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Pods/abseil/absl/strings/internal/str_format/checker.h

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+// Copyright 2020 The Abseil 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.
+
+#ifndef ABSL_STRINGS_INTERNAL_STR_FORMAT_CHECKER_H_
+#define ABSL_STRINGS_INTERNAL_STR_FORMAT_CHECKER_H_
+
+#include <algorithm>
+
+#include "absl/base/attributes.h"
+#include "absl/strings/internal/str_format/arg.h"
+#include "absl/strings/internal/str_format/constexpr_parser.h"
+#include "absl/strings/internal/str_format/extension.h"
+
+// Compile time check support for entry points.
+
+#ifndef ABSL_INTERNAL_ENABLE_FORMAT_CHECKER
+// We disable format checker under vscode intellisense compilation.
+// See https://github.com/microsoft/vscode-cpptools/issues/3683 for
+// more details.
+#if ABSL_HAVE_ATTRIBUTE(enable_if) && !defined(__native_client__) && \
+    !defined(__INTELLISENSE__)
+#define ABSL_INTERNAL_ENABLE_FORMAT_CHECKER 1
+#endif  // ABSL_HAVE_ATTRIBUTE(enable_if) && !defined(__native_client__) &&
+        // !defined(__INTELLISENSE__)
+#endif  // ABSL_INTERNAL_ENABLE_FORMAT_CHECKER
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace str_format_internal {
+
+#ifdef ABSL_INTERNAL_ENABLE_FORMAT_CHECKER
+
+template <FormatConversionCharSet... C>
+constexpr bool ValidFormatImpl(string_view format) {
+  int next_arg = 0;
+  const char* p = format.data();
+  const char* const end = p + format.size();
+  constexpr FormatConversionCharSet
+      kAllowedConvs[(std::max)(sizeof...(C), size_t{1})] = {C...};
+  bool used[(std::max)(sizeof...(C), size_t{1})]{};
+  constexpr int kNumArgs = sizeof...(C);
+  while (p != end) {
+    while (p != end && *p != '%') ++p;
+    if (p == end) {
+      break;
+    }
+    if (p + 1 >= end) return false;
+    if (p[1] == '%') {
+      // %%
+      p += 2;
+      continue;
+    }
+
+    UnboundConversion conv(absl::kConstInit);
+    p = ConsumeUnboundConversion(p + 1, end, &conv, &next_arg);
+    if (p == nullptr) return false;
+    if (conv.arg_position <= 0 || conv.arg_position > kNumArgs) {
+      return false;
+    }
+    if (!Contains(kAllowedConvs[conv.arg_position - 1], conv.conv)) {
+      return false;
+    }
+    used[conv.arg_position - 1] = true;
+    for (auto extra : {conv.width, conv.precision}) {
+      if (extra.is_from_arg()) {
+        int pos = extra.get_from_arg();
+        if (pos <= 0 || pos > kNumArgs) return false;
+        used[pos - 1] = true;
+        if (!Contains(kAllowedConvs[pos - 1], '*')) {
+          return false;
+        }
+      }
+    }
+  }
+  if (sizeof...(C) != 0) {
+    for (bool b : used) {
+      if (!b) return false;
+    }
+  }
+  return true;
+}
+
+#endif  // ABSL_INTERNAL_ENABLE_FORMAT_CHECKER
+
+}  // namespace str_format_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_CHECKER_H_