text: /* markdown.c - generic markdown parser */
  
  /*
   * Copyright (c) 2009, Natacha Porté
   * Copyright (c) 2011, Vicent Marti
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include "markdown.h"
  #include "stack.h"
  
  #include <assert.h>
  #include <string.h>
  #include <ctype.h>
  #include <stdio.h>
  
  #if defined(_WIN32)
  #define strncasecmp	_strnicmp
  #endif
  
  #define REF_TABLE_SIZE 8
  
  #define BUFFER_BLOCK 0
  #define BUFFER_SPAN 1
  
  #define MKD_LI_END 8	/* internal list flag */
  
  #define gperf_case_strncmp(s1, s2, n) strncasecmp(s1, s2, n)
  #define GPERF_DOWNCASE 1
  #define GPERF_CASE_STRNCMP 1
  #include "html_blocks.h"
  
  /***************
   * LOCAL TYPES *
   ***************/
  
  /* link_ref: reference to a link */
  struct link_ref {
  	unsigned int id;
  
  	struct buf *link;
  	struct buf *title;
  
  	struct link_ref *next;
  };
  
  /* char_trigger: function pointer to render active chars */
  /*   returns the number of chars taken care of */
  /*   data is the pointer of the beginning of the span */
  /*   offset is the number of valid chars before data */
  struct sd_markdown;
  typedef size_t
  (*char_trigger)(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  
  static size_t char_emphasis(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_linebreak(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_codespan(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_escape(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_entity(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_langle_tag(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_autolink_url(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_autolink_email(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_autolink_www(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_link(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  static size_t char_superscript(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
  
  enum markdown_char_t {
  	MD_CHAR_NONE = 0,
  	MD_CHAR_EMPHASIS,
  	MD_CHAR_CODESPAN,
  	MD_CHAR_LINEBREAK,
  	MD_CHAR_LINK,
  	MD_CHAR_LANGLE,
  	MD_CHAR_ESCAPE,
  	MD_CHAR_ENTITITY,
  	MD_CHAR_AUTOLINK_URL,
  	MD_CHAR_AUTOLINK_EMAIL,
  	MD_CHAR_AUTOLINK_WWW,
  	MD_CHAR_SUPERSCRIPT,
  };
  
  static char_trigger markdown_char_ptrs[] = {
  	NULL,
  	&char_emphasis,
  	&char_codespan,
  	&char_linebreak,
  	&char_link,
  	&char_langle_tag,
  	&char_escape,
  	&char_entity,
  	&char_autolink_url,
  	&char_autolink_email,
  	&char_autolink_www,
  	&char_superscript,
  };
  
  /* render • structure containing one particular render */
  struct sd_markdown {
  	struct sd_callbacks	cb;
  	void *opaque;
  
  	struct link_ref *refs[REF_TABLE_SIZE];
  	uint8_t active_char[256];
  	struct stack work_bufs[2];
  	unsigned int ext_flags;
  	size_t max_nesting;
  	int in_link_body;
  };
  
  /***************************
   * HELPER FUNCTIONS *
   ***************************/
  
  static inline struct buf *
  rndr_newbuf(struct sd_markdown *rndr, int type)
  {
  	static const size_t buf_size[2] = {256, 64};
  	struct buf *work = NULL;
  	struct stack *pool = &rndr->work_bufs[type];
  
  	if (pool->size < pool->asize &&
  		pool->item[pool->size] != NULL) {
  		work = pool->item[pool->size++];
  		work->size = 0;
  	} else {
  		work = bufnew(buf_size[type]);
  		stack_push(pool, work);
  	}
  
  	return work;
  }
  
  static inline void
  rndr_popbuf(struct sd_markdown *rndr, int type)
  {
  	rndr->work_bufs[type].size--;
  }
  
  static void
  unscape_text(struct buf *ob, struct buf *src)
  {
  	size_t i = 0, org;
  	while (i < src->size) {
  		org = i;
  		while (i < src->size && src->data[i] != '\\')
  			i++;
  
  		if (i > org)
  			bufput(ob, src->data + org, i - org);
  
  		if (i + 1 >= src->size)
  			break;
  
  		bufputc(ob, src->data[i + 1]);
  		i += 2;
  	}
  }
  
  static unsigned int
  hash_link_ref(const uint8_t *link_ref, size_t length)
  {
  	size_t i;
  	unsigned int hash = 0;
  
  	for (i = 0; i < length; ++i)
  		hash = tolower(link_ref[i]) + (hash << 6) + (hash << 16) - hash;
  
  	return hash;
  }
  
  static struct link_ref *
  add_link_ref(
  	struct link_ref **references,
  	const uint8_t *name, size_t name_size)
  {
  	struct link_ref *ref = calloc(1, sizeof(struct link_ref));
  
  	if (!ref)
  		return NULL;
  
  	ref->id = hash_link_ref(name, name_size);
  	ref->next = references[ref->id % REF_TABLE_SIZE];
  
  	references[ref->id % REF_TABLE_SIZE] = ref;
  	return ref;
  }
  
  static struct link_ref *
  find_link_ref(struct link_ref **references, uint8_t *name, size_t length)
  {
  	unsigned int hash = hash_link_ref(name, length);
  	struct link_ref *ref = NULL;
  
  	ref = references[hash % REF_TABLE_SIZE];
  
  	while (ref != NULL) {
  		if (ref->id == hash)
  			return ref;
  
  		ref = ref->next;
  	}
  
  	return NULL;
  }
  
  static void
  free_link_refs(struct link_ref **references)
  {
  	size_t i;
  
  	for (i = 0; i < REF_TABLE_SIZE; ++i) {
  		struct link_ref *r = references[i];
  		struct link_ref *next;
  
  		while (r) {
  			next = r->next;
  			bufrelease(r->link);
  			bufrelease(r->title);
  			free(r);
  			r = next;
  		}
  	}
  }
  
  /*
   * Check whether a char is a Markdown space.
  
