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

[Henry Wong via Phabricator via llvm-commits]

MTC created this revision.
MTC added reviewers: mehdi_amini, zturner, beanz.
Herald added a subscriber: llvm-commits.

Add `StringRef::rsplit(StringRef Separator)` to achieve the function of getting the tail substring according to the separator. A typical usage is to get `data` in `std::basic_string::data`.


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
@@ -749,6 +749,24 @@
       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


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D47406.148707.patch
Type: text/x-patch
Size: 2043 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180526/c9007c17/attachment.bin>