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/*
* stringbuf.cc
* Copyright 2014 John Lindgren
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions, and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions, and the following disclaimer in the documentation
* provided with the distribution.
*
* This software is provided "as is" and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising from
* the use of this software.
*/
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <new>
#include "objects.h"
#ifdef _WIN32
#include <windows.h>
#else
#include <sys/mman.h>
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
#endif
struct StringStack
{
static constexpr int Size = 1048576; // 1 MB
char * top;
char buf[Size - sizeof top];
};
// adds one byte for null character and rounds up to word boundary
static constexpr int align (int len)
{
return (len + sizeof (void *)) & ~(sizeof (void *) - 1);
}
static pthread_key_t key;
static pthread_once_t once = PTHREAD_ONCE_INIT;
#ifdef _WIN32
static HANDLE mapping;
#endif
static void free_stack (void * stack)
{
if (stack)
#ifdef _WIN32
UnmapViewOfFile (stack);
#else
munmap (stack, sizeof (StringStack));
#endif
}
static void make_key ()
{
pthread_key_create (& key, free_stack);
#ifdef _WIN32
mapping = CreateFileMappingW (INVALID_HANDLE_VALUE, nullptr, PAGE_READWRITE,
0, sizeof (StringStack), nullptr);
if (! mapping)
throw std::bad_alloc ();
#endif
}
static StringStack * get_stack ()
{
pthread_once (& once, make_key);
StringStack * stack = (StringStack *) pthread_getspecific (key);
if (! stack)
{
#ifdef _WIN32
stack = (StringStack *) MapViewOfFile (mapping, FILE_MAP_COPY, 0, 0, sizeof (StringStack));
if (! stack)
throw std::bad_alloc ();
#else
stack = (StringStack *) mmap (nullptr, sizeof (StringStack),
PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (stack == MAP_FAILED)
throw std::bad_alloc ();
#endif
stack->top = stack->buf;
pthread_setspecific (key, stack);
}
return stack;
}
EXPORT void StringBuf::resize (int len)
{
if (! stack)
{
stack = get_stack ();
m_data = stack->top;
}
else
{
if (m_data + align (m_len) != stack->top)
throw std::bad_alloc ();
}
if (len < 0)
{
stack->top = stack->buf + sizeof stack->buf;
m_len = stack->top - m_data - 1;
if (m_len < 0)
throw std::bad_alloc ();
}
else
{
stack->top = m_data + align (len);
if (stack->top - stack->buf > (int) sizeof stack->buf)
throw std::bad_alloc ();
m_data[len] = 0;
m_len = len;
}
}
EXPORT StringBuf::~StringBuf ()
{
if (m_data)
{
if (m_data + align (m_len) != stack->top)
throw std::bad_alloc ();
stack->top = m_data;
}
}
EXPORT void StringBuf::steal (StringBuf && other)
{
if (other.m_data)
{
if (m_data)
{
if (m_data + align (m_len) != other.m_data ||
other.m_data + align (other.m_len) != stack->top)
throw std::bad_alloc ();
m_len = other.m_len;
memmove (m_data, other.m_data, m_len + 1);
stack->top = m_data + align (m_len);
}
else
{
stack = other.stack;
m_data = other.m_data;
m_len = other.m_len;
}
other.stack = nullptr;
other.m_data = nullptr;
other.m_len = 0;
}
else
{
if (m_data)
{
this->~StringBuf ();
stack = nullptr;
m_data = nullptr;
m_len = 0;
}
}
}
EXPORT void StringBuf::combine (StringBuf && other)
{
if (! other.m_data)
return;
if (m_data)
{
if (m_data + align (m_len) != other.m_data ||
other.m_data + align (other.m_len) != stack->top)
throw std::bad_alloc ();
memmove (m_data + m_len, other.m_data, other.m_len + 1);
m_len += other.m_len;
stack->top = m_data + align (m_len);
}
else
{
stack = other.stack;
m_data = other.m_data;
m_len = other.m_len;
}
other.stack = nullptr;
other.m_data = nullptr;
other.m_len = 0;
}
EXPORT void StringBuf::insert (int pos, const char * s, int len)
{
int len0 = m_len;
if (pos < 0)
pos = len0;
if (len < 0)
len = strlen (s);
resize (len0 + len);
memmove (m_data + pos + len, m_data + pos, len0 - pos);
memcpy (m_data + pos, s, len);
}
EXPORT void StringBuf::remove (int pos, int len)
{
int after = m_len - pos - len;
memmove (m_data + pos, m_data + pos + len, after);
resize (pos + after);
}
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