Add StringRef class, with fixes.

llvm-svn: 76543

llvm/include/llvm/ADT/StringRef.h

@@ -0,0 +1,127 @@
+//===--- StringRef.h - Constant String Reference Wrapper --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_STRINGREF_H
+#define LLVM_ADT_STRINGREF_H
+
+#include <cstring>
+#include <string>
+
+namespace llvm {
+  /// StringRef - Represent a constant reference to a string, i.e. a character
+  /// array and a length, which need not be null terminated.
+  ///
+  /// This class does not own the string data, it is expected to be used in
+  /// situations where the character data resides in some other buffer, whose
+  /// lifetime extends past that of the StringRef. For this reason, it is not in
+  /// general safe to store a StringRef.
+  class StringRef {
+  public:
+    typedef const char *iterator;
+
+  private:
+    /// The start of the string, in an external buffer.
+    const char *Data;
+
+    /// The length of the string.
+    unsigned Length;
+
+  public:
+    /// @name Constructors
+    /// @{
+
+    /// Construct an empty string ref.
+    /*implicit*/ StringRef() : Data(0), Length(0) {}
+
+    /// Construct a string ref from a cstring.
+    /*implicit*/ StringRef(const char *Str) 
+      : Data(Str), Length(::strlen(Str)) {}
+ 
+    /// Construct a string ref from a pointer and length.
+    /*implicit*/ StringRef(const char *_Data, unsigned _Length)
+      : Data(_Data), Length(_Length) {}
+
+    /// Construct a string ref from an std::string.
+    /*implicit*/ StringRef(const std::string &Str) 
+      : Data(Str.c_str()), Length(Str.length()) {}
+
+    /// @}
+    /// @name Iterators
+    /// @{
+
+    iterator begin() const { return Data; }
+
+    iterator end() const { return Data + Length; }
+
+    /// @}
+    /// @name String Operations
+    /// @{
+
+    /// data - Get a pointer to the start of the string (which may not be null
+    /// terminated).
+    const char *data() const { return Data; }
+
+    /// empty - Check if the string is empty.
+    bool empty() const { return Length == 0; }
+
+    /// size - Get the string size.
+    unsigned size() const { return Length; }
+
+    /// compare - Compare two strings; the result is -1, 0, or 1 if this string
+    /// is lexicographically less than, equal to, or greater than the \arg RHS.
+    int compare(const StringRef &RHS) const {
+      // Check the prefix for a mismatch.
+      if (int Res = memcmp(Data, RHS.Data, std::min(Length, RHS.Length)))
+        return Res < 0 ? -1 : 1;
+
+      // Otherwise the prefixes match, so we only need to check the lengths.
+      if (Length == RHS.Length)
+        return 0;
+      return Length < RHS.Length ? -1 : 1;
+    }
+
+    /// str - Get the contents as an std::string.
+    std::string str() const { return std::string(Data, Length); }
+
+    /// @}
+    /// @name Operator Overloads
+    /// @{
+
+    bool operator==(const StringRef &RHS) const { 
+      return Length == RHS.Length && memcmp(Data, RHS.Data, Length) == 0; 
+    }
+
+    bool operator!=(const StringRef &RHS) const { return !(*this == RHS); }
+
+    bool operator<(const StringRef &RHS) const { return compare(RHS) == -1; }
+
+    bool operator<=(const StringRef &RHS) const { return compare(RHS) != 1; }
+
+    bool operator>(const StringRef &RHS) const { return compare(RHS) == 1; }
+
+    bool operator>=(const StringRef &RHS) const { return compare(RHS) != -1; }
+
+    char operator[](size_t Index) const { 
+      assert(Index < Length && "Invalid index!");
+      return Data[Index]; 
+    }
+
+    /// @}
+    /// @name Type Conversions
+    /// @{
+
+    operator std::string() const {
+      return str();
+    }
+
+    /// @}
+  };
+}
+
+#endif

llvm/unittests/ADT/StringRefTest.cpp

@@ -0,0 +1,59 @@
+//===- llvm/unittest/ADT/StringRefTest.cpp - StringRef unit tests ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/ADT/StringRef.h"
+using namespace llvm;
+
+namespace {
+
+TEST(StringRefTest, Construction) {
+  EXPECT_TRUE(StringRef() == "");
+  EXPECT_TRUE(StringRef("hello") == "hello");
+  EXPECT_TRUE(StringRef("hello world", 5) == "hello");
+  EXPECT_TRUE(StringRef(std::string("hello")) == "hello");
+}
+
+TEST(StringRefTest, Iteration) {
+  StringRef S("hello");
+  const char *p = "hello";
+  for (const char *it = S.begin(), *ie = S.end(); it != ie; ++it, ++p)
+    EXPECT_TRUE(*p == *it);
+}
+
+TEST(StringRefTest, StringOps) {
+  const char *p = "hello";
+  EXPECT_EQ(p, StringRef(p, 0).data());
+  EXPECT_TRUE(StringRef().empty());
+  EXPECT_EQ((size_t) 5, StringRef("hello").size());
+  EXPECT_EQ(-1, StringRef("aab").compare("aad"));
+  EXPECT_EQ( 0, StringRef("aab").compare("aab"));
+  EXPECT_EQ( 1, StringRef("aab").compare("aaa"));
+  EXPECT_EQ(-1, StringRef("aab").compare("aabb"));
+  EXPECT_EQ( 1, StringRef("aab").compare("aa"));
+}
+
+TEST(StringRefTest, Operators) {
+  EXPECT_TRUE(StringRef() == "");
+  EXPECT_TRUE(StringRef("aab") < StringRef("aad"));
+  EXPECT_FALSE(StringRef("aab") < StringRef("aab"));
+  EXPECT_TRUE(StringRef("aab") <= StringRef("aab"));
+  EXPECT_FALSE(StringRef("aab") <= StringRef("aaa"));
+  EXPECT_TRUE(StringRef("aad") > StringRef("aab"));
+  EXPECT_FALSE(StringRef("aab") > StringRef("aab"));
+  EXPECT_TRUE(StringRef("aab") >= StringRef("aab"));
+  EXPECT_FALSE(StringRef("aaa") >= StringRef("aab"));
+  EXPECT_TRUE(StringRef("aab") == StringRef("aab"));
+  EXPECT_FALSE(StringRef("aab") == StringRef("aac"));
+  EXPECT_FALSE(StringRef("aab") != StringRef("aab"));
+  EXPECT_TRUE(StringRef("aab") != StringRef("aac"));
+  EXPECT_EQ('a', StringRef("aab")[1]);
+}
+
+} // end anonymous namespace