1 files changed, 173 insertions, 0 deletions
diff --git a/xpcom/reflect/xptcall/xptcall.h b/xpcom/reflect/xptcall/xptcall.h
new file mode 100644
index 0000000000..a36ca53d23
--- /dev/null
+++ b/xpcom/reflect/xptcall/xptcall.h
@@ -0,0 +1,173 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Public declarations for xptcall. */
+
+#ifndef xptcall_h___
+#define xptcall_h___
+
+#include "nscore.h"
+#include "nsISupports.h"
+#include "xptinfo.h"
+#include "js/Value.h"
+#include "mozilla/MemoryReporting.h"
+
+struct nsXPTCMiniVariant {
+  // No ctors or dtors so that we can use arrays of these on the stack
+  // with no penalty.
+  union Union {
+    int8_t i8;
+    int16_t i16;
+    int32_t i32;
+    int64_t i64;
+    uint8_t u8;
+    uint16_t u16;
+    uint32_t u32;
+    uint64_t u64;
+    float f;
+    double d;
+    bool b;
+    char c;
+    char16_t wc;
+    void* p;
+  };
+
+  Union val;
+};
+
+static_assert(offsetof(nsXPTCMiniVariant, val) == 0,
+              "nsXPTCMiniVariant must be a thin wrapper");
+
+struct nsXPTCVariant {
+  union ExtendedVal {
+    // ExtendedVal is an extension on nsXPTCMiniVariant. It contains types
+    // unknown to the assembly implementations which must be passed by indirect
+    // semantics.
+    //
+    // nsXPTCVariant contains enough space to store ExtendedVal inline, which
+    // can be used to store these types when IsIndirect() is true.
+    nsXPTCMiniVariant mini;
+
+    nsID nsid;
+    nsCString nscstr;
+    nsString nsstr;
+    JS::Value jsval;
+    xpt::detail::UntypedTArray array;
+
+    // This type contains non-standard-layout types, so needs an explicit
+    // Ctor/Dtor - we'll just delete them.
+    ExtendedVal() = delete;
+    ~ExtendedVal() = delete;
+  };
+
+  union {
+    // The `val` field from nsXPTCMiniVariant.
+    nsXPTCMiniVariant::Union val;
+
+    // Storage for any extended variants.
+    ExtendedVal ext;
+  };
+
+  nsXPTType type;
+  uint8_t flags;
+
+  // Clear to a valid, null state.
+  nsXPTCVariant() {
+    memset(this, 0, sizeof(nsXPTCVariant));
+    type = nsXPTType::T_VOID;
+  }
+
+  enum {
+    //
+    // Bitflag definitions
+    //
+
+    // Indicates that we &val.p should be passed n the stack, i.e. that
+    // val should be passed by reference.
+    IS_INDIRECT = 0x1,
+  };
+
+  void ClearFlags() { flags = 0; }
+  void SetIndirect() { flags |= IS_INDIRECT; }
+
+  bool IsIndirect() const { return 0 != (flags & IS_INDIRECT); }
+
+  // Implicitly convert to nsXPTCMiniVariant.
+  operator nsXPTCMiniVariant&() { return *(nsXPTCMiniVariant*)&val; }
+  operator const nsXPTCMiniVariant&() const {
+    return *(const nsXPTCMiniVariant*)&val;
+  }
+
+  // As this type contains an anonymous union, we need to provide an explicit
+  // destructor.
+  ~nsXPTCVariant() {}
+};
+
+static_assert(offsetof(nsXPTCVariant, val) == offsetof(nsXPTCVariant, ext),
+              "nsXPTCVariant::{ext,val} must have matching offsets");
+
+// static_assert that nsXPTCVariant::ExtendedVal is large enough and
+// well-aligned enough for every XPT-supported type.
+#define XPT_CHECK_SIZEOF(xpt, type)                                            \
+  static_assert(sizeof(nsXPTCVariant::ExtendedVal) >= sizeof(type),            \
+                "nsXPTCVariant::ext not big enough for " #xpt " (" #type ")"); \
+  static_assert(MOZ_ALIGNOF(nsXPTCVariant::ExtendedVal) >= MOZ_ALIGNOF(type),  \
+                "nsXPTCVariant::ext not aligned enough for " #xpt " (" #type   \
+                ")");
+XPT_FOR_EACH_TYPE(XPT_CHECK_SIZEOF)
+#undef XPT_CHECK_SIZEOF
+
+class nsIXPTCProxy : public nsISupports {
+ public:
+  NS_IMETHOD CallMethod(uint16_t aMethodIndex, const nsXPTMethodInfo* aInfo,
+                        nsXPTCMiniVariant* aParams) = 0;
+};
+
+/**
+ * This is a typedef to avoid confusion between the canonical
+ * nsISupports* that provides object identity and an interface pointer
+ * for inheriting interfaces that aren't known at compile-time.
+ */
+typedef nsISupports nsISomeInterface;
+
+/**
+ * Get a proxy object to implement the specified interface.
+ *
+ * @param aIID    The IID of the interface to implement.
+ * @param aOuter  An object to receive method calls from the proxy object.
+ *                The stub forwards QueryInterface/AddRef/Release to the
+ *                outer object. The proxy object does not hold a reference to
+ *                the outer object; it is the caller's responsibility to
+ *                ensure that this pointer remains valid until the stub has
+ *                been destroyed.
+ * @param aStub   Out parameter for the new proxy object. The object is
+ *                not addrefed. The object never destroys itself. It must be
+ *                explicitly destroyed by calling
+ *                NS_DestroyXPTCallStub when it is no longer needed.
+ */
+XPCOM_API(nsresult)
+NS_GetXPTCallStub(REFNSIID aIID, nsIXPTCProxy* aOuter,
+                  nsISomeInterface** aStub);
+
+/**
+ * Destroys an XPTCall stub previously created with NS_GetXPTCallStub.
+ */
+XPCOM_API(void)
+NS_DestroyXPTCallStub(nsISomeInterface* aStub);
+
+/**
+ * Measures the size of an XPTCall stub previously created with
+ * NS_GetXPTCallStub.
+ */
+XPCOM_API(size_t)
+NS_SizeOfIncludingThisXPTCallStub(const nsISomeInterface* aStub,
+                                  mozilla::MallocSizeOf aMallocSizeOf);
+
+// this is extern "C" because on some platforms it is implemented in assembly
+extern "C" nsresult NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                                     uint32_t paramCount,
+                                     nsXPTCVariant* params);
+
+#endif /* xptcall_h___ */