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#ifndef STRINGUTIL_HH
#define STRINGUTIL_HH
#include <assert.h>
#if !defined(NDEBUG)
#define NDEBUG BLONDE
#endif
class String_handle;
/// Internal String struct
class StringData {
// GNU malloc: storage overhead is 8 bytes anyway.
const int INITIALMAX =8; // how to do this in ANSI C++ ?
friend class String_handle;
int maxlen; // maxlen is arraysize-1
int length;
char* string;
int references;
/// init to ""
StringData() {
references=0;
maxlen = INITIALMAX;
string = new char[maxlen + 1];
string[0] = 0;
length = 0;
}
/// init from src. Conservative allocation.
StringData(StringData const &src) {
references=0;
maxlen = length = src.length;
string = new char[maxlen+1]; // should calc GNU 8byte overhead.
strcpy(string, src.string);
}
~StringData() {
assert(references == 0);
delete[] string;
}
void setmax(int j) {
OKW();
if (j > maxlen) {
delete string;
maxlen = j;
string = new char[maxlen + 1];
string[0] = 0;
length = 0;
}
}
/** POST: maxlen >= j.
IN: j, maximum stringlength.
contents thrown away.
*/
///
void remax(int j) {
OKW();
if (j > maxlen) {
maxlen = j;
char *p = new char[maxlen + 1];
strcpy(p,string);
delete[] string;
string = p;
// length = strlen(string);
}
}
/** POST: maxlen >= j.
IN: j, maximum stringlength.
contents are kept if it grows.
*/
/// check if writeable.
void OKW() {
assert (references == 1);
}
/// check state.
void OK() {
assert(strlen(string) == size_t(length));
assert(maxlen >= length);
assert(bool(string));
assert(references >= 1);
}
// needed?
void update() {
length = strlen (string);
}
/// reduce memory usage.
void tighten() { // should be dec'd const
maxlen = length;
char *p = new char[maxlen + 1];
strcpy(p,string);
delete[] string;
string = p;
}
// assignment.
void set(const char *s) {
OKW();
assert(s);
length = strlen (s);
remax(length);
strcpy(string,s);
}
/// concatenation.
void operator += (const char *s) {
OK();
OKW();
int old = length;
length += strlen(s);
remax (length);
strcpy(string + old, s);
}
/// the array itself
operator const char *() const { return string; }
// idem, non const
char *array_for_modify() {
OKW();
return string;
}
void trunc(int j) {
OKW();
assert(j >= 0 && j <= length);
string[j] = 0;
length = j;
}
/** not really safe. Can alter length without StringData knowing it.
*/
char &operator [](int j) {
assert(j >= 0 && j <= length);
return string[j] ;
}
char operator [](int j) const {
assert(j >= 0 && j <= length);
return string[j];
}
};
/**
the data itself. Handles simple tasks (resizing, resetting)
*/
/****************************************************************/
/// ref. counting for strings
class String_handle {
StringData* data;
/// decrease ref count. Named kind of like a Tanenbaum semafore
void down() { if (!(--data->references)) delete data; data = 0; }
/// increase ref count
void up(StringData *d) { data=d; data->references ++; }
/** make sure data has only one reference.
POST: data->references == 1
*/
void copy() {
if (data->references !=1){
StringData *newdata = new StringData(*data);
down();
up(newdata);
}
}
public:
String_handle() {
up(new StringData);
}
~String_handle() {
down();
}
String_handle(String_handle const & src) {
up(src.data);
}
/// retrieve the actual array.
operator const char *() const { return *data; }
char *array_for_modify() {
copy();
return data->array_for_modify();
}
void operator =(String_handle const &src) {
if (this == &src)
return;
down();
up(src.data);
}
void operator += (const char *s) {
copy();
*data += s;
}
char operator[](int j) const { return (*data)[j]; }
// !NOT SAFE!
// don't use this for loops. Use array_for_modify()
char &operator[](int j) {
copy(); // hmm. Not efficient
return data->array_for_modify()[j];
}
void operator = (char const *p) {
copy();
data->set(p);
}
void trunc(int j) { copy(); data->trunc(j); }
int len() const { return data->length; }
};
/**
handles ref. counting, and provides a very thin
interface using char *
*/
#ifdef NDEBUG
#if (NDEBUG == BLONDE)
#undef NDEBUG
#endif
#endif
#endif // STRINGUTIL_HH
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