Support: Add llvm::center_justify.

Summary: Completes the set.

Reviewers: ruiu

Reviewed By: ruiu

Subscribers: ruiu, llvm-commits

Differential Revision: https://reviews.llvm.org/D35278

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307922 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Format.h

@@ -125,30 +125,39 @@ inline format_object<Ts...> format(const char *Fmt, const Ts &... Vals) {
   return format_object<Ts...>(Fmt, Vals...);
 }
 
-/// This is a helper class used for left_justify() and right_justify().
+/// This is a helper class for left_justify, right_justify, and center_justify.
 class FormattedString {
+public:
+  enum Justification { JustifyNone, JustifyLeft, JustifyRight, JustifyCenter };
+  FormattedString(StringRef S, unsigned W, Justification J)
+      : Str(S), Width(W), Justify(J) {}
+
+private:
   StringRef Str;
   unsigned Width;
-  bool RightJustify;
+  Justification Justify;
   friend class raw_ostream;
-
-public:
-    FormattedString(StringRef S, unsigned W, bool R)
-      : Str(S), Width(W), RightJustify(R) { }
 };
 
 /// left_justify - append spaces after string so total output is
 /// \p Width characters.  If \p Str is larger that \p Width, full string
 /// is written with no padding.
 inline FormattedString left_justify(StringRef Str, unsigned Width) {
-  return FormattedString(Str, Width, false);
+  return FormattedString(Str, Width, FormattedString::JustifyLeft);
 }
 
 /// right_justify - add spaces before string so total output is
 /// \p Width characters.  If \p Str is larger that \p Width, full string
 /// is written with no padding.
 inline FormattedString right_justify(StringRef Str, unsigned Width) {
-  return FormattedString(Str, Width, true);
+  return FormattedString(Str, Width, FormattedString::JustifyRight);
+}
+
+/// center_justify - add spaces before and after string so total output is
+/// \p Width characters.  If \p Str is larger that \p Width, full string
+/// is written with no padding.
+inline FormattedString center_justify(StringRef Str, unsigned Width) {
+  return FormattedString(Str, Width, FormattedString::JustifyCenter);
 }
 
 /// This is a helper class used for format_hex() and format_decimal().

lib/Support/raw_ostream.cpp

@@ -326,13 +326,30 @@ raw_ostream &raw_ostream::operator<<(const formatv_object_base &Obj) {
 }
 
 raw_ostream &raw_ostream::operator<<(const FormattedString &FS) {
-  unsigned Len = FS.Str.size(); 
-  int PadAmount = FS.Width - Len;
-  if (FS.RightJustify && (PadAmount > 0))
-    this->indent(PadAmount);
-  this->operator<<(FS.Str);
-  if (!FS.RightJustify && (PadAmount > 0))
+  if (FS.Str.size() >= FS.Width || FS.Justify == FormattedString::JustifyNone) {
+    this->operator<<(FS.Str);
+    return *this;
+  }
+  const size_t Difference = FS.Width - FS.Str.size();
+  switch (FS.Justify) {
+  case FormattedString::JustifyLeft:
+    this->operator<<(FS.Str);
+    this->indent(Difference);
+    break;
+  case FormattedString::JustifyRight:
+    this->indent(Difference);
+    this->operator<<(FS.Str);
+    break;
+  case FormattedString::JustifyCenter: {
+    int PadAmount = Difference / 2;
     this->indent(PadAmount);
+    this->operator<<(FS.Str);
+    this->indent(Difference - PadAmount);
+    break;
+  }
+  default:
+    llvm_unreachable("Bad Justification");
+  }
   return *this;
 }
 

unittests/Support/raw_ostream_test.cpp

@@ -151,6 +151,11 @@ TEST(raw_ostreamTest, Justify) {
   EXPECT_EQ("   xyz", printToString(right_justify("xyz", 6), 6));
   EXPECT_EQ("abc",    printToString(right_justify("abc", 3), 3));
   EXPECT_EQ("big",    printToString(right_justify("big", 1), 3));
+  EXPECT_EQ("   on    ",    printToString(center_justify("on", 9), 9));
+  EXPECT_EQ("   off    ",    printToString(center_justify("off", 10), 10));
+  EXPECT_EQ("single ",    printToString(center_justify("single", 7), 7));
+  EXPECT_EQ("none",    printToString(center_justify("none", 1), 4));
+  EXPECT_EQ("none",    printToString(center_justify("none", 1), 1));
 }
 
 TEST(raw_ostreamTest, FormatHex) {