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^string.mid(0;bad) fixed

/** @file
	Parser: string class. @see untasize_t.C.

	Copyright (c) 2001, 2002 ArtLebedev Group (http://www.artlebedev.com)
	Author: Alexandr Petrosian <paf@design.ru> (http://paf.design.ru)
*/

static const char* IDENT_STRING_C="$Date: 2002/08/07 13:44:00 $";

#include "pcre.h"

#include "pa_pool.h"
#include "pa_string.h"
#include "pa_hash.h"
#include "pa_exception.h"
#include "pa_common.h"
#include "pa_array.h"
#include "pa_globals.h"
#include "pa_table.h"
#include "pa_dictionary.h"
#include "pa_charset.h"

#define DEBUG_STRING_APPENDS_VS_EXPANDS


#ifdef DEBUG_STRING_APPENDS_VS_EXPANDS
ulong string_piece_appends=0;
#endif

String& String::OnPool(Pool& apool, const char *local_src, size_t src_size, bool tainted) {
	if(local_src && *local_src) {
		if(src_size==0)
			src_size=strlen(local_src);
		
		char *pooled_src=(char *)apool.malloc(src_size);
		memcpy(pooled_src, local_src, src_size);
		return *new(apool) String(apool, pooled_src, src_size, tainted);
	} else
		return *new(apool) String(apool);
}
String::String(Pool& apool, const char *src, size_t src_size, bool tainted) :
	Pooled(apool) {
	last_chunk=&head.chunk;
	head.chunk.count=CR_PREALLOCATED_COUNT;
	append_here=head.chunk.rows;

	if(src)
		if(tainted)
			APPEND_TAINTED(src, src_size, 0, 0);
		else
			APPEND_CLEAN(src, src_size, 0, 0);
}

String::String(const String& src) :	
	Pooled(src.pool()) {
	last_chunk=&head.chunk;
	head.chunk.count=CR_PREALLOCATED_COUNT;
	append_here=head.chunk.rows;

	append(src, UL_UNSPECIFIED);
}

size_t  String::size() const {
	size_t result=0;
	STRING_FOREACH_ROW(
			result+=row->item.size;
	);
	return result;
}

/// @todo not very optimal
uint String::used_rows() const {
	uint result=0;
	STRING_FOREACH_ROW(
		result++;
	);
	return result;
}
void String::expand() {
	uint new_chunk_count=last_chunk->count+CR_GROW_COUNT;
	if(new_chunk_count>max_integral(Chunk::count_type))
		new_chunk_count=max_integral(Chunk::count_type);

	Chunk *new_chunk=static_cast<Chunk *>(malloc(
			sizeof(Chunk)// count+interpadding(?)+rows[CR_PREALLOCATED_COUNT]+tailpadding(??)
			-sizeof(Chunk::rows_type) // PREALLOCATED rows
			+sizeof(Chunk::Row)*new_chunk_count // neaded rows
			+sizeof(Chunk *) // link size
		, 10));
	new_chunk->rows[new_chunk->count=new_chunk_count].link=0;
	last_chunk->rows[last_chunk->count].link=new_chunk;
	
	last_chunk=new_chunk;
	append_here=last_chunk->rows;
}

String& String::real_append(STRING_APPEND_PARAMS) {
	if(!last_chunk) // growth stopped [we're appended as string to somebody]
		throw Exception(0,
			this,
			"string growth stopped (append cstr)");

	if(!src)
		return *this;
	if(!size)
		size=strlen(src);
	if(!size)
		return *this;

#ifdef DEBUG_STRING_APPENDS_VS_EXPANDS
	string_piece_appends++;
#endif

	// manually unrolled to avoid extra check
	while(size>max_integral(Chunk::Row::item_size_type)) {
		if(chunk_is_full())
			expand();

		append_here->item.ptr=src;
		append_here->item.size=max_integral(Chunk::Row::item_size_type);
		append_here->item.lang=lang;
#ifndef NO_STRING_ORIGIN
		append_here->item.origin.file=file;
		append_here->item.origin.line=line;
#endif
		append_here++;

		src+=max_integral(Chunk::Row::item_size_type);
		size-=max_integral(Chunk::Row::item_size_type);
	}

	if(chunk_is_full())
		expand();

	append_here->item.ptr=src;
	append_here->item.size=size;
	append_here->item.lang=lang;
#ifndef NO_STRING_ORIGIN
	append_here->item.origin.file=file;
	append_here->item.origin.line=line;
#endif
	append_here++;

	return *this;
}

char String::first_char() const {
	if(is_empty())
		throw Exception(0,
			this,
			"getting first char of empty string");

	return *head.chunk.rows[0].item.ptr;
}

uint String::hash_code() const {
	uint result=0;
	STRING_FOREACH_ROW(
			result=Hash::generic_code(result, row->item.ptr, row->item.size);
	);
	return result;
}

