comparison osx/include/capnp/dynamic.h @ 134:41e769c91eca

Add Capnp and KJ builds for OSX

+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// This file defines classes that can be used to manipulate messages based on schemas that are not
+// known until runtime.  This is also useful for writing generic code that uses schemas to handle
+// arbitrary types in a generic way.
+//
+// Each of the classes defined here has a to() template method which converts an instance back to a
+// native type.  This method will throw an exception if the requested type does not match the
+// schema.  To convert native types to dynamic, use DynamicFactory.
+//
+// As always, underlying data is validated lazily, so you have to actually traverse the whole
+// message if you want to validate all content.
+
+#ifndef CAPNP_DYNAMIC_H_
+#define CAPNP_DYNAMIC_H_
+
+#if defined(__GNUC__) && !defined(CAPNP_HEADER_WARNINGS)
+#pragma GCC system_header
+#endif
+
+#include "schema.h"
+#include "layout.h"
+#include "message.h"
+#include "any.h"
+#include "capability.h"
+
+namespace capnp {
+
+class MessageReader;
+class MessageBuilder;
+
+struct DynamicValue {
+  DynamicValue() = delete;
+
+  enum Type {
+    UNKNOWN,
+    // Means that the value has unknown type and content because it comes from a newer version of
+    // the schema, or from a newer version of Cap'n Proto that has new features that this version
+    // doesn't understand.
+
+    VOID,
+    BOOL,
+    INT,
+    UINT,
+    FLOAT,
+    TEXT,
+    DATA,
+    LIST,
+    ENUM,
+    STRUCT,
+    CAPABILITY,
+    ANY_POINTER
+  };
+
+  class Reader;
+  class Builder;
+  class Pipeline;
+};
+class DynamicEnum;
+struct DynamicStruct {
+  DynamicStruct() = delete;
+  class Reader;
+  class Builder;
+  class Pipeline;
+};
+struct DynamicList {
+  DynamicList() = delete;
+  class Reader;
+  class Builder;
+};
+struct DynamicCapability {
+  DynamicCapability() = delete;
+  class Client;
+  class Server;
+};
+template <> class Orphan<DynamicValue>;
+
+template <Kind k> struct DynamicTypeFor_;
+template <> struct DynamicTypeFor_<Kind::ENUM> { typedef DynamicEnum Type; };
+template <> struct DynamicTypeFor_<Kind::STRUCT> { typedef DynamicStruct Type; };
+template <> struct DynamicTypeFor_<Kind::LIST> { typedef DynamicList Type; };
+template <> struct DynamicTypeFor_<Kind::INTERFACE> { typedef DynamicCapability Type; };
+
+template <typename T>
+using DynamicTypeFor = typename DynamicTypeFor_<kind<T>()>::Type;
+
+template <typename T>
+ReaderFor<DynamicTypeFor<FromReader<T>>> toDynamic(T&& value);
+template <typename T>
+BuilderFor<DynamicTypeFor<FromBuilder<T>>> toDynamic(T&& value);
+template <typename T>
+DynamicTypeFor<TypeIfEnum<T>> toDynamic(T&& value);
+template <typename T>
+typename DynamicTypeFor<FromServer<T>>::Client toDynamic(kj::Own<T>&& value);
+
+namespace _ {  // private
+
+template <> struct Kind_<DynamicValue     > { static constexpr Kind kind = Kind::OTHER; };
+template <> struct Kind_<DynamicEnum      > { static constexpr Kind kind = Kind::OTHER; };
+template <> struct Kind_<DynamicStruct    > { static constexpr Kind kind = Kind::OTHER; };
+template <> struct Kind_<DynamicList      > { static constexpr Kind kind = Kind::OTHER; };
+template <> struct Kind_<DynamicCapability> { static constexpr Kind kind = Kind::OTHER; };
+
+}  // namespace _ (private)
+
+template <> inline constexpr Style style<DynamicValue     >() { return Style::POINTER;    }
+template <> inline constexpr Style style<DynamicEnum      >() { return Style::PRIMITIVE;  }
+template <> inline constexpr Style style<DynamicStruct    >() { return Style::STRUCT;     }
+template <> inline constexpr Style style<DynamicList      >() { return Style::POINTER;    }
+template <> inline constexpr Style style<DynamicCapability>() { return Style::CAPABILITY; }
+
+// -------------------------------------------------------------------
+
+class DynamicEnum {
+public:
+  DynamicEnum() = default;
+  inline DynamicEnum(EnumSchema::Enumerant enumerant)
+      : schema(enumerant.getContainingEnum()), value(enumerant.getOrdinal()) {}
+  inline DynamicEnum(EnumSchema schema, uint16_t value)
+      : schema(schema), value(value) {}
+
+  template <typename T, typename = kj::EnableIf<kind<T>() == Kind::ENUM>>
+  inline DynamicEnum(T&& value): DynamicEnum(toDynamic(value)) {}
+
+  template <typename T>
+  inline T as() const { return static_cast<T>(asImpl(typeId<T>())); }
+  // Cast to a native enum type.
+
+  inline EnumSchema getSchema() const { return schema; }
+
+  kj::Maybe<EnumSchema::Enumerant> getEnumerant() const;
+  // Get which enumerant this enum value represents.  Returns nullptr if the numeric value does not
+  // correspond to any enumerant in the schema -- this can happen if the data was built using a
+  // newer schema that has more values defined.
+
+  inline uint16_t getRaw() const { return value; }
+  // Returns the raw underlying enum value.
+
+private:
+  EnumSchema schema;
+  uint16_t value;
+
+  uint16_t asImpl(uint64_t requestedTypeId) const;
+
+  friend struct DynamicStruct;
+  friend struct DynamicList;
+  friend struct DynamicValue;
+  template <typename T>
+  friend DynamicTypeFor<TypeIfEnum<T>> toDynamic(T&& value);
+};
+
+// -------------------------------------------------------------------
+
+class DynamicStruct::Reader {
+public:
+  typedef DynamicStruct Reads;
+
+  Reader() = default;
+
+  template <typename T, typename = kj::EnableIf<kind<FromReader<T>>() == Kind::STRUCT>>
+  inline Reader(T&& value): Reader(toDynamic(value)) {}
+
+  inline MessageSize totalSize() const { return reader.totalSize().asPublic(); }
+
+  template <typename T>
+  typename T::Reader as() const;
+  // Convert the dynamic struct to its compiled-in type.
+
+  inline StructSchema getSchema() const { return schema; }
+
+  DynamicValue::Reader get(StructSchema::Field field) const;
+  // Read the given field value.
+
+  bool has(StructSchema::Field field) const;
+  // Tests whether the given field is set to its default value.  For pointer values, this does
+  // not actually traverse the value comparing it with the default, but simply returns true if the
+  // pointer is non-null.  For members of unions, has() returns false if the union member is not
+  // active, but does not necessarily return true if the member is active (depends on the field's
+  // value).
+
+  kj::Maybe<StructSchema::Field> which() const;
+  // If the struct contains an (unnamed) union, and the currently-active field within that union
+  // is known, this returns that field.  Otherwise, it returns null.  In other words, this returns
+  // null if there is no union present _or_ if the union's discriminant is set to an unrecognized
+  // value.  This could happen in particular when receiving a message from a sender who has a
+  // newer version of the protocol and is using a field of the union that you don't know about yet.
+
+  DynamicValue::Reader get(kj::StringPtr name) const;
+  bool has(kj::StringPtr name) const;
+  // Shortcuts to access fields by name.  These throw exceptions if no such field exists.
