Move DOMTokenList:SerializeToString

Make it a public method on SpaceSplitString so that it can be used in
unit tests etc.

Also add some unit tests.

Change-Id: I2169259c29bb6e5a5a62c8dc6245ba8af31bc053
Reviewed-on: https://chromium-review.googlesource.com/991693Reviewed-by: Kent Tamura <tkent@chromium.org>
Reviewed-by: Takayoshi Kochi <kochi@chromium.org>
Commit-Queue: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547656}

third_party/WebKit/Source/core/dom/DOMTokenList.cpp

@@ -29,7 +29,6 @@
 #include "core/dom/ExceptionCode.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "platform/wtf/AutoReset.h"
-#include "platform/wtf/text/StringBuilder.h"
 
 namespace blink {
 
@@ -250,30 +249,10 @@ void DOMTokenList::RemoveTokens(const Vector<String>& tokens) {
   UpdateWithTokenSet(token_set_);
 }
 
-// https://dom.spec.whatwg.org/#concept-ordered-set-serializer
-// The ordered set serializer takes a set and returns the concatenation of the
-// strings in set, separated from each other by U+0020, if set is non-empty, and
-// the empty string otherwise.
-AtomicString DOMTokenList::SerializeTokenSet(
-    const SpaceSplitString& token_set) {
-  size_t size = token_set.size();
-  if (size == 0)
-    return g_empty_atom;
-  if (size == 1)
-    return token_set[0];
-  StringBuilder builder;
-  builder.Append(token_set[0]);
-  for (size_t i = 1; i < size; ++i) {
-    builder.Append(' ');
-    builder.Append(token_set[i]);
-  }
-  return builder.ToAtomicString();
-}
-
 // https://dom.spec.whatwg.org/#concept-dtl-update
 void DOMTokenList::UpdateWithTokenSet(const SpaceSplitString& token_set) {
   AutoReset<bool> updating(&is_in_update_step_, true);
-  setValue(SerializeTokenSet(token_set));
+  setValue(token_set.SerializeToString());
 }
 
 void DOMTokenList::setValue(const AtomicString& value) {

third_party/WebKit/Source/core/dom/DOMTokenList.h

@@ -85,7 +85,6 @@ class CORE_EXPORT DOMTokenList : public ScriptWrappable {
   void AddTokens(const Vector<String>&);
   void RemoveTokens(const Vector<String>&);
   void UpdateWithTokenSet(const SpaceSplitString&);
-  static AtomicString SerializeTokenSet(const SpaceSplitString&);
 
   SpaceSplitString token_set_;
   AtomicString value_;

third_party/WebKit/Source/core/dom/SpaceSplitString.cpp

@@ -23,6 +23,7 @@
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "platform/wtf/HashSet.h"
 #include "platform/wtf/text/AtomicStringHash.h"
+#include "platform/wtf/text/StringBuilder.h"
 #include "platform/wtf/text/StringHash.h"
 
 namespace blink {
@@ -146,11 +147,26 @@ void SpaceSplitString::Remove(size_t index) {
 }
 
 void SpaceSplitString::ReplaceAt(size_t index, const AtomicString& token) {
-  DCHECK_LT(index, size());
+  DCHECK_LT(index, data_->size());
   EnsureUnique();
   (*data_)[index] = token;
 }
 
+AtomicString SpaceSplitString::SerializeToString() const {
+  size_t size = data_->size();
+  if (size == 0)
+    return g_empty_atom;
+  if (size == 1)
+    return (*data_)[0];
+  StringBuilder builder;
+  builder.Append((*data_)[0]);
+  for (size_t i = 1; i < size; ++i) {
+    builder.Append(' ');
+    builder.Append((*data_)[i]);
+  }
+  return builder.ToAtomicString();
+}
+
 SpaceSplitString::DataMap& SpaceSplitString::SharedDataMap() {
   DEFINE_STATIC_LOCAL(DataMap, map, ());
   return map;

third_party/WebKit/Source/core/dom/SpaceSplitString.h

@@ -54,6 +54,12 @@ class CORE_EXPORT SpaceSplitString {
   void Remove(size_t index);
   void ReplaceAt(size_t index, const AtomicString&);
 
+  // https://dom.spec.whatwg.org/#concept-ordered-set-serializer
+  // The ordered set serializer takes a set and returns the concatenation of the
+  // strings in set, separated from each other by U+0020, if set is non-empty,
+  // and the empty string otherwise.
+  AtomicString SerializeToString() const;
+
   size_t size() const { return data_ ? data_->size() : 0; }
   bool IsNull() const { return !data_; }
   const AtomicString& operator[](size_t i) const { return (*data_)[i]; }

third_party/WebKit/Source/core/dom/SpaceSplitStringTest.cpp

@@ -32,4 +32,22 @@ TEST(SpaceSplitStringTest, Set) {
   EXPECT_EQ(AtomicString("foo"), tokens[0]);
   EXPECT_EQ(AtomicString("bar"), tokens[1]);
 }
+
+TEST(SpaceSplitStringTest, SerializeToString) {
+  SpaceSplitString tokens;
+
+  tokens.Set("foo");
+  EXPECT_EQ("foo", tokens.SerializeToString());
+
+  tokens.Set("foo bar");
+  EXPECT_EQ("foo bar", tokens.SerializeToString());
+
+  tokens.Set("foo");
+  tokens.Add("bar");
+  EXPECT_EQ("foo bar", tokens.SerializeToString());
+
+  tokens.Set("bar");
+  tokens.Add("foo");
+  EXPECT_EQ("bar foo", tokens.SerializeToString());
+}
 }