   * Right now we only consider spaces the actual
   * space and a newline: tabs and carriage returns
   * are filtered out during the preprocessing phase.
   *
   * If we wanted to actually be UTF-8 compliant, we
   * should instead extract an Unicode codepoint from
   * this character and check for space properties.
   */
  static inline int
  _isspace(int c)
  {
  	return c == ' ' || c == '\n';
  }
  
  /****************************
   * INLINE PARSING FUNCTIONS *
   ****************************/
  
  /* is_mail_autolink • looks for the address part of a mail autolink and '>' */
  /* this is less strict than the original markdown e-mail address matching */
  static size_t
  is_mail_autolink(uint8_t *data, size_t size)
  {
  	size_t i = 0, nb = 0;
  
  	/* address is assumed to be: [-@._a-zA-Z0-9]+ with exactly one '@' */
  	for (i = 0; i < size; ++i) {
  		if (isalnum(data[i]))
  			continue;
  
  		switch (data[i]) {
  			case '@':
  				nb++;
  
  			case '-':
  			case '.':
  			case '_':
  				break;
  
  			case '>':
  				return (nb == 1) ? i + 1 : 0;
  
  			default:
  				return 0;
  		}
  	}
  
  	return 0;
  }
  
  /* tag_length • returns the length of the given tag, or 0 is it's not valid */
  static size_t
  tag_length(uint8_t *data, size_t size, enum mkd_autolink *autolink)
  {
  	size_t i, j;
  
  	/* a valid tag can't be shorter than 3 chars */
  	if (size < 3) return 0;
  
  	/* begins with a '<' optionally followed by '/', followed by letter or number */
  	if (data[0] != '<') return 0;
  	i = (data[1] == '/') ? 2 : 1;
  
  	if (!isalnum(data[i]))
  		return 0;
  
  	/* scheme test */
  	*autolink = MKDA_NOT_AUTOLINK;
  
  	/* try to find the beginning of an URI */
  	while (i < size && (isalnum(data[i]) || data[i] == '.' || data[i] == '+' || data[i] == '-'))
  		i++;
  
  	if (i > 1 && data[i] == '@') {
  		if ((j = is_mail_autolink(data + i, size - i)) != 0) {
  			*autolink = MKDA_EMAIL;
  			return i + j;
  		}
  	}
  
  	if (i > 2 && data[i] == ':') {
  		*autolink = MKDA_NORMAL;
  		i++;
  	}
  
  	/* completing autolink test: no whitespace or ' or " */
  	if (i >= size)
  		*autolink = MKDA_NOT_AUTOLINK;
  
  	else if (*autolink) {
  		j = i;
  
  		while (i < size) {
  			if (data[i] == '\\') i += 2;
  			else if (data[i] == '>' || data[i] == '\'' ||
  					data[i] == '"' || data[i] == ' ' || data[i] == '\n')
  					break;
  			else i++;
  		}
  
  		if (i >= size) return 0;
  		if (i > j && data[i] == '>') return i + 1;
  		/* one of the forbidden chars has been found */
  		*autolink = MKDA_NOT_AUTOLINK;
  	}
  
  	/* looking for sometinhg looking like a tag end */
  	while (i < size && data[i] != '>') i++;
  	if (i >= size) return 0;
  	return i + 1;
  }
  
  /* parse_inline • parses inline markdown elements */
  static void
  parse_inline(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	size_t i = 0, end = 0;
  	uint8_t action = 0;
  	struct buf work = { 0, 0, 0, 0 };
  
  	if (rndr->work_bufs[BUFFER_SPAN].size +
  		rndr->work_bufs[BUFFER_BLOCK].size > rndr->max_nesting)
  		return;
  
  	while (i < size) {
  		/* copying inactive chars into the output */
  		while (end < size && (action = rndr->active_char[data[end]]) == 0) {
  			end++;
  		}
  
  		if (rndr->cb.normal_text) {
  			work.data = data + i;
  			work.size = end - i;
  			rndr->cb.normal_text(ob, &work, rndr->opaque);
  		}
  		else
  			bufput(ob, data + i, end - i);
  
  		if (end >= size) break;
  		i = end;
  
  		end = markdown_char_ptrs[(int)action](ob, rndr, data + i, i, size - i);
  		if (!end) /* no action from the callback */
  			end = i + 1;
  		else {
  			i += end;
  			end = i;
  		}
  	}
  }
  
  /* find_emph_char • looks for the next emph uint8_t, skipping other constructs */
  static size_t
  find_emph_char(uint8_t *data, size_t size, uint8_t c)
  {
  	size_t i = 1;
  
  	while (i < size) {
  		while (i < size && data[i] != c && data[i] != '`' && data[i] != '[')
  			i++;
  
  		if (i == size)
  			return 0;
  
  		if (data[i] == c)
  			return i;
  
  		/* not counting escaped chars */
  		if (i && data[i - 1] == '\\') {
  			i++; continue;
  		}
  
  		if (data[i] == '`') {
  			size_t span_nb = 0, bt;
  			size_t tmp_i = 0;
  
  			/* counting the number of opening backticks */
  			while (i < size && data[i] == '`') {
  				i++; span_nb++;
  			}
  
  			if (i >= size) return 0;
  
  			/* finding the matching closing sequence */
  			bt = 0;
  			while (i < size && bt < span_nb) {
  				if (!tmp_i && data[i] == c) tmp_i = i;
  				if (data[i] == '`') bt++;
  				else bt = 0;
  				i++;
  			}
  
  			if (i >= size) return tmp_i;
  		}
  		/* skipping a link */
  		else if (data[i] == '[') {
  			size_t tmp_i = 0;
  			uint8_t cc;
  
  			i++;
  			while (i < size && data[i] != ']') {
  				if (!tmp_i && data[i] == c) tmp_i = i;
  				i++;
  			}
  
  			i++;
  			while (i < size && (data[i] == ' ' || data[i] == '\n'))
  				i++;
  
  			if (i >= size)
  				return tmp_i;
  
  			switch (data[i]) {
  			case '[':
  				cc = ']'; break;
  
  			case '(':
  				cc = ')'; break;
  
  			default:
  				if (tmp_i)
  					return tmp_i;
  				else
  					continue;
  			}
  
  			i++;
  			while (i < size && data[i] != cc) {
  				if (!tmp_i && data[i] == c) tmp_i = i;
  				i++;
  			}
  
  			if (i >= size)
  				return tmp_i;
  
  			i++;
  		}
  	}
  
  	return 0;
  }
  
  /* parse_emph1 • parsing single emphase */
  /* closed by a symbol not preceded by whitespace and not followed by symbol */
  static size_t
  parse_emph1(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, uint8_t c)
  {
  	size_t i = 0, len;
  	struct buf *work = 0;
  	int r;
  
  	if (!rndr->cb.emphasis) return 0;
  
