/*
* MD4C: Markdown parser for C
* (http://github.com/mity/md4c)
*
* Copyright (c) 2016-2019 Martin Mitas
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <stdio.h>
#include <string.h>
#include "md4c-html.h"
#include "entity.h"
#if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199409L
/* C89/90 or old compilers in general may not understand "inline". */
#if defined __GNUC__
#define inline __inline__
#elif defined _MSC_VER
#define inline __inline
#else
#define inline
#endif
#endif
#ifdef _WIN32
#define snprintf _snprintf
#endif
typedef struct MD_HTML_tag MD_HTML;
struct MD_HTML_tag {
void (*process_output)(const MD_CHAR*, MD_SIZE, void*);
void* userdata;
unsigned flags;
int image_nesting_level;
char escape_map[256];
};
#define NEED_HTML_ESC_FLAG 0x1
#define NEED_URL_ESC_FLAG 0x2
/*****************************************
*** HTML rendering helper functions ***
*****************************************/
#define ISDIGIT(ch) ('0' <= (ch) && (ch) <= '9')
#define ISLOWER(ch) ('a' <= (ch) && (ch) <= 'z')
#define ISUPPER(ch) ('A' <= (ch) && (ch) <= 'Z')
#define ISALNUM(ch) (ISLOWER(ch) || ISUPPER(ch) || ISDIGIT(ch))
static inline void
render_verbatim(MD_HTML* r, const MD_CHAR* text, MD_SIZE size)
{
r->process_output(text, size, r->userdata);
}
/* Keep this as a macro. Most compiler should then be smart enough to replace
* the strlen() call with a compile-time constant if the string is a C literal. */
#define RENDER_VERBATIM(r, verbatim) \
render_verbatim((r), (verbatim), (MD_SIZE) (strlen(verbatim)))
static void
render_html_escaped(MD_HTML* r, const MD_CHAR* data, MD_SIZE size)
{
MD_OFFSET beg = 0;
MD_OFFSET off = 0;
/* Some characters need to be escaped in normal HTML text. */
#define NEED_HTML_ESC(ch) (r->escape_map[(unsigned char)(ch)] & NEED_HTML_ESC_FLAG)
while(1) {
/* Optimization: Use some loop unrolling. */
while(off + 3 < size && !NEED_HTML_ESC(data[off+0]) && !NEED_HTML_ESC(data[off+1])
&& !NEED_HTML_ESC(data[off+2]) && !NEED_HTML_ESC(data[off+3]))
off += 4;
while(off < size && !NEED_HTML_ESC(data[off]))
off++;
if(off > beg)
render_verbatim(r, data + beg, off - beg);
if(off < size) {
switch(data[off]) {
case '&': RENDER_VERBATIM(r, "&"); break;
case '<': RENDER_VERBATIM(r, "<"); break;
case '>': RENDER_VERBATIM(r, ">"); break;
case '"': RENDER_VERBATIM(r, """); break;
}
off++;
} else {
break;
}
beg = off;
}
}
static void
render_url_escaped(MD_HTML* r, const MD_CHAR* data, MD_SIZE size)
{
static const MD_CHAR hex_chars[] = "0123456789ABCDEF";
MD_OFFSET beg = 0;
MD_OFFSET off = 0;
/* Some characters need to be escaped in URL attributes. */
#define NEED_URL_ESC(ch) (r->escape_map[(unsigned char)(ch)] & NEED_URL_ESC_FLAG)
while(1) {
while(off < size && !NEED_URL_ESC(data[off]))
off++;
if(off > beg)
render_verbatim(r, data + beg, off - beg);
if(off < size) {
char hex[3];
switch(data[off]) {
case '&': RENDER_VERBATIM(r, "&"); break;
default:
hex[0] = '%';
