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#include "creole.h"
#include <assert.h>
#include <ctype.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#define LENGTH(x) (sizeof(x)/sizeof((x)[0]))
#define DEBUG(...) (fprintf(stderr, __VA_ARGS__), fflush(stderr))
void process(const char *begin, const char *end, bool new_block, FILE *out);
int do_headers(const char *begin, const char *end, bool new_block, FILE *out);
int do_paragraph(const char *begin, const char *end, bool new_block, FILE *out);
// A parser takes a (sub)string and returns the number of characters consumed, if any.
//
// The parameter `new_block` determines whether `begin` points to the beginning of a new block.
// The sign of the return value determines whether a new block should begin, after the consumed text.
typedef int (* parser_t)(const char *begin, const char *end, bool new_block, FILE *out);
static parser_t parsers[] = { do_headers, do_paragraph };
int do_headers(const char *begin, const char *end, bool new_block, FILE *out) {
if (!new_block) { // Headers are block-level elements.
return 0;
}
if (*begin != '=') {
return 0;
}
unsigned level = 0;
const char *start = begin;
while (*start == '=') {
level += 1;
start += 1;
}
if (level > 6) {
return 0;
}
while (isspace(*start)) {
start += 1;
}
const char *eol = start;
while (eol != end && *eol != '\n') {
eol += 1;
}
const char *stop = eol;
assert(stop > begin);
while (stop[-1] == '=' || isspace(stop[-1])) {
stop -= 1;
}
fprintf(out, "<h%u>", level);
process(start, stop, false, out);
fprintf(out, "</h%u>", level);
return -(eol - begin);
}
int do_paragraph(const char *begin, const char *end, bool new_block, FILE *out) {
if (!new_block) { // Paragraphs are block-level elements.
return 0;
}
const char *stop = begin + 1;
while (stop + 1 < end) {
if (stop[0] == '\n' && stop[1] == '\n') {
goto found_double_newline;
} else {
stop += 1;
}
}
stop = end;
found_double_newline:
fputs("<p>", out);
process(begin, stop, false, out);
fputs("</p>", out);
return -(stop - begin);
}
void process(const char *begin, const char *end, bool new_block, FILE *out) {
const char *p = begin;
while (p < end) {
// Eat all newlines if we're starting a block.
if (new_block) {
while (*p == '\n') {
p += 1;
if (p == end) {
return;
}
}
}
// Greedily try all parsers.
int affected;
for (unsigned i = 0; i < LENGTH(parsers); ++i) {
affected = parsers[i](p, end, new_block, out);
if (affected) {
break;
}
}
if (affected) {
p += abs(affected);
} else {
fputc(*p, out);
p += 1;
}
if (p + 1 == end) {
// Don't print single newline at end.
if (*p == '\n') {
return;
}
} else {
// Determine whether we've reached a new block.
if (p[0] == '\n' && p[1] == '\n') {
// Double newline characters separate blocks;
// if we've found them, we're starting a new block
new_block = true;
} else {
// ...otherwise the parser gets to decide.
new_block = affected < 0;
}
}
}
}
void render_creole(FILE *out, const char *source, size_t source_length)
{
process(source, source + source_length, true, out);
}
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