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Add StringRef::{slice, split}, two convenient string operations which are simple

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and efficient on a StringRef.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77117 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar 2009-07-26 03:18:15 +00:00
parent abb477f663
commit d61918fc68
2 changed files with 53 additions and 3 deletions
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41
include/llvm/ADT/StringRef.h
View File

@ -10,6 +10,7 @@
#ifndef LLVM_ADT_STRINGREF_H
#define LLVM_ADT_STRINGREF_H
#include <algorithm>
#include <cassert>
#include <cstring>
#include <string>
@ -120,11 +121,11 @@ namespace llvm {
/// @name Utility Functions
/// @{
/// substr - Return a reference to a substring of this object.
/// substr - Return a reference to the substring from [Start, Start + N).
///
/// \param Start - The index of the starting character in the substring; if
/// the index is greater than the length of the string then the empty
/// substring will be returned.
/// the index is npos or greater than the length of the string then the
/// empty substring will be returned.
///
/// \param N - The number of characters to included in the substring. If N
/// exceeds the number of characters remaining in the string, the string
@ -134,6 +135,40 @@ namespace llvm {
return StringRef(Data + Start, std::min(N, Length - Start));
}
/// slice - Return a reference to the substring from [Start, End).
///
/// \param Start - The index of the starting character in the substring; if
/// the index is npos or greater than the length of the string then the
/// 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 \arg Start, or exceeds the
/// number of characters remaining in the string, the string suffix
/// (starting with \arg Start) will be returned.
StringRef slice(size_t Start, size_t End) const {
Start = std::min(Start, Length);
End = std::min(std::max(Start, End), Length);
return StringRef(Data + Start, End - Start);
}
/// split - Split into two substrings around the first occurence of a
/// separator character.
///
/// If \arg Separator is in the string, then the result is a pair (LHS, RHS)
/// such that (*this == LHS + Separator + RHS) is true and RHS is
/// maximal. If \arg Separator is not in the string, then the result is a
/// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
///
/// \param Separator - The character to split on.
/// \return - The split substrings.
std::pair<StringRef, StringRef> split(char Separator) const {
iterator it = std::find(begin(), end(), Separator);
if (it == end())
return std::make_pair(*this, StringRef());
return std::make_pair(StringRef(begin(), it - begin()),
StringRef(it + 1, end() - (it + 1)));
}
/// startswith - Check if this string starts with the given \arg Prefix.
bool startswith(const StringRef &Prefix) const {
return substr(0, Prefix.Length).equals(Prefix);

15
unittests/ADT/StringRefTest.cpp
View File

@ -64,6 +64,21 @@ TEST(StringRefTest, Utilities) {
EXPECT_TRUE(Str.substr(0, 100) == "hello");
EXPECT_TRUE(Str.substr(4, 10) == "o");
EXPECT_TRUE(Str.slice(2, 3) == "l");
EXPECT_TRUE(Str.slice(1, 4) == "ell");
EXPECT_TRUE(Str.slice(2, 100) == "llo");
EXPECT_TRUE(Str.slice(2, 1) == "");
EXPECT_TRUE(Str.slice(10, 20) == "");
EXPECT_TRUE(Str.split('X') == std::make_pair(StringRef("hello"),
StringRef("")));
EXPECT_TRUE(Str.split('e') == std::make_pair(StringRef("h"),
StringRef("llo")));
EXPECT_TRUE(Str.split('h') == std::make_pair(StringRef(""),
StringRef("ello")));
EXPECT_TRUE(Str.split('o') == std::make_pair(StringRef("hell"),
StringRef("")));
EXPECT_TRUE(Str.startswith("he"));
EXPECT_FALSE(Str.startswith("helloworld"));
EXPECT_FALSE(Str.startswith("hi"));