/// @todo move 'lang' skipping to pos
int String::cmp(int& partial, const String& src, 
				size_t this_offset, Untaint_lang lang) const {
	partial=-1;
	size_t a_size=size();
	this_offset=min(this_offset, a_size-1);

	const Chunk *a_chunk=&head.chunk;
	const Chunk *b_chunk=&src.head.chunk;
	const Chunk::Row *a_row=a_chunk->rows;
	const Chunk::Row *b_row=b_chunk->rows;
	size_t a_offset=this_offset;
	size_t b_offset=0;
	Chunk::Row *a_end=append_here;
	Chunk::Row *b_end=src.append_here;
	uint a_countdown=a_chunk->count;
	uint b_countdown=b_chunk->count;
	int result;
	size_t pos=0; 

	bool a_break=a_size==0;
	bool b_break=src.is_empty();
	if(!(a_break || b_break)) while(true) {
		if(pos+a_row->item.size > this_offset) {
			if(lang!=UL_UNSPECIFIED && a_row->item.lang>lang) 
				return -1; // wrong lang -- bail out

			int size_diff=
				(a_row->item.size-a_offset)-
				(b_row->item.size-b_offset);
			
			if(size_diff==0) { // a has same size as b
				result=memcmp(a_row->item.ptr+a_offset, b_row->item.ptr+b_offset, 
					a_row->item.size-a_offset);
				if(result)
					return result;
				pos+=a_row->item.size;
				a_row++; a_countdown--; a_offset=0;
				b_row++; b_countdown--; b_offset=0;
			} else if (size_diff>0) { // a longer
				result=memcmp(a_row->item.ptr+a_offset, b_row->item.ptr+b_offset, 
					b_row->item.size-b_offset);
				if(result)
					return result;
				a_offset+=b_row->item.size-b_offset;
				b_row++; b_countdown--; b_offset=0;
			} else { // b longer
				result=memcmp(a_row->item.ptr+a_offset, b_row->item.ptr+b_offset, 
					a_row->item.size-a_offset);
				if(result)
					return result;
				b_offset+=a_row->item.size-a_offset;
				pos+=a_row->item.size;
				a_row++; a_countdown--; a_offset=0;
			}
			if(b_break=b_row==b_end) {
				a_break=a_row==a_end;
				break;			
			}
			if(!b_countdown) {
				b_chunk=b_row->link;
				b_row=b_chunk->rows;
				b_countdown=b_chunk->count;
			}
		} else {
			a_offset-=a_row->item.size;
			pos+=a_row->item.size;
			a_row++; a_countdown--; 
		}

		if(a_break=a_row==a_end) {
			b_break=b_row==b_end;
			break;
		}
		if(!a_countdown) {
			a_chunk=a_row->link;
			a_row=a_chunk->rows;
			a_countdown=a_chunk->count;
		}
	}
	if(a_break==b_break) { // ended simultaneously
		partial=0; return 0;
	} else if(a_break) { // first bytes equal, but a ended before b
		partial=1; return -1;
	} else {
		partial=2; return +1;
	}
}

/// @todo move 'lang' skipping to pos
int String::cmp(int& partial, const char* b_ptr, size_t src_size, 
				size_t this_offset, Untaint_lang lang) const {
	partial=-1;
	size_t a_size=size();
	size_t b_size=src_size?src_size:b_ptr?strlen(b_ptr):0;
	this_offset=min(this_offset, a_size-1);

	const Chunk *a_chunk=&head.chunk;
	const Chunk::Row *a_row=a_chunk->rows;
	size_t a_offset=this_offset;
	size_t b_offset=0;
	Chunk::Row *a_end=append_here;
	uint a_countdown=a_chunk->count;
	size_t pos=0;

	bool a_break=a_size==0;
	bool b_break=b_size==0;
	if(!(a_break || b_break)) while(true) {
		if(pos+a_row->item.size > this_offset) {
			if(lang!=UL_UNSPECIFIED && a_row->item.lang>lang) 
				return -1; // wrong lang -- bail out

