70 lines
2 KiB
MQL5
70 lines
2 KiB
MQL5
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//+------------------------------------------------------------------+
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//| FileHandle.mqh |
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//| Copyright 2021, MetaQuotes Ltd. |
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//| https://www.mql5.com |
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//+------------------------------------------------------------------+
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#include "MqlError.mqh"
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//+------------------------------------------------------------------+
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//| Helper guard to prevent resource leak |
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//| and unblock file automatically on local context exit |
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//+------------------------------------------------------------------+
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class FileHandle
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{
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int handle;
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public:
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FileHandle(const int h = INVALID_HANDLE) : handle(h)
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{
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}
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FileHandle(int &holder, const int h) : handle(h)
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{
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holder = h;
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}
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~FileHandle()
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{
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close();
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}
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void close()
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{
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if(handle != INVALID_HANDLE)
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{
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ResetLastError();
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FileGetInteger(handle, FILE_SIZE); // marks internal error if handle is incorrect
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if(_LastError == 0)
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{
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#ifdef FILE_DEBUG_PRINT
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Print(__FUNCTION__, ": Automatic close for handle: ", handle);
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#endif
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FileClose(handle);
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}
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else
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{
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PrintFormat("%s: handle %d is incorrect, %s(%d)",
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__FUNCTION__, handle, E2S(_LastError), _LastError);
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}
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}
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handle = INVALID_HANDLE;
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}
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int operator=(const int h)
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{
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// NOTE: if 'handle' is already holding a file reference,
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// we should either close previous one before new assignment
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// or decline the assignment: otherwise the old handle leaks
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close();
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handle = h;
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return h;
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}
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int operator~() const
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{
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return handle;
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}
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};
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//+------------------------------------------------------------------+
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