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

components/password_manager/core/browser/import/csv_reader.cc

Index: components/password_manager/core/browser/import/csv_reader.cc
diff --git a/components/password_manager/core/browser/import/csv_reader.cc b/components/password_manager/core/browser/import/csv_reader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a32ef507e2685c0b838deedc28a9525378e0d549
--- /dev/null
+++ b/components/password_manager/core/browser/import/csv_reader.cc
@@ -0,0 +1,132 @@
+// 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.
+
+#include "components/password_manager/core/browser/import/csv_reader.h"
+
+#include "base/logging.h"
+#include "base/strings/string_util.h"
+#include "third_party/re2/re2/re2.h"
+
+namespace {
+
+// Regular expression that matches and captures the first row in CSV formatted
+// data (i.e., until the first newline that is not enclosed in double quotes).
+// Will throw away the potential trailing EOL character (which is expected to
+// have already been normalized to a single '\n').
+const char kFirstRowRE[] =
+    // Match and capture sequences of 1.) arbitrary characters inside correctly
+    // matched double-quotes, or 2.) characters other than the double quote and
+    // EOL. Note that because literal double-quotes are escaped as two double
+    // quotes and are always enclosed in double quotes, they do not need special
+    // treatment as far as splitting on EOL is concerned. However, this RE will
+    // still accept inputs such as: "a"b"c"\n.
+    "^((?:\"[^\"]*\"|[^\"\\n])*)"
+    // Match and throw away EOL, or match end-of-string.
+    "(?:\n|$)";
+
+// Regular expression that matches and captures the value of the first field in
+// a CSV formatted row of data. Will throw away the potential trailing comma,
+// but not the enclosing double quotes if the value is quoted.
+const char kFirstFieldRE[] =
+    // Match and capture sequences of 1.) arbitrary characters inside correctly
+    // matched double-quotes, or 2.) characters other than the double quote and
+    // the field separator comma (,). We do not allow a mix of both kinds so as
+    // to reject inputs like: "a"b"c".
+    "^((?:\"[^\"]*\")*|[^\",]*)"
+    // Match and throw away the field separator, or match end-of-string.
+    "(?:,|$)";
+
+// Encapsulates the pre-compiled regular expressions and provides the logic to
+// parse fields from a CSV file row by row.
+class CSVParser {
+ public:
+  CSVParser(base::StringPiece csv)
+      : remaining_csv_piece_(csv.data(), csv.size()),
+        first_row_regex_(kFirstRowRE),
+        first_field_regex_(kFirstFieldRE) {}
+
+  // Reads and unescapes values from the next row, and writes them to |fields|.
+  // Consumes the EOL terminator. Returns false on syntax error.
+  bool ParseNextCSVRow(std::vector<std::string>* fields);
+
+  bool HasMoreRows() const {
+    return !remaining_csv_piece_.empty();
+  }
+
+ private:
+  re2::StringPiece remaining_csv_piece_;
+
+  const RE2 first_row_regex_;
+  const RE2 first_field_regex_;
+
+  DISALLOW_COPY_AND_ASSIGN(CSVParser);
+};
+
+bool CSVParser::ParseNextCSVRow(std::vector<std::string>* fields) {
+  fields->clear();
+
+  re2::StringPiece row;
+  if (!RE2::Consume(&remaining_csv_piece_, first_row_regex_, &row))
+    return false;
+
+  re2::StringPiece remaining_row_piece(row);
+  do {
+    re2::StringPiece field;
+    if (!RE2::Consume(&remaining_row_piece, first_field_regex_, &field))
+      return false;
+    if (field.starts_with("\"")) {
+      CHECK(field.ends_with("\""));
+      CHECK_GE(field.size(), 2);
+      field.remove_prefix(1);
+      field.remove_suffix(1);
+    }
+    std::string field_copy(field.as_string());
+    ReplaceSubstringsAfterOffset(&field_copy, 0, "\"\"", "\"");
+    fields->push_back(field_copy);
+  } while (!remaining_row_piece.empty());
+
+  if (row.ends_with(","))
+    fields->push_back(std::string());
+
+  return true;
+}
+
+}  // namespace
+
+namespace password_manager {
+
+bool ReadCSV(base::StringPiece csv,
+             std::vector<std::string>* column_names,
+             std::vector<std::map<std::string, std::string>>* records) {
+  DCHECK(column_names);
+  DCHECK(records);
+
+  column_names->clear();
+  records->clear();
+
+  // Normalize EOL sequences so that we uniformly use a single LF character.
+  std::string normalized_csv(csv.as_string());
+  ReplaceSubstringsAfterOffset(&normalized_csv, 0, "\r\n", "\n");
+
+  // Read header row.
+  CSVParser parser(normalized_csv);
+  if (!parser.ParseNextCSVRow(column_names))
+    return false;
+
+  // Reader data records rows.
+  std::vector<std::string> fields;
+  while (parser.HasMoreRows()) {
+    if (!parser.ParseNextCSVRow(&fields))
+      return false;
+
+    records->resize(records->size() + 1);
+    for (size_t i = 0; i < column_names->size() && i < fields.size(); ++i) {
+      records->back()[(*column_names)[i]].swap(fields[i]);
+    }
+  }
+
+  return true;
+}
+
+}  // namespace password_manager