kstr

kstr is the libk string library. it uses the short naming convention with the glyph s. kstr implies #include <k/mem.h>.

types

struct kstr

struct kstr is a structure for holding pascal strings (length-prefixed strings). it is the basic libk string type. note: if ptr.ref ≠ NULL and sz = 0, the string's length is unknown and should be calculated by any function that operates on a kstr, storing the result in the object if possible. * size_t sz - length of string, excluding any null terminator * kmptr ptr - pointer to string in memory

struct ksraw

struct ksraw is like kstr except it uses raw char pointers instead of a kmptr. * size_t sz - length of string, excluding any null terminator * char* ptr - pointer to string in memory

struct ksbuf

struct ksbuf is a structure used to hold buffers. * size_t sz - maximum size of buffer, including any null terminator * char* buf - region of memory to store buffer in * ksalloc strat - allocation strategy * kmkind rule - kind of allocator to use. only needs to be set if where is NULL. see kmem. * kmcell* where - where to allocate the object, in case of pool or tree allocation.

struct kschain

struct kschain is a structure used for string accumulators that works by aggregating pointers to strings, instead of copying the strings themselves. * kschain_kind kind - kind of chain * kmkind rule - kind of allocation to use if kind ≠ kschain_kind_linked * pstr* ptrs - pointer to pointer list * size_t ptrc - number of pointers * size_t sz - total amount of space in ptrs

enum kschain_kind

• kschain_kind_block - occupies a single block of memory
• kschain_kind_linked - uses a linked list, allocated and deallocated as necessary

enum ksalloc

enum ksalloc is an enumerator that tells libk what strategy to use when filling a ksbuf or kschain struct. * ksalloc_static - do not allocate memory, fill an already-allocated, statically-sized array. * ksalloc_alloc - allocate a string in memory using the specified kind of allocator. * ksalloc_dynamic - fill an already-allocated array if possible, allocate a string in memory if the string length exceeds available space.

functions

kssz

size_t kssz(char* str, size_t max) returns the number of characters in a C string, including the final null. will count at most max characters if max > 0.

kstr

kstr kstr(char* str, size_t max) takes a C string and returns a P-string, calculating the length of str and storing it in the return value. max works as in kssz.

kstoraw

ksraw ksref(kstr) is a simple convenience function that returns the ksraw form of a kstr.

kscomp

char* kscomp(size_t ct, ksraw struct[], kmbuf* buf) is a string composition function. it serves as an efficient, generalized replacement for functions like strcat and strdup.

to use kscomp, create an array of kstr and fill it with the strings you wish to concatenate. for example, to programmatically generate an HTML link tag, you might use the following code.

char mem[512];
kmptr text = <...>;
char* src = <...>;
kmbuf buf = { sizeof mem, &mem, kmkind_none };
kstr chain[] = {
	Kstr("<a href=\""), { 0, src }, Kstr("\">"),
		ksref(text),
	Kstr("</a>")
};
char* html = kscomp([Kmsz(chain)](../kmem/kmem.md), chain, &buf);

kscomp will only calculate the length of individual strings if they are not already known. when it needs to calculate the length of a string, it will store that length in the original array so repeated calls can be made without needing to repeatedly calculate the lengths. this is not always desirable, so the variant kscompc exists, which is exactly the same as kscomp in every respect except that chain is not altered in any way.

macros

if KFclean is not set when <k/str.h> is included, the following macros are defined.

• Kstr(string) - the compile-time equivalent to kstr(). Kstr takes a literal string and inserts the text { sizeof (string), string } into the document, suitable for initializing a kstr.