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optimizations: more functions made inline, added Alloc()/Shrink() function for

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more precise control over string's memory


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@275 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 1998-07-15 17:10:23 +00:00
parent 2ab889ff7b
commit dd1eaa89dd
2 changed files with 218 additions and 220 deletions
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93
include/wx/string.h
View File

@ -26,11 +26,14 @@
#include <stdio.h>
#include <stdarg.h>
#include <limits.h>
#include <stdlib.h>
#ifndef WX_PRECOMP
#include "wx/defs.h" // Robert Roebling
#ifdef WXSTRING_IS_WXOBJECT
#include "wx/object.h"
#endif
#endif
#include "wx/debug.h"
@ -78,7 +81,31 @@ inline size_t WXDLLEXPORT Strlen(const char *psz)
{ return psz ? strlen(psz) : 0; }
/// portable strcasecmp/_stricmp
int WXDLLEXPORT Stricmp(const char *, const char *);
inline int WXDLLEXPORT Stricmp(const char *psz1, const char *psz2)
{
#if defined(_MSC_VER)
return _stricmp(psz1, psz2);
#elif defined(__BORLANDC__)
return stricmp(psz1, psz2);
#elif defined(__UNIX__) || defined(__GNUWIN32__)
return strcasecmp(psz1, psz2);
#else
// almost all compilers/libraries provide this function (unfortunately under
// different names), that's why we don't implement our own which will surely
// be more efficient than this code (uncomment to use):
/*
register char c1, c2;
do {
c1 = tolower(*psz1++);
c2 = tolower(*psz2++);
} while ( c1 && (c1 == c2) );
return c1 - c2;
*/
#error "Please define string case-insensitive compare for your OS/compiler"
#endif // OS/compiler
}
// ----------------------------------------------------------------------------
// global data
@ -110,7 +137,7 @@ struct WXDLLEXPORT wxStringData
// lock/unlock
void Lock() { if ( !IsEmpty() ) nRefs++; }
void Unlock() { if ( !IsEmpty() && --nRefs == 0) delete (char *)this; }
void Unlock() { if ( !IsEmpty() && --nRefs == 0) free(this); }
// if we had taken control over string memory (GetWriteBuf), it's
// intentionally put in invalid state
@ -157,6 +184,15 @@ struct WXDLLEXPORT wxStringData
friend class wxArrayString;
// NB: this data must be here (before all other functions) to be sure that all
// inline functions are really inlined by all compilers
private:
// points to data preceded by wxStringData structure with ref count info
char *m_pchData;
// accessor to string data
wxStringData* GetStringData() const { return (wxStringData*)m_pchData - 1; }
public:
/** @name constructors & dtor */
//@{
@ -179,11 +215,19 @@ public:
/** @name generic attributes & operations */
//@{
/// as standard strlen()
size_t Len() const { return GetStringData()->nDataLength; }
uint Len() const { return GetStringData()->nDataLength; }
/// string contains any characters?
bool IsEmpty() const;
bool IsEmpty() const { return Len() == 0; }
/// reinitialize string (and free data!)
void Empty();
void Empty()
{