+
+private:
+  StructSchema schema;
+  _::StructReader reader;
+
+  inline Reader(StructSchema schema, _::StructReader reader)
+      : schema(schema), reader(reader) {}
+
+  bool isSetInUnion(StructSchema::Field field) const;
+  void verifySetInUnion(StructSchema::Field field) const;
+  static DynamicValue::Reader getImpl(_::StructReader reader, StructSchema::Field field);
+
+  template <typename T, Kind K>
+  friend struct _::PointerHelpers;
+  friend class DynamicStruct::Builder;
+  friend struct DynamicList;
+  friend class MessageReader;
+  friend class MessageBuilder;
+  template <typename T, ::capnp::Kind k>
+  friend struct ::capnp::ToDynamic_;
+  friend kj::StringTree _::structString(
+      _::StructReader reader, const _::RawBrandedSchema& schema);
+  friend class Orphanage;
+  friend class Orphan<DynamicStruct>;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+};
+
+class DynamicStruct::Builder {
+public:
+  typedef DynamicStruct Builds;
+
+  Builder() = default;
+  inline Builder(decltype(nullptr)) {}
+
+  template <typename T, typename = kj::EnableIf<kind<FromBuilder<T>>() == Kind::STRUCT>>
+  inline Builder(T&& value): Builder(toDynamic(value)) {}
+
+  inline MessageSize totalSize() const { return asReader().totalSize(); }
+
+  template <typename T>
+  typename T::Builder as();
+  // Cast to a particular struct type.
+
+  inline StructSchema getSchema() const { return schema; }
+
+  DynamicValue::Builder get(StructSchema::Field field);
+  // Read the given field value.
+
+  inline bool has(StructSchema::Field field) { return asReader().has(field); }
+  // Tests whether the given field is set to its default value.  For pointer values, this does
+  // not actually traverse the value comparing it with the default, but simply returns true if the
+  // pointer is non-null.  For members of unions, has() returns whether the field is currently
+  // active and the union as a whole is non-default -- so, the only time has() will return false
+  // for an active union field is if it is the default active field and it has its default value.
+
+  kj::Maybe<StructSchema::Field> which();
+  // If the struct contains an (unnamed) union, and the currently-active field within that union
+  // is known, this returns that field.  Otherwise, it returns null.  In other words, this returns
+  // null if there is no union present _or_ if the union's discriminant is set to an unrecognized
+  // value.  This could happen in particular when receiving a message from a sender who has a
+  // newer version of the protocol and is using a field of the union that you don't know about yet.
+
+  void set(StructSchema::Field field, const DynamicValue::Reader& value);
+  // Set the given field value.
+
+  DynamicValue::Builder init(StructSchema::Field field);
+  DynamicValue::Builder init(StructSchema::Field field, uint size);
+  // Init a struct, list, or blob field.
+
+  void adopt(StructSchema::Field field, Orphan<DynamicValue>&& orphan);
+  Orphan<DynamicValue> disown(StructSchema::Field field);
+  // Adopt/disown.  This works even for non-pointer fields: adopt() becomes equivalent to set()
+  // and disown() becomes like get() followed by clear().
+
+  void clear(StructSchema::Field field);
+  // Clear a field, setting it to its default value.  For pointer fields, this actually makes the
+  // field null.
+
+  DynamicValue::Builder get(kj::StringPtr name);
+  bool has(kj::StringPtr name);
+  void set(kj::StringPtr name, const DynamicValue::Reader& value);
+  void set(kj::StringPtr name, std::initializer_list<DynamicValue::Reader> value);
+  DynamicValue::Builder init(kj::StringPtr name);
+  DynamicValue::Builder init(kj::StringPtr name, uint size);
+  void adopt(kj::StringPtr name, Orphan<DynamicValue>&& orphan);
+  Orphan<DynamicValue> disown(kj::StringPtr name);
+  void clear(kj::StringPtr name);
+  // Shortcuts to access fields by name.  These throw exceptions if no such field exists.
+
+  Reader asReader() const;
+
+private:
+  StructSchema schema;
+  _::StructBuilder builder;
+
+  inline Builder(StructSchema schema, _::StructBuilder builder)
+      : schema(schema), builder(builder) {}
+
+  bool isSetInUnion(StructSchema::Field field);
+  void verifySetInUnion(StructSchema::Field field);
+  void setInUnion(StructSchema::Field field);
+
+  template <typename T, Kind k>
+  friend struct _::PointerHelpers;
+  friend struct DynamicList;
+  friend class MessageReader;
+  friend class MessageBuilder;
+  template <typename T, ::capnp::Kind k>
+  friend struct ::capnp::ToDynamic_;
+  friend class Orphanage;
+  friend class Orphan<DynamicStruct>;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+};
+
+class DynamicStruct::Pipeline {
+public:
+  typedef DynamicStruct Pipelines;
+
+  inline Pipeline(decltype(nullptr)): typeless(nullptr) {}
+
+  template <typename T>
+  typename T::Pipeline releaseAs();
+  // Convert the dynamic pipeline to its compiled-in type.
+
+  inline StructSchema getSchema() { return schema; }
+
+  DynamicValue::Pipeline get(StructSchema::Field field);
+  // Read the given field value.
+
+  DynamicValue::Pipeline get(kj::StringPtr name);
+  // Get by string name.
+
+private:
+  StructSchema schema;
+  AnyPointer::Pipeline typeless;
+
+  inline explicit Pipeline(StructSchema schema, AnyPointer::Pipeline&& typeless)
+      : schema(schema), typeless(kj::mv(typeless)) {}
+
+  friend class Request<DynamicStruct, DynamicStruct>;
+};
+
+// -------------------------------------------------------------------
+
+class DynamicList::Reader {
+public:
+  typedef DynamicList Reads;
+
+  inline Reader(): reader(ElementSize::VOID) {}
+
+  template <typename T, typename = kj::EnableIf<kind<FromReader<T>>() == Kind::LIST>>
+  inline Reader(T&& value): Reader(toDynamic(value)) {}
+
+  template <typename T>
+  typename T::Reader as() const;
+  // Try to convert to any List<T>, Data, or Text.  Throws an exception if the underlying data
+  // can't possibly represent the requested type.
+
+  inline ListSchema getSchema() const { return schema; }
+
+  inline uint size() const { return reader.size() / ELEMENTS; }
+  DynamicValue::Reader operator[](uint index) const;
+
+  typedef _::IndexingIterator<const Reader, DynamicValue::Reader> Iterator;
+  inline Iterator begin() const { return Iterator(this, 0); }
+  inline Iterator end() const { return Iterator(this, size()); }
+
+private:
+  ListSchema schema;
+  _::ListReader reader;
+
+  Reader(ListSchema schema, _::ListReader reader): schema(schema), reader(reader) {}
+
+  template <typename T, Kind k>
+  friend struct _::PointerHelpers;
+  friend struct DynamicStruct;
+  friend class DynamicList::Builder;
+  template <typename T, ::capnp::Kind k>
+  friend struct ::capnp::ToDynamic_;
+  friend class Orphanage;
+  friend class Orphan<DynamicList>;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+};
+
+class DynamicList::Builder {
+public:
+  typedef DynamicList Builds;
+
+  inline Builder(): builder(ElementSize::VOID) {}
+  inline Builder(decltype(nullptr)): builder(ElementSize::VOID) {}
+
+  template <typename T, typename = kj::EnableIf<kind<FromBuilder<T>>() == Kind::LIST>>
+  inline Builder(T&& value): Builder(toDynamic(value)) {}
+
+  template <typename T>
+  typename T::Builder as();
+  // Try to convert to any List<T>, Data, or Text.  Throws an exception if the underlying data
+  // can't possibly represent the requested type.
+
+  inline ListSchema getSchema() const { return schema; }
+
+  inline uint size() const { return builder.size() / ELEMENTS; }
+  DynamicValue::Builder operator[](uint index);
+  void set(uint index, const DynamicValue::Reader& value);
+  DynamicValue::Builder init(uint index, uint size);
+  void adopt(uint index, Orphan<DynamicValue>&& orphan);
+  Orphan<DynamicValue> disown(uint index);
+
+  typedef _::IndexingIterator<Builder, DynamicStruct::Builder> Iterator;
+  inline Iterator begin() { return Iterator(this, 0); }
+  inline Iterator end() { return Iterator(this, size()); }
+
+  void copyFrom(std::initializer_list<DynamicValue::Reader> value);
+
+  Reader asReader() const;
+
+private:
+  ListSchema schema;
+  _::ListBuilder builder;
+
+  Builder(ListSchema schema, _::ListBuilder builder): schema(schema), builder(builder) {}
+
+  template <typename T, Kind k>
+  friend struct _::PointerHelpers;
+  friend struct DynamicStruct;
+  template <typename T, ::capnp::Kind k>
+  friend struct ::capnp::ToDynamic_;
+  friend class Orphanage;
+  template <typename T, Kind k>
+  friend struct _::OrphanGetImpl;
+  friend class Orphan<DynamicList>;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+};
+
+// -------------------------------------------------------------------
+
+class DynamicCapability::Client: public Capability::Client {
+public:
+  typedef DynamicCapability Calls;
+  typedef DynamicCapability Reads;
+
+  Client() = default;
+
+  template <typename T, typename = kj::EnableIf<kind<FromClient<T>>() == Kind::INTERFACE>>
+  inline Client(T&& client);
+
+  template <typename T, typename = kj::EnableIf<kj::canConvert<T*, DynamicCapability::Server*>()>>
+  inline Client(kj::Own<T>&& server);
+
+  template <typename T, typename = kj::EnableIf<kind<T>() == Kind::INTERFACE>>
+  typename T::Client as();
+  template <typename T, typename = kj::EnableIf<kind<T>() == Kind::INTERFACE>>
+  typename T::Client releaseAs();
+  // Convert to any client type.
