Add ListSchema class

Return it whenever the appropriate Type is converted to a Schema

capnp/includes/capnp_cpp.pxd

@@ -140,10 +140,10 @@ cdef extern from "capnp/schema.h" namespace " ::capnp":
         cbool isStruct()
         cbool isInterface()
 
-        StructSchema asStruct()
+        StructSchema asStruct() except +reraise_kj_exception
-        EnumSchema asEnum()
+        EnumSchema asEnum() except +reraise_kj_exception
-        InterfaceSchema asInterface()
+        InterfaceSchema asInterface() except +reraise_kj_exception
-        # ListSchema asList()
+        ListSchema asList() except +reraise_kj_exception
 
     cdef cppclass Schema:
         Node.Reader getProto() except +reraise_kj_exception
@@ -214,6 +214,9 @@ cdef extern from "capnp/schema.h" namespace " ::capnp":
         Enumerant getEnumerantByName(char * name)
         Node.Reader getProto()
 
+    cdef cppclass ListSchema:
+        SchemaType getElementType()
+
     cdef cppclass ConstSchema:
         pass
 

capnp/lib/capnp.pxd

@@ -1,6 +1,6 @@
 from capnp.includes cimport capnp_cpp as capnp
 from capnp.includes cimport schema_cpp
-from capnp.includes.capnp_cpp cimport Schema as C_Schema, StructSchema as C_StructSchema, InterfaceSchema as C_InterfaceSchema, EnumSchema as C_EnumSchema, DynamicStruct as C_DynamicStruct, DynamicValue as C_DynamicValue, Type as C_Type, DynamicList as C_DynamicList, SchemaParser as C_SchemaParser, ParsedSchema as C_ParsedSchema, VOID, ArrayPtr, StringPtr, String, StringTree, DynamicOrphan as C_DynamicOrphan, AnyPointer as C_DynamicObject, DynamicCapability as C_DynamicCapability, Request, Response, RemotePromise, PyPromise, VoidPromise, CallContext, PyRestorer, RpcSystem, makeRpcServer, makeRpcClient, Capability as C_Capability, TwoPartyVatNetwork as C_TwoPartyVatNetwork, Side, AsyncIoStream, Own, makeTwoPartyVatNetwork, PromiseFulfillerPair as C_PromiseFulfillerPair, copyPromiseFulfillerPair, newPromiseAndFulfiller, PyArray, DynamicStruct_Builder
+from capnp.includes.capnp_cpp cimport Schema as C_Schema, StructSchema as C_StructSchema, InterfaceSchema as C_InterfaceSchema, EnumSchema as C_EnumSchema, ListSchema as C_ListSchema, DynamicStruct as C_DynamicStruct, DynamicValue as C_DynamicValue, Type as C_Type, DynamicList as C_DynamicList, SchemaParser as C_SchemaParser, ParsedSchema as C_ParsedSchema, VOID, ArrayPtr, StringPtr, String, StringTree, DynamicOrphan as C_DynamicOrphan, AnyPointer as C_DynamicObject, DynamicCapability as C_DynamicCapability, Request, Response, RemotePromise, PyPromise, VoidPromise, CallContext, PyRestorer, RpcSystem, makeRpcServer, makeRpcClient, Capability as C_Capability, TwoPartyVatNetwork as C_TwoPartyVatNetwork, Side, AsyncIoStream, Own, makeTwoPartyVatNetwork, PromiseFulfillerPair as C_PromiseFulfillerPair, copyPromiseFulfillerPair, newPromiseAndFulfiller, PyArray, DynamicStruct_Builder
 from capnp.includes.schema_cpp cimport Node as C_Node, EnumNode as C_EnumNode
 from capnp.includes.types cimport *
 from capnp.helpers.non_circular cimport reraise_kj_exception

capnp/lib/capnp.pyx

@@ -2419,6 +2419,19 @@ cdef class _StructSchema:
     def __repr__(self):
         return '<schema for %s>' % self.node.displayName
 
+cdef typeAsSchema(capnp.SchemaType fieldType):
+    # TODO(soon): make sure this is memory safe
+    if fieldType.isInterface():
+        return _InterfaceSchema()._init(fieldType.asInterface())
+    elif fieldType.isStruct():
+        return _StructSchema()._init(fieldType.asStruct())
+    elif fieldType.isEnum():
+        return _EnumSchema()._init(fieldType.asEnum())
+    elif fieldType.isList():
+        return ListSchema()._init(fieldType.asList())
+    else:
+        raise ValueError("Schema type is unknown")
+
 cdef class _StructSchemaField:
     cdef _init(self, C_StructSchema.Field other, parent=None):
         self.thisptr = other
@@ -2433,17 +2446,7 @@ cdef class _StructSchemaField:
     property schema:
         """The schema of this field, or None if it's a type without a schema"""
         def __get__(self):
-            cdef capnp.SchemaType fieldType = self.thisptr.getType()
+            return typeAsSchema(self.thisptr.getType())
-
-            # TODO(soon): make sure this is memory safe
-            if fieldType.isInterface():
-                return _InterfaceSchema()._init(fieldType.asInterface())
-            elif fieldType.isStruct():
-                return _StructSchema()._init(fieldType.asStruct())
-            elif fieldType.isEnum():
-                return _EnumSchema()._init(fieldType.asEnum())
-            else:
-                return None
 
     def __repr__(self):
         return '<field schema for %s>' % self.proto.name
@@ -2563,6 +2566,18 @@ cdef class _EnumSchema:
         def __get__(self):
             return _DynamicStructReader()._init(self.thisptr.getProto(), self)
 
+cdef class ListSchema:
+    cdef C_ListSchema thisptr
+
+    cdef _init(self, C_ListSchema other):
+        self.thisptr = other
+        return self
+
+    property elementType:
+        """The schema of the element type of this list"""
+        def __get__(self):
+            return typeAsSchema(self.thisptr.getElementType())
+
 cdef class _ParsedSchema(_Schema):
     cdef C_ParsedSchema thisptr_child
     cdef _init_child(self, C_ParsedSchema other):

test/test_schema.py

@@ -0,0 +1,20 @@
+import pytest
+import capnp
+import os
+
+this_dir = os.path.dirname(__file__)
+
+
+@pytest.fixture
+def addressbook():
+    return capnp.load(os.path.join(this_dir, 'addressbook.capnp'))
+
+
+def test_basic_schema(addressbook):
+    assert addressbook.Person.schema.fieldnames[0] == 'id'
+
+def test_list_schema(addressbook):
+    peopleField = addressbook.AddressBook.schema.fields['people']
+    personType = peopleField.schema.elementType
+
+    assert personType.node.id == addressbook.Person.schema.node.id