Replace JsonCodec STL maps with KJ maps.

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

@@ -35,6 +35,7 @@
 #include "any.h"
 #include <kj/string.h>
 #include <kj/string-tree.h>
+#include <kj/hash.h>
 
 namespace capnp {
 

c++/src/capnp/schema.c++

@@ -25,6 +25,12 @@
 
 namespace capnp {
 
+namespace schema {
+  uint KJ_HASHCODE(Type::Which w) { return kj::hashCode(static_cast<uint16_t>(w)); }
+  // TODO(cleanup): Cap'n Proto does not declare stringifiers nor hashers for `Which` enums, unlike
+  //   all other enums. Fix that and remove this.
+}
+
 namespace _ {  // private
 
 // Null schemas generated using the below schema file with:
@@ -868,7 +874,7 @@ bool Type::operator==(const Type& other) const {
   KJ_UNREACHABLE;
 }
 
-size_t Type::hashCode() const {
+uint Type::hashCode() const {
   switch (baseType) {
     case schema::Type::VOID:
     case schema::Type::BOOL:
@@ -884,12 +890,12 @@ size_t Type::hashCode() const {
     case schema::Type::FLOAT64:
     case schema::Type::TEXT:
     case schema::Type::DATA:
-      return (static_cast<size_t>(baseType) << 3) + listDepth;
+      return kj::hashCode(baseType, listDepth);
 
     case schema::Type::STRUCT:
     case schema::Type::ENUM:
     case schema::Type::INTERFACE:
-      return reinterpret_cast<size_t>(schema) + listDepth;
+      return kj::hashCode(schema, listDepth);
 
     case schema::Type::LIST:
       KJ_UNREACHABLE;
@@ -897,9 +903,9 @@ size_t Type::hashCode() const {
     case schema::Type::ANY_POINTER: {
       // Trying to comply with strict aliasing rules. Hopefully the compiler realizes that
       // both branches compile to the same instructions and can optimize it away.
-      size_t val = scopeId != 0 || isImplicitParam ?
+      uint16_t val = scopeId != 0 || isImplicitParam ?
           paramIndex : static_cast<uint16_t>(anyPointerKind);
-      return (val << 1 | isImplicitParam) ^ scopeId;
+      return kj::hashCode(val, isImplicitParam, scopeId);
     }
   }
 

c++/src/capnp/schema.h

@@ -30,6 +30,7 @@
 #endif
 
 #include <capnp/schema.capnp.h>
+#include <kj/hash.h>
 #include <kj/windows-sanity.h>  // work-around macro conflict with `VOID`
 
 namespace capnp {
@@ -129,6 +130,8 @@ public:
   // you want to check if two Schemas represent the same type (but possibly different versions of
   // it), compare their IDs instead.
 
+  inline uint hashCode() const { return kj::hashCode(raw); }
+
   template <typename T>
   void requireUsableAs() const;
   // Throws an exception if a value with this Schema cannot safely be cast to a native value of
@@ -302,6 +305,7 @@ public:
 
   inline bool operator==(const Field& other) const;
   inline bool operator!=(const Field& other) const { return !(*this == other); }
+  inline uint hashCode() const;
 
 private:
   StructSchema parent;
@@ -400,6 +404,7 @@ public:
 
   inline bool operator==(const Enumerant& other) const;
   inline bool operator!=(const Enumerant& other) const { return !(*this == other); }
+  inline uint hashCode() const;
 
 private:
   EnumSchema parent;
@@ -492,6 +497,7 @@ public:
 
   inline bool operator==(const Method& other) const;
   inline bool operator!=(const Method& other) const { return !(*this == other); }
+  inline uint hashCode() const;
 
 private:
   InterfaceSchema parent;
@@ -644,7 +650,7 @@ public:
   bool operator==(const Type& other) const;
   inline bool operator!=(const Type& other) const { return !(*this == other); }
 
-  size_t hashCode() const;
+  uint hashCode() const;
 
   inline Type wrapInList(uint depth = 1) const;
   // Return the Type formed by wrapping this type in List() `depth` times.
@@ -796,6 +802,16 @@ inline bool InterfaceSchema::Method::operator==(const Method& other) const {
   return parent == other.parent && ordinal == other.ordinal;
 }
 
+inline uint StructSchema::Field::hashCode() const {
+  return kj::hashCode(parent, index);
+}
+inline uint EnumSchema::Enumerant::hashCode() const {
+  return kj::hashCode(parent, index);
+}
+inline uint InterfaceSchema::Method::hashCode() const {
+  return kj::hashCode(parent, index);
+}
+
 inline ListSchema ListSchema::of(StructSchema elementType) {
   return ListSchema(Type(elementType));
 }