gecko-dev/dom/src/base/nsJSUtils.cpp

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 * for the specific language governing rights and limitations under the
 * License.
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 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
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 * Contributor(s):
 *   Vidur Apparao <vidur@netscape.com>
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/**
 * This is not a generated file. It contains common utility functions
 * invoked from the JavaScript code generated from IDL interfaces.
 * The goal of the utility functions is to cut down on the size of
 * the generated code itself.
 */

#include "nsJSUtils.h"
#include "jsapi.h"
#include "jsdbgapi.h"
#include "prprf.h"
#include "nsIScriptContext.h"
#include "nsIScriptObjectOwner.h"
#include "nsIScriptGlobalObject.h"
#include "nsIServiceManager.h"
#include "nsIXPConnect.h"
#include "nsCOMPtr.h"
#include "nsContentUtils.h"


JSBool
nsJSUtils::GetCallingLocation(JSContext* aContext, const char* *aFilename,
                              PRUint32 *aLineno)
{
  // Get the current filename and line number
  JSStackFrame* frame = nsnull;
  JSScript* script = nsnull;
  do {
    frame = ::JS_FrameIterator(aContext, &frame);

    if (frame) {
      script = ::JS_GetFrameScript(aContext, frame);
    }
  } while (frame && !script);

  if (script) {
    const char* filename = ::JS_GetScriptFilename(aContext, script);

    if (filename) {
      PRUint32 lineno = 0;
      jsbytecode* bytecode = ::JS_GetFramePC(aContext, frame);

      if (bytecode) {
        lineno = ::JS_PCToLineNumber(aContext, script, bytecode);
      }

      *aFilename = filename;
      *aLineno = lineno;
      return JS_TRUE;
    }
  }

  return JS_FALSE;
}

jsval
nsJSUtils::ConvertStringToJSVal(const nsString& aProp, JSContext* aContext)
{
  JSString *jsstring =
    ::JS_NewUCStringCopyN(aContext, NS_REINTERPRET_CAST(const jschar*,
                                                        aProp.get()),
                          aProp.Length());

  // set the return value
  return STRING_TO_JSVAL(jsstring);
}

PRBool
nsJSUtils::ConvertJSValToXPCObject(nsISupports** aSupports, REFNSIID aIID,
                                   JSContext* aContext, jsval aValue)
{
  *aSupports = nsnull;
  if (JSVAL_IS_NULL(aValue)) {
    return JS_TRUE;
  }

  if (JSVAL_IS_OBJECT(aValue)) {
    // WrapJS does all the work to recycle an existing wrapper and/or do a QI
    nsresult rv = nsContentUtils::XPConnect()->
      WrapJS(aContext, JSVAL_TO_OBJECT(aValue), aIID, (void**)aSupports);

    return NS_SUCCEEDED(rv);
  }

  return JS_FALSE;
}

void
nsJSUtils::ConvertJSValToString(nsAString& aString, JSContext* aContext,
                                jsval aValue)
{
  JSString *jsstring;
  if ((jsstring = ::JS_ValueToString(aContext, aValue)) != nsnull) {
    aString.Assign(NS_REINTERPRET_CAST(const PRUnichar*,
                                       ::JS_GetStringChars(jsstring)),
                   ::JS_GetStringLength(jsstring));
  }
  else {
    aString.Truncate();
  }
}

PRBool
nsJSUtils::ConvertJSValToUint32(PRUint32* aProp, JSContext* aContext,
                                jsval aValue)
{
  uint32 temp;
  if (::JS_ValueToECMAUint32(aContext, aValue, &temp)) {
    *aProp = (PRUint32)temp;
  }
  else {
    ::JS_ReportError(aContext, "Parameter must be an integer");
    return JS_FALSE;
  }

  return JS_TRUE;
}

nsIScriptGlobalObject *
nsJSUtils::GetStaticScriptGlobal(JSContext* aContext, JSObject* aObj)
{
  nsISupports* supports;
  JSClass* clazz;
  JSObject* parent;
  JSObject* glob = aObj; // starting point for search

  if (!glob)
    return nsnull;

  while ((parent = ::JS_GetParent(aContext, glob)))
    glob = parent;

  clazz = JS_GET_CLASS(aContext, glob);

  if (!clazz ||
      !(clazz->flags & JSCLASS_HAS_PRIVATE) ||
      !(clazz->flags & JSCLASS_PRIVATE_IS_NSISUPPORTS) ||
      !(supports = (nsISupports*)::JS_GetPrivate(aContext, glob))) {
    return nsnull;
  }

  nsCOMPtr<nsIXPConnectWrappedNative> wrapper(do_QueryInterface(supports));
  NS_ENSURE_TRUE(wrapper, nsnull);

  nsCOMPtr<nsISupports> native;
  wrapper->GetNative(getter_AddRefs(native));

  nsCOMPtr<nsIScriptGlobalObject> sgo(do_QueryInterface(native));

  // We're returning a pointer to something that's about to be
  // released, but that's ok here.
  return sgo;
}

nsIScriptContext *
nsJSUtils::GetStaticScriptContext(JSContext* aContext, JSObject* aObj)
{
  nsIScriptGlobalObject *nativeGlobal = GetStaticScriptGlobal(aContext, aObj);
  if (!nativeGlobal)
    return nsnull;

  return nativeGlobal->GetContext();
}

nsIScriptGlobalObject *
nsJSUtils::GetDynamicScriptGlobal(JSContext* aContext)
{
  nsIScriptContext *scriptCX = GetDynamicScriptContext(aContext);
  if (!scriptCX)
    return nsnull;
  return scriptCX->GetGlobalObject();
}

nsIScriptContext *
nsJSUtils::GetDynamicScriptContext(JSContext *aContext)
{
  return GetScriptContextFromJSContext(aContext);
}