hex[1] = hex_chars[((unsigned)data[off] >> 4) & 0xf];
hex[2] = hex_chars[((unsigned)data[off] >> 0) & 0xf];
render_verbatim(r, hex, 3);
break;
}
off++;
} else {
break;
}
beg = off;
}
}
static unsigned
hex_val(char ch)
{
if('0' <= ch && ch <= '9')
return ch - '0';
if('A' <= ch && ch <= 'Z')
return ch - 'A' + 10;
else
return ch - 'a' + 10;
}
static void
render_utf8_codepoint(MD_HTML* r, unsigned codepoint,
void (*fn_append)(MD_HTML*, const MD_CHAR*, MD_SIZE))
{
static const MD_CHAR utf8_replacement_char[] = { 0xef, 0xbf, 0xbd };
unsigned char utf8[4];
size_t n;
if(codepoint <= 0x7f) {
n = 1;
utf8[0] = codepoint;
} else if(codepoint <= 0x7ff) {
n = 2;
utf8[0] = 0xc0 | ((codepoint >> 6) & 0x1f);
utf8[1] = 0x80 + ((codepoint >> 0) & 0x3f);
} else if(codepoint <= 0xffff) {
n = 3;
utf8[0] = 0xe0 | ((codepoint >> 12) & 0xf);
utf8[1] = 0x80 + ((codepoint >> 6) & 0x3f);
utf8[2] = 0x80 + ((codepoint >> 0) & 0x3f);
} else {
n = 4;
utf8[0] = 0xf0 | ((codepoint >> 18) & 0x7);
utf8[1] = 0x80 + ((codepoint >> 12) & 0x3f);
utf8[2] = 0x80 + ((codepoint >> 6) & 0x3f);
utf8[3] = 0x80 + ((codepoint >> 0) & 0x3f);
}
if(0 < codepoint && codepoint <= 0x10ffff)
fn_append(r, (char*)utf8, (MD_SIZE)n);
else
fn_append(r, utf8_replacement_char, 3);
}
/* Translate entity to its UTF-8 equivalent, or output the verbatim one
* if such entity is unknown (or if the translation is disabled). */
static void
render_entity(MD_HTML* r, const MD_CHAR* text, MD_SIZE size,
void (*fn_append)(MD_HTML*, const MD_CHAR*, MD_SIZE))
{
if(r->flags & MD_HTML_FLAG_VERBATIM_ENTITIES) {
render_verbatim(r, text, size);
return;
}
/* We assume UTF-8 output is what is desired. */
if(size > 3 && text[1] == '#') {
unsigned codepoint = 0;
if(text[2] == 'x' || text[2] == 'X') {
/* Hexadecimal entity (e.g. "�")). */
MD_SIZE i;
for(i = 3; i < size-1; i++)
codepoint = 16 * codepoint + hex_val(text[i]);
} else {
/* Decimal entity (e.g. "&1234;") */
MD_SIZE i;
for(i = 2; i < size-1; i++)
codepoint = 10 * codepoint + (text[i] - '0');
}
render_utf8_codepoint(r, codepoint, fn_append);
return;
} else {
/* Named entity (e.g. " "). */
const struct entity* ent;
ent = entity_lookup(text, size);
if(ent != NULL) {
render_utf8_codepoint(r, ent->codepoints[0], fn_append);
if(ent->codepoints[1])
render_utf8_codepoint(r, ent->codepoints[1], fn_append);
return;
}
}
fn_append(r, text, size);
}
static void
render_attribute(MD_HTML* r, const MD_ATTRIBUTE* attr,
void (*fn_append)(MD_HTML*, const MD_CHAR*, MD_SIZE))
{
int i;
for(i = 0; attr->substr_offsets[i] < attr->size; i++) {
MD_TEXTTYPE type = attr->substr_types[i];
MD_OFFSET off = attr->substr_offsets[i];
MD_SIZE size = attr->substr_offsets[i+1] - off;
const MD_CHAR* text = attr->text + off;
switch(type) {
case MD_TEXT_NULLCHAR: render_utf8_codepoint(r, 0x0000, render_verbatim); break;
case MD_TEXT_ENTITY: render_entity(r, text, size, fn_append); break;
default: fn_append(r, text, size); break;
}
}
}
static void
