forked from OSchip/llvm-project
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
//===-- runtime/connection.h ------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// Fortran I/O connection state (abstracted over internal & external units)
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#ifndef FORTRAN_RUNTIME_IO_CONNECTION_H_
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#define FORTRAN_RUNTIME_IO_CONNECTION_H_
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#include "format.h"
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#include <cinttypes>
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#include <optional>
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namespace Fortran::runtime::io {
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class IoStatementState;
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enum class Direction { Output, Input };
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enum class Access { Sequential, Direct, Stream };
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inline bool IsRecordFile(Access a) { return a != Access::Stream; }
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// These characteristics of a connection are immutable after being
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// established in an OPEN statement.
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struct ConnectionAttributes {
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Access access{Access::Sequential}; // ACCESS='SEQUENTIAL', 'DIRECT', 'STREAM'
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std::optional<bool> isUnformatted; // FORM='UNFORMATTED' if true
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bool isUTF8{false}; // ENCODING='UTF-8'
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std::optional<std::int64_t> openRecl; // RECL= on OPEN
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};
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struct ConnectionState : public ConnectionAttributes {
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bool IsAtEOF() const; // true when read has hit EOF or endfile record
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std::size_t RemainingSpaceInRecord() const;
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bool NeedAdvance(std::size_t) const;
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void HandleAbsolutePosition(std::int64_t);
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void HandleRelativePosition(std::int64_t);
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void BeginRecord() {
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positionInRecord = 0;
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furthestPositionInRecord = 0;
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leftTabLimit.reset();
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}
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std::optional<std::int64_t> EffectiveRecordLength() const {
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// When an input record is longer than an explicit RECL= from OPEN
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// it is effectively truncated on input.
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return openRecl && recordLength && *openRecl < *recordLength ? openRecl
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: recordLength;
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}
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std::optional<std::int64_t> recordLength;
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// Positions in a record file (sequential or direct, not stream)
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std::int64_t currentRecordNumber{1}; // 1 is first
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std::int64_t positionInRecord{0}; // offset in current record
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std::int64_t furthestPositionInRecord{0}; // max(position+bytes)
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// Set at end of non-advancing I/O data transfer
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std::optional<std::int64_t> leftTabLimit; // offset in current record
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// currentRecordNumber value captured after ENDFILE/REWIND/BACKSPACE statement
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// or an end-of-file READ condition on a sequential access file
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std::optional<std::int64_t> endfileRecordNumber;
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// Mutable modes set at OPEN() that can be overridden in READ/WRITE & FORMAT
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MutableModes modes; // BLANK=, DECIMAL=, SIGN=, ROUND=, PAD=, DELIM=, kP
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// Set when processing repeated items during list-directed & NAMELIST input
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// in order to keep a span of records in frame on a non-positionable file,
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// so that backspacing to the beginning of the repeated item doesn't require
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// repositioning the external storage medium when that's impossible.
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bool pinnedFrame{false};
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};
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// Utility class for capturing and restoring a position in an input stream.
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class SavedPosition {
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public:
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explicit SavedPosition(IoStatementState &);
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~SavedPosition();
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private:
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IoStatementState &io_;
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ConnectionState saved_;
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};
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} // namespace Fortran::runtime::io
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#endif // FORTRAN_RUNTIME_IO_CONNECTION_H_
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