clang-tools-extra/clang-doc/BitcodeReader.h

   1 //===--  BitcodeReader.h - ClangDoc Bitcode Reader --------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements a reader for parsing the clang-doc internal
  10 // representation from LLVM bitcode. The reader takes in a stream of bits and
  11 // generates the set of infos that it represents.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_DOC_BITCODEREADER_H
  16 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_DOC_BITCODEREADER_H
  17
  18 #include "BitcodeWriter.h"
  19 #include "Representation.h"
  20 #include "clang/AST/AST.h"
  21 #include "llvm/ADT/SmallVector.h"
  22 #include "llvm/Bitstream/BitstreamReader.h"
  23 #include "llvm/Support/Error.h"
  24 #include <optional>
  25
  26 namespace clang {
  27 namespace doc {
  28
  29 // Class to read bitstream into an InfoSet collection
  30 class ClangDocBitcodeReader {
  31 public:
  32   ClangDocBitcodeReader(llvm::BitstreamCursor &Stream) : Stream(Stream) {}
  33
  34   // Main entry point, calls readBlock to read each block in the given stream.
  35   llvm::Expected<std::vector<std::unique_ptr<Info>>> readBitcode();
  36
  37 private:
  38   enum class Cursor { BadBlock = 1, Record, BlockEnd, BlockBegin };
  39
  40   // Top level parsing
  41   llvm::Error validateStream();
  42   llvm::Error readVersion();
  43   llvm::Error readBlockInfoBlock();
  44
  45   // Read a block of records into a single Info struct, calls readRecord on each
  46   // record found.
  47   template <typename T> llvm::Error readBlock(unsigned ID, T I);
  48
  49   // Step through a block of records to find the next data field.
  50   template <typename T> llvm::Error readSubBlock(unsigned ID, T I);
  51
  52   // Read record data into the given Info data field, calling the appropriate
  53   // parseRecord functions to parse and store the data.
  54   template <typename T> llvm::Error readRecord(unsigned ID, T I);
  55
  56   // Allocate the relevant type of info and add read data to the object.
  57   template <typename T>
  58   llvm::Expected<std::unique_ptr<Info>> createInfo(unsigned ID);
  59
  60   // Helper function to step through blocks to find and dispatch the next record
  61   // or block to be read.
  62   Cursor skipUntilRecordOrBlock(unsigned &BlockOrRecordID);
  63
  64   // Helper function to set up the appropriate type of Info.
  65   llvm::Expected<std::unique_ptr<Info>> readBlockToInfo(unsigned ID);
  66
  67   llvm::BitstreamCursor &Stream;
  68   std::optional<llvm::BitstreamBlockInfo> BlockInfo;
  69   FieldId CurrentReferenceField;
  70 };
  71
  72 } // namespace doc
  73 } // namespace clang
  74
  75 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_DOC_BITCODEREADER_H