[mod] add documentation about searx.utils

This module is a toolbox for the engines.
Is should be documented.

In addition, searx/utils.py is checked by pylint.

docs/src/searx.utils.rst

@@ -0,0 +1,8 @@
+.. _searx.utils:
+
+=================================
+Utility functions for the engines
+=================================
+
+.. automodule:: searx.utils
+  :members:

searx/utils.py

@@ -1,7 +1,13 @@
-# -*- coding: utf-8 -*-
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# lint: pylint
+# pyright: basic
+"""Utility functions for the engines
+
+"""
 import re
 import importlib
 
+from typing import Optional, Union, Any, Set, List, Dict, MutableMapping, Tuple, Callable
 from numbers import Number
 from os.path import splitext, join
 from random import choice
@@ -23,42 +29,56 @@ from searx import logger
 
 logger = logger.getChild('utils')
 
-blocked_tags = ('script', 'style')
+XPathSpecType = Union[str, XPath]
+
+_BLOCKED_TAGS = ('script', 'style')
+
+_ECMA_UNESCAPE4_RE = re.compile(r'%u([0-9a-fA-F]{4})', re.UNICODE)
+_ECMA_UNESCAPE2_RE = re.compile(r'%([0-9a-fA-F]{2})', re.UNICODE)
 
-ecma_unescape4_re = re.compile(r'%u([0-9a-fA-F]{4})', re.UNICODE)
-ecma_unescape2_re = re.compile(r'%([0-9a-fA-F]{2})', re.UNICODE)
+_STORAGE_UNIT_VALUE: Dict[str, int] = {
+    'TB': 1024 * 1024 * 1024 * 1024,
+    'GB': 1024 * 1024 * 1024,
+    'MB': 1024 * 1024,
+    'TiB': 1000 * 1000 * 1000 * 1000,
+    'MiB': 1000 * 1000,
+    'KiB': 1000,
+}
 
-xpath_cache = dict()
-lang_to_lc_cache = dict()
+_XPATH_CACHE = {}
+_LANG_TO_LC_CACHE = {}
 
 
-class NotSetClass:
-    pass
+class _NotSetClass:  # pylint: disable=too-few-public-methods
+    """Internal class for this module, do not create instance of this class.
+    Replace the None value, allow explicitly pass None as a function argument"""
 
 
-NOTSET = NotSetClass()
+_NOTSET = _NotSetClass()
 
 
-def searx_useragent():
+def searx_useragent() -> str:
     """Return the searx User Agent"""
     return 'searx/{searx_version} {suffix}'.format(
         searx_version=VERSION_TAG, suffix=settings['outgoing']['useragent_suffix']
     ).strip()
 
 
-def gen_useragent(os=None):
+def gen_useragent(os_string: str = None) -> str:
     """Return a random browser User Agent
 
     See searx/data/useragents.json
     """
-    return str(USER_AGENTS['ua'].format(os=os or choice(USER_AGENTS['os']), version=choice(USER_AGENTS['versions'])))
+    return USER_AGENTS['ua'].format(os=os_string or choice(USER_AGENTS['os']), version=choice(USER_AGENTS['versions']))
 
 
-class HTMLTextExtractorException(Exception):
-    pass
+class _HTMLTextExtractorException(Exception):
+    """Internal exception raised when the HTML is invalid"""
 
 
-class HTMLTextExtractor(HTMLParser):  # pylint: disable=W0223  # (see https://bugs.python.org/issue31844)
+class _HTMLTextExtractor(HTMLParser):  # pylint: disable=W0223  # (see https://bugs.python.org/issue31844)
+    """Internal class to extract text from HTML"""
+
     def __init__(self):
         HTMLParser.__init__(self)
         self.result = []
@@ -72,12 +92,12 @@ class HTMLTextExtractor(HTMLParser):  # pylint: disable=W0223  # (see https://bu
             return
 
         if tag != self.tags[-1]:
-            raise HTMLTextExtractorException()
+            raise _HTMLTextExtractorException()
 
         self.tags.pop()
 
     def is_valid_tag(self):
-        return not self.tags or self.tags[-1] not in blocked_tags
+        return not self.tags or self.tags[-1] not in _BLOCKED_TAGS
 
     def handle_data(self, data):
         if not self.is_valid_tag():
@@ -104,7 +124,7 @@ class HTMLTextExtractor(HTMLParser):  # pylint: disable=W0223  # (see https://bu
         return ''.join(self.result).strip()
 
 
-def html_to_text(html_str):
+def html_to_text(html_str: str) -> str:
     """Extract text from a HTML string
 
