More dynamic API WIP.

c++/src/capnproto/arena.h

@@ -45,6 +45,9 @@ class ReaderArena;
 class BuilderArena;
 class ReadLimiter;
 
+class Segment;
+typedef Id<uint32_t, Segment> SegmentId;
+
 class ReadLimiter {
   // Used to keep track of how much data has been processed from a message, and cut off further
   // processing if and when a particular limit is reached.  This is primarily intended to guard

c++/src/capnproto/generated-header-support.h

@@ -31,6 +31,8 @@
 
 namespace capnproto {
 
+class SchemaPool;   // Needs to be declared for dynamic Object accessors.
+
 class DynamicStruct;  // So that it can be declared a friend.
 
 template <typename T>
@@ -52,7 +54,7 @@ struct PointerHelpers<T, Kind::STRUCT> {
   }
   static inline void set(StructBuilder builder, WireReferenceCount index,
                          typename T::Reader value) {
-    // TODO(soon)
+    // TODO(now):  schemaless copy
     CAPNPROTO_INLINE_PRECOND(false, "Not implemented:  set() for struct fields.");
   }
   static inline typename T::Builder init(StructBuilder builder, WireReferenceCount index) {

c++/src/capnproto/layout-test.c++

@@ -138,7 +138,7 @@ static void setupStruct(StructBuilder builder) {
         2 * REFERENCES, 4 * ELEMENTS, STRUCTLIST_ELEMENT_SIZE);
     EXPECT_EQ(4 * ELEMENTS, list.size());
     for (int i = 0; i < 4; i++) {
-      StructBuilder element = list.getStructElement(i * ELEMENTS, STRUCTLIST_ELEMENT_SIZE);
+      StructBuilder element = list.getStructElement(i * ELEMENTS);
       element.setDataField<int32_t>(0 * ELEMENTS, 300 + i);
       element.initStructField(0 * REFERENCES,
                               StructSize(1 * WORDS, 0 * REFERENCES, FieldSize::EIGHT_BYTES))
@@ -193,7 +193,7 @@ static void checkStruct(StructBuilder builder) {
     ListBuilder list = builder.getListField(2 * REFERENCES, nullptr);
     ASSERT_EQ(4 * ELEMENTS, list.size());
     for (int i = 0; i < 4; i++) {
-      StructBuilder element = list.getStructElement(i * ELEMENTS, STRUCTLIST_ELEMENT_SIZE);
+      StructBuilder element = list.getStructElement(i * ELEMENTS);
       EXPECT_EQ(300 + i, element.getDataField<int32_t>(0 * ELEMENTS));
       EXPECT_EQ(400 + i,
           element.getStructField(0 * REFERENCES,

c++/src/capnproto/layout.c++

@@ -1250,11 +1250,11 @@ Data::Builder ListBuilder::asData() {
   return Data::Builder(reinterpret_cast<char*>(ptr), elementCount / ELEMENTS);
 }
 
-StructBuilder ListBuilder::getStructElement(ElementCount index, StructSize elementSize) const {
+StructBuilder ListBuilder::getStructElement(ElementCount index) const {
   BitCount64 indexBit = ElementCount64(index) * step;
   byte* structData = ptr + indexBit / BITS_PER_BYTE;
   return StructBuilder(segment, structData,
-      reinterpret_cast<WireReference*>(structData) + elementSize.data / WORDS_PER_REFERENCE,
+      reinterpret_cast<WireReference*>(structData + structDataSize / BITS_PER_BYTE),
       structDataSize, structReferenceCount, indexBit % BITS_PER_BYTE);
 }
 
@@ -1310,9 +1310,9 @@ Data::Builder ListBuilder::getBlobElement<Data>(ElementCount index) const {
       0 * BYTES);
 }
 
-ObjectBuilder ListBuilder::getObjectElement(ElementCount index, const word* defaultValue) const {
+ObjectBuilder ListBuilder::getObjectElement(ElementCount index) const {
   return WireHelpers::getWritableObjectReference(
-      segment, reinterpret_cast<WireReference*>(ptr + index * step / BITS_PER_BYTE), defaultValue);
+      segment, reinterpret_cast<WireReference*>(ptr + index * step / BITS_PER_BYTE), nullptr);
 }
 
 ListReader ListBuilder::asReader() const {
@@ -1403,9 +1403,9 @@ Data::Reader ListReader::getBlobElement<Data>(ElementCount index) const {
       nullptr, 0 * BYTES);
 }
 
-ObjectReader ListReader::getObjectElement(ElementCount index, const word* defaultValue) const {
+ObjectReader ListReader::getObjectElement(ElementCount index) const {
   return WireHelpers::readObjectReference(
-      segment, checkAlignment(ptr + index * step / BITS_PER_BYTE), defaultValue, nestingLimit);
+      segment, checkAlignment(ptr + index * step / BITS_PER_BYTE), nullptr, nestingLimit);
 }
 
 }  // namespace internal

c++/src/capnproto/layout.h

@@ -502,7 +502,7 @@ public:
       ElementCount index, typename NoInfer<T>::Type value) const);
   // Set the element at the given index.
 