			int size_diff=
				(a_row->item.size-a_offset)-
				(b_size-b_offset);
			
			if(size_diff==0) { // a has same size as b
				if(int result=memcmp(a_row->item.ptr+a_offset, b_ptr+b_offset, 
					a_row->item.size-a_offset)!=0)
					return result;
				pos+=a_row->item.size;
				a_row++; a_countdown--; a_offset=0;
				b_break=true;
			} else if (size_diff>0) { // a longer
				if(int result=memcmp(a_row->item.ptr+a_offset, b_ptr+b_offset, 
					b_size-b_offset)!=0)
					return result;
				a_offset+=b_size-b_offset;
				b_break=true;
			} else { // b longer
				if(int result=memcmp(a_row->item.ptr+a_offset, b_ptr+b_offset, 
					a_row->item.size-a_offset)!=0)
					return result;
				b_offset+=a_row->item.size-a_offset;
				pos+=a_row->item.size;
				a_row++; a_countdown--; a_offset=0;
			}
		} else {
			a_offset-=a_row->item.size; 
			pos+=a_row->item.size;
			a_row++; a_countdown--; 
		}

		a_break=a_row==a_end;
		if(a_break || b_break)
			break;
		if(!a_countdown) {
			a_chunk=a_row->link;
			a_row=a_chunk->rows;
			a_countdown=a_chunk->count;
		}
	}
	if(a_break==b_break) { // ended simultaneously
		partial=0; return 0;
	} else if(a_break) { // first bytes equal, but a ended before b
		partial=1; return -1;
	} else {
		partial=2; return +1;
	}
}

#ifndef NO_STRING_ORIGIN
const Origin& String::origin() const { 
	if(is_empty()) {
		static const Origin empty_origin={"empty string"};
		return empty_origin;
	}
	
	// determining origin by first piece or last appended piece
	// because any of them can be constant=without origin: 
	// ex: ^load[/file] "document_root" + "/file"
	// when last peice is constant, 
	// ex: parser_root_auto_path{dynamic} / auto.p{const}
	// using first piece
	Origin& first_origin=head.chunk.rows[0].item.origin;
	return first_origin.file ? first_origin : append_here[-1].item.origin;
}
#endif

String& String::mid(size_t start, size_t finish) const {
	String& result=*NEW String(pool());

	start=min(start, size());
	finish=max(finish, start);
	if(start==finish)
		return result;

	size_t pos=0;
	STRING_FOREACH_ROW(
		size_t item_finish=pos+row->item.size;
		if(item_finish > start) { // started now or already?
			bool started=result.is_empty(); // started now?
			bool finished=finish <= item_finish; // finished now?
			size_t offset=started?start-pos:0;
			size_t size=finished?finish-pos:row->item.size;
			result.APPEND(
				row->item.ptr+offset, size-offset, 
				row->item.lang,
				row->item.origin.file, row->item.origin.line);
			if(finished)
				goto break2;
		}
		pos+=row->item.size;
	);
break2:
//	SAPI::log(pool(), "piece of '%s' from %d to %d is '%s'",
		//cstr(), start, finish, result.cstr());
	return result;
}

int String::pos(const String& substr, 
				int result, Untaint_lang lang) const {
	size_t self_size=size();
	for(; size_t(result)<self_size; result++) {
		int partial; cmp(partial, substr, result, lang);
		if(
			partial==0 || // full match
			partial==2) // 'substr' starts 'this'+'result'
			return result;
	}
	
	return -1;
}

int String::pos(const char *substr, size_t substr_size, 
				int result, Untaint_lang lang) const {
	size_t self_size=size();
	for(; size_t(result)<self_size; result++) {
		int partial; cmp(partial, substr, substr_size, result, lang);
		if(
			partial==0 || // full match
			partial==2) // 'substr' starts 'this'+'result'
			return result;
	}
	
	return -1;
}

void String::split(Array& result, 
				   size_t* pos_after_ref, 
				   const char *delim, size_t delim_size, 
				   Untaint_lang lang, int limit) const {
	size_t self_size=size();
	if(delim_size) {
		size_t pos_after=pos_after_ref?*pos_after_ref:0;
		int pos_before;
		// while we have 'delim'...
		for(; (pos_before=pos(delim, delim_size, pos_after, lang))>=0 && limit; limit--) {
			result+=&mid(pos_after, pos_before);
			pos_after=pos_before+delim_size;
		}
		// last piece
		if(pos_after<self_size && limit) {
			result+=&mid(pos_after, self_size);
			pos_after=self_size;
		}
		if(pos_after_ref)
			*pos_after_ref=pos_after;
	} else { // empty delim
		result+=this;
		if(pos_after_ref)
			*pos_after_ref+=self_size;
	}
}

