Implement chrome.experimental.downloads.search()

content/browser/download/download_query.cc

Index: content/browser/download/download_query.cc
diff --git a/content/browser/download/download_query.cc b/content/browser/download/download_query.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c7e4e29566982d834abdb33d7029d6dde73fcb38
--- /dev/null
+++ b/content/browser/download/download_query.cc
@@ -0,0 +1,372 @@
+// Copyright (c) 2011 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 "content/browser/download/download_query.h"
+
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/stl_util.h"
+#include "base/string16.h"
+#include "base/string_split.h"
+#include "base/utf_string_conversions.h"
+#include "unicode/regex.h"
+#include "content/browser/download/download_item.h"
+
+namespace download_util {
+
+// The FieldInterfaces allow us to keep the templateyness out of the header.
+
+// Filter fields can be used to filter DownloadItems out of the result set.
+class DownloadQuery::FilterFieldInterface {
+ public:
+  virtual ~FilterFieldInterface() {}
+  virtual DownloadQuery::FilterFieldName name() const = 0;
+  virtual bool is_set() const = 0;
+  virtual bool Matches(const DownloadItem& item) const = 0;
+};
+
+// Sort fields are used by DownloadComparator to sort DownloadItems.
+class DownloadQuery::SortFieldInterface {
+ public:
+  virtual ~SortFieldInterface() {}
+  virtual DownloadQuery::SortFieldName name() const = 0;
+
+  // Return 0 when left's field is equivalent to right's field, -1 when left <
+  // right, or 1 when left > right.
+  virtual int Compare(const DownloadItem& left,
+                      const DownloadItem& right) const = 0;
+};
+
+namespace {
+
+// Functor passed to std::sort to sort DownloadItems.
+class DownloadComparator {
+ public:
+  DownloadComparator(const DownloadQuery::OrderTerms& order_terms,
+                     const DownloadQuery::SortFields& sort_fields)
+    : order_terms_(order_terms),
+      sort_fields_(sort_fields) {
+  }
+
+  // Returns true if |left| sorts before |right|.
+  bool operator() (const DownloadItem* left, const DownloadItem* right);
+
+ private:
+  const DownloadQuery::OrderTerms& order_terms_;
+  const DownloadQuery::SortFields& sort_fields_;
+
+  // std::sort requires this class to be copyable.
+};
+
+bool DownloadComparator::operator() (const DownloadItem* left,
+                                     const DownloadItem* right) {
+  for (DownloadQuery::OrderTerms::const_iterator order_term =
+       order_terms_.begin(); order_term != order_terms_.end(); ++order_term) {
+    DownloadQuery::SortFields::const_iterator sort_field_iter =
+      sort_fields_.find(order_term->name);
+    CHECK(sort_field_iter != sort_fields_.end()) << order_term->name;
+    const DownloadQuery::SortFieldInterface* sort_field =
+      sort_field_iter->second;
+    CHECK(sort_field);
+    CHECK_EQ(sort_field->name(), order_term->name);
+    int comparison = sort_field->Compare(*left, *right);
+    if (comparison != 0)
+      return order_term->ascending == (comparison < 0);
+  }
+  if (left->id() != right->id())
+    return left->id() < right->id();
+  CHECK_NE(left->db_handle(), right->db_handle());
+  return left->db_handle() < right->db_handle();
+}
+
+static int get_start_time(const DownloadItem& item) {

[asanka, 2011/10/20 19:29:16]

Nit: These aren't trivial accessors.