-  StructBuilder getStructElement(ElementCount index, StructSize elementSize) const;
+  StructBuilder getStructElement(ElementCount index) const;
   // Get the struct element at the given index.
 
   ListBuilder initListElement(
@@ -532,7 +532,7 @@ public:
   typename T::Builder getBlobElement(ElementCount index) const;
   // Get the blob element.  If it is not initialized, return an empty blob builder.
 
-  ObjectBuilder getObjectElement(ElementCount index, const word* defaultValue) const;
+  ObjectBuilder getObjectElement(ElementCount index) const;
   // Gets a pointer element of arbitrary type.
 
   ListReader asReader() const;
@@ -591,7 +591,7 @@ public:
   typename T::Reader getBlobElement(ElementCount index) const;
   // Gets the text or data field.  If it is not initialized, returns an empty blob reader.
 
-  ObjectReader getObjectElement(ElementCount index, const word* defaultValue) const;
+  ObjectReader getObjectElement(ElementCount index) const;
   // Gets a pointer element of arbitrary type.
 
 private:

c++/src/capnproto/list.h

@@ -297,8 +297,7 @@ struct List<T, Kind::STRUCT> {
 
     inline uint size() const { return builder.size() / ELEMENTS; }
     inline typename T::Builder operator[](uint index) const {
-      return typename T::Builder(builder.getStructElement(
-          index * ELEMENTS, internal::structSize<T>()));
+      return typename T::Builder(builder.getStructElement(index * ELEMENTS));
     }
 
     typedef internal::IndexingIterator<Builder, typename T::Builder> iterator;

c++/src/capnproto/message.c++

@@ -49,7 +49,7 @@ internal::StructReader MessageReader::getRootInternal() {
     allocatedArena = true;
   }
 
-  internal::SegmentReader* segment = arena()->tryGetSegment(SegmentId(0));
+  internal::SegmentReader* segment = arena()->tryGetSegment(internal::SegmentId(0));
   VALIDATE_INPUT(segment != nullptr &&
       segment->containsInterval(segment->getStartPtr(), segment->getStartPtr() + 1),
       "Message did not contain a root pointer.") {
@@ -70,7 +70,7 @@ MessageBuilder::~MessageBuilder() {
 
 internal::SegmentBuilder* MessageBuilder::getRootSegment() {
   if (allocatedArena) {
-    return arena()->getSegment(SegmentId(0));
+    return arena()->getSegment(internal::SegmentId(0));
   } else {
     static_assert(sizeof(internal::BuilderArena) <= sizeof(arenaSpace),
         "arenaSpace is too small to hold a BuilderArena.  Please increase it.  This will break "
@@ -80,7 +80,7 @@ internal::SegmentBuilder* MessageBuilder::getRootSegment() {
 
     WordCount refSize = 1 * REFERENCES * WORDS_PER_REFERENCE;
     internal::SegmentBuilder* segment = arena()->getSegmentWithAvailable(refSize);
-    CHECK(segment->getSegmentId() == SegmentId(0),
+    CHECK(segment->getSegmentId() == internal::SegmentId(0),
         "First allocated word of new arena was not in segment ID 0.");
     word* location = segment->allocate(refSize);
     CHECK(location == segment->getPtrUnchecked(0 * WORDS),

c++/src/capnproto/message.h

@@ -37,8 +37,7 @@ namespace internal {
   class BuilderArena;
 }
 
-class Segment;
-typedef Id<uint32_t, Segment> SegmentId;
+class SchemaPool;
 
 // =======================================================================================
 
@@ -97,6 +96,13 @@ public:
 
   template <typename RootType>
   typename RootType::Reader getRoot();
+  // Get the root struct of the message, interpreting it as the given struct type.
+
+  template <typename RootType>
+  typename RootType::Reader getRoot(const SchemaPool& pool, uint64_t typeId);
+  // Dynamically interpret the root struct of the message using the type with the given ID.
+  // RootType in this case must be DynamicStruct, and you must #include <capnproto/dynamic.h> to
+  // use this.
 
