[PATCH] D90386: [ADT] Add methods to SmallString for efficient concatenation

[Nathan James via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGcf8d19f4fb2c: [ADT] Add methods to SmallString for efficient concatenation (authored by njames93).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D90386/new/

https://reviews.llvm.org/D90386

Files:
  llvm/include/llvm/ADT/SmallString.h
  llvm/unittests/ADT/SmallStringTest.cpp


Index: llvm/unittests/ADT/SmallStringTest.cpp
===================================================================
--- llvm/unittests/ADT/SmallStringTest.cpp
+++ llvm/unittests/ADT/SmallStringTest.cpp
@@ -71,6 +71,12 @@
   EXPECT_STREQ("abc", theString.c_str());
 }
 
+TEST_F(SmallStringTest, AssignStringRefs) {
+  theString.assign({"abc", "def", "ghi"});
+  EXPECT_EQ(9u, theString.size());
+  EXPECT_STREQ("abcdefghi", theString.c_str());
+}
+
 TEST_F(SmallStringTest, AppendIterPair) {
   StringRef abc = "abc";
   theString.append(abc.begin(), abc.end());
@@ -96,6 +102,19 @@
   EXPECT_STREQ("abcabc", theString.c_str());
 }
 
+TEST_F(SmallStringTest, AppendStringRefs) {
+  theString.append({"abc", "def", "ghi"});
+  EXPECT_EQ(9u, theString.size());
+  EXPECT_STREQ("abcdefghi", theString.c_str());
+  StringRef Jkl = "jkl";
+  std::string Mno = "mno";
+  SmallString<4> Pqr("pqr");
+  const char *Stu = "stu";
+  theString.append({Jkl, Mno, Pqr, Stu});
+  EXPECT_EQ(21u, theString.size());
+  EXPECT_STREQ("abcdefghijklmnopqrstu", theString.c_str());
+}
+
 TEST_F(SmallStringTest, StringRefConversion) {
   StringRef abc = "abc";
   theString.assign(abc.begin(), abc.end());
Index: llvm/include/llvm/ADT/SmallString.h
===================================================================
--- llvm/include/llvm/ADT/SmallString.h
+++ llvm/include/llvm/ADT/SmallString.h
@@ -30,6 +30,12 @@
   /// Initialize from a StringRef.
   SmallString(StringRef S) : SmallVector<char, InternalLen>(S.begin(), S.end()) {}
 
+  /// Initialize by concatenating a list of StringRefs.
+  SmallString(std::initializer_list<StringRef> Refs)
+      : SmallVector<char, InternalLen>() {
+    this->append(Refs);
+  }
+
   /// Initialize with a range.
   template<typename ItTy>
   SmallString(ItTy S, ItTy E) : SmallVector<char, InternalLen>(S, E) {}
@@ -65,6 +71,12 @@
     SmallVectorImpl<char>::append(RHS.begin(), RHS.end());
   }
 
+  /// Assign from a list of StringRefs.
+  void assign(std::initializer_list<StringRef> Refs) {
+    this->clear();
+    append(Refs);
+  }
+
   /// @}
   /// @name String Concatenation
   /// @{
@@ -89,6 +101,20 @@
     SmallVectorImpl<char>::append(RHS.begin(), RHS.end());
   }
 
+  /// Append from a list of StringRefs.
+  void append(std::initializer_list<StringRef> Refs) {
+    size_t SizeNeeded = this->size();
+    for (const StringRef &Ref : Refs)
+      SizeNeeded += Ref.size();
+    this->reserve(SizeNeeded);
+    auto CurEnd = this->end();
+    for (const StringRef &Ref : Refs) {
+      this->uninitialized_copy(Ref.begin(), Ref.end(), CurEnd);
+      CurEnd += Ref.size();
+    }
+    this->set_size(SizeNeeded);
+  }
+
   /// @}
   /// @name String Comparison
   /// @{


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