util.h

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// Copyright 2021 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#pragma once
 
#include <cctype>
#include <cstddef>
#include <string_view>
 
#include "pw_assert/assert.h"
#include "pw_polyfill/language_feature_macros.h"
#include "pw_result/result.h"
#include "pw_span/span.h"
#include "pw_status/status.h"
#include "pw_status/status_with_size.h"
#include "pw_string/internal/length.h"
#include "pw_string/string.h"
 
namespace pw {
namespace string {
namespace internal {
 
PW_CONSTEXPR_CPP20 inline StatusWithSize CopyToSpan(std::string_view source,
                                                    span<char> dest) {
  if (dest.empty()) {
    return StatusWithSize::ResourceExhausted();
  }
 
  const size_t copied = source.copy(dest.data(), dest.size() - 1);
  dest[copied] = '\0';
 
  return StatusWithSize(
      copied == source.size() ? OkStatus() : Status::ResourceExhausted(),
      copied);
}
 
}  // namespace internal
 
constexpr std::string_view ClampedCString(span<const char> str) {
  return std::string_view(str.data(),
                          internal::ClampedLength(str.data(), str.size()));
}
 
constexpr std::string_view ClampedCString(const char* str, size_t max_len) {
  return ClampedCString(span<const char>(str, max_len));
}
 
constexpr Result<size_t> NullTerminatedLength(span<const char> str) {
  PW_DASSERT(str.data() != nullptr);
 
  const size_t length = internal::ClampedLength(str.data(), str.size());
  if (length == str.size()) {
    return Status::OutOfRange();
  }
 
  return length;
}
 
constexpr Result<size_t> NullTerminatedLength(const char* str, size_t max_len) {
  return NullTerminatedLength(span<const char>(str, max_len));
}
 
template <typename Span>
PW_CONSTEXPR_CPP20 inline StatusWithSize Copy(std::string_view source,
                                              Span&& dest) {
  static_assert(
      !std::is_base_of_v<InlineString<>, std::decay_t<Span>>,
      "Do not use pw::string::Copy() with pw::InlineString<>. Instead, use "
      "pw::InlineString<>'s assignment operator or assign() function, or "
      "pw::string::Append().");
  return internal::CopyToSpan(source, std::forward<Span>(dest));
}
 
template <typename Span>
PW_CONSTEXPR_CPP20 inline StatusWithSize Copy(const char* source, Span&& dest) {
  PW_DASSERT(source != nullptr);
  return Copy(ClampedCString(source, std::size(dest)),
              std::forward<Span>(dest));
}
 
PW_CONSTEXPR_CPP20 inline StatusWithSize Copy(const char* source,
                                              char* dest,
                                              size_t num) {
  return Copy(source, span<char>(dest, num));
}
 
inline Status Assign(InlineString<>& string, std::string_view view) {
  const size_t chars_copied =
      std::min(view.size(), static_cast<size_t>(string.capacity()));
  string.assign(view, 0, static_cast<string_impl::size_type>(chars_copied));
  return chars_copied == view.size() ? OkStatus() : Status::ResourceExhausted();
}
 
inline Status Assign(InlineString<>& string, const char* c_string) {
  PW_DASSERT(c_string != nullptr);
  // Clamp to capacity + 1 so strings larger than the capacity yield an error.
  return Assign(string, ClampedCString(c_string, string.capacity() + 1));
}
 
inline Status Append(InlineString<>& string, std::string_view view) {
  const size_t chars_copied = std::min(
      view.size(), static_cast<size_t>(string.capacity() - string.size()));
  string.append(view, 0, static_cast<string_impl::size_type>(chars_copied));
  return chars_copied == view.size() ? OkStatus() : Status::ResourceExhausted();
}
 
inline Status Append(InlineString<>& string, const char* c_string) {
  PW_DASSERT(c_string != nullptr);
  // Clamp to capacity + 1 so strings larger than the capacity yield an error.
  return Append(string, ClampedCString(c_string, string.capacity() + 1));
}
 
PW_CONSTEXPR_CPP20 inline StatusWithSize PrintableCopy(std::string_view source,
                                                       span<char> dest) {
  StatusWithSize copy_result = Copy(source, dest);
  for (size_t i = 0; i < copy_result.size(); i++) {
    dest[i] = std::isprint(dest[i]) ? dest[i] : '.';
  }
 
  return copy_result;
}
 
}  // namespace string
}  // namespace pw