void String::split(Array& result, 
				   size_t* pos_after_ref, 
				   const String& delim, Untaint_lang lang, 
				   int limit) const {
	if(!delim.is_empty()) {
		size_t pos_after=pos_after_ref?*pos_after_ref:0;
		int pos_before;
		// while we have 'delim'...
		for(; (pos_before=pos(delim, pos_after, lang))>=0 && limit; limit--) {
			result+=&mid(pos_after, pos_before);
			pos_after=pos_before+delim.size();
		}
		// last piece
		if(pos_after<size() && limit) {
			result+=&mid(pos_after, size());
			pos_after=size();
		}
		if(pos_after_ref)
			*pos_after_ref=pos_after;
	} else { // empty delim
		result+=this;
		if(pos_after_ref)
			*pos_after_ref+=size();
	}
}

static void regex_options(const String *options, int *result, bool& need_pre_post_match){
    struct Regex_option {
		const char *keyL;
		const char *keyU;
		int clear, set;
		int *result;
		bool *flag;
    } regex_option[]={
		{"i", "I", 0, PCRE_CASELESS, result}, // a=A
		{"s", "S", 0, PCRE_DOTALL, result}, // \n\n$ [default]
		{"x", "U", 0, PCRE_EXTENDED, result}, // whitespace in regex ignored
		{"m", "M", PCRE_DOTALL, PCRE_MULTILINE, result}, // ^aaa\n$^bbb\n$
		{"g", "G", 0, true, result+1}, // many rows
		{"'", 0, 0, 0, 0, &need_pre_post_match},
		{0}
    };
	result[0]=PCRE_EXTRA | PCRE_DOTALL;
	result[1]=0;

    if(options) 
		for(Regex_option *o=regex_option; o->keyL; o++) 
			if(options->pos(o->keyL)>=0
				|| (o->keyU && options->pos(o->keyU)>=0)) {
				if(o->flag)
					*o->flag=true;
				else { // result
					*o->result &= ~o->clear;
					*o->result |= o->set;
				}
			}
}

/// @todo make replacement Table stacked
bool String::match(
				   const String *aorigin,
				   const String& regexp, 
				   const String *options,
				   Table **table,
				   Row_action row_action, void *info,
				   bool *was_global) const { 

	if(regexp.is_empty())
		throw Exception(0,
			aorigin,
			"regexp is empty");

	const char *pattern=regexp.cstr();
	const char *errptr;
	int erroffset;
    bool need_pre_post_match=false;
	int option_bits[2];  regex_options(options, option_bits, need_pre_post_match);
	if(was_global)
		*was_global=option_bits[1]!=0;
	pcre *code=pcre_compile(pattern, option_bits[0], 
		&errptr, &erroffset,
		pool().get_source_charset().pcre_tables);

	if(!code)
		throw Exception(0,
			&regexp.mid(erroffset, regexp.size()),
			"regular expression syntax error - %s", errptr);
	
	int info_substrings=pcre_info(code, 0, 0);
	if(info_substrings<0) {
		pcre_free(code);
		throw Exception(0,
			aorigin,
			"pcre_info error (%d)", 
				info_substrings);
	}

	const char *subject=cstr();
	int length=strlen(subject);
	const int ovecsize=(1/*match*/+MAX_STRING_MATCH_TABLE_COLUMNS)*3;
	int ovector[ovecsize];

	// create table
	*table=NEW Table(pool(), *string_match_table_template);

	int exec_option_bits=0;
	int prestart=0;
	int poststart=0;
	int postfinish=size();
	while(true) {
		int exec_substrings=pcre_exec(code, 0,
			subject, length, prestart,
			exec_option_bits, ovector, ovecsize);
		
		if(exec_substrings==PCRE_ERROR_NOMATCH) {
			pcre_free(code);
			row_action(**table, 0/*last time, no row*/, 0, 0, poststart, postfinish, info);
			return option_bits[1]!=0; // global=true+table, not global=false
		}

		if(exec_substrings<0) {
			pcre_free(code);
			throw Exception(0,
				aorigin,
				"regular expression execute error (%d)", 
					exec_substrings);
		}