render_open_ol_block(MD_HTML* r, const MD_BLOCK_OL_DETAIL* det)
{
char buf[64];
if(det->start == 1) {
RENDER_VERBATIM(r, "<ol>\n");
return;
}
snprintf(buf, sizeof(buf), "<ol start=\"%u\">\n", det->start);
RENDER_VERBATIM(r, buf);
}
static void
render_open_li_block(MD_HTML* r, const MD_BLOCK_LI_DETAIL* det)
{
if(det->is_task) {
RENDER_VERBATIM(r, "<li class=\"task-list-item\">"
"<input type=\"checkbox\" class=\"task-list-item-checkbox\" disabled");
if(det->task_mark == 'x' || det->task_mark == 'X')
RENDER_VERBATIM(r, " checked");
RENDER_VERBATIM(r, ">");
} else {
RENDER_VERBATIM(r, "<li>");
}
}
static void
render_open_code_block(MD_HTML* r, const MD_BLOCK_CODE_DETAIL* det)
{
RENDER_VERBATIM(r, "<pre><code");
/* If known, output the HTML 5 attribute class="language-LANGNAME". */
if(det->lang.text != NULL) {
RENDER_VERBATIM(r, " class=\"language-");
render_attribute(r, &det->lang, render_html_escaped);
RENDER_VERBATIM(r, "\"");
}
RENDER_VERBATIM(r, ">");
}
static void
render_open_td_block(MD_HTML* r, const MD_CHAR* cell_type, const MD_BLOCK_TD_DETAIL* det)
{
RENDER_VERBATIM(r, "<");
RENDER_VERBATIM(r, cell_type);
switch(det->align) {
case MD_ALIGN_LEFT: RENDER_VERBATIM(r, " align=\"left\">"); break;
case MD_ALIGN_CENTER: RENDER_VERBATIM(r, " align=\"center\">"); break;
case MD_ALIGN_RIGHT: RENDER_VERBATIM(r, " align=\"right\">"); break;
default: RENDER_VERBATIM(r, ">"); break;
}
}
static void
render_open_a_span(MD_HTML* r, const MD_SPAN_A_DETAIL* det)
{
RENDER_VERBATIM(r, "<a href=\"");
render_attribute(r, &det->href, render_url_escaped);
if(det->title.text != NULL) {
RENDER_VERBATIM(r, "\" title=\"");
render_attribute(r, &det->title, render_html_escaped);
}
RENDER_VERBATIM(r, "\">");
}
static void
render_open_img_span(MD_HTML* r, const MD_SPAN_IMG_DETAIL* det)
{
RENDER_VERBATIM(r, "<img src=\"");
render_attribute(r, &det->src, render_url_escaped);
RENDER_VERBATIM(r, "\" alt=\"");
r->image_nesting_level++;
}
static void
render_close_img_span(MD_HTML* r, const MD_SPAN_IMG_DETAIL* det)
{
if(det->title.text != NULL) {
RENDER_VERBATIM(r, "\" title=\"");
render_attribute(r, &det->title, render_html_escaped);
}
RENDER_VERBATIM(r, (r->flags & MD_HTML_FLAG_XHTML) ? "\" />" : "\">");
r->image_nesting_level--;
}
static void
render_open_wikilink_span(MD_HTML* r, const MD_SPAN_WIKILINK_DETAIL* det)
{
RENDER_VERBATIM(r, "<x-wikilink data-target=\"");
render_attribute(r, &det->target, render_html_escaped);
RENDER_VERBATIM(r, "\">");
}
/**************************************
*** HTML renderer implementation ***
**************************************/
static int
enter_block_callback(MD_BLOCKTYPE type, void* detail, void* userdata)
{
static const MD_CHAR* head[6] = { "<h1>", "<h2>", "<h3>", "<h4>", "<h5>", "<h6>" };
MD_HTML* r = (MD_HTML*) userdata;
switch(type) {
case MD_BLOCK_DOC: /* noop */ break;
case MD_BLOCK_QUOTE: RENDER_VERBATIM(r, "<blockquote>\n"); break;
case MD_BLOCK_UL: RENDER_VERBATIM(r, "<ul>\n"); break;