if ( GetStringData()->nDataLength != 0 )
Reinit();
wxASSERT( GetStringData()->nDataLength == 0 );
wxASSERT( GetStringData()->nAllocLength == 0 );
}
/// Is an ascii value
bool IsAscii() const;
/// Is a number
@ -248,22 +292,29 @@ public:
/** @name in place concatenation */
//@{
/// string += string
void operator+=(const wxString& string);
void operator+=(const wxString& s) { (void)operator<<(s); }
/// string += C string
void operator+=(const char *psz);
void operator+=(const char *psz) { (void)operator<<(psz); }
/// string += char
void operator+=(char ch);
void operator+=(char ch) { (void)operator<<(ch); }
//@}
/** @name concatenate and return the result
left to right associativity of << allows to write
things like "str << str1 << str2 << ..." */
//@{
/// as +=
wxString& operator<<(const wxString& string);
wxString& operator<<(const wxString& s)
{
wxASSERT( s.GetStringData()->IsValid() );
ConcatSelf(s.Len(), s);
return *this;
}
/// as +=
wxString& operator<<(char ch);
wxString& operator<<(const char *psz)
{ ConcatSelf(Strlen(psz), psz); return *this; }
/// as +=
wxString& operator<<(const char *psz);
wxString& operator<<(char ch) { ConcatSelf(1, &ch); return *this; }
//@}
/** @name return resulting string */
@ -378,12 +429,18 @@ public:
/** @name raw access to string memory */
//@{
/// ensure that string has space for at least nLen characters
// only works if the data of this string is not shared
void Alloc(uint nLen);
/// minimize the string's memory
// only works if the data of this string is not shared
void Shrink();
/**
get writable buffer of at least nLen bytes.
Unget() *must* be called a.s.a.p. to put string back in a reasonable
state!
*/
char *GetWriteBuf(int nLen);
char *GetWriteBuf(uint nLen);
/// call this immediately after GetWriteBuf() has been used
void UngetWriteBuf();
//@}
@ -586,7 +643,7 @@ public:
size_t find(char ch, size_t nStart = 0) const;
// wxWin compatibility
inline bool Contains(const wxString& str) { return (Find(str) != -1); }
inline bool Contains(const wxString& str) { return Find(str) != -1; }
//@}
@ -669,12 +726,8 @@ public:
//@}
#endif
protected:
// points to data preceded by wxStringData structure with ref count info
char *m_pchData;
private:
// accessor to string data
wxStringData* GetStringData() const { return (wxStringData*)m_pchData - 1; }
// string (re)initialization functions
// initializes the string to the empty value (must be called only from
@ -683,7 +736,7 @@ protected:
// initializaes the string with (a part of) C-string
void InitWith(const char *psz, size_t nPos = 0, size_t nLen = STRING_MAXLEN);
// as Init, but also frees old data
inline void Reinit();
void Reinit() { GetStringData()->Unlock(); Init(); }
// memory allocation
// allocates memory for string of lenght nLen
@ -744,6 +797,8 @@ public:
void Clear();
/// preallocates memory for given number of items
void Alloc(size_t nCount);
/// minimzes the memory usage (by freeing all extra memory)
void Shrink();
//@}
/** @name simple accessors */

