Implement CSVReader and CSVWriter to be used for password import and export.

components/password_manager/core/browser/export/csv_writer.h

Index: components/password_manager/core/browser/export/csv_writer.h
diff --git a/components/password_manager/core/browser/export/csv_writer.h b/components/password_manager/core/browser/export/csv_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..d485b4b87b40559dbbd063d4e30552ebc7950641
--- /dev/null
+++ b/components/password_manager/core/browser/export/csv_writer.h
@@ -0,0 +1,41 @@
+// Copyright 2014 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 COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_EXPORT_CSV_WRITER_H_
+#define COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_EXPORT_CSV_WRITER_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+
+namespace password_manager {
+
+// Writes tabular data into CSV (Comma Separated Values) format as defined in
+// RFC 4180, with the following caveats:
+//   * The output encoding will be UTF-8. No code points will be escaped.
+//   * Lines will be separated by the platform-specific EOL terminator.
+//   * Values will be enclosed in double-quotes if and only if they contain
+//     either of the following characters: CR, LF, double-quote ("), comma (,).
+class CSVWriter {

[vabr (Chromium), 2014/09/25 14:44:27]

Why is this a class and not just a helper method?

[engedy, 2014/11/06 14:55:39]

For consistency with JSONWriter.

[vabr (Chromium), 2014/11/06 16:16:02]

But the situation is different for JSONWriter -- JSONWriter is a class, because
although the interface is just a static method, every call to it is realised by
constructing an instance of JSONWriter, which does a non-trivial thing.

Here you only have static methods, therefore I don't think this should be a
class.

[engedy, 2014/11/07 16:26:11]

Yes, this is what I mean by consistency: there is no dire need to make it a
class, but this way it is similar to JSONWriter.

My arguments for making it a class+static are:
  * Having global functions looks weird.
  * Having so much comment for a single method looks weird.
  * I kinda like that it acts as a namespace, so that the typedef is not hanging
out there as the global.

I can be convinced to change it to a global if you feel strongly about it. :-)

[Peter Kasting, 2014/11/07 18:38:29]

I think it would be better as a global*, assuming you name it WriteCSV() instead
of just Write().

*It's not really global, it's namespace-scoped to password_manager, which also
makes this more palatable.  Also I thought you were going to get rid of the
typedef due to being able to use auto?

[engedy, 2014/11/07 19:39:43]

OK, I have to concede.

The typedef cannot be removed, unfortunately, that is needed for the function
declaration. :(

[Peter Kasting, 2014/11/07 21:33:44]

Oh, you can't just write "const std::vector<std::map<std::string,
std::string>>&"?

It may be ugly enough that the typedef is better, though.

[engedy, 2014/11/10 09:33:29]

Done. It turned out not so ugly after all.

+ public:
+  typedef std::map<std::string, std::string> ColumnNameToValueMap;
+
+  // Generates the CSV representation of the supplied data into |csv|. The first

[vabr (Chromium), 2014/09/25 14:44:27]

nit: Please specify if the generated data gets appended to |csv|, or if |csv| is
overwritten.

[engedy, 2014/11/06 14:55:39]

Done.

+  // line of the file will contain |column_names|, followed by as many lines as
+  // there are elements in |records|. Each element in |records| should be a
+  // dictionary that maps column names to values, so they can be output in the
+  // right order. All passed in strings should be UTF-8 encoded.
+  static void Write(const std::vector<std::string>& column_names,
+                    const std::vector<ColumnNameToValueMap>& records,
+                    std::string* csv);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(CSVWriter);
+};
+
+} // namespace password_manager
+
+#endif  // COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_EXPORT_CSV_WRITER_H_