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tjp/core/io/memstream.h

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+// License: Modified MIT (NON-AI)
+// See the LICENSE file in the root directory for license information.
+// Copyright 2025 Timothy Prepscius
+
+#pragma once
+
+namespace tjp::core::io {
+
+struct imembuf;
+struct imemstream;
+
+struct omembuf;
+struct omemstream;
+
+}

tjp/core/io/memstream.hpp

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+// License: Modified MIT (NON-AI)
+// See the LICENSE file in the root directory for license information.
+// Copyright 2025 Timothy Prepscius
+
+#pragma once
+
+#include "memstream.h"
+
+#include <iostream>
+#include <vector>
+#include <string>
+
+namespace tjp::core::io {
+
+// https://stackoverflow.com/questions/13059091/creating-an-input-stream-from-constant-memory/13059195#13059195
+struct imembuf: std::streambuf
+{
+    imembuf(char const* base, size_t size) {
+        char* p(const_cast<char*>(base));
+        this->setg(p, p, p + size);
+    }
+};
+
+struct imemstream: virtual imembuf, std::istream
+{
+    imemstream(char const* base, size_t size)
+        : imembuf(base, size)
+        , std::istream(static_cast<std::streambuf*>(this)) {
+    }
+
+    imemstream(const std::string_view &s)
+        : imembuf(s.data(), s.size())
+        , std::istream(static_cast<std::streambuf*>(this)) {
+    }
+
+};
+
+struct omembuf: std::streambuf {
+	std::vector<char> &v;
+	size_t offset = 0;
+    omembuf(std::vector<char> &v_) : v(v_) {
+		
+    }
+    
+	// ------------------------ OUTPUT FUNCTIONS ------------------------
+
+	int_type overflow ( int_type c) override
+	{
+		if (c != EOF) v.push_back(static_cast<char>(c));
+		offset = v.size();
+		return c;
+	}
+
+	std::streamsize xsputn ( const char* s, std::streamsize num) override
+	{
+		auto written = num;
+		while(num && offset < v.size())
+		{
+			v[offset++] = *s++;
+			num--;
+		}
+			
+		v.insert(v.end(), s, s+num);
+		offset += num;
+		
+		return written;
+	}
+	
+	pos_type seekpos(
+		pos_type pos,
+		std::ios_base::openmode which = std::ios_base::in | std::ios_base::out
+	) override
+	{
+		if (pos > v.size())
+			return pos_type(-1);
+			
+		offset = pos;
+		return pos;
+	}
+	
+	pos_type seekoff(
+		off_type off, std::ios_base::seekdir dir,
+		std::ios_base::openmode which = std::ios_base::in | std::ios_base::out
+	) override
+	{
+		if (off < 0 && -off > offset)
+			return pos_type(-1);
+			
+		return seekpos(offset + off);
+	}
+};
+
+struct omemstream: virtual omembuf, std::ostream {
+    omemstream(std::vector<char> &v_)
+        : omembuf(v_)
+        , std::ostream(static_cast<std::streambuf*>(this)) {
+    }
+};
+
+struct omemstream_: virtual omembuf, std::ostream {
+	std::vector<char> data;
+
+    omemstream_()
+        : omembuf(data)
+        , std::ostream(static_cast<std::streambuf*>(this)) {
+    }
+};
+
+} // namespace
+