  	/* skipping one symbol if coming from emph3 */
  	if (size > 1 && data[0] == c && data[1] == c) i = 1;
  
  	while (i < size) {
  		len = find_emph_char(data + i, size - i, c);
  		if (!len) return 0;
  		i += len;
  		if (i >= size) return 0;
  
  		if (data[i] == c && !_isspace(data[i - 1])) {
  
  			if (rndr->ext_flags & MKDEXT_NO_INTRA_EMPHASIS) {
  				if (!(i + 1 == size || _isspace(data[i + 1]) || ispunct(data[i + 1])))
  					continue;
  			}
  
  			work = rndr_newbuf(rndr, BUFFER_SPAN);
  			parse_inline(work, rndr, data, i);
  			r = rndr->cb.emphasis(ob, work, rndr->opaque);
  			rndr_popbuf(rndr, BUFFER_SPAN);
  			return r ? i + 1 : 0;
  		}
  	}
  
  	return 0;
  }
  
  /* parse_emph2 • parsing single emphase */
  static size_t
  parse_emph2(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, uint8_t c)
  {
  	int (*render_method)(struct buf *ob, const struct buf *text, void *opaque);
  	size_t i = 0, len;
  	struct buf *work = 0;
  	int r;
  
  	render_method = (c == '~') ? rndr->cb.strikethrough : rndr->cb.double_emphasis;
  
  	if (!render_method)
  		return 0;
  
  	while (i < size) {
  		len = find_emph_char(data + i, size - i, c);
  		if (!len) return 0;
  		i += len;
  
  		if (i + 1 < size && data[i] == c && data[i + 1] == c && i && !_isspace(data[i - 1])) {
  			work = rndr_newbuf(rndr, BUFFER_SPAN);
  			parse_inline(work, rndr, data, i);
  			r = render_method(ob, work, rndr->opaque);
  			rndr_popbuf(rndr, BUFFER_SPAN);
  			return r ? i + 2 : 0;
  		}
  		i++;
  	}
  	return 0;
  }
  
  /* parse_emph3 • parsing single emphase */
  /* finds the first closing tag, and delegates to the other emph */
  static size_t
  parse_emph3(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, uint8_t c)
  {
  	size_t i = 0, len;
  	int r;
  
  	while (i < size) {
  		len = find_emph_char(data + i, size - i, c);
  		if (!len) return 0;
  		i += len;
  
  		/* skip whitespace preceded symbols */
  		if (data[i] != c || _isspace(data[i - 1]))
  			continue;
  
  		if (i + 2 < size && data[i + 1] == c && data[i + 2] == c && rndr->cb.triple_emphasis) {
  			/* triple symbol found */
  			struct buf *work = rndr_newbuf(rndr, BUFFER_SPAN);
  
  			parse_inline(work, rndr, data, i);
  			r = rndr->cb.triple_emphasis(ob, work, rndr->opaque);
  			rndr_popbuf(rndr, BUFFER_SPAN);
  			return r ? i + 3 : 0;
  
  		} else if (i + 1 < size && data[i + 1] == c) {
  			/* double symbol found, handing over to emph1 */
  			len = parse_emph1(ob, rndr, data - 2, size + 2, c);
  			if (!len) return 0;
  			else return len - 2;
  
  		} else {
  			/* single symbol found, handing over to emph2 */
  			len = parse_emph2(ob, rndr, data - 1, size + 1, c);
  			if (!len) return 0;
  			else return len - 1;
  		}
  	}
  	return 0;
  }
  
  /* char_emphasis • single and double emphasis parsing */
  static size_t
  char_emphasis(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	uint8_t c = data[0];
  	size_t ret;
  
  	if (size > 2 && data[1] != c) {
  		/* whitespace cannot follow an opening emphasis;
  		 * strikethrough only takes two characters '~~' */
  		if (c == '~' || _isspace(data[1]) || (ret = parse_emph1(ob, rndr, data + 1, size - 1, c)) == 0)
  			return 0;
  
  		return ret + 1;
  	}
  
  	if (size > 3 && data[1] == c && data[2] != c) {
  		if (_isspace(data[2]) || (ret = parse_emph2(ob, rndr, data + 2, size - 2, c)) == 0)
  			return 0;
  
  		return ret + 2;
  	}
  
  	if (size > 4 && data[1] == c && data[2] == c && data[3] != c) {
  		if (c == '~' || _isspace(data[3]) || (ret = parse_emph3(ob, rndr, data + 3, size - 3, c)) == 0)
  			return 0;
  
  		return ret + 3;
  	}
  
  	return 0;
  }
  
  
  /* char_linebreak • '\n' preceded by two spaces (assuming linebreak != 0) */
  static size_t
  char_linebreak(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	if (offset < 2 || data[-1] != ' ' || data[-2] != ' ')
  		return 0;
  
  	/* removing the last space from ob and rendering */
  	while (ob->size && ob->data[ob->size - 1] == ' ')
  		ob->size--;
  
  	return rndr->cb.linebreak(ob, rndr->opaque) ? 1 : 0;
  }
  
  
  /* char_codespan • '`' parsing a code span (assuming codespan != 0) */
  static size_t
  char_codespan(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	size_t end, nb = 0, i, f_begin, f_end;
  
  	/* counting the number of backticks in the delimiter */
  	while (nb < size && data[nb] == '`')
  		nb++;
  
  	/* finding the next delimiter */
  	i = 0;
  	for (end = nb; end < size && i < nb; end++) {
  		if (data[end] == '`') i++;
  		else i = 0;
  	}
  
  	if (i < nb && end >= size)
  		return 0; /* no matching delimiter */
  
  	/* trimming outside whitespaces */
  	f_begin = nb;
  	while (f_begin < end && data[f_begin] == ' ')
  		f_begin++;
  
  	f_end = end - nb;
  	while (f_end > nb && data[f_end-1] == ' ')
  		f_end--;
  
  	/* real code span */
  	if (f_begin < f_end) {
  		struct buf work = { data + f_begin, f_end - f_begin, 0, 0 };
  		if (!rndr->cb.codespan(ob, &work, rndr->opaque))
  			end = 0;
  	} else {
  		if (!rndr->cb.codespan(ob, 0, rndr->opaque))
  			end = 0;
  	}
  
  	return end;
  }
  
  
  /* char_escape • '\\' backslash escape */
  static size_t
  char_escape(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	static const char *escape_chars = "\\`*_{}[]()#+-.!:|&<>^~";
  	struct buf work = { 0, 0, 0, 0 };
  
  	if (size > 1) {
  		if (strchr(escape_chars, data[1]) == NULL)
  			return 0;
  
  		if (rndr->cb.normal_text) {
  			work.data = data + 1;
  			work.size = 1;
  			rndr->cb.normal_text(ob, &work, rndr->opaque);
  		}
  		else bufputc(ob, data[1]);
  	} else if (size == 1) {
  		bufputc(ob, data[0]);
  	}
  
