Use pipe as ID separator and add inverse functions for MakeUniqueID

components/ntp_snippets/content_suggestions_provider.cc

Index: components/ntp_snippets/content_suggestions_provider.cc
diff --git a/components/ntp_snippets/content_suggestions_provider.cc b/components/ntp_snippets/content_suggestions_provider.cc
index e4565e59d1c708b6f67650e3999940c5e44dd937..5e8a3750bb04f52caad75cf5bcb9281aea00f978 100644
--- a/components/ntp_snippets/content_suggestions_provider.cc
+++ b/components/ntp_snippets/content_suggestions_provider.cc
@@ -4,13 +4,15 @@
 
 #include "components/ntp_snippets/content_suggestions_provider.h"
 
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 
 namespace ntp_snippets {
 
 namespace {
 
-const char kCombinedIDFormat[] = "%d:%s";
+const char kCombinedIDFormat[] = "%d|%s";
+const char kSeparator[] = "|";

[Marc Treib, 2016/07/19 12:31:11]

Can you make this an actual char, rather than a string?

[Philipp Keck, 2016/07/19 13:02:37]

Done.

 
 }  // namespace
 
@@ -28,4 +30,25 @@ std::string ContentSuggestionsProvider::MakeUniqueID(
                             within_category_id.c_str());
 }
 
+ContentSuggestionsCategory ContentSuggestionsProvider::GetCategoryFromUniqueID(

[Marc Treib, 2016/07/19 12:31:11]

Add
// static
above, also for the other method below.

[Philipp Keck, 2016/07/19 13:02:38]

Done.

+    const std::string& unique_id) {
+  size_t colon_index = unique_id.find(kSeparator);
+  DCHECK_NE(std::string::npos, colon_index) << "Not a valid unique_id: "
+                                            << unique_id;
+  int category;
+  DCHECK(base::StringToInt(unique_id.substr(0, colon_index), &category))
+      << "Non-numeric category part in unique_id: " << unique_id;
+  DCHECK(0 <= category && category < int(ContentSuggestionsCategory::COUNT))
+      << "Category does not exist: " << category;
+  return ContentSuggestionsCategory(category);
+}
+
+std::string ContentSuggestionsProvider::GetWithinCategoryIDFromUniqueID(
+    const std::string& unique_id) {
+  size_t colon_index = unique_id.find(kSeparator);
+  DCHECK_NE(std::string::npos, colon_index) << "Not a valid unique_id: "
+                                            << unique_id;
+  return unique_id.substr(colon_index + 1);
+}
+
 }  // namespace ntp_snippets