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[csv iterate] string-builder iterate

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This commit is contained in:
John Kerl 2015-08-22 21:08:49 -04:00
parent e5c8f53e3c
commit 5da855c331
2 changed files with 19 additions and 9 deletions
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9
c/csv-rfc.txt
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@ -1,6 +1,13 @@
================================================================
--> parser option: write a grammar like the below. be careful to
preserve the streaming property!
--> I don't see a way to line-at-a-time it in the formal grammar.
Other option is to find end of line via string arithmetic,
then pass that (null-terminated) string to the parser. But
correctly determining EOL in the presence of double-quote
semantics *is* the problem; nothing interesting left for the
parser to do.
--> state-machine option:
* each field either does or does not begin & end w/ "
@ -24,6 +31,8 @@
public fcn append_char, public fcn append_string,
private fcn realloc resizing with minimal copy, public fcn zterm & produce.
================================================================
Offlineable (subway-tunnelable) excerpt from https://tools.ietf.org/html/rfc4180
================================================================
Definition of the CSV Format

19
c/lib/string_builder.c
View file

@ -4,14 +4,10 @@
#include "../lib/mlrutil.h"
#include "../lib/mlr_globals.h"
// Private method:
static void sb_enlarge(string_builder_t* psb);
// typedef struct _string_builder_t {
// int used_length;
// int alloc_length;
// char* buffer;
// } string_builder_t;
// ----------------------------------------------------------------
void sb_init(string_builder_t* psb, int alloc_length) {
if (alloc_length < 1) {
fprintf(stderr, "%s: string_builder alloc_length must be >= 1; got %d.\n",
@ -23,26 +19,31 @@ void sb_init(string_builder_t* psb, int alloc_length) {
psb->buffer = mlr_malloc_or_die(alloc_length); // xxx malloc ...
}
// ----------------------------------------------------------------
void sb_append_char(string_builder_t* psb, char c) {
if (psb->used_length >= psb->alloc_length)
sb_enlarge(psb);
psb->buffer[psb->used_length++] = c;
}
// ----------------------------------------------------------------
void sb_append_string(string_builder_t* psb, char* s) {
for (char* p = s; *p; p++)
sb_append_char(psb, *p);
}
// ----------------------------------------------------------------
// Keep and reuse the internal buffer. Allocate to the caller only
// the size needed.
char* sb_finish(string_builder_t* psb) {
sb_append_char(psb, '\0');
char* rv = psb->buffer;
char* rv = mlr_malloc_or_die(psb->used_length);
memcpy(rv, psb->buffer, psb->used_length);
psb->used_length = 0;
psb->alloc_length = 0;
psb->buffer = NULL;
return rv;
}
// ----------------------------------------------------------------
static void sb_enlarge(string_builder_t* psb) {
int new_alloc_length = psb->alloc_length * 2;
char* new_buffer = mlr_malloc_or_die(new_alloc_length);