numbers: implement currency formatting with long display names.

Fixes #578

3 files changed, 109 insertions, 0 deletions

diff --git a/babel/numbers.py b/babel/numbers.py
index 564d7ce..9df19e9 100644
--- a/babel/numbers.py
+++ b/babel/numbers.py
@@ -442,6 +442,17 @@ def format_currency(
         ...
     UnknownCurrencyFormatError: "'unknown' is not a known currency format type"
 
+    You can also pass format_type='name' to use long display names. The order of
+    the number and currency name, along with the correct localized plural form
+    of the currency name, is chosen according to locale:
+
+    >>> format_currency(1, 'USD', locale='en_US', format_type='name')
+    u'1.00 US dollar'
+    >>> format_currency(1099.98, 'USD', locale='en_US', format_type='name')
+    u'1,099.98 US dollars'
+    >>> format_currency(1099.98, 'USD', locale='ee', format_type='name')
+    u'us ga dollar 1,099.98'
+
     By default the locale is allowed to truncate and round a high-precision
     number by forcing its format pattern onto the decimal part. You can bypass
     this behavior with the `decimal_quantization` parameter:
@@ -459,7 +470,12 @@ def format_currency(
     :param format_type: the currency format type to use
     :param decimal_quantization: Truncate and round high-precision numbers to
                                  the format pattern. Defaults to `True`.
+
     """
+    if format_type == 'name':
+        return _format_currency_long_name(number, currency, format=format,
+                                          locale=locale, currency_digits=currency_digits,
+                                          decimal_quantization=decimal_quantization)
     locale = Locale.parse(locale)
     if format:
         pattern = parse_pattern(format)
@@ -475,6 +491,52 @@ def format_currency(
         decimal_quantization=decimal_quantization)
 
 
+def _format_currency_long_name(
+        number, currency, format=None, locale=LC_NUMERIC, currency_digits=True,
+        format_type='standard', decimal_quantization=True):
+    # Algorithm described here:
+    # https://www.unicode.org/reports/tr35/tr35-numbers.html#Currencies
+    locale = Locale.parse(locale)
+    # Step 1.
+    # There are no examples of items with explicit count (0 or 1) in current
+    # locale data. So there is no point implementing that.
+    # Step 2.
+    if isinstance(number, string_types):
+        plural_category = locale.plural_form(float(number))
+    else:
+        plural_category = locale.plural_form(number)
+
+    # Step 3.
+    try:
+        unit_pattern = locale._data['currency_unit_patterns'][plural_category]
+    except LookupError:
+        unit_pattern = locale._data['currency_unit_patterns']['other']
+
+    # Step 4.
+    try:
+        display_name = locale._data['currency_names_plural'][currency][plural_category]
+    except LookupError:
+        try:
+            display_name = locale._data['currency_names_plural'][currency]['other']
+        except LookupError:
+            try:
+                display_name = locale._data['currency_names'][currency]
+            except LookupError:
+                display_name = currency
+
+    # Step 5.
+    if not format:
+        format = locale.decimal_formats.get(format)
+
+    pattern = parse_pattern(format)
+
+    number_part = pattern.apply(
+        number, locale, currency=currency, currency_digits=currency_digits,
+        decimal_quantization=decimal_quantization)
+
+    return unit_pattern.format(number_part, display_name)
+
+
 def format_percent(
         number, format=None, locale=LC_NUMERIC, decimal_quantization=True):
     """Return formatted percent value for a specific locale.
diff --git a/scripts/import_cldr.py b/scripts/import_cldr.py
index 60aa6c2..40887f0 100755
--- a/scripts/import_cldr.py
+++ b/scripts/import_cldr.py
@@ -423,6 +423,7 @@ def _process_local_datas(sup, srcdir, destdir, force=False, dump_json=False):
         parse_percent_formats(data, tree)
 
         parse_currency_formats(data, tree)
+        parse_currency_unit_patterns(data, tree)
         parse_currency_names(data, tree)
         parse_unit_patterns(data, tree)
         parse_date_fields(data, tree)
@@ -903,6 +904,14 @@ def parse_currency_formats(data, tree):
                         currency_formats[type] = numbers.parse_pattern(pattern)
 
 
+def parse_currency_unit_patterns(data, tree):
+    currency_unit_patterns = data.setdefault('currency_unit_patterns', {})
+    for unit_pattern_elem in tree.findall('.//currencyFormats/unitPattern'):
+        count = unit_pattern_elem.attrib['count']
+        pattern = text_type(unit_pattern_elem.text)
+        currency_unit_patterns[count] = pattern
+
+
 def parse_day_period_rules(tree):
     """
     Parse dayPeriodRule data into a dict.
diff --git a/tests/test_numbers.py b/tests/test_numbers.py
index 493c1a7..f0239cb 100644
--- a/tests/test_numbers.py
+++ b/tests/test_numbers.py
@@ -415,6 +415,44 @@ def test_format_currency_quantization():
             '0.9999999999', 'USD', locale=locale_code, decimal_quantization=False).find('9999999999') > -1
 
 
+def test_format_currency_long_display_name():
+    assert (numbers.format_currency(1099.98, 'USD', locale='en_US', format_type='name')
+            == u'1,099.98 US dollars')
+    assert (numbers.format_currency(1.00, 'USD', locale='en_US', format_type='name')
+            == u'1.00 US dollar')
+    assert (numbers.format_currency(1.00, 'EUR', locale='en_US', format_type='name')
+            == u'1.00 euro')
+    assert (numbers.format_currency(2, 'EUR', locale='en_US', format_type='name')
+            == u'2.00 euros')
+    # This tests that '{1} {0}' unitPatterns are found:
+    assert (numbers.format_currency(1, 'USD', locale='sw', format_type='name')
+            == u'dola ya Marekani 1.00')
+    # This tests unicode chars:
+    assert (numbers.format_currency(1099.98, 'USD', locale='es_GT', format_type='name')
+            == u'dólares estadounidenses 1,099.98')
+    # Test for completely unknown currency, should fallback to currency code
+    assert (numbers.format_currency(1099.98, 'XAB', locale='en_US', format_type='name')
+            == u'1,099.98 XAB')
+
+
+def test_format_currency_long_display_name_all():
+    for locale_code in localedata.locale_identifiers():
+        assert numbers.format_currency(
+            1, 'USD', locale=locale_code, format_type='name').find('1') > -1
+        assert numbers.format_currency(
+            '1', 'USD', locale=locale_code, format_type='name').find('1') > -1
+
+
+def test_format_currency_long_display_name_custom_format():
+    assert (numbers.format_currency(1099.98, 'USD', locale='en_US',
+                                    format_type='name', format='##0')
+            == '1099.98 US dollars')
+    assert (numbers.format_currency(1099.98, 'USD', locale='en_US',
+                                    format_type='name', format='##0',
+                                    currency_digits=False)
+            == '1100 US dollars')
+
+
 def test_format_percent():
     assert numbers.format_percent(0.34, locale='en_US') == u'34%'
     assert numbers.format_percent(0, locale='en_US') == u'0%'