+
+  Client upcast(InterfaceSchema requestedSchema);
+  // Upcast to a superclass.  Throws an exception if `schema` is not a superclass.
+
+  inline InterfaceSchema getSchema() { return schema; }
+
+  Request<DynamicStruct, DynamicStruct> newRequest(
+      InterfaceSchema::Method method, kj::Maybe<MessageSize> sizeHint = nullptr);
+  Request<DynamicStruct, DynamicStruct> newRequest(
+      kj::StringPtr methodName, kj::Maybe<MessageSize> sizeHint = nullptr);
+
+private:
+  InterfaceSchema schema;
+
+  Client(InterfaceSchema schema, kj::Own<ClientHook>&& hook)
+      : Capability::Client(kj::mv(hook)), schema(schema) {}
+
+  template <typename T>
+  inline Client(InterfaceSchema schema, kj::Own<T>&& server);
+
+  friend struct Capability;
+  friend struct DynamicStruct;
+  friend struct DynamicList;
+  friend struct DynamicValue;
+  friend class Orphan<DynamicCapability>;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+  template <typename T, Kind k>
+  friend struct _::PointerHelpers;
+};
+
+class DynamicCapability::Server: public Capability::Server {
+public:
+  typedef DynamicCapability Serves;
+
+  Server(InterfaceSchema schema): schema(schema) {}
+
+  virtual kj::Promise<void> call(InterfaceSchema::Method method,
+                                 CallContext<DynamicStruct, DynamicStruct> context) = 0;
+
+  kj::Promise<void> dispatchCall(uint64_t interfaceId, uint16_t methodId,
+                                 CallContext<AnyPointer, AnyPointer> context) override final;
+
+  inline InterfaceSchema getSchema() const { return schema; }
+
+private:
+  InterfaceSchema schema;
+};
+
+template <>
+class Request<DynamicStruct, DynamicStruct>: public DynamicStruct::Builder {
+  // Specialization of `Request<T, U>` for DynamicStruct.
+
+public:
+  inline Request(DynamicStruct::Builder builder, kj::Own<RequestHook>&& hook,
+                 StructSchema resultSchema)
+      : DynamicStruct::Builder(builder), hook(kj::mv(hook)), resultSchema(resultSchema) {}
+
+  RemotePromise<DynamicStruct> send();
+  // Send the call and return a promise for the results.
+
+private:
+  kj::Own<RequestHook> hook;
+  StructSchema resultSchema;
+
+  friend class Capability::Client;
+  friend struct DynamicCapability;
+  template <typename, typename>
+  friend class CallContext;
+  friend class RequestHook;
+};
+
+template <>
+class CallContext<DynamicStruct, DynamicStruct>: public kj::DisallowConstCopy {
+  // Wrapper around CallContextHook with a specific return type.
+  //
+  // Methods of this class may only be called from within the server's event loop, not from other
+  // threads.
+
+public:
+  explicit CallContext(CallContextHook& hook, StructSchema paramType, StructSchema resultType);
+
+  DynamicStruct::Reader getParams();
+  void releaseParams();
+  DynamicStruct::Builder getResults(kj::Maybe<MessageSize> sizeHint = nullptr);
+  DynamicStruct::Builder initResults(kj::Maybe<MessageSize> sizeHint = nullptr);
+  void setResults(DynamicStruct::Reader value);
+  void adoptResults(Orphan<DynamicStruct>&& value);
+  Orphanage getResultsOrphanage(kj::Maybe<MessageSize> sizeHint = nullptr);
+  template <typename SubParams>
+  kj::Promise<void> tailCall(Request<SubParams, DynamicStruct>&& tailRequest);
+  void allowCancellation();
+
+private:
+  CallContextHook* hook;
+  StructSchema paramType;
+  StructSchema resultType;
+
+  friend class DynamicCapability::Server;
+};
+
+// -------------------------------------------------------------------
+
+// Make sure ReaderFor<T> and BuilderFor<T> work for DynamicEnum, DynamicStruct, and
+// DynamicList, so that we can define DynamicValue::as().
+
+template <> struct ReaderFor_ <DynamicEnum, Kind::OTHER> { typedef DynamicEnum Type; };
+template <> struct BuilderFor_<DynamicEnum, Kind::OTHER> { typedef DynamicEnum Type; };
+template <> struct ReaderFor_ <DynamicStruct, Kind::OTHER> { typedef DynamicStruct::Reader Type; };
+template <> struct BuilderFor_<DynamicStruct, Kind::OTHER> { typedef DynamicStruct::Builder Type; };
+template <> struct ReaderFor_ <DynamicList, Kind::OTHER> { typedef DynamicList::Reader Type; };
+template <> struct BuilderFor_<DynamicList, Kind::OTHER> { typedef DynamicList::Builder Type; };
+template <> struct ReaderFor_ <DynamicCapability, Kind::OTHER> { typedef DynamicCapability::Client Type; };
+template <> struct BuilderFor_<DynamicCapability, Kind::OTHER> { typedef DynamicCapability::Client Type; };
+template <> struct PipelineFor_<DynamicCapability, Kind::OTHER> { typedef DynamicCapability::Client Type; };
+
+class DynamicValue::Reader {
+public:
+  typedef DynamicValue Reads;
+
+  inline Reader(decltype(nullptr) n = nullptr);  // UNKNOWN
+  inline Reader(Void value);
+  inline Reader(bool value);
+  inline Reader(char value);
+  inline Reader(signed char value);
+  inline Reader(short value);
+  inline Reader(int value);
+  inline Reader(long value);
+  inline Reader(long long value);
+  inline Reader(unsigned char value);
+  inline Reader(unsigned short value);
+  inline Reader(unsigned int value);
+  inline Reader(unsigned long value);
+  inline Reader(unsigned long long value);
+  inline Reader(float value);
+  inline Reader(double value);
+  inline Reader(const char* value);  // Text
+  inline Reader(const Text::Reader& value);
+  inline Reader(const Data::Reader& value);
+  inline Reader(const DynamicList::Reader& value);
+  inline Reader(DynamicEnum value);
+  inline Reader(const DynamicStruct::Reader& value);
+  inline Reader(const AnyPointer::Reader& value);
+  inline Reader(DynamicCapability::Client& value);
+  inline Reader(DynamicCapability::Client&& value);
+  template <typename T, typename = kj::EnableIf<kj::canConvert<T*, DynamicCapability::Server*>()>>
+  inline Reader(kj::Own<T>&& value);
+  Reader(ConstSchema constant);
+
+  template <typename T, typename = decltype(toDynamic(kj::instance<T>()))>
+  inline Reader(T&& value): Reader(toDynamic(kj::mv(value))) {}
+
+  Reader(const Reader& other);
+  Reader(Reader&& other) noexcept;
+  ~Reader() noexcept(false);
+  Reader& operator=(const Reader& other);
+  Reader& operator=(Reader&& other);
+  // Unfortunately, we cannot use the implicit definitions of these since DynamicCapability is not
+  // trivially copyable.
+
+  template <typename T>
+  inline ReaderFor<T> as() const { return AsImpl<T>::apply(*this); }
+  // Use to interpret the value as some Cap'n Proto type.  Allowed types are:
+  // - Void, bool, [u]int{8,16,32,64}_t, float, double, any enum:  Returns the raw value.
+  // - Text, Data, AnyPointer, any struct type:  Returns the corresponding Reader.