     Args:
@@ -122,15 +142,15 @@ def html_to_text(html_str):
     """
     html_str = html_str.replace('\n', ' ')
     html_str = ' '.join(html_str.split())
-    s = HTMLTextExtractor()
+    s = _HTMLTextExtractor()
     try:
         s.feed(html_str)
-    except HTMLTextExtractorException:
+    except _HTMLTextExtractorException:
         logger.debug("HTMLTextExtractor: invalid HTML\n%s", html_str)
     return s.get_text()
 
 
-def extract_text(xpath_results, allow_none=False):
+def extract_text(xpath_results, allow_none: bool = False):
     """Extract text from a lxml result
 
     * if xpath_results is list, extract the text from each result and concat the list
@@ -142,24 +162,23 @@ def extract_text(xpath_results, allow_none=False):
         # it's list of result : concat everything using recursive call
         result = ''
         for e in xpath_results:
-            result = result + extract_text(e)
+            result = result + (extract_text(e) or '')
         return result.strip()
-    elif isinstance(xpath_results, ElementBase):
+    if isinstance(xpath_results, ElementBase):
         # it's a element
-        text = html.tostring(xpath_results, encoding='unicode', method='text', with_tail=False)
+        text: str = html.tostring(xpath_results, encoding='unicode', method='text', with_tail=False)
         text = text.strip().replace('\n', ' ')
         return ' '.join(text.split())
-    elif isinstance(xpath_results, (_ElementStringResult, _ElementUnicodeResult, str, Number, bool)):
+    if isinstance(xpath_results, (_ElementStringResult, _ElementUnicodeResult, str, Number, bool)):
         return str(xpath_results)
-    elif xpath_results is None and allow_none:
+    if xpath_results is None and allow_none:
         return None
-    elif xpath_results is None and not allow_none:
+    if xpath_results is None and not allow_none:
         raise ValueError('extract_text(None, allow_none=False)')
-    else:
-        raise ValueError('unsupported type')
+    raise ValueError('unsupported type')
 
 
-def normalize_url(url, base_url):
+def normalize_url(url: str, base_url: str) -> str:
     """Normalize URL: add protocol, join URL with base_url, add trailing slash if there is no path
 
     Args:
@@ -209,7 +228,7 @@ def normalize_url(url, base_url):
     return url
 
 
-def extract_url(xpath_results, base_url):
+def extract_url(xpath_results, base_url) -> str:
     """Extract and normalize URL from lxml Element
 
     Args:
@@ -248,7 +267,7 @@ def extract_url(xpath_results, base_url):
     return normalize_url(url, base_url)
 
 
-def dict_subset(d, properties):
+def dict_subset(dictionnary: MutableMapping, properties: Set[str]) -> Dict:
     """Extract a subset of a dict
 
     Examples:
@@ -257,10 +276,10 @@ def dict_subset(d, properties):
         >>> >> dict_subset({'A': 'a', 'B': 'b', 'C': 'c'}, ['A', 'D'])
         {'A': 'a'}
     """
-    return {k: d[k] for k in properties if k in d}
+    return {k: dictionnary[k] for k in properties if k in dictionnary}
 
 
-def get_torrent_size(filesize, filesize_multiplier):
+def get_torrent_size(filesize: str, filesize_multiplier: str) -> Optional[int]:
     """
 
     Args:
@@ -277,39 +296,20 @@ def get_torrent_size(filesize, filesize_multiplier):
         3140000
     """
     try:
-        filesize = float(filesize)
-
-        if filesize_multiplier == 'TB':
-            filesize = int(filesize * 1024 * 1024 * 1024 * 1024)
-        elif filesize_multiplier == 'GB':
-            filesize = int(filesize * 1024 * 1024 * 1024)
-        elif filesize_multiplier == 'MB':
-            filesize = int(filesize * 1024 * 1024)
-        elif filesize_multiplier == 'KB':
-            filesize = int(filesize * 1024)
-        elif filesize_multiplier == 'TiB':
-            filesize = int(filesize * 1000 * 1000 * 1000 * 1000)
-        elif filesize_multiplier == 'GiB':
-            filesize = int(filesize * 1000 * 1000 * 1000)
-        elif filesize_multiplier == 'MiB':
-            filesize = int(filesize * 1000 * 1000)
-        elif filesize_multiplier == 'KiB':
-            filesize = int(filesize * 1000)
+        multiplier = _STORAGE_UNIT_VALUE.get(filesize_multiplier, 1)
+        return int(float(filesize) * multiplier)
     except ValueError:
-        filesize = None
-
-    return filesize
+        return None
 
 
-def convert_str_to_int(number_str):
+def convert_str_to_int(number_str: str) -> int:
     """Convert number_str to int or 0 if number_str is not a number."""
     if number_str.isdigit():
         return int(number_str)
-    else:
-        return 0
+    return 0
 
 
-def int_or_zero(num):
+def int_or_zero(num: Union[List[str], str]) -> int:
     """Convert num to int or 0. num can be either a str or a list.
     If num is a list, the first element is converted to int (or return 0 if the list is empty).
     If num is a str, see convert_str_to_int
@@ -321,12 +321,12 @@ def int_or_zero(num):
     return convert_str_to_int(num)
 
 
-def is_valid_lang(lang):
+def is_valid_lang(lang) -> Optional[Tuple[bool, str, str]]:
     """Return language code and name if lang describe a language.
 