case MD_BLOCK_OL: render_open_ol_block(r, (const MD_BLOCK_OL_DETAIL*)detail); break;
case MD_BLOCK_LI: render_open_li_block(r, (const MD_BLOCK_LI_DETAIL*)detail); break;
case MD_BLOCK_HR: RENDER_VERBATIM(r, (r->flags & MD_HTML_FLAG_XHTML) ? "<hr />\n" : "<hr>\n"); break;
case MD_BLOCK_H: RENDER_VERBATIM(r, head[((MD_BLOCK_H_DETAIL*)detail)->level - 1]); break;
case MD_BLOCK_CODE: render_open_code_block(r, (const MD_BLOCK_CODE_DETAIL*) detail); break;
case MD_BLOCK_HTML: /* noop */ break;
case MD_BLOCK_P: RENDER_VERBATIM(r, "<p>"); break;
case MD_BLOCK_TABLE: RENDER_VERBATIM(r, "<table>\n"); break;
case MD_BLOCK_THEAD: RENDER_VERBATIM(r, "<thead>\n"); break;
case MD_BLOCK_TBODY: RENDER_VERBATIM(r, "<tbody>\n"); break;
case MD_BLOCK_TR: RENDER_VERBATIM(r, "<tr>\n"); break;
case MD_BLOCK_TH: render_open_td_block(r, "th", (MD_BLOCK_TD_DETAIL*)detail); break;
case MD_BLOCK_TD: render_open_td_block(r, "td", (MD_BLOCK_TD_DETAIL*)detail); break;
}
return 0;
}
static int
leave_block_callback(MD_BLOCKTYPE type, void* detail, void* userdata)
{
static const MD_CHAR* head[6] = { "</h1>\n", "</h2>\n", "</h3>\n", "</h4>\n", "</h5>\n", "</h6>\n" };
MD_HTML* r = (MD_HTML*) userdata;
switch(type) {
case MD_BLOCK_DOC: /*noop*/ break;
case MD_BLOCK_QUOTE: RENDER_VERBATIM(r, "</blockquote>\n"); break;
case MD_BLOCK_UL: RENDER_VERBATIM(r, "</ul>\n"); break;
case MD_BLOCK_OL: RENDER_VERBATIM(r, "</ol>\n"); break;
case MD_BLOCK_LI: RENDER_VERBATIM(r, "</li>\n"); break;
case MD_BLOCK_HR: /*noop*/ break;
case MD_BLOCK_H: RENDER_VERBATIM(r, head[((MD_BLOCK_H_DETAIL*)detail)->level - 1]); break;
case MD_BLOCK_CODE: RENDER_VERBATIM(r, "</code></pre>\n"); break;
case MD_BLOCK_HTML: /* noop */ break;
case MD_BLOCK_P: RENDER_VERBATIM(r, "</p>\n"); break;
case MD_BLOCK_TABLE: RENDER_VERBATIM(r, "</table>\n"); break;
case MD_BLOCK_THEAD: RENDER_VERBATIM(r, "</thead>\n"); break;
case MD_BLOCK_TBODY: RENDER_VERBATIM(r, "</tbody>\n"); break;
case MD_BLOCK_TR: RENDER_VERBATIM(r, "</tr>\n"); break;
case MD_BLOCK_TH: RENDER_VERBATIM(r, "</th>\n"); break;
case MD_BLOCK_TD: RENDER_VERBATIM(r, "</td>\n"); break;
}
return 0;
}
static int
enter_span_callback(MD_SPANTYPE type, void* detail, void* userdata)
{
MD_HTML* r = (MD_HTML*) userdata;
if(r->image_nesting_level > 0) {
/* We are inside a Markdown image label. Markdown allows to use any
* emphasis and other rich contents in that context similarly as in
* any link label.
*
* However, unlike in the case of links (where that contents becomes
* contents of the <a>...</a> tag), in the case of images the contents
* is supposed to fall into the attribute alt: <img alt="...">.
*
* In that context we naturally cannot output nested HTML tags. So lets
* suppress them and only output the plain text (i.e. what falls into
* text() callback).
*
* This make-it-a-plain-text approach is the recommended practice by
* CommonMark specification (for HTML output).
