diff

source/diff.d

@@ -0,0 +1,197 @@
+module diff;
+
+import std.exception : enforce;
+import std.file : read, exists; // бинарное чтение
+import std.array : Appender, appender;
+import std.string : representation, format;
+import std.datetime : Clock, UTC;
+
+import core.stdc.string : memcpy;
+import core.stdc.stdlib : malloc, free, realloc;
+
+import xdiff;
+
+//-----------------------------
+// Аллокатор для libxdiff (обязателен на ряде сборок)
+//-----------------------------
+private extern (C) void* _wrap_malloc(void*, uint size)
+{
+	return malloc(size);
+}
+
+private extern (C) void _wrap_free(void*, void* ptr)
+{
+	free(ptr);
+}
+
+private extern (C) void* _wrap_realloc(void*, void* ptr, uint size)
+{
+	return realloc(ptr, size);
+}
+
+private __gshared bool _allocatorReady = false;
+
+private void ensureAllocator()
+{
+	if (_allocatorReady)
+		return;
+	memallocator_t malt;
+	malt.priv = null;
+	malt.malloc = &_wrap_malloc;
+	malt.free = &_wrap_free;
+	malt.realloc = &_wrap_realloc;
+	enforce(xdl_set_allocator(&malt) == 0, "xdl_set_allocator failed");
+	_allocatorReady = true;
+}
+
+//-----------------------------
+// RAII для mmfile_t
+//-----------------------------
+private struct MmFile
+{
+	mmfile_t mf;
+
+	static MmFile fromBytes(const(ubyte)[] data,
+		long bsize = 8 * 1024,
+		ulong flags = XDL_MMF_ATOMIC)
+	{
+		ensureAllocator(); // критично: до init/writeallocate
+		MmFile m;
+		enforce(xdl_init_mmfile(&m.mf, bsize, flags) == 0, "xdl_init_mmfile failed");
+
+		if (data.length)
+		{
+			auto dst = cast(char*) xdl_mmfile_writeallocate(&m.mf, data.length);
+			enforce(dst !is null, "xdl_mmfile_writeallocate failed");
+			memcpy(dst, data.ptr, data.length);
+		}
+		return m;
+	}
+
+	~this()
+	{
+		xdl_free_mmfile(&mf);
+	}
+}
+
+//-----------------------------
+// Синк-коллектор вывода libxdiff
+//-----------------------------
+private class BufferSink
+{
+	Appender!(ubyte[]) outbuf;
+
+	this()
+	{
+		outbuf = appender!(ubyte[])();
+	}
+
+	extern (C) static int writeCB(void* priv, mmbuffer_t* mb, int nbuf)
+	{
+		auto self = cast(BufferSink) priv;
+		foreach (i; 0 .. nbuf)
+		{
+			size_t sz = cast(size_t) mb[i].size;
+			if (sz == 0)
+				continue;
+			self.outbuf.put((cast(ubyte*) mb[i].ptr)[0 .. sz]);
+		}
+		return 0;
+	}
+
+	string toStringOwned() @trusted
+	{
+		return cast(string) outbuf.data.idup;
+	}
+}
+
+//-----------------------------
+// Публичный движок unified-diff
+//-----------------------------
+final class DiffEngine
+{
+	private long _ctxlen;
+	private bool _stripTrailingNewline;
+
+	this(long ctxlen = 3, bool stripTrailingNewline = false)
+	{
+		_ctxlen = ctxlen;
+		_stripTrailingNewline = stripTrailingNewline;
+	}
+
+	/// Diff двух текстов (UTF-8 строки)
+	string diffText(string oldText, string newText,
+		string oldLabel = "old", string newLabel = "new")
+	{
+		const(ubyte)[] a = _prep(oldText);
+		const(ubyte)[] b = _prep(newText);
+		return diffBytes(a, b, oldLabel, newLabel);
+	}
+
+	/// Diff по путям (файлы читаются целиком, бинарно)
+	string diffFiles(string oldPath, string newPath,
+		string oldLabel = "", string newLabel = "")
+	{
+		enforce(exists(oldPath), "no such file: " ~ oldPath);
+		enforce(exists(newPath), "no such file: " ~ newPath);
+
+		auto a = cast(const(ubyte)[]) read(oldPath); // бинарное чтение
+		auto b = cast(const(ubyte)[]) read(newPath);
+
+		if (oldLabel.length == 0)
+			oldLabel = oldPath;
+		if (newLabel.length == 0)
+			newLabel = newPath;
+
+		return diffBytes(a, b, oldLabel, newLabel);
+	}
+
+	/// Базовый метод: diff двух буферов
+	string diffBytes(const(ubyte)[] oldBytes, const(ubyte)[] newBytes,
+		string oldLabel = "old", string newLabel = "new")
+	{
+		auto a = MmFile.fromBytes(oldBytes);
+		auto b = MmFile.fromBytes(newBytes);
+
+		auto sink = new BufferSink;
+		xdemitcb_t ecb;
+		ecb.priv = cast(void*) sink;
+		ecb.outf = &BufferSink.writeCB;
+
+		xpparam_t xpp;
+		xpp.flags = 0;
+
+		xdemitconf_t xecfg;
+		xecfg.ctxlen = _ctxlen;
+
+		auto pre = formatHeaders(oldLabel, newLabel);
+
+		auto rc = xdl_diff(&a.mf, &b.mf, &xpp, &xecfg, &ecb);
+		enforce(rc >= 0, format("xdl_diff failed (rc=%s)", rc));
+
+		return pre ~ sink.toStringOwned();
+	}
+
+	static string formatHeaders(string oldLabel, string newLabel)
+	{
+		auto ts = Clock.currTime(UTC()).toISOExtString(); // YYYY-MM-DDTHH:MM:SS
+		return "--- " ~ oldLabel ~ "\t" ~ ts ~ "\n"
+			~ "+++ " ~ newLabel ~ "\t" ~ ts ~ "\n";
+	}
+
+private:
+	const(ubyte)[] _prep(string s) @trusted
+	{
+		auto bytes = cast(const(ubyte)[]) s.representation;
+		if (_stripTrailingNewline && (bytes.length && bytes[$ - 1] != '\n'))
+		{
+			ubyte[] tmp;
+			tmp.length = bytes.length + 1;
+			if (bytes.length)
+				memcpy(tmp.ptr, bytes.ptr, bytes.length);
+			tmp[$ - 1] = cast(ubyte) '\n';
+			return cast(const(ubyte)[]) tmp;
+		}
+		return bytes;
+	}
+}