+  // - List<T> for any T listed above:  Returns List<T>::Reader.
+  // - DynamicEnum:  Returns the corresponding type.
+  // - DynamicStruct, DynamicList:  Returns the corresponding Reader.
+  // - Any capability type, including DynamicCapability:  Returns the corresponding Client.
+  //   (TODO(perf):  On GCC 4.8 / Clang 3.3, provide rvalue-qualified version that avoids
+  //   refcounting.)
+  //
+  // DynamicValue allows various implicit conversions, mostly just to make the interface friendlier.
+  // - Any integer can be converted to any other integer type so long as the actual value is within
+  //   the new type's range.
+  // - Floating-point types can be converted to integers as long as no information would be lost
+  //   in the conversion.
+  // - Integers can be converted to floating points.  This may lose information, but won't throw.
+  // - Float32/Float64 can be converted between each other.  Converting Float64 -> Float32 may lose
+  //   information, but won't throw.
+  // - Text can be converted to an enum, if the Text matches one of the enumerant names (but not
+  //   vice-versa).
+  // - Capabilities can be upcast (cast to a supertype), but not downcast.
+  //
+  // Any other conversion attempt will throw an exception.
+
+  inline Type getType() const { return type; }
+  // Get the type of this value.
+
+private:
+  Type type;
+
+  union {
+    Void voidValue;
+    bool boolValue;
+    int64_t intValue;
+    uint64_t uintValue;
+    double floatValue;
+    Text::Reader textValue;
+    Data::Reader dataValue;
+    DynamicList::Reader listValue;
+    DynamicEnum enumValue;
+    DynamicStruct::Reader structValue;
+    AnyPointer::Reader anyPointerValue;
+
+    mutable DynamicCapability::Client capabilityValue;
+    // Declared mutable because `Client`s normally cannot be const.
+
+    // Warning:  Copy/move constructors assume all these types are trivially copyable except
+    //   Capability.
+  };
+
+  template <typename T, Kind kind = kind<T>()> struct AsImpl;
+  // Implementation backing the as() method.  Needs to be a struct to allow partial
+  // specialization.  Has a method apply() which does the work.
+
+  friend class Orphanage;  // to speed up newOrphanCopy(DynamicValue::Reader)
+};
+
+class DynamicValue::Builder {
+public:
+  typedef DynamicValue Builds;
+
+  inline Builder(decltype(nullptr) n = nullptr);  // UNKNOWN
+  inline Builder(Void value);
+  inline Builder(bool value);
+  inline Builder(char value);
+  inline Builder(signed char value);
+  inline Builder(short value);
+  inline Builder(int value);
+  inline Builder(long value);
+  inline Builder(long long value);
+  inline Builder(unsigned char value);
+  inline Builder(unsigned short value);
+  inline Builder(unsigned int value);
+  inline Builder(unsigned long value);
+  inline Builder(unsigned long long value);
+  inline Builder(float value);
+  inline Builder(double value);
+  inline Builder(Text::Builder value);
+  inline Builder(Data::Builder value);
+  inline Builder(DynamicList::Builder value);
+  inline Builder(DynamicEnum value);
+  inline Builder(DynamicStruct::Builder value);
+  inline Builder(AnyPointer::Builder value);
+  inline Builder(DynamicCapability::Client& value);
+  inline Builder(DynamicCapability::Client&& value);
+
+  template <typename T, typename = decltype(toDynamic(kj::instance<T>()))>
+  inline Builder(T value): Builder(toDynamic(value)) {}
+
+  Builder(Builder& other);
+  Builder(Builder&& other) noexcept;
+  ~Builder() noexcept(false);
+  Builder& operator=(Builder& other);
+  Builder& operator=(Builder&& other);
+  // Unfortunately, we cannot use the implicit definitions of these since DynamicCapability is not
+  // trivially copyable.
+
+  template <typename T>
+  inline BuilderFor<T> as() { return AsImpl<T>::apply(*this); }
+  // See DynamicValue::Reader::as().
+
+  inline Type getType() { return type; }
+  // Get the type of this value.
+
+  Reader asReader() const;
+
+private:
+  Type type;
+
+  union {
+    Void voidValue;
+    bool boolValue;
+    int64_t intValue;
+    uint64_t uintValue;
+    double floatValue;
+    Text::Builder textValue;
+    Data::Builder dataValue;
+    DynamicList::Builder listValue;
+    DynamicEnum enumValue;
+    DynamicStruct::Builder structValue;
+    AnyPointer::Builder anyPointerValue;
+
+    mutable DynamicCapability::Client capabilityValue;
+    // Declared mutable because `Client`s normally cannot be const.
+  };
+
+  template <typename T, Kind kind = kind<T>()> struct AsImpl;
+  // Implementation backing the as() method.  Needs to be a struct to allow partial
+  // specialization.  Has a method apply() which does the work.
+
+  friend class Orphan<DynamicValue>;
+};
+
+class DynamicValue::Pipeline {
+public:
+  typedef DynamicValue Pipelines;
+
+  inline Pipeline(decltype(nullptr) n = nullptr);
+  inline Pipeline(DynamicStruct::Pipeline&& value);
+  inline Pipeline(DynamicCapability::Client&& value);
+
+  Pipeline(Pipeline&& other) noexcept;
+  Pipeline& operator=(Pipeline&& other);
+  ~Pipeline() noexcept(false);
+
+  template <typename T>
+  inline PipelineFor<T> releaseAs() { return AsImpl<T>::apply(*this); }
+
+  inline Type getType() { return type; }
+  // Get the type of this value.
+
+private:
+  Type type;
+  union {
+    DynamicStruct::Pipeline structValue;
+    DynamicCapability::Client capabilityValue;
+  };
+
+  template <typename T, Kind kind = kind<T>()> struct AsImpl;
+  // Implementation backing the releaseAs() method.  Needs to be a struct to allow partial
+  // specialization.  Has a method apply() which does the work.
+};
+
+kj::StringTree KJ_STRINGIFY(const DynamicValue::Reader& value);
+kj::StringTree KJ_STRINGIFY(const DynamicValue::Builder& value);
+kj::StringTree KJ_STRINGIFY(DynamicEnum value);
+kj::StringTree KJ_STRINGIFY(const DynamicStruct::Reader& value);
+kj::StringTree KJ_STRINGIFY(const DynamicStruct::Builder& value);
+kj::StringTree KJ_STRINGIFY(const DynamicList::Reader& value);
+kj::StringTree KJ_STRINGIFY(const DynamicList::Builder& value);
+
+// -------------------------------------------------------------------
+// Orphan <-> Dynamic glue
+
+template <>
+class Orphan<DynamicStruct> {
+public:
+  Orphan() = default;
+  KJ_DISALLOW_COPY(Orphan);
+  Orphan(Orphan&&) = default;
+  Orphan& operator=(Orphan&&) = default;
+
+  template <typename T, typename = kj::EnableIf<kind<T>() == Kind::STRUCT>>
+  inline Orphan(Orphan<T>&& other): schema(Schema::from<T>()), builder(kj::mv(other.builder)) {}
+
+  DynamicStruct::Builder get();
+  DynamicStruct::Reader getReader() const;
+
+  template <typename T>
+  Orphan<T> releaseAs();
+  // Like DynamicStruct::Builder::as(), but coerces the Orphan type.  Since Orphans are move-only,
+  // the original Orphan<DynamicStruct> is no longer valid after this call; ownership is
+  // transferred to the returned Orphan<T>.
+
+  inline bool operator==(decltype(nullptr)) const { return builder == nullptr; }
+  inline bool operator!=(decltype(nullptr)) const { return builder != nullptr; }
+
+private:
+  StructSchema schema;
+  _::OrphanBuilder builder;
+
+  inline Orphan(StructSchema schema, _::OrphanBuilder&& builder)
+      : schema(schema), builder(kj::mv(builder)) {}
+
+  template <typename, Kind>
+  friend struct _::PointerHelpers;
+  friend struct DynamicList;
+  friend class Orphanage;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+  friend class MessageBuilder;
+};
+
+template <>
+class Orphan<DynamicList> {
+public:
+  Orphan() = default;
+  KJ_DISALLOW_COPY(Orphan);
+  Orphan(Orphan&&) = default;
+  Orphan& operator=(Orphan&&) = default;
+
+  template <typename T, typename = kj::EnableIf<kind<T>() == Kind::LIST>>
+  inline Orphan(Orphan<T>&& other): schema(Schema::from<T>()), builder(kj::mv(other.builder)) {}
+
+  DynamicList::Builder get();
+  DynamicList::Reader getReader() const;
+
+  template <typename T>
+  Orphan<T> releaseAs();
+  // Like DynamicList::Builder::as(), but coerces the Orphan type.  Since Orphans are move-only,
+  // the original Orphan<DynamicStruct> is no longer valid after this call; ownership is
+  // transferred to the returned Orphan<T>.