+  return (item.start_time() - base::Time::UnixEpoch()).InMilliseconds();
+}
+
+static int get_end_time(const DownloadItem& item) {
+  return 0;  // TODO(benjhayden): endTime
+}
+
+static bool get_danger_accepted(const DownloadItem& item) {
+  return (item.safety_state() == DownloadItem::DANGEROUS_BUT_VALIDATED);
+}
+
+static string16 get_filename(const DownloadItem& item) {
+  return item.full_path().LossyDisplayName();
+}
+
+template <typename ValueType>
+class FilterField : public DownloadQuery::FilterFieldInterface {
+ public:
+  explicit FilterField(DownloadQuery::FilterFieldName name)
+    : name_(name),
+      is_set_(false) {
+  }
+  virtual ~FilterField() {}
+
+  virtual DownloadQuery::FilterFieldName name() const { return name_; }
+
+  virtual bool Set(const ValueType& value) {
+    value_ = value;
+    is_set_ = true;
+    return true;
+  }
+
+  virtual bool is_set() const { return is_set_; }
+
+ protected:
+  const ValueType& value() const { return value_; }
+
+ private:
+  DownloadQuery::FilterFieldName name_;
+  ValueType value_;
+  bool is_set_;
+};
+
+template <typename ValueType>
+class SortField : public DownloadQuery::SortFieldInterface {
+ public:
+  explicit SortField(DownloadQuery::SortFieldName name)
+    : name_(name) {
+  }
+  virtual ~SortField() {}
+
+  virtual DownloadQuery::SortFieldName name() const { return name_; }
+
+  virtual ValueType GetField(const DownloadItem& item) const = 0;
+
+  virtual int Compare(const DownloadItem& left,
+                      const DownloadItem& right) const {
+    ValueType left_value = GetField(left), right_value = GetField(right);
+    if (left_value > right_value) return 1;
+    if (left_value < right_value) return -1;
+    if (left_value == right_value) return 0;
+    NOTREACHED();
+    return 0;
+  }
+
+ private:
+  DownloadQuery::SortFieldName name_;
+};
+
+class FilterFieldQuery : public FilterField<string16> {
+ public:
+  FilterFieldQuery()
+    : FilterField<string16>(DownloadQuery::FILTER_FIELD_QUERY) {
+  }
+  virtual ~FilterFieldQuery() {}
+  virtual bool Set(const string16& value) {
+    base::SplitString(value, L' ', &terms_);
+    // TODO(benjhayden): Split query more intelligently. Quopri?
+    return FilterField<string16>::Set(value);
+  }
+
+  virtual bool Matches(const DownloadItem& item) const {
+    for (std::vector<string16>::const_iterator term = terms_.begin();
+         term != terms_.end(); ++term) {
+      if (!item.MatchesQuery(*term))
+        return false;
+    }
+    return true;
+  }
+
+ private:
+  std::vector<string16> terms_;
+};
+
+template <typename StringType>
+class FilterFieldRegex : public FilterField<StringType> {
+ public:
+  explicit FilterFieldRegex(DownloadQuery::FilterFieldName name)
+    : FilterField<StringType>(name) {
+  }
+  virtual ~FilterFieldRegex() {}
+  virtual bool Set(const StringType& value) {
+    UParseError re_err;
+    UErrorCode re_status = U_ZERO_ERROR;
+    pattern_.reset(icu::RegexPattern::compile(
+        icu::UnicodeString::fromUTF8(ToUTF8(value)),
+        re_err, re_status));
+    return U_SUCCESS(re_status) &&
