131 lines
2.7 KiB
C++
131 lines
2.7 KiB
C++
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// stringpool.cc -- a string pool for gold
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#include "gold.h"
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#include <cassert>
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#include <cstring>
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#include "stringpool.h"
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namespace gold
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{
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Stringpool::Stringpool()
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: string_set_(), strings_()
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{
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}
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Stringpool::~Stringpool()
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{
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for (std::list<stringdata*>::iterator p = this->strings_.begin();
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p != this->strings_.end();
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++p)
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delete[] reinterpret_cast<char*>(*p);
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}
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// Hash function.
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size_t
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Stringpool::Stringpool_hash::operator()(const char* s) const
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{
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// Fowler/Noll/Vo (FNV) hash (type FNV-1a).
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if (sizeof(size_t) == 8)
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{
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size_t result = 14695981039346656037ULL;
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while (*s != '\0')
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{
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result &= (size_t) *s++;
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result *= 1099511628211ULL;
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}
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return result;
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}
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else
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{
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size_t result = 2166136261UL;
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while (*s != '\0')
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{
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result ^= (size_t) *s++;
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result *= 16777619UL;
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}
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return result;
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}
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}
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// Add a string to the list of canonical strings. Return a pointer to
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// the canonical string.
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const char*
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Stringpool::add_string(const char* s)
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{
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const size_t buffer_size = 1000;
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size_t len = strlen(s);
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size_t alc;
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bool front = true;
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if (len >= buffer_size)
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{
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alc = sizeof(stringdata) + len;
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front = false;
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}
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else if (this->strings_.empty())
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alc = sizeof(stringdata) + buffer_size;
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else
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{
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stringdata *psd = this->strings_.front();
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if (len >= psd->alc - psd->len)
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alc = sizeof(stringdata) + buffer_size;
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else
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{
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char* ret = psd->data + psd->len;
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memcpy(ret, s, len + 1);
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psd->len += len + 1;
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return ret;
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}
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}
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stringdata *psd = reinterpret_cast<stringdata*>(new char[alc]);
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psd->alc = alc;
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memcpy(psd->data, s, len + 1);
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psd->len = len + 1;
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if (front)
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this->strings_.push_front(psd);
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else
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this->strings_.push_back(psd);
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return psd->data;
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}
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// Add a string to a string pool.
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const char*
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Stringpool::add(const char* s)
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{
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// FIXME: This will look up the entry twice in the hash table. The
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// problem is that we can't insert S before we canonicalize it. I
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// don't think there is a way to handle this correct with
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// unordered_set, so this should be replaced with custom code to do
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// what we need, which is to return the empty slot.
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String_set_type::const_iterator p = this->string_set_.find(s);
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if (p != this->string_set_.end())
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return *p;
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const char* ret = this->add_string(s);
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std::pair<String_set_type::iterator, bool> ins =
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this->string_set_.insert(ret);
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assert(ins.second);
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return ret;
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}
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// Add a prefix of a string to a string pool.
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const char*
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Stringpool::add(const char* s, size_t len)
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{
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// FIXME: This implementation should be rewritten when we rewrite
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// the hash table to avoid copying.
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std::string st(s, len);
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return this->add(st);
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}
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} // End namespace gold.
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