 private:
   ReaderOptions options;
@@ -125,8 +131,23 @@ public:
 
   template <typename RootType>
   typename RootType::Builder initRoot();
+  // Initialize the root struct of the message as the given struct type.
+
   template <typename RootType>
   typename RootType::Builder getRoot();
+  // Get the root struct of the message, interpreting it as the given struct type.
+
+  template <typename RootType>
+  typename RootType::Builder getRoot(const SchemaPool& pool, uint64_t typeId);
+  // Dynamically interpret the root struct of the message using the type with the given ID.
+  // RootType in this case must be DynamicStruct, and you must #include <capnproto/dynamic.h> to
+  // use this.
+
+  template <typename RootType>
+  typename RootType::Builder initRoot(const SchemaPool& pool, uint64_t typeId);
+  // Dynamically init the root struct of the message using the type with the given ID.
+  // RootType in this case must be DynamicStruct, and you must #include <capnproto/dynamic.h> to
+  // use this.
 
   ArrayPtr<const ArrayPtr<const word>> getSegmentsForOutput();
 
@@ -270,16 +291,19 @@ inline const ReaderOptions& MessageReader::getOptions() {
 
 template <typename RootType>
 inline typename RootType::Reader MessageReader::getRoot() {
+  static_assert(kind<RootType>() == Kind::STRUCT, "Root type must be a Cap'n Proto struct type.");
   return typename RootType::Reader(getRootInternal());
 }
 
 template <typename RootType>
 inline typename RootType::Builder MessageBuilder::initRoot() {
+  static_assert(kind<RootType>() == Kind::STRUCT, "Root type must be a Cap'n Proto struct type.");
   return typename RootType::Builder(initRoot(internal::structSize<RootType>()));
 }
 
 template <typename RootType>
 inline typename RootType::Builder MessageBuilder::getRoot() {
+  static_assert(kind<RootType>() == Kind::STRUCT, "Root type must be a Cap'n Proto struct type.");
   return typename RootType::Builder(getRoot(internal::structSize<RootType>()));
 }
 

c++/src/capnproto/schema.capnp

@@ -219,6 +219,11 @@ struct StructNode {
   }
 
   struct Field {
+    index @3 :UInt16;
+    # The index of this field within the containing struct or union's member list.  This is
+    # redundant information, but it can be useful for the dynamic API which uses Field pointers as
+    # identifiers.
+
     offset @0 :UInt32;
     # Offset, in units of the field's size, from the beginning of the section in which the field
     # resides.  E.g. for a UInt32 field, multiply this by 4 to get the byte offset from the

compiler/src/WireFormat.hs

@@ -575,7 +575,7 @@ encodeSchema requestedFiles allFiles = encRoot where
                      , (16, encUInt16 $ structPointerCount desc)
                      , (32, encUInt16 (fieldSizeEnum preferredListEncoding::Word16))
                      ]
-        ptrValues = [ (0, encStructList memberSize $ map encMember $
+        ptrValues = [ (0, encStructList memberSize $ zipWith encMember [0::Word16 ..] $
                               sortMembers $ structMembers desc) ]
 
         preferredListEncoding = case (structDataSize desc, structPointerCount desc) of
@@ -597,7 +597,7 @@ encodeSchema requestedFiles allFiles = encRoot where
         selectFieldOrUnion _ = Nothing
 
         memberSize = (DataSectionWords 1, 3)
-        encMember (codeOrder, (_, DescField field)) = (dataValues2, ptrValues2) where
+        encMember index (codeOrder, (_, DescField field)) = (dataValues2, ptrValues2) where
             dataValues2 = [ (0, encUInt16 $ fieldNumber field)
                           , (16, encUInt16 codeOrder)
                           , (32, encUInt16 (0::Word16))  -- discriminant
@@ -608,7 +608,8 @@ encodeSchema requestedFiles allFiles = encRoot where
                          ]
 
             -- StructNode.Field
-            dataValues3 = [ (0, encUInt32 $ offsetToInt $ fieldOffset field) ]
+            dataValues3 = [ (0, encUInt32 $ offsetToInt $ fieldOffset field)
+                          , (32, encUInt16 index) ]
             ptrValues3 = [ (0, encStruct typeSize $ encType $ fieldType field)
                          , (1, encStruct valueSize $ encValue (fieldType field) $
                                    fieldDefaultValue field)
@@ -620,7 +621,7 @@ encodeSchema requestedFiles allFiles = encRoot where
             offsetToInt (InlineCompositeOffset {}) =
                 error "Inline types not currently supported by codegen plugins."
 