+
+  // TODO(someday): Support truncate().
+
+  inline bool operator==(decltype(nullptr)) const { return builder == nullptr; }
+  inline bool operator!=(decltype(nullptr)) const { return builder != nullptr; }
+
+private:
+  ListSchema schema;
+  _::OrphanBuilder builder;
+
+  inline Orphan(ListSchema schema, _::OrphanBuilder&& builder)
+      : schema(schema), builder(kj::mv(builder)) {}
+
+  template <typename, Kind>
+  friend struct _::PointerHelpers;
+  friend struct DynamicList;
+  friend class Orphanage;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+};
+
+template <>
+class Orphan<DynamicCapability> {
+public:
+  Orphan() = default;
+  KJ_DISALLOW_COPY(Orphan);
+  Orphan(Orphan&&) = default;
+  Orphan& operator=(Orphan&&) = default;
+
+  template <typename T, typename = kj::EnableIf<kind<T>() == Kind::INTERFACE>>
+  inline Orphan(Orphan<T>&& other): schema(Schema::from<T>()), builder(kj::mv(other.builder)) {}
+
+  DynamicCapability::Client get();
+  DynamicCapability::Client getReader() const;
+
+  template <typename T>
+  Orphan<T> releaseAs();
+  // Like DynamicCapability::Client::as(), but coerces the Orphan type.  Since Orphans are move-only,
+  // the original Orphan<DynamicCapability> is no longer valid after this call; ownership is
+  // transferred to the returned Orphan<T>.
+
+  inline bool operator==(decltype(nullptr)) const { return builder == nullptr; }
+  inline bool operator!=(decltype(nullptr)) const { return builder != nullptr; }
+
+private:
+  InterfaceSchema schema;
+  _::OrphanBuilder builder;
+
+  inline Orphan(InterfaceSchema schema, _::OrphanBuilder&& builder)
+      : schema(schema), builder(kj::mv(builder)) {}
+
+  template <typename, Kind>
+  friend struct _::PointerHelpers;
+  friend struct DynamicList;
+  friend class Orphanage;
+  friend class Orphan<DynamicValue>;
+  friend class Orphan<AnyPointer>;
+};
+
+template <>
+class Orphan<DynamicValue> {
+public:
+  inline Orphan(decltype(nullptr) n = nullptr): type(DynamicValue::UNKNOWN) {}
+  inline Orphan(Void value);
+  inline Orphan(bool value);
+  inline Orphan(char value);
+  inline Orphan(signed char value);
+  inline Orphan(short value);
+  inline Orphan(int value);
+  inline Orphan(long value);
+  inline Orphan(long long value);
+  inline Orphan(unsigned char value);
+  inline Orphan(unsigned short value);
+  inline Orphan(unsigned int value);
+  inline Orphan(unsigned long value);
+  inline Orphan(unsigned long long value);
+  inline Orphan(float value);
+  inline Orphan(double value);
+  inline Orphan(DynamicEnum value);
+  Orphan(Orphan&&) = default;
+  template <typename T>
+  Orphan(Orphan<T>&&);
+  Orphan(Orphan<AnyPointer>&&);
+  Orphan(void*) = delete;  // So Orphan(bool) doesn't accept pointers.
+  KJ_DISALLOW_COPY(Orphan);
+
+  Orphan& operator=(Orphan&&) = default;
+
+  inline DynamicValue::Type getType() { return type; }
+
+  DynamicValue::Builder get();
+  DynamicValue::Reader getReader() const;
+
+  template <typename T>
+  Orphan<T> releaseAs();
+  // Like DynamicValue::Builder::as(), but coerces the Orphan type.  Since Orphans are move-only,
+  // the original Orphan<DynamicStruct> is no longer valid after this call; ownership is
+  // transferred to the returned Orphan<T>.
+
+private:
+  DynamicValue::Type type;
+  union {
+    Void voidValue;
+    bool boolValue;
+    int64_t intValue;
+    uint64_t uintValue;
+    double floatValue;
+    DynamicEnum enumValue;
+    StructSchema structSchema;
+    ListSchema listSchema;
+    InterfaceSchema interfaceSchema;
+  };
+
+  _::OrphanBuilder builder;
+  // Only used if `type` is a pointer type.
+
+  Orphan(DynamicValue::Builder value, _::OrphanBuilder&& builder);
+  Orphan(DynamicValue::Type type, _::OrphanBuilder&& builder)
+      : type(type), builder(kj::mv(builder)) {}
+  Orphan(StructSchema structSchema, _::OrphanBuilder&& builder)
+      : type(DynamicValue::STRUCT), structSchema(structSchema), builder(kj::mv(builder)) {}
+  Orphan(ListSchema listSchema, _::OrphanBuilder&& builder)
+      : type(DynamicValue::LIST), listSchema(listSchema), builder(kj::mv(builder)) {}
+
+  template <typename, Kind>
+  friend struct _::PointerHelpers;
+  friend struct DynamicStruct;
+  friend struct DynamicList;
+  friend struct AnyPointer;
+  friend class Orphanage;
+};
+
+template <typename T>
+inline Orphan<DynamicValue>::Orphan(Orphan<T>&& other)
+    : Orphan(other.get(), kj::mv(other.builder)) {}
+
+inline Orphan<DynamicValue>::Orphan(Orphan<AnyPointer>&& other)
+    : type(DynamicValue::ANY_POINTER), builder(kj::mv(other.builder)) {}
+
+template <typename T>
+Orphan<T> Orphan<DynamicStruct>::releaseAs() {
+  get().as<T>();  // type check
+  return Orphan<T>(kj::mv(builder));
+}
+
+template <typename T>
+Orphan<T> Orphan<DynamicList>::releaseAs() {
+  get().as<T>();  // type check
+  return Orphan<T>(kj::mv(builder));
+}
+
+template <typename T>
+Orphan<T> Orphan<DynamicCapability>::releaseAs() {
+  get().as<T>();  // type check
+  return Orphan<T>(kj::mv(builder));
+}
+
+template <typename T>
+Orphan<T> Orphan<DynamicValue>::releaseAs() {
+  get().as<T>();  // type check
+  type = DynamicValue::UNKNOWN;
+  return Orphan<T>(kj::mv(builder));
+}
+
+template <>
+Orphan<AnyPointer> Orphan<DynamicValue>::releaseAs<AnyPointer>();
+template <>
+Orphan<DynamicStruct> Orphan<DynamicValue>::releaseAs<DynamicStruct>();
+template <>
+Orphan<DynamicList> Orphan<DynamicValue>::releaseAs<DynamicList>();
+template <>
+Orphan<DynamicCapability> Orphan<DynamicValue>::releaseAs<DynamicCapability>();
+
+template <>
+struct Orphanage::GetInnerBuilder<DynamicStruct, Kind::OTHER> {
+  static inline _::StructBuilder apply(DynamicStruct::Builder& t) {
+    return t.builder;
+  }
+};
+
+template <>
+struct Orphanage::GetInnerBuilder<DynamicList, Kind::OTHER> {
+  static inline _::ListBuilder apply(DynamicList::Builder& t) {
+    return t.builder;
+  }
+};
+
+template <>
+inline Orphan<DynamicStruct> Orphanage::newOrphanCopy<DynamicStruct::Reader>(
+    DynamicStruct::Reader copyFrom) const {
+  return Orphan<DynamicStruct>(
+      copyFrom.getSchema(), _::OrphanBuilder::copy(arena, capTable, copyFrom.reader));
+}
+
+template <>
+inline Orphan<DynamicList> Orphanage::newOrphanCopy<DynamicList::Reader>(
+    DynamicList::Reader copyFrom) const {
+  return Orphan<DynamicList>(copyFrom.getSchema(),
+      _::OrphanBuilder::copy(arena, capTable, copyFrom.reader));
+}
+
+template <>
+inline Orphan<DynamicCapability> Orphanage::newOrphanCopy<DynamicCapability::Client>(
+    DynamicCapability::Client copyFrom) const {
+  return Orphan<DynamicCapability>(
+      copyFrom.getSchema(), _::OrphanBuilder::copy(arena, capTable, copyFrom.hook->addRef()));
+}
+
+template <>
+Orphan<DynamicValue> Orphanage::newOrphanCopy<DynamicValue::Reader>(
+    DynamicValue::Reader copyFrom) const;
+
+namespace _ {  // private
+
+template <>
+struct PointerHelpers<DynamicStruct, Kind::OTHER> {
+  // getDynamic() is used when an AnyPointer's get() accessor is passed arguments, because for
+  // non-dynamic types PointerHelpers::get() takes a default value as the third argument, and we
+  // don't want people to accidentally be able to provide their own default value.