  	return 2;
  }
  
  /* char_entity • '&' escaped when it doesn't belong to an entity */
  /* valid entities are assumed to be anything matching &#?[A-Za-z0-9]+; */
  static size_t
  char_entity(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	size_t end = 1;
  	struct buf work = { 0, 0, 0, 0 };
  
  	if (end < size && data[end] == '#')
  		end++;
  
  	while (end < size && isalnum(data[end]))
  		end++;
  
  	if (end < size && data[end] == ';')
  		end++; /* real entity */
  	else
  		return 0; /* lone '&' */
  
  	if (rndr->cb.entity) {
  		work.data = data;
  		work.size = end;
  		rndr->cb.entity(ob, &work, rndr->opaque);
  	}
  	else bufput(ob, data, end);
  
  	return end;
  }
  
  /* char_langle_tag • '<' when tags or autolinks are allowed */
  static size_t
  char_langle_tag(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	enum mkd_autolink altype = MKDA_NOT_AUTOLINK;
  	size_t end = tag_length(data, size, &altype);
  	struct buf work = { data, end, 0, 0 };
  	int ret = 0;
  
  	if (end > 2) {
  		if (rndr->cb.autolink && altype != MKDA_NOT_AUTOLINK) {
  			struct buf *u_link = rndr_newbuf(rndr, BUFFER_SPAN);
  			work.data = data + 1;
  			work.size = end - 2;
  			unscape_text(u_link, &work);
  			ret = rndr->cb.autolink(ob, u_link, altype, rndr->opaque);
  			rndr_popbuf(rndr, BUFFER_SPAN);
  		}
  		else if (rndr->cb.raw_html_tag)
  			ret = rndr->cb.raw_html_tag(ob, &work, rndr->opaque);
  	}
  
  	if (!ret) return 0;
  	else return end;
  }
  
  static size_t
  char_autolink_www(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	struct buf *link, *link_url, *link_text;
  	size_t link_len, rewind;
  
  	if (!rndr->cb.link || rndr->in_link_body)
  		return 0;
  
  	link = rndr_newbuf(rndr, BUFFER_SPAN);
  
  	if ((link_len = sd_autolink__www(&rewind, link, data, offset, size, 0)) > 0) {
  		link_url = rndr_newbuf(rndr, BUFFER_SPAN);
  		BUFPUTSL(link_url, "http://");
  		bufput(link_url, link->data, link->size);
  
  		ob->size -= rewind;
  		if (rndr->cb.normal_text) {
  			link_text = rndr_newbuf(rndr, BUFFER_SPAN);
  			rndr->cb.normal_text(link_text, link, rndr->opaque);
  			rndr->cb.link(ob, link_url, NULL, link_text, rndr->opaque);
  			rndr_popbuf(rndr, BUFFER_SPAN);
  		} else {
  			rndr->cb.link(ob, link_url, NULL, link, rndr->opaque);
  		}
  		rndr_popbuf(rndr, BUFFER_SPAN);
  	}
  
  	rndr_popbuf(rndr, BUFFER_SPAN);
  	return link_len;
  }
  
  static size_t
  char_autolink_email(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	struct buf *link;
  	size_t link_len, rewind;
  
  	if (!rndr->cb.autolink || rndr->in_link_body)
  		return 0;
  
  	link = rndr_newbuf(rndr, BUFFER_SPAN);
  
  	if ((link_len = sd_autolink__email(&rewind, link, data, offset, size, 0)) > 0) {
  		ob->size -= rewind;
  		rndr->cb.autolink(ob, link, MKDA_EMAIL, rndr->opaque);
  	}
  
  	rndr_popbuf(rndr, BUFFER_SPAN);
  	return link_len;
  }
  
  static size_t
  char_autolink_url(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	struct buf *link;
  	size_t link_len, rewind;
  
  	if (!rndr->cb.autolink || rndr->in_link_body)
  		return 0;
  
  	link = rndr_newbuf(rndr, BUFFER_SPAN);
  
  	if ((link_len = sd_autolink__url(&rewind, link, data, offset, size, 1)) > 0) {
  		ob->size -= rewind;
  		rndr->cb.autolink(ob, link, MKDA_NORMAL, rndr->opaque);
  	}
  
  	rndr_popbuf(rndr, BUFFER_SPAN);
  	return link_len;
  }
  
  /* char_link • '[': parsing a link or an image */
  static size_t
  char_link(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	int is_img = (offset && data[-1] == '!'), level;
  	size_t i = 1, txt_e, link_b = 0, link_e = 0, title_b = 0, title_e = 0;
  	struct buf *content = 0;
  	struct buf *link = 0;
  	struct buf *title = 0;
  	struct buf *u_link = 0;
  	size_t org_work_size = rndr->work_bufs[BUFFER_SPAN].size;
  	int text_has_nl = 0, ret = 0;
  	int in_title = 0, qtype = 0;
  
  	/* checking whether the correct renderer exists */
  	if ((is_img && !rndr->cb.image) || (!is_img && !rndr->cb.link))
  		goto cleanup;
  
  	/* looking for the matching closing bracket */
  	for (level = 1; i < size; i++) {
  		if (data[i] == '\n')
  			text_has_nl = 1;
  
  		else if (data[i - 1] == '\\')
  			continue;
  
  		else if (data[i] == '[')
  			level++;
  
  		else if (data[i] == ']') {
  			level--;
  			if (level <= 0)
  				break;
  		}
  	}
  
  	if (i >= size)
  		goto cleanup;
  
  	txt_e = i;
  	i++;
  
  	/* skip any amount of whitespace or newline */
  	/* (this is much more laxist than original markdown syntax) */
  	while (i < size && _isspace(data[i]))
  		i++;
  
  	/* inline style link */
  	if (i < size && data[i] == '(') {
  		/* skipping initial whitespace */
  		i++;
  
  		while (i < size && _isspace(data[i]))
  			i++;
  
  		link_b = i;
  
  		/* looking for link end: ' " ) */
  		while (i < size) {
  			if (data[i] == '\\') i += 2;
  			else if (data[i] == ')') break;
  			else if (i >= 1 && _isspace(data[i-1]) && (data[i] == '\'' || data[i] == '"')) break;
  			else i++;
  		}
  
  		if (i >= size) goto cleanup;
  		link_e = i;
  
  		/* looking for title end if present */
  		if (data[i] == '\'' || data[i] == '"') {
  			qtype = data[i];
  			in_title = 1;
  			i++;
  			title_b = i;
  
  			while (i < size) {
  				if (data[i] == '\\') i += 2;
  				else if (data[i] == qtype) {in_title = 0; i++;}
  				else if ((data[i] == ')') && !in_title) break;
  				else i++;
  			}
  
  			if (i >= size) goto cleanup;
  
