[Support/StringRef] Add find_last_not_of and {r,l,}trim.

llvm-svn: 156652

include/llvm/ADT/StringRef.h

@@ -292,6 +292,16 @@ namespace llvm {
     /// Note: O(size() + Chars.size())
     size_type find_last_of(StringRef Chars, size_t From = npos) const;
 
+    /// find_last_not_of - Find the last character in the string that is not
+    /// \arg C, or npos if not found.
+    size_type find_last_not_of(char C, size_t From = npos) const;
+
+    /// find_last_not_of - Find the last character in the string that is not in
+    /// \arg Chars, or npos if not found.
+    ///
+    /// Note: O(size() + Chars.size())
+    size_type find_last_not_of(StringRef Chars, size_t From = npos) const;
+
     /// @}
     /// @name Helpful Algorithms
     /// @{
@@ -480,6 +490,18 @@ namespace llvm {
       return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
     }
 
+    StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const {
+      return drop_front(std::min(Length, find_first_not_of(Chars)));
+    }
+
+    StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const {
+      return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1));
+    }
+
+    StringRef trim(StringRef Chars = " \t\n\v\f\r") const {
+      return ltrim(Chars).rtrim(Chars);
+    }
+
     /// @}
   };
 

lib/Support/StringRef.cpp

@@ -12,6 +12,7 @@
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/edit_distance.h"
+
 #include <bitset>
 
 using namespace llvm;
@@ -230,6 +231,31 @@ StringRef::size_type StringRef::find_last_of(StringRef Chars,
   return npos;
 }
 
+/// find_last_not_of - Find the last character in the string that is not
+/// \arg C, or npos if not found.
+StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const {
+  for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
+    if (Data[i] != C)
+      return i;
+  return npos;
+}
+
+/// find_last_not_of - Find the last character in the string that is not in
+/// \arg Chars, or npos if not found.
+///
+/// Note: O(size() + Chars.size())
+StringRef::size_type StringRef::find_last_not_of(StringRef Chars,
+                                                 size_t From) const {
+  std::bitset<1 << CHAR_BIT> CharBits;
+  for (size_type i = 0, e = Chars.size(); i != e; ++i)
+    CharBits.set((unsigned char)Chars[i]);
+
+  for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
+    if (!CharBits.test((unsigned char)Data[i]))
+      return i;
+  return npos;
+}
+
 void StringRef::split(SmallVectorImpl<StringRef> &A,
                       StringRef Separators, int MaxSplit,
                       bool KeepEmpty) const {

unittests/ADT/StringRefTest.cpp

@@ -221,6 +221,30 @@ TEST(StringRefTest, Split2) {
   EXPECT_TRUE(parts == expected);
 }
 
+TEST(StringRefTest, Trim) {
+  StringRef Str0("hello");
+  StringRef Str1(" hello ");
+  StringRef Str2("  hello  ");
+
+  EXPECT_EQ(StringRef("hello"), Str0.rtrim());
+  EXPECT_EQ(StringRef(" hello"), Str1.rtrim());
+  EXPECT_EQ(StringRef("  hello"), Str2.rtrim());
+  EXPECT_EQ(StringRef("hello"), Str0.ltrim());
+  EXPECT_EQ(StringRef("hello "), Str1.ltrim());
+  EXPECT_EQ(StringRef("hello  "), Str2.ltrim());
+  EXPECT_EQ(StringRef("hello"), Str0.trim());
+  EXPECT_EQ(StringRef("hello"), Str1.trim());
+  EXPECT_EQ(StringRef("hello"), Str2.trim());
+
+  EXPECT_EQ(StringRef("ello"), Str0.trim("hhhhhhhhhhh"));
+
+  EXPECT_EQ(StringRef(""), StringRef("").trim());
+  EXPECT_EQ(StringRef(""), StringRef(" ").trim());
+  EXPECT_EQ(StringRef("\0", 1), StringRef(" \0 ", 3).trim());
+  EXPECT_EQ(StringRef("\0\0", 2), StringRef("\0\0", 2).trim());
+  EXPECT_EQ(StringRef("x"), StringRef("\0\0x\0\0", 5).trim(StringRef("\0", 1)));
+}
+
 TEST(StringRefTest, StartsWith) {
   StringRef Str("hello");
   EXPECT_TRUE(Str.startswith("he"));
@@ -267,6 +291,10 @@ TEST(StringRefTest, Find) {
   EXPECT_EQ(1U, Str.find_first_not_of('h'));
   EXPECT_EQ(4U, Str.find_first_not_of("hel"));
   EXPECT_EQ(StringRef::npos, Str.find_first_not_of("hello"));
+
+  EXPECT_EQ(3U, Str.find_last_not_of('o'));
+  EXPECT_EQ(1U, Str.find_last_not_of("lo"));
+  EXPECT_EQ(StringRef::npos, Str.find_last_not_of("helo"));
 }
 
 TEST(StringRefTest, Count) {