+  static DynamicStruct::Reader getDynamic(PointerReader reader, StructSchema schema);
+  static DynamicStruct::Builder getDynamic(PointerBuilder builder, StructSchema schema);
+  static void set(PointerBuilder builder, const DynamicStruct::Reader& value);
+  static DynamicStruct::Builder init(PointerBuilder builder, StructSchema schema);
+  static inline void adopt(PointerBuilder builder, Orphan<DynamicStruct>&& value) {
+    builder.adopt(kj::mv(value.builder));
+  }
+  static inline Orphan<DynamicStruct> disown(PointerBuilder builder, StructSchema schema) {
+    return Orphan<DynamicStruct>(schema, builder.disown());
+  }
+};
+
+template <>
+struct PointerHelpers<DynamicList, Kind::OTHER> {
+  // getDynamic() is used when an AnyPointer's get() accessor is passed arguments, because for
+  // non-dynamic types PointerHelpers::get() takes a default value as the third argument, and we
+  // don't want people to accidentally be able to provide their own default value.
+  static DynamicList::Reader getDynamic(PointerReader reader, ListSchema schema);
+  static DynamicList::Builder getDynamic(PointerBuilder builder, ListSchema schema);
+  static void set(PointerBuilder builder, const DynamicList::Reader& value);
+  static DynamicList::Builder init(PointerBuilder builder, ListSchema schema, uint size);
+  static inline void adopt(PointerBuilder builder, Orphan<DynamicList>&& value) {
+    builder.adopt(kj::mv(value.builder));
+  }
+  static inline Orphan<DynamicList> disown(PointerBuilder builder, ListSchema schema) {
+    return Orphan<DynamicList>(schema, builder.disown());
+  }
+};
+
+template <>
+struct PointerHelpers<DynamicCapability, Kind::OTHER> {
+  // getDynamic() is used when an AnyPointer's get() accessor is passed arguments, because for
+  // non-dynamic types PointerHelpers::get() takes a default value as the third argument, and we
+  // don't want people to accidentally be able to provide their own default value.
+  static DynamicCapability::Client getDynamic(PointerReader reader, InterfaceSchema schema);
+  static DynamicCapability::Client getDynamic(PointerBuilder builder, InterfaceSchema schema);
+  static void set(PointerBuilder builder, DynamicCapability::Client& value);
+  static void set(PointerBuilder builder, DynamicCapability::Client&& value);
+  static inline void adopt(PointerBuilder builder, Orphan<DynamicCapability>&& value) {
+    builder.adopt(kj::mv(value.builder));
+  }
+  static inline Orphan<DynamicCapability> disown(PointerBuilder builder, InterfaceSchema schema) {
+    return Orphan<DynamicCapability>(schema, builder.disown());
+  }
+};
+
+}  // namespace _ (private)
+
+template <typename T>
+inline ReaderFor<T> AnyPointer::Reader::getAs(StructSchema schema) const {
+  return _::PointerHelpers<T>::getDynamic(reader, schema);
+}
+template <typename T>
+inline ReaderFor<T> AnyPointer::Reader::getAs(ListSchema schema) const {
+  return _::PointerHelpers<T>::getDynamic(reader, schema);
+}
+template <typename T>
+inline ReaderFor<T> AnyPointer::Reader::getAs(InterfaceSchema schema) const {
+  return _::PointerHelpers<T>::getDynamic(reader, schema);
+}
+template <typename T>
+inline BuilderFor<T> AnyPointer::Builder::getAs(StructSchema schema) {
+  return _::PointerHelpers<T>::getDynamic(builder, schema);
+}
+template <typename T>
+inline BuilderFor<T> AnyPointer::Builder::getAs(ListSchema schema) {
+  return _::PointerHelpers<T>::getDynamic(builder, schema);
+}
+template <typename T>
+inline BuilderFor<T> AnyPointer::Builder::getAs(InterfaceSchema schema) {
+  return _::PointerHelpers<T>::getDynamic(builder, schema);
+}
+template <typename T>
+inline BuilderFor<T> AnyPointer::Builder::initAs(StructSchema schema) {
+  return _::PointerHelpers<T>::init(builder, schema);
+}
+template <typename T>
+inline BuilderFor<T> AnyPointer::Builder::initAs(ListSchema schema, uint elementCount) {
+  return _::PointerHelpers<T>::init(builder, schema, elementCount);
+}
+template <>
+inline void AnyPointer::Builder::setAs<DynamicStruct>(DynamicStruct::Reader value) {
+  return _::PointerHelpers<DynamicStruct>::set(builder, value);
+}
+template <>
+inline void AnyPointer::Builder::setAs<DynamicList>(DynamicList::Reader value) {
+  return _::PointerHelpers<DynamicList>::set(builder, value);
+}
+template <>
+inline void AnyPointer::Builder::setAs<DynamicCapability>(DynamicCapability::Client value) {
+  return _::PointerHelpers<DynamicCapability>::set(builder, kj::mv(value));
+}
+template <>
+void AnyPointer::Builder::adopt<DynamicValue>(Orphan<DynamicValue>&& orphan);
+template <typename T>
+inline Orphan<T> AnyPointer::Builder::disownAs(StructSchema schema) {
+  return _::PointerHelpers<T>::disown(builder, schema);
+}
+template <typename T>
+inline Orphan<T> AnyPointer::Builder::disownAs(ListSchema schema) {
+  return _::PointerHelpers<T>::disown(builder, schema);
+}
+template <typename T>
+inline Orphan<T> AnyPointer::Builder::disownAs(InterfaceSchema schema) {
+  return _::PointerHelpers<T>::disown(builder, schema);
+}
+
+template <>
+DynamicStruct::Builder Orphan<AnyPointer>::getAs<DynamicStruct>(StructSchema schema);
+template <>
+DynamicList::Builder Orphan<AnyPointer>::getAs<DynamicList>(ListSchema schema);
+template <>
+DynamicCapability::Client Orphan<AnyPointer>::getAs<DynamicCapability>(InterfaceSchema schema);
+template <>
+DynamicStruct::Reader Orphan<AnyPointer>::getAsReader<DynamicStruct>(StructSchema schema) const;
+template <>
+DynamicList::Reader Orphan<AnyPointer>::getAsReader<DynamicList>(ListSchema schema) const;
+template <>
+DynamicCapability::Client Orphan<AnyPointer>::getAsReader<DynamicCapability>(
+    InterfaceSchema schema) const;
+template <>
+Orphan<DynamicStruct> Orphan<AnyPointer>::releaseAs<DynamicStruct>(StructSchema schema);
+template <>
+Orphan<DynamicList> Orphan<AnyPointer>::releaseAs<DynamicList>(ListSchema schema);
+template <>
+Orphan<DynamicCapability> Orphan<AnyPointer>::releaseAs<DynamicCapability>(
+    InterfaceSchema schema);
+
+// =======================================================================================
+// Inline implementation details.
