Add `isInconsistent` property hook to all constructed types (#170)

Added `isInconsistent` property to all constructed types. This property
conceptually replaces `verifySizeSpec` method to serve a more general
purpose e.g. ensuring all required fields are in a good shape. By
default this check invokes subtype constraints verification and is run
by codecs on value de/serialisation.

6 files changed, 43 insertions, 10 deletions

diff --git a/pyasn1/codec/ber/decoder.py b/pyasn1/codec/ber/decoder.py
index 3f2d180..5759ab8 100644
--- a/pyasn1/codec/ber/decoder.py
+++ b/pyasn1/codec/ber/decoder.py
@@ -695,7 +695,9 @@ class UniversalConstructedTypeDecoder(AbstractConstructedDecoder):
                                 asn1Object.setComponentByPosition(idx, component)
 
             else:
-                asn1Object.verifySizeSpec()
+                inconsistency = asn1Object.isInconsistent
+                if inconsistency:
+                    raise inconsistency
 
         else:
             asn1Object = asn1Spec.clone()
@@ -879,7 +881,9 @@ class UniversalConstructedTypeDecoder(AbstractConstructedDecoder):
                                     asn1Object.setComponentByPosition(idx, component)
 
                 else:
-                    asn1Object.verifySizeSpec()
+                    inconsistency = asn1Object.isInconsistent
+                    if inconsistency:
+                        raise inconsistency
 
         else:
             asn1Object = asn1Spec.clone()
diff --git a/pyasn1/codec/ber/encoder.py b/pyasn1/codec/ber/encoder.py
index a5d5fd3..778aa86 100644
--- a/pyasn1/codec/ber/encoder.py
+++ b/pyasn1/codec/ber/encoder.py
@@ -537,7 +537,9 @@ class SequenceEncoder(AbstractItemEncoder):
 
         if asn1Spec is None:
             # instance of ASN.1 schema
-            value.verifySizeSpec()
+            inconsistency = value.isInconsistent
+            if inconsistency:
+                raise inconsistency
 
             namedTypes = value.componentType
 
@@ -643,7 +645,9 @@ class SequenceOfEncoder(AbstractItemEncoder):
     def _encodeComponents(self, value, asn1Spec, encodeFun, **options):
 
         if asn1Spec is None:
-            value.verifySizeSpec()
+            inconsistency = value.isInconsistent
+            if inconsistency:
+                raise inconsistency
 
         else:
             asn1Spec = asn1Spec.componentType
diff --git a/pyasn1/codec/cer/encoder.py b/pyasn1/codec/cer/encoder.py
index 6a9db97..935b696 100644
--- a/pyasn1/codec/cer/encoder.py
+++ b/pyasn1/codec/cer/encoder.py
@@ -169,7 +169,9 @@ class SetEncoder(encoder.SequenceEncoder):
 
         if asn1Spec is None:
             # instance of ASN.1 schema
-            value.verifySizeSpec()
+            inconsistency = value.isInconsistent
+            if inconsistency:
+                raise inconsistency
 
             namedTypes = value.componentType
 
diff --git a/pyasn1/codec/native/encoder.py b/pyasn1/codec/native/encoder.py
index 4c5908d..4318abd 100644
--- a/pyasn1/codec/native/encoder.py
+++ b/pyasn1/codec/native/encoder.py
@@ -72,7 +72,9 @@ class SetEncoder(AbstractItemEncoder):
     protoDict = dict
 
     def encode(self, value, encodeFun, **options):
-        value.verifySizeSpec()
+        inconsistency = value.isInconsistent
+        if inconsistency:
+            raise inconsistency
 
         namedTypes = value.componentType
         substrate = self.protoDict()
@@ -90,7 +92,9 @@ class SequenceEncoder(SetEncoder):
 
 class SequenceOfEncoder(AbstractItemEncoder):
     def encode(self, value, encodeFun, **options):
-        value.verifySizeSpec()
+        inconsistency = value.isInconsistent
+        if inconsistency:
+            raise inconsistency
         return [encodeFun(x, **options) for x in value]
 
 
diff --git a/pyasn1/type/base.py b/pyasn1/type/base.py
index 21e4041..1fd69f9 100644
--- a/pyasn1/type/base.py
+++ b/pyasn1/type/base.py
@@ -655,8 +655,23 @@ class ConstructedAsn1Type(Asn1Type):
 
         return clone
 
-    def verifySizeSpec(self):
-        self.sizeSpec(self)
+    @property
+    def isInconsistent(self):
+        """Run necessary checks to ensure object consistency.
+
+        Default action is to verify |ASN.1| object against constraints imposed
+        by `subtypeSpec`.
+
+        Raises
+        ------
+        :py:class:`~pyasn1.error.PyAsn1tError` on any inconsistencies found
+        """
+        try:
+            self.sizeSpec(self)
+
+        except error.PyAsn1Error:
+            exc = sys.exc_info()[1]
+            return exc
 
     def getComponentByPosition(self, idx):
         raise error.PyAsn1Error('Method not implemented')
@@ -679,5 +694,9 @@ class ConstructedAsn1Type(Asn1Type):
     def getComponentType(self):
         return self.componentType
 
+    def verifySizeSpec(self):
+        self.sizeSpec(self)
+
+
 # Backward compatibility
 AbstractConstructedAsn1Item = ConstructedAsn1Type
diff --git a/pyasn1/type/univ.py b/pyasn1/type/univ.py
index b39c533..4f305f6 100644
--- a/pyasn1/type/univ.py
+++ b/pyasn1/type/univ.py
@@ -3004,7 +3004,7 @@ class Choice(Set):
         if self._currentIdx is not None:
             yield self.componentType[self._currentIdx].getName(), self[self._currentIdx]
 
-    def verifySizeSpec(self):
+    def checkConsistency(self):
         if self._currentIdx is None:
             raise error.PyAsn1Error('Component not chosen')