src/bindings/java_stream_adapters.h

   1 /*********************                                                        */
   2 /*! \file java_stream_adapters.h
   3  ** \verbatim
   4  ** Original author: Morgan Deters
   5  ** Major contributors: none
   6  ** Minor contributors (to current version): none
   7  ** This file is part of the CVC4 project.
   8  ** Copyright (c) 2009-2013  New York University and The University of Iowa
   9  ** See the file COPYING in the top-level source directory for licensing
  10  ** information.\endverbatim
  11  **
  12  ** \brief An OutputStream adapter for the Java bindings
  13  **
  14  ** An OutputStream adapter for the Java bindings.  This works with a lot
  15  ** of help from SWIG, and custom typemaps in the ".i" SWIG interface files
  16  ** for CVC4.  The basic idea is that, when a CVC4 function with a
  17  ** std::ostream& parameter is called, a Java-side binding is generated
  18  ** taking a java.io.OutputStream.  Now, the problem is that std::ostream
  19  ** has no Java equivalent, and java.io.OutputStream has no C++ equivalent,
  20  ** so we use this class (which exists on both sides) as the go-between.
  21  ** The wrapper connecting the Java function (taking an OutputStream) and
  22  ** the C++ function (taking an ostream) creates a JavaOutputStreamAdapter,
  23  ** and call the C++ function with the stringstream inside.  After the call,
  24  ** the generated stream material is collected and output to the Java-side
  25  ** OutputStream.
  26  **/
  27
  28 // private to the bindings layer
  29 #ifndef SWIGJAVA
  30 #  error This should only be included from the Java bindings layer.
  31 #endif /* SWIGJAVA */
  32
  33 #include <sstream>
  34 #include <set>
  35 #include <cassert>
  36 #include <iostream>
  37 #include <string>
  38 #include <jni.h>
  39
  40 #ifndef __CVC4__BINDINGS__JAVA_STREAM_ADAPTERS_H
  41 #define __CVC4__BINDINGS__JAVA_STREAM_ADAPTERS_H
  42
  43 namespace CVC4 {
  44
  45 class JavaOutputStreamAdapter : public std::ostringstream {
  46 public:
  47   std::string toString() { return str(); }
  48 };/* class JavaOutputStreamAdapter */
  49
  50 class JavaInputStreamAdapter : public std::stringstream {
  51   static std::set<JavaInputStreamAdapter*> s_adapters;
  52   jobject inputStream;
  53
  54   JavaInputStreamAdapter& operator=(const JavaInputStreamAdapter&);
  55   JavaInputStreamAdapter(const JavaInputStreamAdapter&);
  56
  57 public:
  58   JavaInputStreamAdapter(jobject inputStream) : inputStream(inputStream) {
  59     s_adapters.insert(this);
  60   }
  61
  62   ~JavaInputStreamAdapter() {
  63     s_adapters.erase(this);
  64   }
  65
  66   static void pullAdapters(JNIEnv* jenv) {
  67     for(std::set<JavaInputStreamAdapter*>::iterator i = s_adapters.begin();
  68         i != s_adapters.end();
  69         ++i) {
  70       (*i)->pull(jenv);
  71     }
  72   }
  73
  74   jobject getInputStream() const {
  75     return inputStream;
  76   }
  77
  78   void pull(JNIEnv* jenv) {
  79     if(fail() || eof()) {
  80       clear();
  81     }
  82     jclass clazz = jenv->FindClass("java/io/InputStream");
  83     assert(clazz != NULL && jenv->ExceptionOccurred() == NULL);
  84     jmethodID method = jenv->GetMethodID(clazz, "available", "()I");
  85     assert(method != NULL && jenv->ExceptionOccurred() == NULL);
  86     jint available = jenv->CallIntMethod(inputStream, method);
  87     assert(jenv->ExceptionOccurred() == NULL);
  88     jbyteArray bytes = jenv->NewByteArray(available);
  89     assert(bytes != NULL && jenv->ExceptionOccurred() == NULL);
  90     method = jenv->GetMethodID(clazz, "read", "([B)I");
  91     assert(method != NULL && jenv->ExceptionOccurred() == NULL);
  92     jint nread = jenv->CallIntMethod(inputStream, method, bytes);
  93     assert(jenv->ExceptionOccurred() == NULL);
  94     jbyte* bptr = jenv->GetByteArrayElements(bytes, NULL);
  95     assert(jenv->ExceptionOccurred() == NULL);
  96     std::copy(bptr, bptr + nread, std::ostream_iterator<char>(*this));
  97     *this << std::flush;
  98     jenv->ReleaseByteArrayElements(bytes, bptr, 0);
  99     assert(jenv->ExceptionOccurred() == NULL);
 100     assert(good());
 101     assert(!eof());
 102   }
 103
 104 };/* class JavaInputStreamAdapter */
 105
 106 }/* CVC4 namespace */
 107
 108 #endif /* __CVC4__BINDINGS__JAVA_STREAM_ADAPTERS_H */