schema: add Pattern class

This patches introduces a new Pattern class that represents a pattern
statement. A new pattern_details method is added to access the pattern
statements of a node.

Fixes: #92
Signed-off-by: Stefan Gula <steweg@gmail.com>
Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>

Author: steweg

cffi/cdefs.h

@@ -792,6 +792,21 @@ struct lysc_must {
     struct lysc_ext_instance *exts;
 };
 
+struct pcre2_real_code;
+typedef struct pcre2_real_code pcre2_code;
+
+struct lysc_pattern {
+    const char *expr;
+    pcre2_code *code;
+    const char *dsc;
+    const char *ref;
+    const char *emsg;
+    const char *eapptag;
+    struct lysc_ext_instance *exts;
+    uint32_t inverted : 1;
+    uint32_t refcount : 31;
+};
+
 #define LYSP_RESTR_PATTERN_ACK ...
 #define LYSP_RESTR_PATTERN_NACK ...
 

libyang/__init__.py

@@ -75,6 +75,7 @@
     IfOrFeatures,
     Module,
     Must,
+    Pattern,
     Revision,
     SContainer,
     SLeaf,
@@ -146,6 +147,7 @@
     "NodeTypeRemoved",
     "OrderedByUserAdded",
     "OrderedByUserRemoved",
+    "Pattern",
     "PatternAdded",
     "PatternRemoved",
     "PresenceAdded",

libyang/schema.py

@@ -448,6 +448,24 @@ class Bit(_EnumBit):
     pass
 
 
+# -------------------------------------------------------------------------------------
+class Pattern:
+    __slots__ = ("context", "cdata")
+
+    def __init__(self, context: "libyang.Context", cdata):
+        self.context = context
+        self.cdata = cdata  # C type: "struct lysc_pattern *"
+
+    def expression(self) -> str:
+        return c2str(self.cdata.expr)
+
+    def inverted(self) -> bool:
+        return self.cdata.inverted
+
+    def error_message(self) -> Optional[str]:
+        return c2str(self.cdata.emsg) if self.cdata.emsg != ffi.NULL else None
+
+
 # -------------------------------------------------------------------------------------
 class Type:
     __slots__ = ("context", "cdata", "cdata_parsed", "__dict__")
@@ -681,6 +699,24 @@ def all_patterns(self) -> Iterator[Tuple[str, bool]]:
         else:
             yield from self.patterns()
 
+    def pattern_details(self) -> Iterator[Pattern]:
+        if self.cdata.basetype != self.STRING:
+            return
+        t = ffi.cast("struct lysc_type_str *", self.cdata)
+        if t.patterns == ffi.NULL:
+            return
+        for p in ly_array_iter(t.patterns):
+            if not p:
+                continue
+            yield Pattern(self.context, p)
+
+    def all_pattern_details(self) -> Iterator[Pattern]:
+        if self.cdata.basetype == lib.LY_TYPE_UNION:
+            for t in self.union_types():
+                yield from t.all_pattern_details()
+        else:
+            yield from self.pattern_details()
+
     def require_instance(self) -> Optional[bool]:
         if self.cdata.basetype != self.LEAFREF:
             return None

tests/test_schema.py

@@ -13,6 +13,7 @@
     LibyangError,
     Module,
     Must,
+    Pattern,
     Revision,
     SContainer,
     SLeaf,
@@ -439,6 +440,15 @@ def test_leaf_type_pattern(self):
         t = leaf.type()
         self.assertIsInstance(t, Type)
         self.assertEqual(list(t.patterns()), [("[a-z.]+", False), ("1", True)])
+        patterns = list(t.all_pattern_details())
+        self.assertEqual(len(patterns), 2)
+        self.assertIsInstance(patterns[0], Pattern)
+        self.assertEqual(patterns[0].expression(), "[a-z.]+")
+        self.assertFalse(patterns[0].inverted())
+        self.assertEqual(patterns[0].error_message(), "ERROR1")
+        self.assertEqual(patterns[1].expression(), "1")
+        self.assertTrue(patterns[1].inverted())
+        self.assertIsNone(patterns[1].error_message())
 
     def test_leaf_type_union(self):
         leaf = next(self.ctx.find_path("/yolo-system:conf/yolo-system:number"))

tests/yang/yolo/yolo-system.yang

@@ -85,7 +85,9 @@ module yolo-system {
       }
       leaf host {
         type string {
-          pattern "[a-z.]+";
+          pattern "[a-z.]+" {
+            error-message "ERROR1";
+          }
           pattern "1" {
             modifier "invert-match";
           }