Add a new QUIC platform API for text utilities.

net/quic/platform/api/quic_text_utils.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_QUIC_PLATFORM_API_QUIC_TEXT_UTILS_H_
+#define NET_QUIC_PLATFORM_API_QUIC_TEXT_UTILS_H_
+
+#include "base/strings/string_piece.h"
+#include "net/quic/platform/impl/quic_text_utils_impl.h"
+
+namespace net {
+
+// Various utilities for manipulating text.
+class QuicTextUtils {
+ public:
+  // Returns true of |data| starts with |prefix|, case sensitively.
+  static bool StartsWith(base::StringPiece data, base::StringPiece prefix) {
+    return QuicTextUtilsImpl::StartsWith(data, prefix);
+  }
+
+  // Returns true of |data| ends with |suffix|, case insensitively.
+  static bool EndsWithIgnoreCase(base::StringPiece data,
+                                 base::StringPiece suffix) {
+    return QuicTextUtilsImpl::EndsWithIgnoreCase(data, suffix);
+  }
+
+  // Returns a new std::string in which |data| has been converted to lower case.
+  static std::string ToLower(base::StringPiece data) {
+    return QuicTextUtilsImpl::ToLower(data);
+  }
+
+  // Remove leading and trailing whitespace from |data|.
+  static void RemoveLeadingAndTrailingWhitespace(base::StringPiece* data) {
+    QuicTextUtilsImpl::RemoveLeadingAndTrailingWhitespace(data);
+  }
+
+  // Returns true if |in| represents a valid uint64, and stores that value in
+  // |out|.
+  static bool StringToUint64(base::StringPiece in, uint64_t* out) {
+    return QuicTextUtilsImpl::StringToUint64(in, out);
+  }
+
+  // Returns a new std::string representing |in|.
+  static std::string Uint64ToString(uint64_t in) {
+    return QuicTextUtilsImpl::Uint64ToString(in);
+  }
+
+  // This converts |length| bytes of binary to a 2*|length|-character
+  // hexadecimal representation.

[Jana, 2016/12/27 23:52:48]

How does the conversion cause the output to be 2*|length| ?

[Ryan Hamilton, 2016/12/28 01:48:38]

'cause each byte turns into two ascii bytes:

H => 48
' ' => 20
etc.

[Jana, 2016/12/28 03:11:51]

Ah, right. I think the comment should probably say "ASCII" instead of "binary"
then for the input... the input is an ASCII string, right? Your call.

[Ryan Hamilton, 2016/12/28 19:15:04]

No, the input is a sequence of bytes, each of which can have any value in
[0,255]. An ASCII string is a sequence of bytes in which each characters is
[0,127] or more likely the printable range.

+  // Return value: 2*|length| characters of ASCII std::string.
+  static std::string HexEncode(const char* data, size_t length) {
+    return HexEncode(base::StringPiece(data, length));
+  }
+
+  // This converts |length| bytes of binary to a 2*|length|-character
+  // hexadecimal representation.
+  // Return value: 2*|length| characters of ASCII std::string.
+  static std::string HexEncode(base::StringPiece data) {
+    return QuicTextUtilsImpl::HexEncode(data);
+  }
+
+  // Converts |data| from a hexadecimal ASCII std::string to binary.

[Jana, 2016/12/27 23:52:48]

nit: "from a  hexadecimal number in ASCII std::string form to a binary number in
ASCII std::string form."

Also, I would suggest making the comments for HexEncode and HexDecode uniform.

[Ryan Hamilton, 2016/12/28 01:48:38]

But it doesn't take a "number", does it? It just takes binary data.

(removed the extra std:: in the comments)
Done (and in the internal version of this CL).

+  static std::string HexDecode(base::StringPiece data) {
+    return QuicTextUtilsImpl::HexDecode(data);
+  }
+
+  // Base64 encodes with no padding |data_len| bytes of |data| into |output|.
+  static void Base64Encode(uint8_t* data,
+                           size_t data_len,
+                           std::string* output) {
+    return QuicTextUtilsImpl::Base64Encode(data, data_len, output);
+  }
+
+  // Returns a std::string containing hex and ASCII representations of |binary|,
+  // side-by-side in the style of hexdump. Non-printable characters will be
+  // printed as '.' in the ASCII output.
+  // For example:
+  // "0x0000:  4865 6c6c 6f2c 2051 5549 4321 0102 0304  Hello,.QUIC!...."
+  static std::string HexDump(base::StringPiece binary_data) {
+    return QuicTextUtilsImpl::HexDump(binary_data);
+  }
+
+  // Returns true if |data| contains any uppercase characters.
+  static bool ContainsUpperCase(base::StringPiece data) {
+    return QuicTextUtilsImpl::ContainsUpperCase(data);
+  }
+
+  // Splits |data| into a vector of pieces delimited by |delim|.
+  static std::vector<base::StringPiece> Split(base::StringPiece data,
+                                              char delim) {
+    return QuicTextUtilsImpl::Split(data, delim);
+  }
+};
+
+}  // namespace net
+
+#endif  // NET_QUIC_PLATFORM_API_QUIC_TEXT_UTILS_H_