+
+template <typename T>
+struct ToDynamic_<T, Kind::STRUCT> {
+  static inline DynamicStruct::Reader apply(const typename T::Reader& value) {
+    return DynamicStruct::Reader(Schema::from<T>(), value._reader);
+  }
+  static inline DynamicStruct::Builder apply(typename T::Builder& value) {
+    return DynamicStruct::Builder(Schema::from<T>(), value._builder);
+  }
+};
+
+template <typename T>
+struct ToDynamic_<T, Kind::LIST> {
+  static inline DynamicList::Reader apply(const typename T::Reader& value) {
+    return DynamicList::Reader(Schema::from<T>(), value.reader);
+  }
+  static inline DynamicList::Builder apply(typename T::Builder& value) {
+    return DynamicList::Builder(Schema::from<T>(), value.builder);
+  }
+};
+
+template <typename T>
+struct ToDynamic_<T, Kind::INTERFACE> {
+  static inline DynamicCapability::Client apply(typename T::Client value) {
+    return DynamicCapability::Client(kj::mv(value));
+  }
+  static inline DynamicCapability::Client apply(typename T::Client&& value) {
+    return DynamicCapability::Client(kj::mv(value));
+  }
+};
+
+template <typename T>
+ReaderFor<DynamicTypeFor<FromReader<T>>> toDynamic(T&& value) {
+  return ToDynamic_<FromReader<T>>::apply(value);
+}
+template <typename T>
+BuilderFor<DynamicTypeFor<FromBuilder<T>>> toDynamic(T&& value) {
+  return ToDynamic_<FromBuilder<T>>::apply(value);
+}
+template <typename T>
+DynamicTypeFor<TypeIfEnum<T>> toDynamic(T&& value) {
+  return DynamicEnum(Schema::from<kj::Decay<T>>(), static_cast<uint16_t>(value));
+}
+template <typename T>
+typename DynamicTypeFor<FromServer<T>>::Client toDynamic(kj::Own<T>&& value) {
+  return typename FromServer<T>::Client(kj::mv(value));
+}
+
+inline DynamicValue::Reader::Reader(std::nullptr_t n): type(UNKNOWN) {}
+inline DynamicValue::Builder::Builder(std::nullptr_t n): type(UNKNOWN) {}
+
+#define CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(cppType, typeTag, fieldName) \
+inline DynamicValue::Reader::Reader(cppType value) \
+    : type(typeTag), fieldName##Value(value) {} \
+inline DynamicValue::Builder::Builder(cppType value) \
+    : type(typeTag), fieldName##Value(value) {} \
+inline Orphan<DynamicValue>::Orphan(cppType value) \
+    : type(DynamicValue::typeTag), fieldName##Value(value) {}
+
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(Void, VOID, void);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(bool, BOOL, bool);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(char, INT, int);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(signed char, INT, int);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(short, INT, int);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(int, INT, int);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(long, INT, int);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(long long, INT, int);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(unsigned char, UINT, uint);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(unsigned short, UINT, uint);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(unsigned int, UINT, uint);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(unsigned long, UINT, uint);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(unsigned long long, UINT, uint);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(float, FLOAT, float);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(double, FLOAT, float);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(DynamicEnum, ENUM, enum);
+#undef CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR
+
+#define CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(cppType, typeTag, fieldName) \
+inline DynamicValue::Reader::Reader(const cppType::Reader& value) \
+    : type(typeTag), fieldName##Value(value) {} \
+inline DynamicValue::Builder::Builder(cppType::Builder value) \
+    : type(typeTag), fieldName##Value(value) {}
+
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(Text, TEXT, text);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(Data, DATA, data);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(DynamicList, LIST, list);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(DynamicStruct, STRUCT, struct);
+CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR(AnyPointer, ANY_POINTER, anyPointer);
+
+#undef CAPNP_DECLARE_DYNAMIC_VALUE_CONSTRUCTOR
+
+inline DynamicValue::Reader::Reader(DynamicCapability::Client& value)
+    : type(CAPABILITY), capabilityValue(value) {}
+inline DynamicValue::Reader::Reader(DynamicCapability::Client&& value)
+    : type(CAPABILITY), capabilityValue(kj::mv(value)) {}
+template <typename T, typename>
+inline DynamicValue::Reader::Reader(kj::Own<T>&& value)
+    : type(CAPABILITY), capabilityValue(kj::mv(value)) {}
+inline DynamicValue::Builder::Builder(DynamicCapability::Client& value)
+    : type(CAPABILITY), capabilityValue(value) {}
+inline DynamicValue::Builder::Builder(DynamicCapability::Client&& value)
+    : type(CAPABILITY), capabilityValue(kj::mv(value)) {}
+
+inline DynamicValue::Reader::Reader(const char* value): Reader(Text::Reader(value)) {}
+
+#define CAPNP_DECLARE_TYPE(discrim, typeName) \
+template <> \
+struct DynamicValue::Reader::AsImpl<typeName> { \
+  static ReaderFor<typeName> apply(const Reader& reader); \
+}; \
+template <> \
+struct DynamicValue::Builder::AsImpl<typeName> { \
+  static BuilderFor<typeName> apply(Builder& builder); \
+};
+
+//CAPNP_DECLARE_TYPE(VOID, Void)
+CAPNP_DECLARE_TYPE(BOOL, bool)
+CAPNP_DECLARE_TYPE(INT8, int8_t)
+CAPNP_DECLARE_TYPE(INT16, int16_t)
+CAPNP_DECLARE_TYPE(INT32, int32_t)
+CAPNP_DECLARE_TYPE(INT64, int64_t)
+CAPNP_DECLARE_TYPE(UINT8, uint8_t)
+CAPNP_DECLARE_TYPE(UINT16, uint16_t)
+CAPNP_DECLARE_TYPE(UINT32, uint32_t)
+CAPNP_DECLARE_TYPE(UINT64, uint64_t)
+CAPNP_DECLARE_TYPE(FLOAT32, float)
+CAPNP_DECLARE_TYPE(FLOAT64, double)
+
+CAPNP_DECLARE_TYPE(TEXT, Text)
+CAPNP_DECLARE_TYPE(DATA, Data)
+CAPNP_DECLARE_TYPE(LIST, DynamicList)
+CAPNP_DECLARE_TYPE(STRUCT, DynamicStruct)
+CAPNP_DECLARE_TYPE(INTERFACE, DynamicCapability)
+CAPNP_DECLARE_TYPE(ENUM, DynamicEnum)
+CAPNP_DECLARE_TYPE(ANY_POINTER, AnyPointer)
+#undef CAPNP_DECLARE_TYPE
+
+// CAPNP_DECLARE_TYPE(Void) causes gcc 4.7 to segfault.  If I do it manually and remove the
+// ReaderFor<> and BuilderFor<> wrappers, it works.
