The Chunk Class

/*
**	(c) COPYRIGHT MIT 1995.
**	Please first read the full copyright statement in the file COPYRIGH.
*/

The Chunk Class  defines a way to automatically handle dynamic strings and other data types. You create a chunk with an initial size and it will then automatically grow to accomodate added data to the chunk. It is a general utility module. It is garanteed that the array is '\0' terminated at all times (and hence is a valid C type string). The method HTChunkTerminate can be used to explicitly add a terminating '\0' and then to include this character in the chunk size. If left out, the terminating character is not considered part of the chunk.

Note: The names without a "_" (made as a #define's) are only provided for backwards compatibility and should not be used.

This module is implemented by HTChunk.c, and it is a part of the W3C Sample Code Library.

#ifndef HTCHUNK_H
#define HTCHUNK_H

The Chunk Class

This structure should not be referenced outside this module! We only keep it here to maintain high performance. Don't use it directly!

typedef struct {
	int	size;		/* In bytes			*/
	int	growby;		/* Allocation unit in bytes	*/
	int	allocated;	/* Current size of *data	*/
	char *	data;		/* Pointer to malloced area or 0 */
} HTChunk;

Create new chunk

Create a new chunk and specify the number of bytes to allocate at a time when the chunk is later extended. Arbitrary but normally a trade-off time vs. memory

#define HTChunkCreate(growby) HTChunk_new(growby)
extern HTChunk * HTChunk_new (int growby);

Free a chunk

Free a chunk created by HTChunkCreatefrom memory

#define HTChunkFree(ch) HTChunk_delete(ch)
extern void HTChunk_delete (HTChunk * ch);

Clear a chunk

Keep the chunk in memory but clear all data kept inside. This can be used if you know that you can reuse the allocated memory instead of allocating new memory.

#define HTChunkClear(ch) HTChunk_clear(ch)
extern void HTChunk_clear (HTChunk * ch);

Ensure a Chunk has a Certain Amount of Free Space

Make sure that a chunk has a certain size. If this is not the case then the chunk is expanded. Nothing is done if the current size if bigger than the size requested.

#define HTChunkEnsure(ch, s) HTChunk_ensure(ch, s)
extern void HTChunk_ensure (HTChunk * ch, int s);

Append a character to a chunk

Add the character and increment the size of the chunk by one character

#define HTChunkPutc(ch, c) HTChunk_putc(ch, c)
extern void HTChunk_putc (HTChunk * ch, char c);

Append a string to a chunk

Add the string and increment the size of the chunk by the length of the string (without the trailing zero)

#define HTChunkPuts(ch, str) HTChunk_puts(ch, str)
extern void HTChunk_puts (HTChunk * ch, const char *str);

Append a block to a chunk

Add the block and increment the size of the chunk by the len

extern void HTChunk_putb (HTChunk * ch, const char *block, int len);

Zero Terminate a chunk

As a chunk often is a dynamic string, it needs to be terminated by a zero in order to be used in C. However, by default any chunk is always zero terminated, so the only purpose of this function is to increment the size counter with one corresponding to the zero.

#define HTChunkTerminate(ch)	HTChunk_terminate(ch)
#define HTChunk_terminate(ch)	HTChunk_putc((ch), '\0')

Return Pointer to Data

This define converts a chunk to a normal char pointer so that it can be parsed to any ANSI C string function.

#define HTChunkData(me)         ((me) ? (me)->data : NULL)
#define HTChunk_data(me)         ((me) ? (me)->data : NULL)

CString conversions

A Chunk may be build from an allocated string. The chunk assumes control of the passes string, elminating the need for additional allocations and string copies.
Once a string is built, the chunk may be destroyed and the string kept around.

extern HTChunk * HTChunk_fromCString	(char * str, int grow);
extern char * HTChunk_toCString		(HTChunk * ch);

Return Current Size

Returns the current size of the chunk

#define HTChunkSize(me)         ((me) ? (me)->size : -1)
#define HTChunk_size(me)         ((me) ? (me)->size : -1)

#endif