+           FilterField<StringType>::Set(value);
+  }
+
+ protected:
+  bool RegexMatches(const StringType& text) const {
+    UErrorCode status = U_ZERO_ERROR;
+    scoped_ptr<icu::RegexMatcher> matcher(pattern_->matcher(
+        icu::UnicodeString::fromUTF8(ToUTF8(text)), status));
+    return U_SUCCESS(status) &&
+           matcher->find(0, status);
+  }
+
+  virtual std::string ToUTF8(const StringType& s) const = 0;
+
+ private:
+  scoped_ptr<icu::RegexPattern> pattern_;
+};
+
+class FilterFieldUrlRegex : public FilterFieldRegex<std::string> {
+ public:
+  FilterFieldUrlRegex()
+    : FilterFieldRegex<std::string>(DownloadQuery::FILTER_FIELD_URL_REGEX) {
+  }
+  virtual ~FilterFieldUrlRegex() {}
+  virtual bool Matches(const DownloadItem& item) const {
+    return RegexMatches(item.original_url().spec());
+  }
+
+ protected:
+  virtual std::string ToUTF8(const std::string& s) const { return s; }
+};
+
+class FilterFieldFilenameRegex : public FilterFieldRegex<string16> {
+ public:
+  FilterFieldFilenameRegex()
+    : FilterFieldRegex<string16>(DownloadQuery::FILTER_FIELD_FILENAME_REGEX) {
+  }
+  virtual ~FilterFieldFilenameRegex() {}
+  virtual bool Matches(const DownloadItem& item) const {
+    return RegexMatches(get_filename(item));
+  }
+
+ protected:
+  virtual std::string ToUTF8(const string16& s) const { return UTF16ToUTF8(s); }
+};
+
+}  // anonymous namespace
+
+void DownloadQuery::SetSortField(DownloadQuery::SortFieldName name,
+                                 DownloadQuery::SortFieldInterface* field) {
+  DCHECK(sort_fields_.find(name) == sort_fields_.end());
+  sort_fields_[name] = field;
+}
+
+void DownloadQuery::SetFilterField(DownloadQuery::FilterFieldName name,
+                                   DownloadQuery::FilterFieldInterface* field) {
+  DCHECK(filter_fields_.find(name) == filter_fields_.end());
+  filter_fields_[name] = field;
+}
+
+#define DEFINE_FIELD(name_enum, class_name, field_type, value_type, \
+                     method_sig, expr) \
+  Set ## field_type ## Field(name_enum, ({ \
+    class class_name : public field_type ## Field<value_type> { \
+     public: \
+      class_name() : field_type ## Field<value_type>(name_enum) {} \
+      virtual method_sig(const DownloadItem& item) const { return expr; } \
+    }; \
+    new class_name(); \
+  }))
+#define SORT_FIELD(name, type, expr) \
+  DEFINE_FIELD(SORT_FIELD_ ## name, SortField ## name, Sort, type, \
+               type GetField, expr); \
+  DEFINE_FIELD(FILTER_FIELD_ ## name, FilterField ## name, Filter, type, \
+               bool Matches, (expr) == value())
+#define FILTER_FIELD(name, type, expr) \
+  DEFINE_FIELD(FILTER_FIELD_ ## name, FilterField ## name, Filter, type, \
+               bool Matches, expr)
+
+DownloadQuery::DownloadQuery()
+  : limit_(kuint32max),
+    delete_sort_fields_(&sort_fields_),
+    delete_filter_fields_(&filter_fields_) {
+  // All sort fields are also filter fields, but not all filter fields are sort
+  // fields.
+  // If you define a new sort or filter field, make sure that the type is
+  // enumerated in INSTANTIATE_SET below.