+template <>
+struct DynamicValue::Reader::AsImpl<Void> {
+  static Void apply(const Reader& reader);
+};
+template <>
+struct DynamicValue::Builder::AsImpl<Void> {
+  static Void apply(Builder& builder);
+};
+
+template <typename T>
+struct DynamicValue::Reader::AsImpl<T, Kind::ENUM> {
+  static T apply(const Reader& reader) {
+    return reader.as<DynamicEnum>().as<T>();
+  }
+};
+template <typename T>
+struct DynamicValue::Builder::AsImpl<T, Kind::ENUM> {
+  static T apply(Builder& builder) {
+    return builder.as<DynamicEnum>().as<T>();
+  }
+};
+
+template <typename T>
+struct DynamicValue::Reader::AsImpl<T, Kind::STRUCT> {
+  static typename T::Reader apply(const Reader& reader) {
+    return reader.as<DynamicStruct>().as<T>();
+  }
+};
+template <typename T>
+struct DynamicValue::Builder::AsImpl<T, Kind::STRUCT> {
+  static typename T::Builder apply(Builder& builder) {
+    return builder.as<DynamicStruct>().as<T>();
+  }
+};
+
+template <typename T>
+struct DynamicValue::Reader::AsImpl<T, Kind::LIST> {
+  static typename T::Reader apply(const Reader& reader) {
+    return reader.as<DynamicList>().as<T>();
+  }
+};
+template <typename T>
+struct DynamicValue::Builder::AsImpl<T, Kind::LIST> {
+  static typename T::Builder apply(Builder& builder) {
+    return builder.as<DynamicList>().as<T>();
+  }
+};
+
+template <typename T>
+struct DynamicValue::Reader::AsImpl<T, Kind::INTERFACE> {
+  static typename T::Client apply(const Reader& reader) {
+    return reader.as<DynamicCapability>().as<T>();
+  }
+};
+template <typename T>
+struct DynamicValue::Builder::AsImpl<T, Kind::INTERFACE> {
+  static typename T::Client apply(Builder& builder) {
+    return builder.as<DynamicCapability>().as<T>();
+  }
+};
+
+inline DynamicValue::Pipeline::Pipeline(std::nullptr_t n): type(UNKNOWN) {}
+inline DynamicValue::Pipeline::Pipeline(DynamicStruct::Pipeline&& value)
+    : type(STRUCT), structValue(kj::mv(value)) {}
+inline DynamicValue::Pipeline::Pipeline(DynamicCapability::Client&& value)
+    : type(CAPABILITY), capabilityValue(kj::mv(value)) {}
+
+template <typename T>
+struct DynamicValue::Pipeline::AsImpl<T, Kind::STRUCT> {
+  static typename T::Pipeline apply(Pipeline& pipeline) {
+    return pipeline.releaseAs<DynamicStruct>().releaseAs<T>();
+  }
+};
+template <typename T>
+struct DynamicValue::Pipeline::AsImpl<T, Kind::INTERFACE> {
+  static typename T::Client apply(Pipeline& pipeline) {
+    return pipeline.releaseAs<DynamicCapability>().releaseAs<T>();
+  }
+};
+template <>
+struct DynamicValue::Pipeline::AsImpl<DynamicStruct, Kind::OTHER> {
+  static PipelineFor<DynamicStruct> apply(Pipeline& pipeline);
+};
+template <>
+struct DynamicValue::Pipeline::AsImpl<DynamicCapability, Kind::OTHER> {
+  static PipelineFor<DynamicCapability> apply(Pipeline& pipeline);
+};
+
+// -------------------------------------------------------------------
+
+template <typename T>
+typename T::Reader DynamicStruct::Reader::as() const {
+  static_assert(kind<T>() == Kind::STRUCT,
+                "DynamicStruct::Reader::as<T>() can only convert to struct types.");
+  schema.requireUsableAs<T>();
+  return typename T::Reader(reader);
+}
+
+template <typename T>
+typename T::Builder DynamicStruct::Builder::as() {
+  static_assert(kind<T>() == Kind::STRUCT,
+                "DynamicStruct::Builder::as<T>() can only convert to struct types.");
+  schema.requireUsableAs<T>();
+  return typename T::Builder(builder);
+}
+
+template <>
+inline DynamicStruct::Reader DynamicStruct::Reader::as<DynamicStruct>() const {
+  return *this;
+}
+template <>
+inline DynamicStruct::Builder DynamicStruct::Builder::as<DynamicStruct>() {
+  return *this;
+}
+
+inline DynamicStruct::Reader DynamicStruct::Builder::asReader() const {
+  return DynamicStruct::Reader(schema, builder.asReader());
+}
+
+template <>
+inline AnyStruct::Reader DynamicStruct::Reader::as<AnyStruct>() const {
+  return AnyStruct::Reader(reader);
+}
+
+template <>
+inline AnyStruct::Builder DynamicStruct::Builder::as<AnyStruct>() {
+  return AnyStruct::Builder(builder);
+}
+
+template <typename T>
+typename T::Pipeline DynamicStruct::Pipeline::releaseAs() {
+  static_assert(kind<T>() == Kind::STRUCT,
+                "DynamicStruct::Pipeline::releaseAs<T>() can only convert to struct types.");
+  schema.requireUsableAs<T>();
+  return typename T::Pipeline(kj::mv(typeless));
+}
+
+// -------------------------------------------------------------------
+
+template <typename T>
+typename T::Reader DynamicList::Reader::as() const {
+  static_assert(kind<T>() == Kind::LIST,
+                "DynamicStruct::Reader::as<T>() can only convert to list types.");
+  schema.requireUsableAs<T>();
+  return typename T::Reader(reader);
+}
+template <typename T>
+typename T::Builder DynamicList::Builder::as() {
+  static_assert(kind<T>() == Kind::LIST,
+                "DynamicStruct::Builder::as<T>() can only convert to list types.");
+  schema.requireUsableAs<T>();
+  return typename T::Builder(builder);
+}
+
+template <>
+inline DynamicList::Reader DynamicList::Reader::as<DynamicList>() const {
+  return *this;
+}
+template <>
+inline DynamicList::Builder DynamicList::Builder::as<DynamicList>() {
+  return *this;
+}
+
+// -------------------------------------------------------------------
+
+template <typename T, typename>
+inline DynamicCapability::Client::Client(T&& client)
+    : Capability::Client(kj::mv(client)), schema(Schema::from<FromClient<T>>()) {}
+
+template <typename T, typename>
+inline DynamicCapability::Client::Client(kj::Own<T>&& server)
+    : Client(server->getSchema(), kj::mv(server)) {}
+template <typename T>
+inline DynamicCapability::Client::Client(InterfaceSchema schema, kj::Own<T>&& server)
+    : Capability::Client(kj::mv(server)), schema(schema) {}
+
+template <typename T, typename>
+typename T::Client DynamicCapability::Client::as() {
+  static_assert(kind<T>() == Kind::INTERFACE,
+                "DynamicCapability::Client::as<T>() can only convert to interface types.");
+  schema.requireUsableAs<T>();
+  return typename T::Client(hook->addRef());
+}
+
+template <typename T, typename>
+typename T::Client DynamicCapability::Client::releaseAs() {
+  static_assert(kind<T>() == Kind::INTERFACE,
+                "DynamicCapability::Client::as<T>() can only convert to interface types.");
+  schema.requireUsableAs<T>();
+  return typename T::Client(kj::mv(hook));
+}
+
+inline CallContext<DynamicStruct, DynamicStruct>::CallContext(
+    CallContextHook& hook, StructSchema paramType, StructSchema resultType)
+    : hook(&hook), paramType(paramType), resultType(resultType) {}
+inline DynamicStruct::Reader CallContext<DynamicStruct, DynamicStruct>::getParams() {
+  return hook->getParams().getAs<DynamicStruct>(paramType);
+}
+inline void CallContext<DynamicStruct, DynamicStruct>::releaseParams() {
+  hook->releaseParams();
+}
+inline DynamicStruct::Builder CallContext<DynamicStruct, DynamicStruct>::getResults(
+    kj::Maybe<MessageSize> sizeHint) {
+  return hook->getResults(sizeHint).getAs<DynamicStruct>(resultType);
+}
+inline DynamicStruct::Builder CallContext<DynamicStruct, DynamicStruct>::initResults(
+    kj::Maybe<MessageSize> sizeHint) {
+  return hook->getResults(sizeHint).initAs<DynamicStruct>(resultType);
+}
+inline void CallContext<DynamicStruct, DynamicStruct>::setResults(DynamicStruct::Reader value) {
+  hook->getResults(value.totalSize()).setAs<DynamicStruct>(value);
+}
+inline void CallContext<DynamicStruct, DynamicStruct>::adoptResults(Orphan<DynamicStruct>&& value) {
+  hook->getResults(MessageSize { 0, 0 }).adopt(kj::mv(value));
+}
+inline Orphanage CallContext<DynamicStruct, DynamicStruct>::getResultsOrphanage(
+    kj::Maybe<MessageSize> sizeHint) {
+  return Orphanage::getForMessageContaining(hook->getResults(sizeHint));
+}
+template <typename SubParams>
+inline kj::Promise<void> CallContext<DynamicStruct, DynamicStruct>::tailCall(
+    Request<SubParams, DynamicStruct>&& tailRequest) {
+  return hook->tailCall(kj::mv(tailRequest.hook));
+}
+inline void CallContext<DynamicStruct, DynamicStruct>::allowCancellation() {
+  hook->allowCancellation();
+}
+
+template <>
+inline DynamicCapability::Client Capability::Client::castAs<DynamicCapability>(
+    InterfaceSchema schema) {
+  return DynamicCapability::Client(schema, hook->addRef());
+}
+
+// -------------------------------------------------------------------
+
+template <typename T>
+ReaderFor<T> ConstSchema::as() const {
+  return DynamicValue::Reader(*this).as<T>();
+}
+
+}  // namespace capnp
+
+#endif  // CAPNP_DYNAMIC_H_