  			/* skipping whitespaces after title */
  			title_e = i - 1;
  			while (title_e > title_b && _isspace(data[title_e]))
  				title_e--;
  
  			/* checking for closing quote presence */
  			if (data[title_e] != '\'' &&  data[title_e] != '"') {
  				title_b = title_e = 0;
  				link_e = i;
  			}
  		}
  
  		/* remove whitespace at the end of the link */
  		while (link_e > link_b && _isspace(data[link_e - 1]))
  			link_e--;
  
  		/* remove optional angle brackets around the link */
  		if (data[link_b] == '<') link_b++;
  		if (data[link_e - 1] == '>') link_e--;
  
  		/* building escaped link and title */
  		if (link_e > link_b) {
  			link = rndr_newbuf(rndr, BUFFER_SPAN);
  			bufput(link, data + link_b, link_e - link_b);
  		}
  
  		if (title_e > title_b) {
  			title = rndr_newbuf(rndr, BUFFER_SPAN);
  			bufput(title, data + title_b, title_e - title_b);
  		}
  
  		i++;
  	}
  
  	/* reference style link */
  	else if (i < size && data[i] == '[') {
  		struct buf id = { 0, 0, 0, 0 };
  		struct link_ref *lr;
  
  		/* looking for the id */
  		i++;
  		link_b = i;
  		while (i < size && data[i] != ']') i++;
  		if (i >= size) goto cleanup;
  		link_e = i;
  
  		/* finding the link_ref */
  		if (link_b == link_e) {
  			if (text_has_nl) {
  				struct buf *b = rndr_newbuf(rndr, BUFFER_SPAN);
  				size_t j;
  
  				for (j = 1; j < txt_e; j++) {
  					if (data[j] != '\n')
  						bufputc(b, data[j]);
  					else if (data[j - 1] != ' ')
  						bufputc(b, ' ');
  				}
  
  				id.data = b->data;
  				id.size = b->size;
  			} else {
  				id.data = data + 1;
  				id.size = txt_e - 1;
  			}
  		} else {
  			id.data = data + link_b;
  			id.size = link_e - link_b;
  		}
  
  		lr = find_link_ref(rndr->refs, id.data, id.size);
  		if (!lr)
  			goto cleanup;
  
  		/* keeping link and title from link_ref */
  		link = lr->link;
  		title = lr->title;
  		i++;
  	}
  
  	/* shortcut reference style link */
  	else {
  		struct buf id = { 0, 0, 0, 0 };
  		struct link_ref *lr;
  
  		/* crafting the id */
  		if (text_has_nl) {
  			struct buf *b = rndr_newbuf(rndr, BUFFER_SPAN);
  			size_t j;
  
  			for (j = 1; j < txt_e; j++) {
  				if (data[j] != '\n')
  					bufputc(b, data[j]);
  				else if (data[j - 1] != ' ')
  					bufputc(b, ' ');
  			}
  
  			id.data = b->data;
  			id.size = b->size;
  		} else {
  			id.data = data + 1;
  			id.size = txt_e - 1;
  		}
  
  		/* finding the link_ref */
  		lr = find_link_ref(rndr->refs, id.data, id.size);
  		if (!lr)
  			goto cleanup;
  
  		/* keeping link and title from link_ref */
  		link = lr->link;
  		title = lr->title;
  
  		/* rewinding the whitespace */
  		i = txt_e + 1;
  	}
  
  	/* building content: img alt is escaped, link content is parsed */
  	if (txt_e > 1) {
  		content = rndr_newbuf(rndr, BUFFER_SPAN);
  		if (is_img) {
  			bufput(content, data + 1, txt_e - 1);
  		} else {
  			/* disable autolinking when parsing inline the
  			 * content of a link */
  			rndr->in_link_body = 1;
  			parse_inline(content, rndr, data + 1, txt_e - 1);
  			rndr->in_link_body = 0;
  		}
  	}
  
  	if (link) {
  		u_link = rndr_newbuf(rndr, BUFFER_SPAN);
  		unscape_text(u_link, link);
  	}
  
  	/* calling the relevant rendering function */
  	if (is_img) {
  		if (ob->size && ob->data[ob->size - 1] == '!')
  			ob->size -= 1;
  
  		ret = rndr->cb.image(ob, u_link, title, content, rndr->opaque);
  	} else {
  		ret = rndr->cb.link(ob, u_link, title, content, rndr->opaque);
  	}
  
  	/* cleanup */
  cleanup:
  	rndr->work_bufs[BUFFER_SPAN].size = (int)org_work_size;
  	return ret ? i : 0;
  }
  
  static size_t
  char_superscript(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
  {
  	size_t sup_start, sup_len;
  	struct buf *sup;
  
  	if (!rndr->cb.superscript)
  		return 0;
  
  	if (size < 2)
  		return 0;
  
  	if (data[1] == '(') {
  		sup_start = sup_len = 2;
  
  		while (sup_len < size && data[sup_len] != ')' && data[sup_len - 1] != '\\')
  			sup_len++;
  
  		if (sup_len == size)
  			return 0;
  	} else {
  		sup_start = sup_len = 1;
  
  		while (sup_len < size && !_isspace(data[sup_len]))
  			sup_len++;
  	}
  
  	if (sup_len - sup_start == 0)
  		return (sup_start == 2) ? 3 : 0;
  
  	sup = rndr_newbuf(rndr, BUFFER_SPAN);
  	parse_inline(sup, rndr, data + sup_start, sup_len - sup_start);
  	rndr->cb.superscript(ob, sup, rndr->opaque);
  	rndr_popbuf(rndr, BUFFER_SPAN);
  
  	return (sup_start == 2) ? sup_len + 1 : sup_len;
  }
  
  /*********************************
   * BLOCK-LEVEL PARSING FUNCTIONS *
   *********************************/
  
  /* is_empty • returns the line length when it is empty, 0 otherwise */
  static size_t
  is_empty(uint8_t *data, size_t size)
  {
  	size_t i;
  
  	for (i = 0; i < size && data[i] != '\n'; i++)
  		if (data[i] != ' ')
  			return 0;
  
  	return i + 1;
  }
  
  /* is_hrule • returns whether a line is a horizontal rule */
  static int
  is_hrule(uint8_t *data, size_t size)
  {
  	size_t i = 0, n = 0;
  	uint8_t c;
  