		int prefinish=ovector[0];
		poststart=ovector[1];
		Array& row=*NEW Array(pool());
		row+=need_pre_post_match?&mid(0, prefinish):0; // .prematch column value
		row+=need_pre_post_match?&mid(prefinish, poststart):0; // .match
		row+=need_pre_post_match?&mid(poststart, postfinish):0; // .postmatch
		
		for(int i=1; i<exec_substrings; i++) {
			// -1:-1 case handled peacefully by mid() itself
			row+=&mid(ovector[i*2+0], ovector[i*2+1]); // .i column value
		}
		
		row_action(**table, &row, prestart, prefinish, poststart, postfinish, info);

		if(!option_bits[1] || prestart==poststart) { // not global | going to hang
			pcre_free(code);
			row_action(**table, 0/*last time, no row*/, 0, 0, poststart, postfinish, info);
			return true;
		}
		prestart=poststart;

/*
		if(option_bits[0] & PCRE_MULTILINE)
			exec_option_bits|=PCRE_NOTBOL; // start of subject+startoffset not BOL
*/
	}
}

String& String::change_case(Pool& pool, 
							Change_case_kind kind) const {
	const unsigned char *tables=pool.get_source_charset().pcre_tables;
	String& result=*new(pool) String(pool);

	const unsigned char *a;
	const unsigned char *b;
	switch(kind) {
	case CC_UPPER:
		a=tables+lcc_offset;
		b=tables+fcc_offset;
		break;
	case CC_LOWER:
		a=tables+lcc_offset;
		b=0;
		break;
	default:
		throw Exception(0, 
			this, 
			"unknown change case kind #%d", 
				static_cast<int>(kind)); // never
		a=b=0; // calm, compiler
		break; // never
	}	

	STRING_FOREACH_ROW(
		char *new_cstr=(char *)pool.malloc(row->item.size, 12);
		char *dest=new_cstr;
		const char *src=row->item.ptr; 
		for(int size=row->item.size; size--; src++) {
			unsigned char c=a[(unsigned char)*src];
			if(b)
				c=b[c];

			*dest++=(char)c;
		}
		
		result.APPEND(new_cstr, row->item.size, 
			row->item.lang,
			row->item.origin.file, row->item.origin.line);
	);

	return result;
}

/// @test if in some piece were found no dict words, append it, not it's duplicate
String& String::replace(Pool& pool, Dictionary& dict) const {
//	return reconstruct(pool).replace_in_reconstructed(pool, dict);
	String& result=*new(pool) String(pool);

	STRING_FOREACH_ROW(
		const char *src=row->item.ptr; 
		size_t src_size=row->item.size;
		char *new_cstr=(char *)pool.malloc((size_t)ceil(src_size*dict.max_ratio()), 14);
		char *dest=new_cstr;
		while(src_size) {
			// there is a row where first column starts 'src'
			if(Table::Item *item=dict.first_that_starts(src, src_size)) {
				// get a=>b values
				const String& a=*static_cast<Array *>(item)->get_string(0);
				const String& b=*static_cast<Array *>(item)->get_string(1);
				// skip 'a' in 'src' && reduce work size
				src+=a.size();  src_size-=a.size();
				// write 'b' to 'dest' && skip 'b' in 'dest'
				b.store_to(dest);  dest+=b.size();
			} else {
				// write a char to b && reduce work size
				*dest++=*src++;  src_size--;
			}
		}

		result.APPEND(new_cstr, dest-new_cstr, row->item.lang,
			row->item.origin.file, row->item.origin.line);
	);
	return result;
}

String& String::join_chains(Pool& pool, char** acstr) const {
	char *lcstr=cstr();
	const char *current=lcstr;

	String& result=*new(pool) String(pool);
	STRING_FOREACH_ROW(
IFNDEF_NO_STRING_ORIGIN(
		const char *joined_origin_file=row->item.origin.file;
		const size_t joined_origin_line=row->item.origin.line;
);
		uchar joined_lang=row->item.lang;
		const char *joined_ptr=current;
		// calc size
		size_t joined_size=0;
		STRING_PREPARED_FOREACH_ROW(*this, 
			if(row->item.lang==joined_lang)
				joined_size+=row->item.size;
			else
				break; // before non-ours
		);
		current+=joined_size;