[asanka, 2011/10/20 19:29:16]

Have you considered lazy initialization for these, or would that make things
much more complicated?  Lazy initialization would let you have a set of
FilterFields and SortFields that contain the minimal set of objects necessary
for this query.

In addition, you can remove the lookup in DownloadComparator and remove
is_set().

I suspect that only a few of these fields would be used for any single query.

+  SORT_FIELD(START_TIME, int, get_start_time(item));
+  SORT_FIELD(URL, std::string, item.original_url().spec());
+  SORT_FIELD(FILENAME, string16, get_filename(item));
+  SORT_FIELD(DANGER, DownloadItem::DangerType, item.GetDangerType());
+  SORT_FIELD(DANGER_ACCEPTED, bool, get_danger_accepted(item));
+  SORT_FIELD(STATE, DownloadItem::DownloadState, item.state());
+  SORT_FIELD(PAUSED, bool, item.is_paused());
+  SORT_FIELD(MIME, std::string, item.mime_type());
+  SORT_FIELD(END_TIME, int, get_end_time(item));
+  SORT_FIELD(BYTES_RECEIVED, int, item.received_bytes());
+  SORT_FIELD(TOTAL_BYTES, int, item.total_bytes());
+  SORT_FIELD(FILE_SIZE, int, 0);  // TODO
+  SORT_FIELD(ERROR, int, 0);  // TODO
+
+  FILTER_FIELD(STARTED_BEFORE, int, get_start_time(item) < value());
+  FILTER_FIELD(STARTED_AFTER, int, get_start_time(item) > value());
+  FILTER_FIELD(ENDED_BEFORE, int, get_end_time(item) < value());
+  FILTER_FIELD(ENDED_AFTER, int, get_end_time(item) > value());
+  FILTER_FIELD(TOTAL_BYTES_GREATER, int, item.total_bytes() > value());
+  FILTER_FIELD(TOTAL_BYTES_LESS, int, item.total_bytes() < value());
+  FILTER_FIELD(FILE_SIZE_GREATER, int, false);  // TODO
+  FILTER_FIELD(FILE_SIZE_LESS, int, false);  // TODO
+  FILTER_FIELD(FILTER, base::Callback<bool(const DownloadItem& item)>,
+               value().Run(item));
+
+  SetFilterField(FILTER_FIELD_QUERY, new FilterFieldQuery());
+  SetFilterField(FILTER_FIELD_FILENAME_REGEX, new FilterFieldFilenameRegex());
+  SetFilterField(FILTER_FIELD_URL_REGEX, new FilterFieldUrlRegex());
+}
+
+#undef FILTER_FIELD
+#undef SORT_FIELD
+
+DownloadQuery::~DownloadQuery() {
+}
+
+template <typename ValueType>
+bool DownloadQuery::Set(DownloadQuery::FilterFieldName name,
+                        const ValueType& value) {
+  FilterFields::iterator iter = filter_fields_.find(name);
+  return (iter != filter_fields_.end()) &&
+         (iter->second != NULL) &&
+         (iter->second->name() == name) &&
+         static_cast<FilterField<ValueType>*>(iter->second)->Set(value);

[asanka, 2011/10/20 19:29:16]

Would this do the correct thing for something like
query_.Set(SORT_FIELD_FILENAME, 1u)?  It should return false without changing
the query.

+}
+
+#define INSTANTIATE_SET(type) \

[cbentzel, 2011/10/20 18:18:53]

Dumb question: Why do you need to do the instantiation here? Isn't this handled
at the call sites? 

+  template bool DownloadQuery::Set( \
+      DownloadQuery::FilterFieldName name, const type& value)
+INSTANTIATE_SET(int);
+INSTANTIATE_SET(bool);
+INSTANTIATE_SET(std::string);
+INSTANTIATE_SET(string16);
+INSTANTIATE_SET(base::Callback<bool(const DownloadItem& item)>);
+INSTANTIATE_SET(DownloadItem::DownloadState);
+INSTANTIATE_SET(DownloadItem::DangerType);
+#undef INSTANTIATE_SET
+
+bool DownloadQuery::Matches(const DownloadItem& item) const {
+  for (FilterFields::const_iterator filter_field = filter_fields_.begin();
+        filter_field != filter_fields_.end(); ++filter_field) {
+    if (filter_field->second->is_set() && !filter_field->second->Matches(item))
+      return false;
+  }
+  return true;
+}
+
+template <typename InputIterator>
+void DownloadQuery::Search(InputIterator iter, const InputIterator last,
+                           DownloadQuery::DownloadItems* results) const {
+  results->clear();
+  for (; iter != last; ++iter) {
+    if (Matches(**iter))
+      results->push_back(*iter);
+  }
+  if (!order_by_fields_.empty())
+    std::sort(results->begin(), results->end(),
+              DownloadComparator(order_by_fields_, sort_fields_));
+  if (results->size() > limit_)
+    results->resize(limit_);
+}
+
+#define INSTANTIATE_SEARCH(type) \
+  template void DownloadQuery::Search(type iter, const type last, \
+      DownloadQuery::DownloadItems* results) const
+INSTANTIATE_SEARCH(std::set<DownloadItem*>::const_iterator);
+INSTANTIATE_SEARCH(std::vector<DownloadItem*>::const_iterator);
+#undef INSTANTIATE_SEARCH
+
+}  // namespace download_util
+