Revert "schema: use Pattern class for patterns method"

This reverts commit a6c7164.

It actually breaks compatibility, remove this.

Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>

Author: samuel-gauthier

libyang/schema.py

@@ -681,8 +681,20 @@ def all_lengths(self) -> Iterator[str]:
                 yield length
 
     def patterns(self) -> Iterator[Tuple[str, bool]]:
-        for pattern in self.pattern_details():
-            yield pattern.expression(), pattern.inverted()
+        if not self.cdata_parsed or self.cdata.basetype != self.STRING:
+            return
+        if self.cdata_parsed.patterns == ffi.NULL:
+            return
+        for p in ly_array_iter(self.cdata_parsed.patterns):
+            if not p:
+                continue
+            # in case of pattern restriction, the first byte has a special meaning:
+            # 0x06 (ACK) for regular match and 0x15 (NACK) for invert-match
+            invert_match = p.arg.str[0] == b"\x15"
+            # yield tuples like:
+            #     ('[a-zA-Z_][a-zA-Z0-9\-_.]*', False)
+            #     ('[xX][mM][lL].*', True)
+            yield c2str(p.arg.str + 1), invert_match
 
     def all_patterns(self) -> Iterator[Tuple[str, bool]]:
         if self.cdata.basetype == lib.LY_TYPE_UNION: