1 files changed, 29 insertions, 3 deletions

diff --git a/include/llvm/ADT/StringRef.h b/include/llvm/ADT/StringRef.h
index 350032b8c4e7..398ca6920249 100644
--- a/include/llvm/ADT/StringRef.h
+++ b/include/llvm/ADT/StringRef.h
@@ -10,6 +10,7 @@
 #ifndef LLVM_ADT_STRINGREF_H
 #define LLVM_ADT_STRINGREF_H
 
+#include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Compiler.h"
 #include <algorithm>
 #include <cassert>
@@ -101,6 +102,9 @@ namespace llvm {
     const unsigned char *bytes_end() const {
       return reinterpret_cast<const unsigned char *>(end());
     }
+    iterator_range<const unsigned char *> bytes() const {
+      return make_range(bytes_begin(), bytes_end());
+    }
 
     /// @}
     /// @name String Operations
@@ -133,6 +137,9 @@ namespace llvm {
 
     // copy - Allocate copy in Allocator and return StringRef to it.
     template <typename Allocator> StringRef copy(Allocator &A) const {
+      // Don't request a length 0 copy from the allocator.
+      if (empty())
+        return StringRef();
       char *S = A.template Allocate<char>(Length);
       std::copy(begin(), end(), S);
       return StringRef(S, Length);
@@ -443,9 +450,10 @@ namespace llvm {
     /// empty substring will be returned.
     ///
     /// \param End The index following the last character to include in the
-    /// substring. If this is npos, or less than \p Start, or exceeds the
-    /// number of characters remaining in the string, the string suffix
-    /// (starting with \p Start) will be returned.
+    /// substring. If this is npos or exceeds the number of characters
+    /// remaining in the string, the string suffix (starting with \p Start)
+    /// will be returned. If this is less than \p Start, an empty string will
+    /// be returned.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
     StringRef slice(size_t Start, size_t End) const {
       Start = std::min(Start, Length);
@@ -539,18 +547,36 @@ namespace llvm {
       return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
     }
 
+    /// Return string with consecutive \p Char characters starting from the
+    /// the left removed.
+    StringRef ltrim(char Char) const {
+      return drop_front(std::min(Length, find_first_not_of(Char)));
+    }
+
     /// Return string with consecutive characters in \p Chars starting from
     /// the left removed.
     StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const {
       return drop_front(std::min(Length, find_first_not_of(Chars)));
     }
 
+    /// Return string with consecutive \p Char characters starting from the
+    /// right removed.
+    StringRef rtrim(char Char) const {
+      return drop_back(Length - std::min(Length, find_last_not_of(Char) + 1));
+    }
+
     /// Return string with consecutive characters in \p Chars starting from
     /// the right removed.
     StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const {
       return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1));
     }
 
+    /// Return string with consecutive \p Char characters starting from the
+    /// left and right removed.
+    StringRef trim(char Char) const {
+      return ltrim(Char).rtrim(Char);
+    }
+
     /// Return string with consecutive characters in \p Chars starting from
     /// the left and right removed.
     StringRef trim(StringRef Chars = " \t\n\v\f\r") const {