Add ostream helpers for FX String classes.

testing/fx_string_testhelpers.cpp

+// Copyright 2014 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "fx_string_testhelpers.h"
+
+#include <ios>
+#include <iomanip>
+
+namespace {
+
+template <typename T>
+std::ostream& output_string(std::ostream& out, const T& str) {
+  out << std::hex << std::setfill('0') << '"';

[brucedawson, 2015/01/07 00:35:24]

I assume that the goal is just to produce a reasonable representation of the
string, not necessarily one that can be parsed back into the original data?

I'm not familiar with Google's conventions for logging of data so I just wanted
to verify.

[Tom Sepez, 2015/01/07 00:42:24]

Exactly.  There's no inverse operation provided.

+  for (size_t i = 0; i < str.GetLength(); ++i) {
+    unsigned int c = str.GetAt(i);
+    if (c >= 0x20 && c < 0x7F) {
+      out << static_cast<char>(c);
+      continue;
+    }
+    if (sizeof(typename T::value_type) == 1) {
+      if (c < 0x100) {

[brucedawson, 2015/01/07 00:35:24]

Are there any plausible platforms where this check is needed, given the sizeof()
check above?

[Tom Sepez, 2015/01/07 00:42:24]

Done.

+        out << "\\x" << std::setw(2) << c << std::setw(0);
+        continue;
+      }
+    } else {
+      if (c < 0x10000) {
+        out << "\\u" << std::setw(4) << c << std::setw(0);
+        continue;
+      }
+    }
+    out << "<invalid>";
+  }
+  out << '"' << std::dec << std::setfill(' ');
+  return out;
+}
+
+}  // namespace
+
+std::ostream& operator<<(std::ostream& out, const CFX_ByteStringC& str) {
+  return output_string<CFX_ByteStringC>(out, str);

[brucedawson, 2015/01/07 00:35:24]

The explicit template parameter in this call and in the other three is not
needed -- the compiler can infer the templatization parameter from the second
argument (tested with VC++). It's harmless (a mismatch would produce an error)
but doesn't feel like it adds value.

[Tom Sepez, 2015/01/07 00:42:24]

Done.

+}
+
+std::ostream& operator<<(std::ostream& out, const CFX_ByteString& str) {
+  return output_string<CFX_ByteString>(out, str);
+}
+
+std::ostream& operator<<(std::ostream& out, const CFX_WideStringC& str) {
+  return output_string<CFX_WideStringC>(out, str);
+}
+
+std::ostream& operator<<(std::ostream& out, const CFX_WideString& str) {
+  return output_string<CFX_WideString>(out, str);
+}