Re: [9front] libjson can print invalid json

["Dave MacFarlane" <driusan@driusan.net>]

It certainly looks more elegant than my code, but when I tested it it's missing the
beginning and ending quote character of the json string.

After I added them, it passed the tests I wrote for my code.

static int
printstring(Fmt *f, char *s)
{
	int n;
	
	n = fmtrune(f, '"');
	for(; *s; s++){
		switch(*s){
		case '\\':	n += fmtstrcpy(f, "\\\\");	break;
		case '\f':	n += fmtstrcpy(f, "\\f");	break;
		case '\b':	n += fmtstrcpy(f, "\\b");	break;
		case '\n':	n += fmtstrcpy(f, "\\n");	break;
		case '\r':	n += fmtstrcpy(f, "\\r");	break;
		case '\"':	n += fmtstrcpy(f, "\\\"");	break;
		default:
			if(*s < 0x20)
				n += fmtprint(f, "\\u%04x", *s);
			else
				n += fmtrune(f, *s);
		}
	}
	n = fmtrune(f, '"');
	return n;
}

Here's what I used to test it:

#include <u.h>
#include <libc.h>
#include <json.h>

void testJSON(char *s) {
	print("%s\n", s);
	JSON *j = jsonparse(s);
	print("%J\n", j);
	char *str = smprint("%J", j);
	assert(jsonparse(str) != nil);
	free(j);
	free(str);
}
void main(void) {
	JSON *j;
	char *str;

	JSONfmtinstall();

	testJSON("{\"abc\": \"\"}");
	testJSON("{\"abc\": \"hello\"}");
	testJSON("{\"abc\": \"\\\"hello\"}");
	testJSON("{\"abc\": \"hello\\\"\"}");
	testJSON("{\"abc\": \"he\\\"llo\"}");
	testJSON("{\"abc\": \"\\\"he\\\"llo\\\"\"}");
	testJSON("{\"abc\": \"hello\\t\"}");
	exits("");
}