handle( $fh )

Writes the MO binary format to a file handle.

Returns: true

MO binary layout written:

1. Magic number: 0x950412de
2. Revision: 0
3. Total count (entries + 1 for headers)
4. Originals table offset (28)
5. Translations table offset
6. Hash size (0) and hash offset
7. Originals length/offset table
8. Translations length/offset table
9. Original strings (null-separated)
10. Translation strings (null-separated)

Entries are sorted by key before export. Only entries passing is_entry_good_for_export() are included.

is_entry_good_for_export( $entry )

Checks if an entry should be included in export.

Returns: bool — false if translations are empty or all falsy.

export_original( $entry )

Formats an entry’s original string for MO format.

Returns: string — Format: [contextx04]singular[x00plural]

export_translations( $entry )

Formats an entry’s translations for MO format.

Returns: string — Plural translations joined by x00, or single translation.

export_headers()

Formats headers as a string (Header: valuen per line).

Returns: string

get_byteorder( $magic )

Determines byte order from the MO magic number.

Parameters:

Returns: string|false — 'little', 'big', or false if not a valid MO magic number.

Magic values recognized:

• Empty original → parsed as headers via make_headers()
• Non-empty → parsed via make_entry() into Translation_Entry

&make_entry( $original, $translation )

Builds a Translation_Entry from raw MO original and translation strings.

Returns: Translation_Entry (by reference)

Parsing:

• Empty original → parsed as headers via make_headers()
• Non-empty → parsed via make_entry() into Translation_Entry

select_plural_form( $count )

Delegates to gettext_select_plural_form() from Gettext_Translations.

Returns: string (return type in source; effectively int)

get_plural_forms_count()

Returns $_nplurals.

Returns: int