  	/* skipping initial spaces */
  	if (size < 3) return 0;
  	if (data[0] == ' ') { i++;
  	if (data[1] == ' ') { i++;
  	if (data[2] == ' ') { i++; } } }
  
  	/* looking at the hrule uint8_t */
  	if (i + 2 >= size
  	|| (data[i] != '*' && data[i] != '-' && data[i] != '_'))
  		return 0;
  	c = data[i];
  
  	/* the whole line must be the char or whitespace */
  	while (i < size && data[i] != '\n') {
  		if (data[i] == c) n++;
  		else if (data[i] != ' ')
  			return 0;
  
  		i++;
  	}
  
  	return n >= 3;
  }
  
  /* check if a line begins with a code fence; return the
   * width of the code fence */
  static size_t
  prefix_codefence(uint8_t *data, size_t size)
  {
  	size_t i = 0, n = 0;
  	uint8_t c;
  
  	/* skipping initial spaces */
  	if (size < 3) return 0;
  	if (data[0] == ' ') { i++;
  	if (data[1] == ' ') { i++;
  	if (data[2] == ' ') { i++; } } }
  
  	/* looking at the hrule uint8_t */
  	if (i + 2 >= size || !(data[i] == '~' || data[i] == '`'))
  		return 0;
  
  	c = data[i];
  
  	/* the whole line must be the uint8_t or whitespace */
  	while (i < size && data[i] == c) {
  		n++; i++;
  	}
  
  	if (n < 3)
  		return 0;
  
  	return i;
  }
  
  /* check if a line is a code fence; return its size if it is */
  static size_t
  is_codefence(uint8_t *data, size_t size, struct buf *syntax)
  {
  	size_t i = 0, syn_len = 0;
  	uint8_t *syn_start;
  
  	i = prefix_codefence(data, size);
  	if (i == 0)
  		return 0;
  
  	while (i < size && data[i] == ' ')
  		i++;
  
  	syn_start = data + i;
  
  	if (i < size && data[i] == '{') {
  		i++; syn_start++;
  
  		while (i < size && data[i] != '}' && data[i] != '\n') {
  			syn_len++; i++;
  		}
  
  		if (i == size || data[i] != '}')
  			return 0;
  
  		/* strip all whitespace at the beginning and the end
  		 * of the {} block */
  		while (syn_len > 0 && _isspace(syn_start[0])) {
  			syn_start++; syn_len--;
  		}
  
  		while (syn_len > 0 && _isspace(syn_start[syn_len - 1]))
  			syn_len--;
  
  		i++;
  	} else {
  		while (i < size && !_isspace(data[i])) {
  			syn_len++; i++;
  		}
  	}
  
  	if (syntax) {
  		syntax->data = syn_start;
  		syntax->size = syn_len;
  	}
  
  	while (i < size && data[i] != '\n') {
  		if (!_isspace(data[i]))
  			return 0;
  
  		i++;
  	}
  
  	return i + 1;
  }
  
  /* is_atxheader • returns whether the line is a hash-prefixed header */
  static int
  is_atxheader(struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	if (data[0] != '#')
  		return 0;
  
  	if (rndr->ext_flags & MKDEXT_SPACE_HEADERS) {
  		size_t level = 0;
  
  		while (level < size && level < 6 && data[level] == '#')
  			level++;
  
  		if (level < size && data[level] != ' ')
  			return 0;
  	}
  
  	return 1;
  }
  
  /* is_headerline • returns whether the line is a setext-style hdr underline */
  static int
  is_headerline(uint8_t *data, size_t size)
  {
  	size_t i = 0;
  
  	/* test of level 1 header */
  	if (data[i] == '=') {
  		for (i = 1; i < size && data[i] == '='; i++);
  		while (i < size && data[i] == ' ') i++;
  		return (i >= size || data[i] == '\n') ? 1 : 0; }
  
  	/* test of level 2 header */
  	if (data[i] == '-') {
  		for (i = 1; i < size && data[i] == '-'; i++);
  		while (i < size && data[i] == ' ') i++;
  		return (i >= size || data[i] == '\n') ? 2 : 0; }
  
  	return 0;
  }
  
  static int
  is_next_headerline(uint8_t *data, size_t size)
  {
  	size_t i = 0;
  
  	while (i < size && data[i] != '\n')
  		i++;
  
  	if (++i >= size)
  		return 0;
  
  	return is_headerline(data + i, size - i);
  }
  
  /* prefix_quote • returns blockquote prefix length */
  static size_t
  prefix_quote(uint8_t *data, size_t size)
  {
  	size_t i = 0;
  	if (i < size && data[i] == ' ') i++;
  	if (i < size && data[i] == ' ') i++;
  	if (i < size && data[i] == ' ') i++;
  
  	if (i < size && data[i] == '>') {
  		if (i + 1 < size && data[i + 1] == ' ')
  			return i + 2;
  
  		return i + 1;
  	}
  
  	return 0;
  }
  
  /* prefix_code • returns prefix length for block code*/
  static size_t
  prefix_code(uint8_t *data, size_t size)
  {
  	if (size > 3 && data[0] == ' ' && data[1] == ' '
  		&& data[2] == ' ' && data[3] == ' ') return 4;
  
  	return 0;
  }
  
  /* prefix_oli • returns ordered list item prefix */
  static size_t
  prefix_oli(uint8_t *data, size_t size)
  {
  	size_t i = 0;
  
  	if (i < size && data[i] == ' ') i++;
  	if (i < size && data[i] == ' ') i++;
  	if (i < size && data[i] == ' ') i++;
  
  	if (i >= size || data[i] < '0' || data[i] > '9')
  		return 0;
  
  	while (i < size && data[i] >= '0' && data[i] <= '9')
  		i++;
  
  	if (i + 1 >= size || data[i] != '.' || data[i + 1] != ' ')
  		return 0;
  
  	if (is_next_headerline(data + i, size - i))
  		return 0;
  
  	return i + 2;
  }
  
  /* prefix_uli • returns ordered list item prefix */
  static size_t
  prefix_uli(uint8_t *data, size_t size)
  {
  	size_t i = 0;
  
  	if (i < size && data[i] == ' ') i++;
  	if (i < size && data[i] == ' ') i++;
  	if (i < size && data[i] == ' ') i++;
  
  	if (i + 1 >= size ||
  		(data[i] != '*' && data[i] != '+' && data[i] != '-') ||
  		data[i + 1] != ' ')
  		return 0;
  
  	if (is_next_headerline(data + i, size - i))
  		return 0;
  
  	return i + 2;
  }
  
  
  /* parse_block • parsing of one block, returning next uint8_t to parse */
  static void parse_block(struct buf *ob, struct sd_markdown *rndr,
  			uint8_t *data, size_t size);
  
