src/bindings/java_stream_adapters.h

   1 /*********************                                                        */
   2 /*! \file java_stream_adapters.h
   3  ** \verbatim
   4  ** Original author: mdeters
   5  ** Major contributors: none
   6  ** Minor contributors (to current version): none
   7  ** This file is part of the CVC4 prototype.
   8  ** Copyright (c) 2009-2012  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 {
  46   std::stringstream d_ss;
  47
  48 public:
  49   JavaOutputStreamAdapter() { }
  50
  51   std::string toString() { return d_ss.str(); }
  52
  53 };/* class JavaOutputStreamAdapter */
  54
  55 class JavaInputStreamAdapter : public std::stringstream {
  56   static std::set<JavaInputStreamAdapter*> s_adapters;
  57   jobject inputStream;
  58
  59   JavaInputStreamAdapter& operator=(const JavaInputStreamAdapter&);
  60   JavaInputStreamAdapter(const JavaInputStreamAdapter&);
  61
  62 public:
  63   JavaInputStreamAdapter(jobject inputStream) : inputStream(inputStream) {
  64     s_adapters.insert(this);
  65   }
  66
  67   ~JavaInputStreamAdapter() {
  68     s_adapters.erase(this);
  69   }
  70
  71   static void pullAdapters(JNIEnv* jenv) {
  72     for(std::set<JavaInputStreamAdapter*>::iterator i = s_adapters.begin();
  73         i != s_adapters.end();
  74         ++i) {
  75       (*i)->pull(jenv);
  76     }
  77   }
  78
  79   jobject getInputStream() const {
  80     return inputStream;
  81   }
  82
  83   void pull(JNIEnv* jenv) {
  84     if(fail() || eof()) {
  85       clear();
  86     }
  87     jclass clazz = jenv->FindClass("java/io/InputStream");
  88     assert(clazz != NULL && jenv->ExceptionOccurred() == NULL);
  89     jmethodID method = jenv->GetMethodID(clazz, "available", "()I");
  90     assert(method != NULL && jenv->ExceptionOccurred() == NULL);
  91     jint available = jenv->CallIntMethod(inputStream, method);
  92     assert(jenv->ExceptionOccurred() == NULL);
  93     jbyteArray bytes = jenv->NewByteArray(available);
  94     assert(bytes != NULL && jenv->ExceptionOccurred() == NULL);
  95     method = jenv->GetMethodID(clazz, "read", "([B)I");
  96     assert(method != NULL && jenv->ExceptionOccurred() == NULL);
  97     jint nread = jenv->CallIntMethod(inputStream, method, bytes);
  98     assert(jenv->ExceptionOccurred() == NULL);
  99     jbyte* bptr = jenv->GetByteArrayElements(bytes, NULL);
 100     assert(jenv->ExceptionOccurred() == NULL);
 101     std::copy(bptr, bptr + nread, std::ostream_iterator<char>(*this));
 102     *this << std::flush;
 103     jenv->ReleaseByteArrayElements(bytes, bptr, 0);
 104     assert(jenv->ExceptionOccurred() == NULL);
 105     assert(good());
 106     assert(!eof());
 107   }
 108
 109 };/* class JavaInputStreamAdapter */
 110
 111 }/* CVC4 namespace */
 112
 113 #endif /* __CVC4__BINDINGS__JAVA_STREAM_ADAPTERS_H */