Add 'ostream' method to class StreamBuffer, and use it.

luprex/core/cpp/streambuffer.cpp

@@ -477,6 +477,38 @@ void *StreamBuffer::lua_reader_ud(int64_t size) {
     return this;
 }
 
+class StreamBufferWriter : public std::streambuf {
+private:
+    StreamBuffer *target_;
+public:
+    StreamBufferWriter(StreamBuffer *t) : target_(t) {}
+
+    virtual int_type overflow(int_type c) {
+    	if (c != EOF) {
+            target_->write_uint8(c);
+	    }
+        return c;
+    }
+};
+
+class StreamBufferOStream : public std::ostream {
+private:
+    StreamBufferWriter writer_;
+public:
+    StreamBufferOStream(StreamBuffer *t) : std::ostream(nullptr), writer_(t) {
+        rdbuf(&writer_);
+    }
+    virtual ~StreamBufferOStream() {
+    }
+};
+
+std::ostream &StreamBuffer::ostream() {
+    if (ostream_ == nullptr) {
+        ostream_.reset(new StreamBufferOStream(this));
+    }
+    return *ostream_;
+}
+
 static bool streq(const char *str, const char *data) {
     int len = strlen(str);
     return memcmp(str, data, len) == 0;
@@ -611,5 +643,11 @@ LuaDefine(unittests_streambuffer, "c") {
     eqsb1.write_int32(34);
     LuaAssert(L, !eqsb1.contents_equal(&eqsb2));
     
+    // Check the OStream functionality.
+    StreamBuffer ossb;
+    ossb.ostream() << "Testing.";
+    ossb.ostream() << "Foo.";
+    LuaAssertStrEq(L, ossb.read_entire_contents(), "Testing.Foo.");
+
     return 0;
 }