  
  /* parse_blockquote • handles parsing of a blockquote fragment */
  static size_t
  parse_blockquote(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	size_t beg, end = 0, pre, work_size = 0;
  	uint8_t *work_data = 0;
  	struct buf *out = 0;
  
  	out = rndr_newbuf(rndr, BUFFER_BLOCK);
  	beg = 0;
  	while (beg < size) {
  		for (end = beg + 1; end < size && data[end - 1] != '\n'; end++);
  
  		pre = prefix_quote(data + beg, end - beg);
  
  		if (pre)
  			beg += pre; /* skipping prefix */
  
  		/* empty line followed by non-quote line */
  		else if (is_empty(data + beg, end - beg) &&
  				(end >= size || (prefix_quote(data + end, size - end) == 0 &&
  				!is_empty(data + end, size - end))))
  			break;
  
  		if (beg < end) { /* copy into the in-place working buffer */
  			/* bufput(work, data + beg, end - beg); */
  			if (!work_data)
  				work_data = data + beg;
  			else if (data + beg != work_data + work_size)
  				memmove(work_data + work_size, data + beg, end - beg);
  			work_size += end - beg;
  		}
  		beg = end;
  	}
  
  	parse_block(out, rndr, work_data, work_size);
  	if (rndr->cb.blockquote)
  		rndr->cb.blockquote(ob, out, rndr->opaque);
  	rndr_popbuf(rndr, BUFFER_BLOCK);
  	return end;
  }
  
  static size_t
  parse_htmlblock(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int do_render);
  
  /* parse_blockquote • handles parsing of a regular paragraph */
  static size_t
  parse_paragraph(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	size_t i = 0, end = 0;
  	int level = 0;
  	struct buf work = { data, 0, 0, 0 };
  
  	while (i < size) {
  		for (end = i + 1; end < size && data[end - 1] != '\n'; end++) /* empty */;
  
  		if (is_empty(data + i, size - i))
  			break;
  
  		if ((level = is_headerline(data + i, size - i)) != 0)
  			break;
  
  		if (is_atxheader(rndr, data + i, size - i) ||
  			is_hrule(data + i, size - i) ||
  			prefix_quote(data + i, size - i)) {
  			end = i;
  			break;
  		}
  
  		/*
  		 * Early termination of a paragraph with the same logic
  		 * as Markdown 1.0.0. If this logic is applied, the
  		 * Markdown 1.0.3 test suite won't pass cleanly
  		 *
  		 * :: If the first character in a new line is not a letter,
  		 * let's check to see if there's some kind of block starting
  		 * here
  		 */
  		if ((rndr->ext_flags & MKDEXT_LAX_SPACING) && !isalnum(data[i])) {
  			if (prefix_oli(data + i, size - i) ||
  				prefix_uli(data + i, size - i)) {
  				end = i;
  				break;
  			}
  
  			/* see if an html block starts here */
  			if (data[i] == '<' && rndr->cb.blockhtml &&
  				parse_htmlblock(ob, rndr, data + i, size - i, 0)) {
  				end = i;
  				break;
  			}
  
  			/* see if a code fence starts here */
  			if ((rndr->ext_flags & MKDEXT_FENCED_CODE) != 0 &&
  				is_codefence(data + i, size - i, NULL) != 0) {
  				end = i;
  				break;
  			}
  		}
  
  		i = end;
  	}
  
  	work.size = i;
  	while (work.size && data[work.size - 1] == '\n')
  		work.size--;
  
  	if (!level) {
  		struct buf *tmp = rndr_newbuf(rndr, BUFFER_BLOCK);
  		parse_inline(tmp, rndr, work.data, work.size);
  		if (rndr->cb.paragraph)
  			rndr->cb.paragraph(ob, tmp, rndr->opaque);
  		rndr_popbuf(rndr, BUFFER_BLOCK);
  	} else {
  		struct buf *header_work;
  
  		if (work.size) {
  			size_t beg;
  			i = work.size;
  			work.size -= 1;
  
  			while (work.size && data[work.size] != '\n')
  				work.size -= 1;
  
  			beg = work.size + 1;
  			while (work.size && data[work.size - 1] == '\n')
  				work.size -= 1;
  
  			if (work.size > 0) {
  				struct buf *tmp = rndr_newbuf(rndr, BUFFER_BLOCK);
  				parse_inline(tmp, rndr, work.data, work.size);
  
  				if (rndr->cb.paragraph)
  					rndr->cb.paragraph(ob, tmp, rndr->opaque);
  
  				rndr_popbuf(rndr, BUFFER_BLOCK);
  				work.data += beg;
  				work.size = i - beg;
  			}
  			else work.size = i;
  		}
  
  		header_work = rndr_newbuf(rndr, BUFFER_SPAN);
  		parse_inline(header_work, rndr, work.data, work.size);
  
  		if (rndr->cb.header)
  			rndr->cb.header(ob, header_work, (int)level, rndr->opaque);
  
  		rndr_popbuf(rndr, BUFFER_SPAN);
  	}
  
  	return end;
  }
  
  /* parse_fencedcode • handles parsing of a block-level code fragment */
  static size_t
  parse_fencedcode(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	size_t beg, end;
  	struct buf *work = 0;
  	struct buf lang = { 0, 0, 0, 0 };
  
  	beg = is_codefence(data, size, &lang);
  	if (beg == 0) return 0;
  
  	work = rndr_newbuf(rndr, BUFFER_BLOCK);
  
  	while (beg < size) {
  		size_t fence_end;
  		struct buf fence_trail = { 0, 0, 0, 0 };
  
  		fence_end = is_codefence(data + beg, size - beg, &fence_trail);
  		if (fence_end != 0 && fence_trail.size == 0) {
  			beg += fence_end;
  			break;
  		}
  
  		for (end = beg + 1; end < size && data[end - 1] != '\n'; end++);
  
  		if (beg < end) {
  			/* verbatim copy to the working buffer,
  				escaping entities */
  			if (is_empty(data + beg, end - beg))
  				bufputc(work, '\n');
  			else bufput(work, data + beg, end - beg);
  		}
  		beg = end;
  	}
  
  	if (work->size && work->data[work->size - 1] != '\n')
  		bufputc(work, '\n');
  
  	if (rndr->cb.blockcode)
  		rndr->cb.blockcode(ob, work, lang.size ? &lang : NULL, rndr->opaque);
  
