flang/lib/Parser/char-buffer.cpp

   1 //===-- lib/Parser/char-buffer.cpp ----------------------------------------===//
   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 #include "flang/Parser/char-buffer.h"
  10 #include "flang/Common/idioms.h"
  11 #include <algorithm>
  12 #include <cstddef>
  13 #include <cstring>
  14
  15 namespace Fortran::parser {
  16
  17 char *CharBuffer::FreeSpace(std::size_t &n) {
  18   int offset{LastBlockOffset()};
  19   if (blocks_.empty()) {
  20     blocks_.emplace_front();
  21     lastBlockEmpty_ = true;
  22   } else if (offset == 0 && !lastBlockEmpty_) {
  23     blocks_.emplace_back();
  24     lastBlockEmpty_ = true;
  25   }
  26   n = Block::capacity - offset;
  27   return blocks_.back().data + offset;
  28 }
  29
  30 void CharBuffer::Claim(std::size_t n) {
  31   if (n > 0) {
  32     bytes_ += n;
  33     lastBlockEmpty_ = false;
  34   }
  35 }
  36
  37 std::size_t CharBuffer::Put(const char *data, std::size_t n) {
  38   std::size_t chunk;
  39   for (std::size_t at{0}; at < n; at += chunk) {
  40     char *to{FreeSpace(chunk)};
  41     chunk = std::min(n - at, chunk);
  42     Claim(chunk);
  43     std::memcpy(to, data + at, chunk);
  44   }
  45   return bytes_ - n;
  46 }
  47
  48 std::size_t CharBuffer::Put(const std::string &str) {
  49   return Put(str.data(), str.size());
  50 }
  51
  52 std::string CharBuffer::Marshal() const {
  53   std::string result;
  54   std::size_t bytes{bytes_};
  55   result.reserve(bytes);
  56   for (const Block &block : blocks_) {
  57     std::size_t chunk{std::min(bytes, Block::capacity)};
  58     for (std::size_t j{0}; j < chunk; ++j) {
  59       result += block.data[j];
  60     }
  61     bytes -= chunk;
  62   }
  63   result.shrink_to_fit();
  64   CHECK(result.size() == bytes_);
  65   return result;
  66 }
  67 } // namespace Fortran::parser