[PATCH] D47406: [ADT] Add `StringRef::rsplit(StringRef Separator)`.

[Henry Wong via Phabricator via llvm-commits]

MTC updated this revision to Diff 150335.
MTC added a comment.

This update  consists of two parts

- Make `rsplit(char)` reuse `rsplit(StringRef)`.
- Make `split(char)` reuse `split(StringRef)`.

Do I need to divide the patch into two parts? One is to add `rsplit(StringRef)`, the other is to refactor `rsplit(char)` and `split(char)`.


Repository:
  rL LLVM

https://reviews.llvm.org/D47406

Files:
  include/llvm/ADT/StringRef.h
  unittests/ADT/StringRefTest.cpp


Index: unittests/ADT/StringRefTest.cpp
===================================================================
--- unittests/ADT/StringRefTest.cpp
+++ unittests/ADT/StringRefTest.cpp
@@ -181,6 +181,17 @@
             Str.rsplit('l'));
   EXPECT_EQ(std::make_pair(StringRef("hell"), StringRef("")),
             Str.rsplit('o'));
+
+  EXPECT_EQ(std::make_pair(StringRef("he"), StringRef("o")),
+		    Str.rsplit("ll"));
+  EXPECT_EQ(std::make_pair(StringRef(""), StringRef("ello")),
+		    Str.rsplit("h"));
+  EXPECT_EQ(std::make_pair(StringRef("hell"), StringRef("")),
+	      Str.rsplit("o"));
+  EXPECT_EQ(std::make_pair(StringRef("hello"), StringRef("")),
+		    Str.rsplit("::"));
+  EXPECT_EQ(std::make_pair(StringRef("hel"), StringRef("o")),
+		    Str.rsplit("l"));
 }
 
 TEST(StringRefTest, Split2) {
Index: include/llvm/ADT/StringRef.h
===================================================================
--- include/llvm/ADT/StringRef.h
+++ include/llvm/ADT/StringRef.h
@@ -725,10 +725,7 @@
     /// \returns The split substrings.
     LLVM_NODISCARD
     std::pair<StringRef, StringRef> split(char Separator) const {
-      size_t Idx = find(Separator);
-      if (Idx == npos)
-        return std::make_pair(*this, StringRef());
-      return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
+      return split(StringRef(&Separator, 1));
     }
 
     /// Split into two substrings around the first occurrence of a separator
@@ -749,6 +746,24 @@
       return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));
     }
 
+    /// Split into two substrings around the last occurrence of a separator
+    /// string.
+    ///
+    /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
+    /// such that (*this == LHS + Separator + RHS) is true and RHS is
+    /// minimal. If \p Separator is not in the string, then the result is a
+    /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
+    ///
+    /// \param Separator - The string to split on.
+    /// \return - The split substrings.
+    LLVM_NODISCARD
+    std::pair<StringRef, StringRef> rsplit(StringRef Separator) const {
+      size_t Idx = rfind(Separator);
+      if (Idx == npos)
+        return std::make_pair(*this, StringRef());
+      return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));
+    }
+
     /// Split into substrings around the occurrences of a separator string.
     ///
     /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most
@@ -796,10 +811,7 @@
     /// \return - The split substrings.
     LLVM_NODISCARD
     std::pair<StringRef, StringRef> rsplit(char Separator) const {
-      size_t Idx = rfind(Separator);
-      if (Idx == npos)
-        return std::make_pair(*this, StringRef());
-      return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
+      return rsplit(StringRef(&Separator, 1));
     }
 
     /// Return string with consecutive \p Char characters starting from the


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