forked from OSchip/llvm-project
Move StringMap's string has function into StringExtras.h
llvm-svn: 84344
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1c0761d6e9
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@ -16,6 +16,7 @@
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#include "llvm/Support/DataTypes.h"
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#include "llvm/ADT/APFloat.h"
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#include "llvm/ADT/StringRef.h"
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#include <cctype>
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#include <cstdio>
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#include <string>
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@ -225,6 +226,19 @@ void UnescapeString(std::string &Str);
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/// doesn't satisfy std::isprint into an escape sequence.
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void EscapeString(std::string &Str);
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/// HashString - Hash funtion for strings.
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///
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/// This is the Bernstein hash function.
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//
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// FIXME: Investigate whether a modified bernstein hash function performs
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// better: http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
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// X*33+c -> X*33^c
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static inline unsigned HashString(StringRef Str, unsigned Result = 0) {
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for (unsigned i = 0, e = Str.size(); i != e; ++i)
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Result = Result * 33 + Str[i];
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return Result;
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}
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} // End llvm namespace
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#endif
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@ -12,6 +12,7 @@
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/StringMap.h"
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#include "llvm/ADT/StringExtras.h"
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#include <cassert>
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using namespace llvm;
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@ -46,20 +47,6 @@ void StringMapImpl::init(unsigned InitSize) {
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}
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/// HashString - Compute a hash code for the specified string.
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///
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static unsigned HashString(const char *Start, const char *End) {
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// Bernstein hash function.
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unsigned int Result = 0;
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// TODO: investigate whether a modified bernstein hash function performs
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// better: http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
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// X*33+c -> X*33^c
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while (Start != End)
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Result = Result * 33 + *Start++;
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Result = Result + (Result >> 5);
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return Result;
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}
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/// LookupBucketFor - Look up the bucket that the specified string should end
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/// up in. If it already exists as a key in the map, the Item pointer for the
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/// specified bucket will be non-null. Otherwise, it will be null. In either
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@ -71,7 +58,7 @@ unsigned StringMapImpl::LookupBucketFor(const StringRef &Name) {
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init(16);
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HTSize = NumBuckets;
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}
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unsigned FullHashValue = HashString(Name.begin(), Name.end());
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unsigned FullHashValue = HashString(Name);
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unsigned BucketNo = FullHashValue & (HTSize-1);
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unsigned ProbeAmt = 1;
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@ -126,7 +113,7 @@ unsigned StringMapImpl::LookupBucketFor(const StringRef &Name) {
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int StringMapImpl::FindKey(const StringRef &Key) const {
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unsigned HTSize = NumBuckets;
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if (HTSize == 0) return -1; // Really empty table?
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unsigned FullHashValue = HashString(Key.begin(), Key.end());
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unsigned FullHashValue = HashString(Key);
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unsigned BucketNo = FullHashValue & (HTSize-1);
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unsigned ProbeAmt = 1;
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