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275 lines
7.8 KiB
C++
275 lines
7.8 KiB
C++
//===-- StringRef.cpp - Lightweight String References ---------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/StringRef.h"
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using namespace llvm;
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// MSVC emits references to this into the translation units which reference it.
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#ifndef _MSC_VER
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const size_t StringRef::npos;
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#endif
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static char ascii_tolower(char x) {
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if (x >= 'A' && x <= 'Z')
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return x - 'A' + 'a';
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return x;
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}
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/// compare_lower - Compare strings, ignoring case.
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int StringRef::compare_lower(StringRef RHS) const {
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for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
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char LHC = ascii_tolower(Data[I]);
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char RHC = ascii_tolower(RHS.Data[I]);
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if (LHC != RHC)
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return LHC < RHC ? -1 : 1;
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}
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if (Length == RHS.Length)
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return 0;
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return Length < RHS.Length ? -1 : 1;
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}
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// Compute the edit distance between the two given strings.
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unsigned StringRef::edit_distance(llvm::StringRef Other,
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bool AllowReplacements) {
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// The algorithm implemented below is the "classic"
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// dynamic-programming algorithm for computing the Levenshtein
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// distance, which is described here:
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//
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// http://en.wikipedia.org/wiki/Levenshtein_distance
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//
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// Although the algorithm is typically described using an m x n
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// array, only two rows are used at a time, so this implemenation
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// just keeps two separate vectors for those two rows.
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size_type m = size();
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size_type n = Other.size();
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const unsigned SmallBufferSize = 64;
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unsigned SmallBuffer[SmallBufferSize];
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unsigned *Allocated = 0;
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unsigned *previous = SmallBuffer;
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if (2*(n + 1) > SmallBufferSize)
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Allocated = previous = new unsigned [2*(n+1)];
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unsigned *current = previous + (n + 1);
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for (unsigned i = 0; i <= n; ++i)
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previous[i] = i;
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for (size_type y = 1; y <= m; ++y) {
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current[0] = y;
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for (size_type x = 1; x <= n; ++x) {
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if (AllowReplacements) {
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current[x] = min(previous[x-1] + ((*this)[y-1] == Other[x-1]? 0u:1u),
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min(current[x-1], previous[x])+1);
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}
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else {
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if ((*this)[y-1] == Other[x-1]) current[x] = previous[x-1];
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else current[x] = min(current[x-1], previous[x]) + 1;
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}
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}
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unsigned *tmp = current;
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current = previous;
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previous = tmp;
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}
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unsigned Result = previous[n];
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delete [] Allocated;
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return Result;
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}
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//===----------------------------------------------------------------------===//
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// String Searching
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//===----------------------------------------------------------------------===//
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/// find - Search for the first string \arg Str in the string.
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///
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/// \return - The index of the first occurence of \arg Str, or npos if not
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/// found.
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size_t StringRef::find(StringRef Str, size_t From) const {
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size_t N = Str.size();
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if (N > Length)
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return npos;
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for (size_t e = Length - N + 1, i = min(From, e); i != e; ++i)
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if (substr(i, N).equals(Str))
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return i;
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return npos;
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}
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/// rfind - Search for the last string \arg Str in the string.
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///
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/// \return - The index of the last occurence of \arg Str, or npos if not
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/// found.
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size_t StringRef::rfind(StringRef Str) const {
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size_t N = Str.size();
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if (N > Length)
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return npos;
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for (size_t i = Length - N + 1, e = 0; i != e;) {
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--i;
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if (substr(i, N).equals(Str))
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return i;
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}
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return npos;
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}
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/// find_first_of - Find the first character in the string that is in \arg
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/// Chars, or npos if not found.
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///
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/// Note: O(size() * Chars.size())
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StringRef::size_type StringRef::find_first_of(StringRef Chars,
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size_t From) const {
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for (size_type i = min(From, Length), e = Length; i != e; ++i)
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if (Chars.find(Data[i]) != npos)
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return i;
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return npos;
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}
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/// find_first_not_of - Find the first character in the string that is not
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/// \arg C or npos if not found.
