Added integer parsing functions in base/string_to_number.h
They provide parsing of numbers from char* and std::string into any of
the fundamental integer types. Values are returned
in an rtc::Optional, which is left empty if parsing was unsuccessful.
BUG=webrtc:5806
Review-Url: https://codereview.webrtc.org/2696003004
Cr-Commit-Position: refs/heads/master@{#17557}
diff --git a/webrtc/base/string_to_number.cc b/webrtc/base/string_to_number.cc
new file mode 100644
index 0000000..f880926
--- /dev/null
+++ b/webrtc/base/string_to_number.cc
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2017 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <cstdlib>
+
+#include "webrtc/base/string_to_number.h"
+
+namespace rtc {
+namespace string_to_number_internal {
+
+rtc::Optional<signed_type> ParseSigned(const char* str, int base) {
+ RTC_DCHECK(str);
+ if (isdigit(str[0]) || str[0] == '-') {
+ char* end = nullptr;
+ errno = 0;
+ const signed_type value = std::strtoll(str, &end, base);
+ if (end && *end == '\0' && errno == 0) {
+ return rtc::Optional<signed_type>(value);
+ }
+ }
+ return rtc::Optional<signed_type>();
+}
+
+rtc::Optional<unsigned_type> ParseUnsigned(const char* str, int base) {
+ RTC_DCHECK(str);
+ if (isdigit(str[0]) || str[0] == '-') {
+ // Explicitly discard negative values. std::strtoull parsing causes unsigned
+ // wraparound. We cannot just reject values that start with -, though, since
+ // -0 is perfectly fine, as is -0000000000000000000000000000000.
+ const bool is_negative = str[0] == '-';
+ char* end = nullptr;
+ errno = 0;
+ const unsigned_type value = std::strtoull(str, &end, base);
+ if (end && *end == '\0' && errno == 0 && (value == 0 || !is_negative)) {
+ return rtc::Optional<unsigned_type>(value);
+ }
+ }
+ return rtc::Optional<unsigned_type>();
+}
+
+} // namespace string_to_number_internal
+} // namespace rtc