Move ElideString() from base/string_util.cc to app/text_elider.cc to

reduce size of widely-included base libraries. 

Committing for tsepez.

BUG=49747
TEST=TextEliderTest.* 

Review URL: http://codereview.chromium.org/6017001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69555 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 77 insertions, 0 deletions

diff --git a/app/text_elider.cc b/app/text_elider.cc
index 79a865e..bfaec34 100644
--- a/app/text_elider.cc
+++ b/app/text_elider.cc
@@ -460,4 +460,41 @@ string16 SortedDisplayURL::AfterHost() const {
   return display_url_.substr(slash_index + sort_host_.length());
 }
 
+bool ElideString(const std::wstring& input, int max_len, std::wstring* output) {
+  DCHECK_GE(max_len, 0);
+  if (static_cast<int>(input.length()) <= max_len) {
+    output->assign(input);
+    return false;
+  }
+
+  switch (max_len) {
+    case 0:
+      output->clear();
+      break;
+    case 1:
+      output->assign(input.substr(0, 1));
+      break;
+    case 2:
+      output->assign(input.substr(0, 2));
+      break;
+    case 3:
+      output->assign(input.substr(0, 1) + L"." +
+                     input.substr(input.length() - 1));
+      break;
+    case 4:
+      output->assign(input.substr(0, 1) + L".." +
+                     input.substr(input.length() - 1));
+      break;
+    default: {
+      int rstr_len = (max_len - 3) / 2;
+      int lstr_len = rstr_len + ((max_len - 3) % 2);
+      output->assign(input.substr(0, lstr_len) + L"..." +
+                     input.substr(input.length() - rstr_len));
+      break;
+    }
+  }
+
+  return true;
+}
+
 }  // namespace gfx
diff --git a/app/text_elider.h b/app/text_elider.h
index 36d12ae..c0d6c33 100644
--- a/app/text_elider.h
+++ b/app/text_elider.h
@@ -88,6 +88,19 @@ class SortedDisplayURL {
   string16 display_url_;
 };
 
+// Function to elide strings when the font information is unknown.  As
+// opposed to the above functions, the ElideString() function operates
+// in terms of character units, not pixels.
+// If the size of |input| is more than |max_len|, this function returns
+// true and |input| is shortened into |output| by removing chars in the
+// middle (they are replaced with up to 3 dots, as size permits).
+// Ex: ElideString(L"Hello", 10, &str) puts Hello in str and returns false.
+// ElideString(L"Hello my name is Tom", 10, &str) puts "Hell...Tom" in str
+// and returns true.
+// TODO(tsepez): Doesn't handle UTF-16 surrogate pairs properly.
+// TODO(tsepez): Doesn't handle bidi properly
+bool ElideString(const std::wstring& input, int max_len, std::wstring* output);
+
 } // namespace gfx.
 
 #endif  // APP_TEXT_ELIDER_H_
diff --git a/app/text_elider_unittest.cc b/app/text_elider_unittest.cc
index 8bb224c..e5a29d9 100644
--- a/app/text_elider_unittest.cc
+++ b/app/text_elider_unittest.cc
@@ -295,3 +295,30 @@ TEST(TextEliderTest, SortedDisplayURLCompare) {
     EXPECT_EQ(-tests[i].compare_result, url2.Compare(url1, collator.get()));
   }
 }
+
+TEST(TextEliderTest, ElideString) {
+  struct TestData {
+    const wchar_t* input;
+    int max_len;
+    bool result;
+    const wchar_t* output;
+  } cases[] = {
+    { L"Hello", 0, true, L"" },
+    { L"", 0, false, L"" },
+    { L"Hello, my name is Tom", 1, true, L"H" },
+    { L"Hello, my name is Tom", 2, true, L"He" },
+    { L"Hello, my name is Tom", 3, true, L"H.m" },
+    { L"Hello, my name is Tom", 4, true, L"H..m" },
+    { L"Hello, my name is Tom", 5, true, L"H...m" },
+    { L"Hello, my name is Tom", 6, true, L"He...m" },
+    { L"Hello, my name is Tom", 7, true, L"He...om" },
+    { L"Hello, my name is Tom", 10, true, L"Hell...Tom" },
+    { L"Hello, my name is Tom", 100, false, L"Hello, my name is Tom" }
+  };
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(cases); ++i) {
+    std::wstring output;
+    EXPECT_EQ(cases[i].result,
+              gfx::ElideString(cases[i].input, cases[i].max_len, &output));
+    EXPECT_TRUE(output == cases[i].output);
+  }
+}