     Examples:
         >>> is_valid_lang('zz')
-        False
+        None
         >>> is_valid_lang('uk')
         (True, 'uk', 'ukrainian')
         >>> is_valid_lang(b'uk')
@@ -346,28 +346,27 @@ def is_valid_lang(lang):
         for l in language_codes:
             if l[0][:2] == lang:
                 return (True, l[0][:2], l[3].lower())
-        return False
-    else:
-        for l in language_codes:
-            if l[1].lower() == lang or l[3].lower() == lang:
-                return (True, l[0][:2], l[3].lower())
-        return False
+        return None
+    for l in language_codes:
+        if l[1].lower() == lang or l[3].lower() == lang:
+            return (True, l[0][:2], l[3].lower())
+    return None
 
 
-def _get_lang_to_lc_dict(lang_list):
+def _get_lang_to_lc_dict(lang_list: List[str]) -> Dict[str, str]:
     key = str(lang_list)
-    value = lang_to_lc_cache.get(key, None)
+    value = _LANG_TO_LC_CACHE.get(key, None)
     if value is None:
-        value = dict()
-        for lc in lang_list:
-            value.setdefault(lc.split('-')[0], lc)
-        lang_to_lc_cache[key] = value
+        value = {}
+        for lang in lang_list:
+            value.setdefault(lang.split('-')[0], lang)
+        _LANG_TO_LC_CACHE[key] = value
     return value
 
 
 # babel's get_global contains all sorts of miscellaneous locale and territory related data
 # see get_global in: https://github.com/python-babel/babel/blob/master/babel/core.py
-def _get_from_babel(lang_code, key):
+def _get_from_babel(lang_code, key: str):
     match = get_global(key).get(lang_code.replace('-', '_'))
     # for some keys, such as territory_aliases, match may be a list
     if isinstance(match, str):
@@ -375,7 +374,7 @@ def _get_from_babel(lang_code, key):
     return match
 
 
-def _match_language(lang_code, lang_list=[], custom_aliases={}):  # pylint: disable=W0102
+def _match_language(lang_code, lang_list=[], custom_aliases={}) -> Optional[str]:  # pylint: disable=W0102
     """auxiliary function to match lang_code in lang_list"""
     # replace language code with a custom alias if necessary
     if lang_code in custom_aliases:
@@ -400,7 +399,7 @@ def _match_language(lang_code, lang_list=[], custom_aliases={}):  # pylint: disa
     return _get_lang_to_lc_dict(lang_list).get(lang_code, None)
 
 
-def match_language(locale_code, lang_list=[], custom_aliases={}, fallback='en-US'):  # pylint: disable=W0102
+def match_language(locale_code, lang_list=[], custom_aliases={}, fallback='en-US') -> str:  # pylint: disable=W0102
     """get the language code from lang_list that best matches locale_code"""
     # try to get language from given locale_code
     language = _match_language(locale_code, lang_list, custom_aliases)
@@ -438,7 +437,7 @@ def match_language(locale_code, lang_list=[], custom_aliases={}, fallback='en-US
     return language or fallback
 
 
-def load_module(filename, module_dir):
+def load_module(filename: str, module_dir: str):
     modname = splitext(filename)[0]
     filepath = join(module_dir, filename)
     # and https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
@@ -448,19 +447,16 @@ def load_module(filename, module_dir):
     return module
 
 
-def to_string(obj):
+def to_string(obj: Any) -> str:
     """Convert obj to its string representation."""
     if isinstance(obj, str):
         return obj
-    if isinstance(obj, Number):
-        return str(obj)
     if hasattr(obj, '__str__'):
         return obj.__str__()
-    if hasattr(obj, '__repr__'):
-        return obj.__repr__()
+    return repr(obj)
 
 
-def ecma_unescape(s):
+def ecma_unescape(string: str) -> str:
     """Python implementation of the unescape javascript function
 
     https://www.ecma-international.org/ecma-262/6.0/#sec-unescape-string
@@ -475,23 +471,23 @@ def ecma_unescape(s):
         'ó'
     """
     # "%u5409" becomes "吉"
-    s = ecma_unescape4_re.sub(lambda e: chr(int(e.group(1), 16)), s)
+    string = _ECMA_UNESCAPE4_RE.sub(lambda e: chr(int(e.group(1), 16)), string)
     # "%20" becomes " ", "%F3" becomes "ó"
-    s = ecma_unescape2_re.sub(lambda e: chr(int(e.group(1), 16)), s)
-    return s
+    string = _ECMA_UNESCAPE2_RE.sub(lambda e: chr(int(e.group(1), 16)), string)
+    return string
 
