Add regex functions as templating helpers (#13631)

* Add regex functions as templating helpers

* Add regex functions as templating helpers - Style fixed

* Templating filters, third time lucky?

homeassistant/helpers/template.py

@@ -516,6 +516,39 @@ def forgiving_float(value):
         return value
 
 
+def regex_match(value, find='', ignorecase=False):
+    """Match value using regex."""
+    if not isinstance(value, str):
+        value = str(value)
+    flags = re.I if ignorecase else 0
+    return bool(re.match(find, value, flags))
+
+
+def regex_replace(value='', find='', replace='', ignorecase=False):
+    """Replace using regex."""
+    if not isinstance(value, str):
+        value = str(value)
+    flags = re.I if ignorecase else 0
+    regex = re.compile(find, flags)
+    return regex.sub(replace, value)
+
+
+def regex_search(value, find='', ignorecase=False):
+    """Search using regex."""
+    if not isinstance(value, str):
+        value = str(value)
+    flags = re.I if ignorecase else 0
+    return bool(re.search(find, value, flags))
+
+
+def regex_findall_index(value, find='', index=0, ignorecase=False):
+    """Find all matches using regex and then pick specific match index."""
+    if not isinstance(value, str):
+        value = str(value)
+    flags = re.I if ignorecase else 0
+    return re.findall(find, value, flags)[index]
+
+
 @contextfilter
 def random_every_time(context, values):
     """Choose a random value.
@@ -545,6 +578,10 @@ ENV.filters['is_defined'] = fail_when_undefined
 ENV.filters['max'] = max
 ENV.filters['min'] = min
 ENV.filters['random'] = random_every_time
+ENV.filters['regex_match'] = regex_match
+ENV.filters['regex_replace'] = regex_replace
+ENV.filters['regex_search'] = regex_search
+ENV.filters['regex_findall_index'] = regex_findall_index
 ENV.globals['log'] = logarithm
 ENV.globals['float'] = forgiving_float
 ENV.globals['now'] = dt_util.now

tests/helpers/test_template.py

@@ -441,6 +441,59 @@ class TestHelpersTemplate(unittest.TestCase):
                 template.Template('{{ utcnow().isoformat() }}',
                                   self.hass).render())
 
+    def test_regex_match(self):
+        """Test regex_match method."""
+        tpl = template.Template("""
+{{ '123-456-7890' | regex_match('(\d{3})-(\d{3})-(\d{4})') }}
+                """, self.hass)
+        self.assertEqual('True', tpl.render())
+
+        tpl = template.Template("""
+{{ 'home assistant test' | regex_match('Home', True) }}
+                """, self.hass)
+        self.assertEqual('True', tpl.render())
+
+        tpl = template.Template("""
+        {{ 'Another home assistant test' | regex_match('home') }}
+                        """, self.hass)
+        self.assertEqual('False', tpl.render())
+
+    def test_regex_search(self):
+        """Test regex_search method."""
+        tpl = template.Template("""
+{{ '123-456-7890' | regex_search('(\d{3})-(\d{3})-(\d{4})') }}
+                """, self.hass)
+        self.assertEqual('True', tpl.render())
+
+        tpl = template.Template("""
+{{ 'home assistant test' | regex_search('Home', True) }}
+                """, self.hass)
+        self.assertEqual('True', tpl.render())
+
+        tpl = template.Template("""
+        {{ 'Another home assistant test' | regex_search('home') }}
+                        """, self.hass)
+        self.assertEqual('True', tpl.render())
+
+    def test_regex_replace(self):
+        """Test regex_replace method."""
+        tpl = template.Template("""
+{{ 'Hello World' | regex_replace('(Hello\s)',) }}
+                """, self.hass)
+        self.assertEqual('World', tpl.render())
+
+    def test_regex_findall_index(self):
+        """Test regex_findall_index method."""
+        tpl = template.Template("""
+{{ 'Flight from JFK to LHR' | regex_findall_index('([A-Z]{3})', 0) }}
+                """, self.hass)
+        self.assertEqual('JFK', tpl.render())
+
+        tpl = template.Template("""
+{{ 'Flight from JFK to LHR' | regex_findall_index('([A-Z]{3})', 1) }}
+                """, self.hass)
+        self.assertEqual('LHR', tpl.render())
+
     def test_distance_function_with_1_state(self):
         """Test distance function with 1 state."""
         self.hass.states.set('test.object', 'happy', {