From 5f0e6e9726824b53a730585486255209a0c3d179 Mon Sep 17 00:00:00 2001
From: Patrick Wuttke <mewin@mewin.de>
Date: Fri, 29 Nov 2024 01:37:50 +0100
Subject: [PATCH] Added STLStream that wraps STL stream types for usage with
 functions that expect a Mijin stream.

---
 source/mijin/io/stlstream.hpp | 128 ++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/source/mijin/io/stlstream.hpp b/source/mijin/io/stlstream.hpp
index e84aac7..db4b595 100644
--- a/source/mijin/io/stlstream.hpp
+++ b/source/mijin/io/stlstream.hpp
@@ -88,6 +88,134 @@ public:
 };
 
 using IOStreamAdapter = BasicIOStreamAdapter<char>;
+
+template<typename TChar, typename TTraits = std::char_traits<TChar>>
+class BasicSTLStream : public Stream
+{
+private:
+    std::basic_istream<TChar, TTraits>* istream_ = nullptr;
+    std::basic_ostream<TChar, TTraits>* ostream_ = nullptr;
+public:
+    explicit BasicSTLStream(std::basic_istream<TChar, TTraits>& istream) : istream_(&istream) {}
+    explicit BasicSTLStream(std::basic_ostream<TChar, TTraits>& ostream) : ostream_(&ostream) {}
+    explicit BasicSTLStream(std::basic_iostream<TChar, TTraits>& iostream) : istream_(&iostream), ostream_(&ostream_) {}
+    StreamError readRaw(std::span<std::uint8_t> buffer, const ReadOptions& options = {}, std::size_t* outBytesRead = nullptr) override
+    {
+        (void) options;
+        
+        if (istream_ != nullptr)
+        {
+            if (buffer.size() % sizeof(TChar) != 0)
+            {
+                // buffer size must be divisible by character size
+                return StreamError::IO_ERROR;
+            }
+            
+            istream_->read(std::bit_cast<TChar*>(buffer.data()), buffer.size() / sizeof(TChar));
+            if (!istream_->good())
+            {
+                return StreamError::IO_ERROR;
+            }
+            if (outBytesRead != nullptr)
+            {
+                *outBytesRead = buffer.size();
+            }
+            return StreamError::SUCCESS;
+        }
+        return StreamError::NOT_SUPPORTED;
+    }
+    
+    StreamError writeRaw(std::span<const std::uint8_t> buffer) override
+    {
+        if (ostream_ != nullptr)
+        {
+            if (buffer.size() % sizeof(TChar) != 0)
+            {
+                // buffer size must be divisible by character size
+                return StreamError::IO_ERROR;
+            }
+            
+            ostream_->write(std::bit_cast<const TChar*>(buffer.data()), buffer.size() / sizeof(TChar));
+            return StreamError::SUCCESS;
+        }
+        return StreamError::NOT_SUPPORTED;
+    }
+    
+    std::size_t tell() override
+    {
+        // kind of weird case, since the streams can have different positions
+        // this is fine, I guess
+        if (istream_ != nullptr)
+        {
+            return istream_->tellg();
+        }
+        if (ostream_ != nullptr)
+        {
+            return ostream_->tellp();
+        }
+        return 0;
+    }
+    
+    StreamError seek(std::intptr_t pos, mijin::SeekMode seekMode = SeekMode::ABSOLUTE) override
+    {
+        std::ios_base::seekdir seekDir = std::ios_base::beg;
+        switch (seekMode)
+        {
+            case mijin::SeekMode::ABSOLUTE:
+                break;
+            case mijin::SeekMode::RELATIVE:
+                seekDir = std::ios_base::cur;
+                break;
+            case mijin::SeekMode::RELATIVE_TO_END:
+                seekDir = std::ios_base::end;
+                break;
+        }
+        if (istream_ != nullptr)
+        {
+            istream_->seekg(pos, seekDir);
+            if (!istream_->good())
+            {
+                return StreamError::IO_ERROR;
+            }
+        }
+        if (ostream_ != nullptr)
+        {
+            ostream_->seekp(pos, seekDir);
+            if (!ostream_->good())
+            {
+                return StreamError::IO_ERROR;
+            }
+        }
+        return StreamError::SUCCESS;
+    }
+    
+    bool isAtEnd() override
+    {
+        if (istream_ != nullptr)
+        {
+            return istream_->peek() == TTraits::eof();
+        }
+        return false;
+    }
+    
+    StreamFeatures getFeatures() override
+    {
+        return {
+            .read = istream_ != nullptr,
+            .write = ostream_ != nullptr,
+            .tell = istream_ != nullptr || ostream_ != nullptr,
+            .seek = istream_ != nullptr || ostream_ != nullptr,
+            .async = false,
+            .readOptions = {
+                .partial = false,
+                .peek = false,
+                .noBlock = false
+            }
+        };
+    }
+};
+
+using STLStream = BasicSTLStream<char>;
 } // namespace mijin
 
 #endif // !defined(MIJIN_IO_STLSTREAM_HPP_INCLUDED)