		// pointers are after joined piece
		// & one step back, see STRING_FOREACH_ROW
		--row;  ++countdown;
		
		result.APPEND(joined_ptr, joined_size, joined_lang,
			joined_origin_file, joined_origin_line);
	);

	if(acstr)
		*acstr=lcstr;
	return result;
}

double String::as_double() const { 
	double result;
	const char *cstr;
	char buf[MAX_NUMBER];
	if(head.chunk.rows+1==append_here) {
		int size=min(head.chunk.rows[0].item.size, MAX_NUMBER-1);
		memcpy(buf, head.chunk.rows[0].item.ptr, size);
		buf[size]=0;
		cstr=buf;
	} else
		cstr=this->cstr();
	while(*cstr && isspace(*cstr))
		cstr++;
	if(!*cstr)
		return 0;

	char *error_pos;
	// 0xABC
	if(cstr[0]=='0')
		if(cstr[1]=='x' || cstr[1]=='X')
			result=(double)(unsigned long)strtol(cstr, &error_pos, 0);
		else
			result=(double)strtod(cstr+1/*skip leading 0*/, &error_pos);
	else
		result=(double)strtod(cstr, &error_pos);

	while(char c=*error_pos++)
		if(!isspace(c))
			throw Exception("number.format",
				this,
				"invalid number (double)");

	return result;
}
int String::as_int() const { 
	int result;
	const char *cstr;
	char buf[MAX_NUMBER];
	if(head.chunk.rows+1==append_here) {
		size_t size=min(head.chunk.rows[0].item.size, MAX_NUMBER-1);
		memcpy(buf, head.chunk.rows[0].item.ptr, size);
		buf[size]=0;
		cstr=buf;
	} else
		cstr=this->cstr();
	while(*cstr && isspace(*cstr))
		cstr++;
	if(!*cstr)
		return 0;

	char *error_pos;
	// 0xABC
	if(cstr[0]=='0')
		if(cstr[1]=='x' || cstr[1]=='X')
			result=(int)(unsigned long)strtol(cstr, &error_pos, 0);
		else
			result=(int)strtol(cstr+1/*skip leading 0*/, &error_pos, 0);
	else
		result=(int)strtol(cstr, &error_pos, 0);

	while(char c=*error_pos++)
		if(!isspace(c))
			throw Exception("number.format",
				this,
				"invalid number (int)");

	return result;
}

inline void ushort2uchars(ushort word, uchar& byte1, uchar& byte2) {
	byte1=word&0xFF;
	byte2=word>>8;
}
inline ushort uchars2ushort(uchar byte1, uchar byte2) {
	return (byte2<<8) | byte1;
}
/* @todo maybe network order worth spending some effort?
	don't bothering myself with network byte order,
	am not planning to be able to move resulting file across platforms
	for now
*/
void String::serialize(size_t prolog_size, void *& buf, size_t& buf_size) const {
	buf_size=
		prolog_size
		+used_rows()*(sizeof(uchar)+sizeof(ushort))
		+size();
	buf=malloc(buf_size,15);
	char *cur=(char *)buf+prolog_size;

	STRING_FOREACH_ROW(
		// lang
		memcpy(cur, &row->item.lang, sizeof(uchar));
		cur+=sizeof(uchar);
		// size
		uchar byte1; uchar byte2;
		ushort2uchars(row->item.size, byte1, byte2);
		memcpy(cur, &byte1, sizeof(uchar)); cur+=sizeof(uchar);
		memcpy(cur, &byte2, sizeof(uchar)); cur+=sizeof(uchar);
		// bytes
		memcpy(cur, row->item.ptr, row->item.size);
		cur+=row->item.size;
	);
}
bool String::deserialize(size_t prolog_size, void *buf, size_t buf_size, const char *file) {
	if(buf_size<=prolog_size)
		return false;

	char *cur=(char *)buf+prolog_size;
	buf_size-=prolog_size;

	while(buf_size) {
		if(sizeof(uchar)+sizeof(ushort)>buf_size) // lang+size
			return false;

		uchar lang=*(uchar *)(cur);		
		ushort size=uchars2ushort(
			*(uchar*)(cur+sizeof(uchar)*1),
			*(uchar*)(cur+sizeof(uchar)*2)
		);

		size_t piece_size=sizeof(uchar)+sizeof(ushort)+size;
		if(piece_size>buf_size) // buffer overrun, can be on incomplete cache files
			return false;

		const char *ptr=(const char*)(cur+sizeof(uchar)*3); 
		APPEND(ptr, size, lang, file, 0);

		cur+=piece_size;
		buf_size-=piece_size;
	}
	return true;
}