(#18) Added implementation of decompress

Published basic decompress() function. Next in the line is to publish
the actual functions that are needed for compression/decompression
support of files.

src/papi/lz4/module.cpp

@@ -28,3 +28,25 @@ py::bytes lz4::compress(const py::bytes& buffer)
 
     return py::bytes(dest.data(), res);
 };
+
+py::bytes lz4::decompress(const py::bytes& buffer, int expectedSize)
+{
+    if (expectedSize < 0) {
+        throw std::exception("Argument out of valid range: 'expectedSize' was negative.");
+    }
+
+    if (expectedSize == 0) {
+        expectedSize = 16*1024;
+    }
+
+    std::string source{buffer};
+    std::vector<char> dest(expectedSize);
+
+    auto res = api::decompress_safe(source, dest);
+    if (res <= 0) {
+        const auto errorMsg = (format("decompression failed with code: %1%") % res).str();
+        throw std::exception(errorMsg.c_str());
+    }
+
+    return py::bytes(dest.data(), res);
+};

src/papi/lz4/module.h

@@ -19,5 +19,6 @@ namespace lz4 {
 
 
     py::bytes compress(const py::bytes& buffer);
+    py::bytes decompress(const py::bytes& buffer, int expectedSize = 0);
 };
 #endif // __CINT_LZ4_MODULE__