Initial commit of sync engine code to browser/sync....

chrome/browser/sync/util/row_iterator.h

+// Copyright (c) 2009 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.
+
+// A handy type for iterating through query results.
+//
+// Just define your Traits type with
+//
+//   RowType
+//   Extract(statement*, RowType);
+//
+// and then pass an sqlite3_stmt into the constructor for begin,
+// and use the no-arg constructor for an end iterator.  Ex:
+//
+//   for (RowIterator<SomeTraits> i(statement), end; i != end; ++i)
+//     ...
+
+#ifndef CHROME_BROWSER_SYNC_UTIL_ROW_ITERATOR_H_
+#define CHROME_BROWSER_SYNC_UTIL_ROW_ITERATOR_H_
+
+#include "base/logging.h"
+#include "third_party/sqlite/preprocessed/sqlite3.h"
+
+template <typename ColumnType, int index = 0>
+struct SingleColumnTraits {
+  typedef ColumnType RowType;
+  inline void Extract(sqlite3_stmt* statement, ColumnType* x) const {
+    GetColumn(statement, index, x);
+  }
+};
+
+template <typename RowTraits>
+class RowIterator : public std::iterator<std::input_iterator_tag,
+                                         const typename RowTraits::RowType> {
+ public:
+  typedef typename RowTraits::RowType RowType;
+  // Statement must have been prepared, but not yet stepped:
+  RowIterator(sqlite3_stmt* statement, RowTraits traits = RowTraits()) {
+    kernel_ = new Kernel;
+    kernel_->done = false;
+    kernel_->refcount = 1;
+    kernel_->statement = statement;
+    kernel_->row_traits = traits;
+    ++(*this);
+  }
+  RowIterator() : kernel_(NULL) { }  // creates end iterator
+
+  RowIterator(const RowIterator& i)
+    : kernel_(NULL) {
+    *this = i;
+  }
+
+  ~RowIterator() {
+    if (kernel_ && 0 == --(kernel_->refcount)) {
+      sqlite3_finalize(kernel_->statement);
+      delete kernel_;
+    }
+  }
+
+  RowIterator& operator = (const RowIterator& i) {
+    if (kernel_ && (0 == --(kernel_->refcount))) {
+      sqlite3_finalize(kernel_->statement);
+      delete kernel_;
+    }
+    kernel_ = i.kernel_;
+    if (kernel_)
+      kernel_->refcount += 1;
+    return *this;
+  }
+
+  RowIterator operator ++(int) {
+    RowIterator i(*this);
+    return ++i;
+  }
+
+  RowIterator& operator ++() {
+    DCHECK(NULL != kernel_);
+    if (SQLITE_ROW == sqlite3_step(kernel_->statement)) {
+      kernel_->row_traits.Extract(kernel_->statement, &kernel_->row);
+    } else {
+      kernel_->done = true;
+    }
+    return *this;
+  }
+
+  const RowType& operator *() const {
+    return *(operator -> ());
+  }
+
+  const RowType* operator ->() const {
+    DCHECK(NULL != kernel_);
+    DCHECK(!kernel_->done);
+    return &(kernel_->row);
+  }
+
+  bool operator == (const RowIterator& i) const {
+    if (kernel_ == i.kernel_)
+      return true;
+    if (NULL == kernel_ && i.kernel_->done)
+      return true;
+    if (NULL == i.kernel_ && kernel_->done)
+      return true;
+    return false;
+  }
+
+  bool operator != (const RowIterator& i) const {
+    return !(*this == i);
+  }
+
+ protected:
+  struct Kernel {
+    int refcount;
+    bool done;
+    RowType row;
+    sqlite3_stmt* statement;
+    RowTraits row_traits;
+  };
+
+  Kernel* kernel_;
+};
+
+#endif  // CHROME_BROWSER_SYNC_UTIL_ROW_ITERATOR_H_