*/
return 0;
}
switch(type) {
case MD_SPAN_EM: RENDER_VERBATIM(r, "<em>"); break;
case MD_SPAN_STRONG: RENDER_VERBATIM(r, "<strong>"); break;
case MD_SPAN_U: RENDER_VERBATIM(r, "<u>"); break;
case MD_SPAN_A: render_open_a_span(r, (MD_SPAN_A_DETAIL*) detail); break;
case MD_SPAN_IMG: render_open_img_span(r, (MD_SPAN_IMG_DETAIL*) detail); break;
case MD_SPAN_CODE: RENDER_VERBATIM(r, "<code>"); break;
case MD_SPAN_DEL: RENDER_VERBATIM(r, "<del>"); break;
case MD_SPAN_LATEXMATH: RENDER_VERBATIM(r, "<x-equation>"); break;
case MD_SPAN_LATEXMATH_DISPLAY: RENDER_VERBATIM(r, "<x-equation type=\"display\">"); break;
case MD_SPAN_WIKILINK: render_open_wikilink_span(r, (MD_SPAN_WIKILINK_DETAIL*) detail); break;
}
return 0;
}
static int
leave_span_callback(MD_SPANTYPE type, void* detail, void* userdata)
{
MD_HTML* r = (MD_HTML*) userdata;
if(r->image_nesting_level > 0) {
/* Ditto as in enter_span_callback(), except we have to allow the
* end of the <img> tag. */
if(r->image_nesting_level == 1 && type == MD_SPAN_IMG)
render_close_img_span(r, (MD_SPAN_IMG_DETAIL*) detail);
return 0;
}
switch(type) {
case MD_SPAN_EM: RENDER_VERBATIM(r, "</em>"); break;
case MD_SPAN_STRONG: RENDER_VERBATIM(r, "</strong>"); break;
case MD_SPAN_U: RENDER_VERBATIM(r, "</u>"); break;
case MD_SPAN_A: RENDER_VERBATIM(r, "</a>"); break;
case MD_SPAN_IMG: /*noop, handled above*/ break;
case MD_SPAN_CODE: RENDER_VERBATIM(r, "</code>"); break;
case MD_SPAN_DEL: RENDER_VERBATIM(r, "</del>"); break;
case MD_SPAN_LATEXMATH: /*fall through*/
case MD_SPAN_LATEXMATH_DISPLAY: RENDER_VERBATIM(r, "</x-equation>"); break;
case MD_SPAN_WIKILINK: RENDER_VERBATIM(r, "</x-wikilink>"); break;
}
return 0;
}
static int
text_callback(MD_TEXTTYPE type, const MD_CHAR* text, MD_SIZE size, void* userdata)
{
MD_HTML* r = (MD_HTML*) userdata;
switch(type) {
case MD_TEXT_NULLCHAR: render_utf8_codepoint(r, 0x0000, render_verbatim); break;
case MD_TEXT_BR: RENDER_VERBATIM(r, (r->image_nesting_level == 0
? ((r->flags & MD_HTML_FLAG_XHTML) ? "<br />\n" : "<br>\n")
: " "));
break;
case MD_TEXT_SOFTBR: RENDER_VERBATIM(r, (r->image_nesting_level == 0 ? "\n" : " ")); break;
case MD_TEXT_HTML: render_verbatim(r, text, size); break;
case MD_TEXT_ENTITY: render_entity(r, text, size, render_html_escaped); break;
default: render_html_escaped(r, text, size); break;
}
return 0;
}
static void
debug_log_callback(const char* msg, void* userdata)
{
MD_HTML* r = (MD_HTML*) userdata;
if(r->flags & MD_HTML_FLAG_DEBUG)
fprintf(stderr, "MD4C: %s\n", msg);
}
int
md_html(const MD_CHAR* input, MD_SIZE input_size,
void (*process_output)(const MD_CHAR*, MD_SIZE, void*),
void* userdata, unsigned parser_flags, unsigned renderer_flags)
{
MD_HTML render = { process_output, userdata, renderer_flags, 0, { 0 } };
int i;
MD_PARSER parser = {
0,
parser_flags,
enter_block_callback,
leave_block_callback,
enter_span_callback,
leave_span_callback,
text_callback,
debug_log_callback,
NULL
};
/* Build map of characters which need escaping. */
for(i = 0; i < 256; i++) {
unsigned char ch = (unsigned char) i;
if(strchr("\"&<>", ch) != NULL)
render.escape_map[i] |= NEED_HTML_ESC_FLAG;
if(!ISALNUM(ch) && strchr("~-_.+!*(),%#@?=;:/,+$", ch) == NULL)
render.escape_map[i] |= NEED_URL_ESC_FLAG;
}
/* Consider skipping UTF-8 byte order mark (BOM). */
if(renderer_flags & MD_HTML_FLAG_SKIP_UTF8_BOM && sizeof(MD_CHAR) == 1) {
static const MD_CHAR bom[3] = { 0xef, 0xbb, 0xbf };
if(input_size >= sizeof(bom) && memcmp(input, bom, sizeof(bom)) == 0) {
input += sizeof(bom);
input_size -= sizeof(bom);
}
}
return md_parse(input, input_size, &parser, (void*) &render);
}