137
src/common/string.cpp
View File

@ -236,8 +236,8 @@ void wxString::AllocBuffer(size_t nLen)
// allocate memory:
// 1) one extra character for '\0' termination
// 2) sizeof(wxStringData) for housekeeping info
wxStringData* pData = (wxStringData*)new char[sizeof(wxStringData) +
(nLen + 1)*sizeof(char)];
wxStringData* pData = (wxStringData*)malloc(sizeof(wxStringData) +
(nLen + 1)*sizeof(char));
pData->nRefs = 1;
pData->data()[nLen] = '\0';
pData->nDataLength = nLen;
@ -245,23 +245,6 @@ void wxString::AllocBuffer(size_t nLen)
m_pchData = pData->data(); // data starts after wxStringData
}
// releases the string memory and reinits it
void wxString::Reinit()
{
GetStringData()->Unlock();
Init();
}
// wrapper around wxString::Reinit
void wxString::Empty()
{
if ( GetStringData()->nDataLength != 0 )
Reinit();
wxASSERT( GetStringData()->nDataLength == 0 );
wxASSERT( GetStringData()->nAllocLength == 0 );
}
// must be called before changing this string
void wxString::CopyBeforeWrite()
{
@ -292,8 +275,44 @@ void wxString::AllocBeforeWrite(size_t nLen)
wxASSERT( !GetStringData()->IsShared() ); // we must be the only owner
}
// allocate enough memory for nLen characters
void wxString::Alloc(uint nLen)
{
wxStringData *pData = GetStringData();
if ( pData->nAllocLength <= nLen ) {
if ( pData->IsEmpty() )
AllocBuffer(nLen);
else {
wxStringData *p = (wxStringData *)
realloc(pData, sizeof(wxStringData) + (nLen + 1)*sizeof(char));
if ( p != NULL && p != pData ) {
// the call succeeded but the pointer changed
pData->Unlock();
free(pData);
p->nRefs = 1;
p->nAllocLength = nLen;
m_pchData = p->data();
}
//else: do nothing: either the call failed or the pointer is unchanged
}
}
//else: we've already got enough
}
// shrink to minimal size (releasing extra memory)
void wxString::Shrink()
{
wxStringData *pData = GetStringData();
void *p = realloc(pData, sizeof(wxStringData) +
(pData->nDataLength + 1)*sizeof(char));
if ( p == NULL ) // huh? can't unallocate memory? unlikely but possible.
return;
wxASSERT( p == pData ); // we're decrementing the size - block shouldn't move!
}
// get the pointer to writable buffer of (at least) nLen bytes
char *wxString::GetWriteBuf(int nLen)
char *wxString::GetWriteBuf(uint nLen)
{
AllocBeforeWrite(nLen);
@ -436,51 +455,6 @@ void wxString::ConcatSelf(int nSrcLen, const char *pszSrcData)
}
}
/*
* string may be concatenated with other string, C string or a character
*/
void wxString::operator+=(const wxString& string)
{
wxASSERT( string.GetStringData()->IsValid() );
ConcatSelf(string.Len(), string);
}
void wxString::operator+=(const char *psz)
{
ConcatSelf(Strlen(psz), psz);
}
void wxString::operator+=(char ch)
{
ConcatSelf(1, &ch);
}
/*
* Same as above but return the result
*/
wxString& wxString::operator<<(const wxString& string)
{
wxASSERT( string.GetStringData()->IsValid() );
ConcatSelf(string.Len(), string);
return *this;
}
wxString& wxString::operator<<(const char *psz)
{
ConcatSelf(Strlen(psz), psz);
return *this;
}
wxString& wxString::operator<<(char ch)
{
ConcatSelf(1, &ch);
return *this;
}
/*
* concatenation functions come in 5 flavours:
* string + string
@ -720,10 +694,6 @@ bool wxString::IsNumber() const
return(TRUE);
}
// kludge: we don't have declaraton of wxStringData here, so we add offsets
// manually to get to the "length" field of wxStringData structure
bool wxString::IsEmpty() const { return Len() == 0; }
wxString wxString::Strip(stripType w) const
{
wxString s = *this;
@ -732,33 +702,6 @@ wxString wxString::Strip(stripType w) const
return s;
}
/// case-insensitive strcmp() (platform independent)
int Stricmp(const char *psz1, const char *psz2)
{
#if defined(_MSC_VER)
return _stricmp(psz1, psz2);
#elif defined(__BORLANDC__)
return stricmp(psz1, psz2);
#elif defined(__UNIX__) || defined(__GNUWIN32__)
return strcasecmp(psz1, psz2);
#else
// almost all compilers/libraries provide this function (unfortunately under
// different names), that's why we don't implement our own which will surely
// be more efficient than this code (uncomment to use):
/*
register char c1, c2;
do {
c1 = tolower(*psz1++);
c2 = tolower(*psz2++);
} while ( c1 && (c1 == c2) );
return c1 - c2;
*/
#error "Please define string case-insensitive compare for your OS/compiler"
#endif // OS/compiler
}
// ---------------------------------------------------------------------------
// case conversion
// ---------------------------------------------------------------------------
@ -1158,7 +1101,7 @@ wxArrayString& wxArrayString::operator=(const wxArrayString& src)
m_nCount = src.m_nCount;
if ( m_nSize != 0 )
m_pItems = new char *[m_nSize];
m_pItems = new char *[m_nCount];
else
m_pItems = NULL;