-        encMember (codeOrder, (_, DescUnion union)) = (dataValues2, ptrValues2) where
+        encMember _ (codeOrder, (_, DescUnion union)) = (dataValues2, ptrValues2) where
             dataValues2 = [ (0, encUInt16 $ unionNumber union)
                           , (16, encUInt16 codeOrder)
                           , (32, encUInt16 (1::Word16))  -- discriminant
@@ -632,9 +633,9 @@ encodeSchema requestedFiles allFiles = encRoot where
 
             -- StructNode.Union
             dataValues3 = [ (0, encUInt32 $ unionTagOffset union) ]
-            ptrValues3 = [ (0, encStructList memberSize $ map encMember $ sortMembers $
+            ptrValues3 = [ (0, encStructList memberSize $ zipWith encMember [0..] $ sortMembers $
                                    unionMembers union) ]
-        encMember _ = error "Not a field or union?"
+        encMember _ _ = error "Not a field or union?"
 
     enumNodeSize = (DataSectionWords 0, 1)
     encEnumNode desc = (dataValues, ptrValues) where

compiler/src/c++-header.mustache

@@ -157,6 +157,8 @@ public:
 {{/fieldIsPrimitive}}
 {{#fieldIsGenericObject}}
   template <typename T> inline typename T::Reader get{{fieldTitleCase}}();
+  template <typename T, typename... Params> inline typename T::Reader get{{fieldTitleCase}}(
+      const ::capnproto::SchemaPool& pool, Params&&... params);
 {{/fieldIsGenericObject}}
 {{/typeFields}}
 private:
@@ -209,6 +211,11 @@ public:
   template <typename T> inline void set{{fieldTitleCase}}(typename T::Reader value);
   template <typename T> inline typename T::Builder init{{fieldTitleCase}}();
   template <typename T> inline typename T::Builder init{{fieldTitleCase}}(unsigned int size);
+
+  template <typename T, typename... Params> inline typename T::Builder get{{fieldTitleCase}}(
+      const ::capnproto::SchemaPool& pool, Params&&... params);
+  template <typename T, typename... Params> inline typename T::Builder init{{fieldTitleCase}}(
+      const ::capnproto::SchemaPool& pool, Params&&... params);
 {{/fieldIsGenericObject}}
 {{/typeFields}}
 private:
@@ -394,6 +401,42 @@ inline typename T::Builder {{typeFullName}}::Builder::init{{fieldTitleCase}}(uns
       _builder, {{fieldOffset}} * ::capnproto::REFERENCES, size);
 }
 
+template <typename T, typename... Params>
+inline typename T::Reader {{typeFullName}}::Reader::get{{fieldTitleCase}}(
+    const ::capnproto::SchemaPool& pool, Params&&... params) {
+{{#fieldUnion}}
+  CAPNPROTO_INLINE_DPRECOND(which() == {{unionTitleCase}}::{{fieldUpperCase}},
+                            "Must check which() before get()ing a union member.");
+{{/fieldUnion}}
+  return ::capnproto::internal::PointerHelpers<T>::get(
+      _reader, {{fieldOffset}} * ::capnproto::REFERENCES,
+      pool, ::capnproto::forward<Params>(params)...);
+}
+
+template <typename T, typename... Params>
+inline typename T::Builder {{typeFullName}}::Builder::get{{fieldTitleCase}}(
+    const ::capnproto::SchemaPool& pool, Params&&... params) {
+{{#fieldUnion}}
+  CAPNPROTO_INLINE_DPRECOND(which() == {{unionTitleCase}}::{{fieldUpperCase}},
+                            "Must check which() before get()ing a union member.");
+{{/fieldUnion}}
+  return ::capnproto::internal::PointerHelpers<T>::get(
+      _builder, {{fieldOffset}} * ::capnproto::REFERENCES,
+      pool, ::capnproto::forward<Params>(params)...);
+}
+
+template <typename T, typename... Params>
+inline typename T::Builder {{typeFullName}}::Builder::init{{fieldTitleCase}}(
+    const ::capnproto::SchemaPool& pool, Params&&... params) {
+{{#fieldUnion}}
+  _builder.setDataField<{{unionTitleCase}}::Which>(
+      {{unionTagOffset}} * ::capnproto::ELEMENTS, {{unionTitleCase}}::{{fieldUpperCase}});
+{{/fieldUnion}}
+  return ::capnproto::internal::PointerHelpers<T>::init(
+      _builder, {{fieldOffset}} * ::capnproto::REFERENCES,
+      pool, ::capnproto::forward<Params>(params)...);
+}
+
 {{/fieldIsGenericObject}}
 {{/typeFields}}
 {{/typeStructOrUnion}}