 
-def get_string_replaces_function(replaces):
+def get_string_replaces_function(replaces: Dict[str, str]) -> Callable:
     rep = {re.escape(k): v for k, v in replaces.items()}
     pattern = re.compile("|".join(rep.keys()))
 
-    def f(text):
+    def func(text):
         return pattern.sub(lambda m: rep[re.escape(m.group(0))], text)
 
-    return f
+    return func
 
 
-def get_engine_from_settings(name):
+def get_engine_from_settings(name: str) -> Dict:
     """Return engine configuration from settings.yml of a given engine name"""
 
     if 'engines' not in settings:
@@ -506,7 +502,7 @@ def get_engine_from_settings(name):
     return {}
 
 
-def get_xpath(xpath_spec):
+def get_xpath(xpath_spec: XPathSpecType) -> XPath:
     """Return cached compiled XPath
 
     There is no thread lock.
@@ -523,13 +519,13 @@ def get_xpath(xpath_spec):
         * SearxXPathSyntaxException: Raise when there is a syntax error in the XPath
     """
     if isinstance(xpath_spec, str):
-        result = xpath_cache.get(xpath_spec, None)
+        result = _XPATH_CACHE.get(xpath_spec, None)
         if result is None:
             try:
                 result = XPath(xpath_spec)
             except XPathSyntaxError as e:
                 raise SearxXPathSyntaxException(xpath_spec, str(e.msg)) from e
-            xpath_cache[xpath_spec] = result
+            _XPATH_CACHE[xpath_spec] = result
         return result
 
     if isinstance(xpath_spec, XPath):
@@ -538,7 +534,7 @@ def get_xpath(xpath_spec):
     raise TypeError('xpath_spec must be either a str or a lxml.etree.XPath')
 
 
-def eval_xpath(element, xpath_spec):
+def eval_xpath(element: ElementBase, xpath_spec: XPathSpecType):
     """Equivalent of element.xpath(xpath_str) but compile xpath_str once for all.
     See https://lxml.de/xpathxslt.html#xpath-return-values
 
@@ -562,7 +558,7 @@ def eval_xpath(element, xpath_spec):
         raise SearxEngineXPathException(xpath_spec, arg) from e
 
 
-def eval_xpath_list(element, xpath_spec, min_len=None):
+def eval_xpath_list(element: ElementBase, xpath_spec: XPathSpecType, min_len: int = None):
     """Same as eval_xpath, check if the result is a list
 
     Args:
@@ -586,7 +582,7 @@ def eval_xpath_list(element, xpath_spec, min_len=None):
     return result
 
 
-def eval_xpath_getindex(elements, xpath_spec, index, default=NOTSET):
+def eval_xpath_getindex(elements: ElementBase, xpath_spec: XPathSpecType, index: int, default=_NOTSET):
     """Call eval_xpath_list then get one element using the index parameter.
     If the index does not exist, either aise an exception is default is not set,
     other return the default value (can be None).
@@ -606,9 +602,9 @@ def eval_xpath_getindex(elements, xpath_spec, index, default=NOTSET):
         * result (bool, float, list, str): Results.
     """
     result = eval_xpath_list(elements, xpath_spec)
-    if index >= -len(result) and index < len(result):
+    if -len(result) <= index < len(result):
         return result[index]
-    if default == NOTSET:
+    if default == _NOTSET:
         # raise an SearxEngineXPathException instead of IndexError
         # to record xpath_spec
         raise SearxEngineXPathException(xpath_spec, 'index ' + str(index) + ' not found')

tests/unit/test_utils.py

@@ -128,7 +128,7 @@ class TestUtils(SearxTestCase):
 
 class TestHTMLTextExtractor(SearxTestCase):
     def setUp(self):
-        self.html_text_extractor = utils.HTMLTextExtractor()
+        self.html_text_extractor = utils._HTMLTextExtractor()
 
     def test__init__(self):
         self.assertEqual(self.html_text_extractor.result, [])
@@ -149,7 +149,7 @@ class TestHTMLTextExtractor(SearxTestCase):
 
     def test_invalid_html(self):
         text = '<p><b>Lorem ipsum</i>dolor sit amet</p>'
-        with self.assertRaises(utils.HTMLTextExtractorException):
+        with self.assertRaises(utils._HTMLTextExtractorException):
             self.html_text_extractor.feed(text)