Simple PMP reader to parse Picasa's metadata

webkit/fileapi/media/picasa/pmp_table_reader.cc

Index: webkit/fileapi/media/picasa/pmp_table_reader.cc
diff --git a/webkit/fileapi/media/picasa/pmp_table_reader.cc b/webkit/fileapi/media/picasa/pmp_table_reader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cf85d17debe1ed5fad96f708a6e0c8edd766f467
--- /dev/null
+++ b/webkit/fileapi/media/picasa/pmp_table_reader.cc
@@ -0,0 +1,93 @@
+// Copyright (c) 2013 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 "webkit/fileapi/media/picasa/pmp_table_reader.h"
+
+#include <algorithm>
+
+#include "base/file_util.h"
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "webkit/fileapi/media/picasa/pmp_column_reader.h"
+#include "webkit/fileapi/media/picasa/pmp_constants.h"
+
+namespace fileapi {
+
+namespace {
+
+COMPILE_ASSERT(sizeof(double) == 8, double_must_be_8_bytes_long);
+
+}  // namespace
+
+PmpTableReader::PmpTableReader(const std::string& table_name,
+                               const base::FilePath& directory_path,
+                               const std::vector<std::string>& columns)
+    : table_name_(table_name),
+      directory_path_(directory_path),
+      columns_(columns),
+      column_readers_(),
+      max_row_count_(0) { }
+
+PmpTableReader::~PmpTableReader() { }
+
+bool PmpTableReader::ReadFromDisk() {
+  // Expect to read some columns, otherwise, a programming error.
+  DCHECK(!columns_.empty());
+
+  // Directory must exist.
+  if(!file_util::DirectoryExists(directory_path_))
+    return false;
+
+  std::string table_prefix = table_name_ + "_";
+
+  // Look for the "%s_0".format(table_name_) file, indicating table existence.
+  base::FilePath indicator_file = directory_path_.Append(table_prefix + "0");
+
+  // Expect the indicator file to exist but not be a directory.
+  if(!file_util::PathExists(indicator_file) ||
+     file_util::DirectoryExists(indicator_file)) {
+    return false;
+  }
+
+  ScopedVector<PmpColumnReader> current_col_readers;

[vandebo (ex-Chrome), 2013/03/28 00:56:04]

column_readers

[tommycli, 2013/03/29 00:16:01]

Done.

+  uint32 current_max_rows_parsed = 0;

[vandebo (ex-Chrome), 2013/03/28 00:56:04]

max_row_count ?

[tommycli, 2013/03/29 00:16:01]

Done.

+
+  // Construct the column readers.
+  for (std::vector<std::string>::const_iterator it = columns_.begin();
+       it != columns_.end(); it++) {
+    base::FilePath column_file_path = directory_path_.Append(
+        table_prefix + *it + "." + kPmpExtension);
+
+    PmpColumnReader* column_reader = new PmpColumnReader(*it);
+    current_col_readers.push_back(column_reader);
+
+    uint32 row_cnt;
+
+    // If file is not initialized, too small, or too large (50MB), fail out.

[vandebo (ex-Chrome), 2013/03/28 00:56:04]

redundant comment.

[tommycli, 2013/03/29 00:16:01]

Done.

+    if (!column_reader->ReadFromFile(column_file_path, &row_cnt))
+      return false;
+
+    current_max_rows_parsed = std::max(current_max_rows_parsed, row_cnt);
+  }
+
+  // Actually succeeded. Set member data.
+  column_readers_.clear();

[vandebo (ex-Chrome), 2013/03/28 00:56:04]

Do you need to clear before assignment ?

[tommycli, 2013/03/29 00:16:01]

Done.

+  column_readers_ = current_col_readers.Pass();
+  max_row_count_ = current_max_rows_parsed;
+
+  return true;
+}
+
+uint32 PmpTableReader::RowCount() const {
+  return max_row_count_;
+}
+
+std::vector<const PmpColumnReader*> PmpTableReader::GetColumns() const {
+  std::vector<const PmpColumnReader*> readers;
+  std::copy(column_readers_.begin(), column_readers_.end(),
+            std::back_inserter(readers));
+  return readers;
+}
+
+}  // namespace fileapi