add named captures, groups and references

remagic/interface.py

@@ -63,3 +63,11 @@ def after(pattern):
 
 def not_after(pattern):
     return rf"(?<!={Pattern(pattern)})"
+
+
+def ref(reference):
+    if isinstance(reference, int) and reference > 0:
+        return rf"\{reference}"
+    elif isinstance(reference, str):
+        return rf"(?P={reference})"
+    return Pattern(reference)

remagic/pattern.py

@@ -35,6 +35,19 @@ def add(self, other: Union[str, "Pattern"]):
     def repeat(self, num: Union[int, Tuple[int, int]]) -> "Pattern":
         return self * num
 
+    def label(self, name):
+        return Pattern(rf"(?P<{name}>{self._pattern})")
+
+    def group(self):
+        return Pattern(rf"({self._pattern})")
+
+    def ref(self, reference):
+        if isinstance(reference, int) and reference > 0:
+            return self.add(rf"\{reference}")
+        elif isinstance(reference, str):
+            return self.add(rf"(?P={reference})")
+        return self.add(Pattern(reference))
+
     @property
     def pattern(self) -> str:
         return self._pattern

tests/test_refs.py

@@ -0,0 +1,31 @@
+# flake8: noqa
+
+import pytest
+
+from remagic import *
+
+
+@pytest.mark.parametrize(
+    "capture, name, expected_output",
+    [
+        ("captured", "text", "(?P<text>captured)(?P=text)"),
+    ],
+)
+def test_refs(capture, name, expected_output):
+    output = create(capture).label("text").ref("text")
+    assert output._pattern == expected_output, "{} != {}".format(
+        output, expected_output
+    )
+
+
+@pytest.mark.parametrize(
+    "capture, expected_output",
+    [
+        ("captured", r"(captured)\1"),
+    ],
+)
+def test_groups(capture, expected_output):
+    output = create(capture).group().ref(1)
+    assert output._pattern == expected_output, "{} != {}".format(
+        output, expected_output
+    )