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StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
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for (size_type i = min(From, Length), e = Length; i != e; ++i)
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if (Data[i] != C)
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return i;
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return npos;
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}
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/// find_first_not_of - Find the first character in the string that is not
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/// in the string \arg Chars, or npos if not found.
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///
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/// Note: O(size() * Chars.size())
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StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
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size_t From) const {
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for (size_type i = min(From, Length), e = Length; i != e; ++i)
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if (Chars.find(Data[i]) == npos)
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return i;
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return npos;
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}
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//===----------------------------------------------------------------------===//
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// Helpful Algorithms
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//===----------------------------------------------------------------------===//
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/// count - Return the number of non-overlapped occurrences of \arg Str in
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/// the string.
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size_t StringRef::count(StringRef Str) const {
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size_t Count = 0;
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size_t N = Str.size();
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if (N > Length)
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return 0;
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for (size_t i = 0, e = Length - N + 1; i != e; ++i)
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if (substr(i, N).equals(Str))
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++Count;
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return Count;
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}
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/// GetAsUnsignedInteger - Workhorse method that converts a integer character
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/// sequence of radix up to 36 to an unsigned long long value.
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static bool GetAsUnsignedInteger(StringRef Str, unsigned Radix,
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unsigned long long &Result) {
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// Autosense radix if not specified.
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if (Radix == 0) {
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if (Str.startswith("0x")) {
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Str = Str.substr(2);
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Radix = 16;
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} else if (Str.startswith("0b")) {
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Str = Str.substr(2);
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Radix = 2;
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} else if (Str.startswith("0"))
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Radix = 8;
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else
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Radix = 10;
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}
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// Empty strings (after the radix autosense) are invalid.
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if (Str.empty()) return true;
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// Parse all the bytes of the string given this radix. Watch for overflow.
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Result = 0;
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while (!Str.empty()) {
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unsigned CharVal;
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if (Str[0] >= '0' && Str[0] <= '9')
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CharVal = Str[0]-'0';
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else if (Str[0] >= 'a' && Str[0] <= 'z')
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CharVal = Str[0]-'a'+10;
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else if (Str[0] >= 'A' && Str[0] <= 'Z')
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CharVal = Str[0]-'A'+10;
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else
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return true;
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// If the parsed value is larger than the integer radix, the string is
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// invalid.
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if (CharVal >= Radix)
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return true;
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// Add in this character.
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unsigned long long PrevResult = Result;
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Result = Result*Radix+CharVal;
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// Check for overflow.
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if (Result < PrevResult)
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return true;
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Str = Str.substr(1);
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}
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return false;
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}
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bool StringRef::getAsInteger(unsigned Radix, unsigned long long &Result) const {
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return GetAsUnsignedInteger(*this, Radix, Result);
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}
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bool StringRef::getAsInteger(unsigned Radix, long long &Result) const {
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unsigned long long ULLVal;
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// Handle positive strings first.
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if (empty() || front() != '-') {
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if (GetAsUnsignedInteger(*this, Radix, ULLVal) ||
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// Check for value so large it overflows a signed value.
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(long long)ULLVal < 0)
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return true;
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Result = ULLVal;
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return false;
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}
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// Get the positive part of the value.
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if (GetAsUnsignedInteger(substr(1), Radix, ULLVal) ||
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// Reject values so large they'd overflow as negative signed, but allow
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// "-0". This negates the unsigned so that the negative isn't undefined
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// on signed overflow.
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(long long)-ULLVal > 0)
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return true;
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Result = -ULLVal;
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return false;
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}
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bool StringRef::getAsInteger(unsigned Radix, int &Result) const {
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long long Val;
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if (getAsInteger(Radix, Val) ||
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(int)Val != Val)
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return true;
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Result = Val;
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return false;
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}
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bool StringRef::getAsInteger(unsigned Radix, unsigned &Result) const {
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unsigned long long Val;
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if (getAsInteger(Radix, Val) ||
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(unsigned)Val != Val)
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return true;
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Result = Val;
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return false;
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}
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