  	rndr_popbuf(rndr, BUFFER_BLOCK);
  	return beg;
  }
  
  static size_t
  parse_blockcode(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	size_t beg, end, pre;
  	struct buf *work = 0;
  
  	work = rndr_newbuf(rndr, BUFFER_BLOCK);
  
  	beg = 0;
  	while (beg < size) {
  		for (end = beg + 1; end < size && data[end - 1] != '\n'; end++) {};
  		pre = prefix_code(data + beg, end - beg);
  
  		if (pre)
  			beg += pre; /* skipping prefix */
  		else if (!is_empty(data + beg, end - beg))
  			/* non-empty non-prefixed line breaks the pre */
  			break;
  
  		if (beg < end) {
  			/* verbatim copy to the working buffer,
  				escaping entities */
  			if (is_empty(data + beg, end - beg))
  				bufputc(work, '\n');
  			else bufput(work, data + beg, end - beg);
  		}
  		beg = end;
  	}
  
  	while (work->size && work->data[work->size - 1] == '\n')
  		work->size -= 1;
  
  	bufputc(work, '\n');
  
  	if (rndr->cb.blockcode)
  		rndr->cb.blockcode(ob, work, NULL, rndr->opaque);
  
  	rndr_popbuf(rndr, BUFFER_BLOCK);
  	return beg;
  }
  
  /* parse_listitem • parsing of a single list item */
  /*	assuming initial prefix is already removed */
  static size_t
  parse_listitem(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int *flags)
  {
  	struct buf *work = 0, *inter = 0;
  	size_t beg = 0, end, pre, sublist = 0, orgpre = 0, i;
  	int in_empty = 0, has_inside_empty = 0, in_fence = 0;
  
  	/* keeping track of the first indentation prefix */
  	while (orgpre < 3 && orgpre < size && data[orgpre] == ' ')
  		orgpre++;
  
  	beg = prefix_uli(data, size);
  	if (!beg)
  		beg = prefix_oli(data, size);
  
  	if (!beg)
  		return 0;
  
  	/* skipping to the beginning of the following line */
  	end = beg;
  	while (end < size && data[end - 1] != '\n')
  		end++;
  
  	/* getting working buffers */
  	work = rndr_newbuf(rndr, BUFFER_SPAN);
  	inter = rndr_newbuf(rndr, BUFFER_SPAN);
  
  	/* putting the first line into the working buffer */
  	bufput(work, data + beg, end - beg);
  	beg = end;
  
  	/* process the following lines */
  	while (beg < size) {
  		size_t has_next_uli = 0, has_next_oli = 0;
  
  		end++;
  
  		while (end < size && data[end - 1] != '\n')
  			end++;
  
  		/* process an empty line */
  		if (is_empty(data + beg, end - beg)) {
  			in_empty = 1;
  			beg = end;
  			continue;
  		}
  
  		/* calculating the indentation */
  		i = 0;
  		while (i < 4 && beg + i < end && data[beg + i] == ' ')
  			i++;
  
  		pre = i;
  
  		if (rndr->ext_flags & MKDEXT_FENCED_CODE) {
  			if (is_codefence(data + beg + i, end - beg - i, NULL) != 0)
  				in_fence = !in_fence;
  		}
  
  		/* Only check for new list items if we are **not** inside
  		 * a fenced code block */
  		if (!in_fence) {
  			has_next_uli = prefix_uli(data + beg + i, end - beg - i);
  			has_next_oli = prefix_oli(data + beg + i, end - beg - i);
  		}
  
  		/* checking for ul/ol switch */
  		if (in_empty && (
  			((*flags & MKD_LIST_ORDERED) && has_next_uli) ||
  			(!(*flags & MKD_LIST_ORDERED) && has_next_oli))){
  			*flags |= MKD_LI_END;
  			break; /* the following item must have same list type */
  		}
  
  		/* checking for a new item */
  		if ((has_next_uli && !is_hrule(data + beg + i, end - beg - i)) || has_next_oli) {
  			if (in_empty)
  				has_inside_empty = 1;
  
  			if (pre == orgpre) /* the following item must have */
  				break;             /* the same indentation */
  
  			if (!sublist)
  				sublist = work->size;
  		}
  		/* joining only indented stuff after empty lines;
  		 * note that now we only require 1 space of indentation
  		 * to continue a list */
  		else if (in_empty && pre == 0) {
  			*flags |= MKD_LI_END;
  			break;
  		}
  		else if (in_empty) {
  			bufputc(work, '\n');
  			has_inside_empty = 1;
  		}
  
  		in_empty = 0;
  
  		/* adding the line without prefix into the working buffer */
  		bufput(work, data + beg + i, end - beg - i);
  		beg = end;
  	}
  
  	/* render of li contents */
  	if (has_inside_empty)
  		*flags |= MKD_LI_BLOCK;
  
  	if (*flags & MKD_LI_BLOCK) {
  		/* intermediate render of block li */
  		if (sublist && sublist < work->size) {
  			parse_block(inter, rndr, work->data, sublist);
  			parse_block(inter, rndr, work->data + sublist, work->size - sublist);
  		}
  		else
  			parse_block(inter, rndr, work->data, work->size);
  	} else {
  		/* intermediate render of inline li */
  		if (sublist && sublist < work->size) {
  			parse_inline(inter, rndr, work->data, sublist);
  			parse_block(inter, rndr, work->data + sublist, work->size - sublist);
  		}
  		else
  			parse_inline(inter, rndr, work->data, work->size);
  	}
  
  	/* render of li itself */
  	if (rndr->cb.listitem)
  		rndr->cb.listitem(ob, inter, *flags, rndr->opaque);
  
  	rndr_popbuf(rndr, BUFFER_SPAN);
  	rndr_popbuf(rndr, BUFFER_SPAN);
  	return beg;
  }
  
  
  /* parse_list • parsing ordered or unordered list block */
  static size_t
  parse_list(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int flags)
  {
  	struct buf *work = 0;
  	size_t i = 0, j;
  
  	work = rndr_newbuf(rndr, BUFFER_BLOCK);
  
  	while (i < size) {
  		j = parse_listitem(work, rndr, data + i, size - i, &flags);
  		i += j;
  
  		if (!j || (flags & MKD_LI_END))
  			break;
  	}
  
  	if (rndr->cb.list)
  		rndr->cb.list(ob, work, flags, rndr->opaque);
  	rndr_popbuf(rndr, BUFFER_BLOCK);
  	return i;
  }
  
  /* parse_atxheader • parsing of atx-style headers */
  static size_t
  parse_atxheader(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	size_t level = 0;
  	size_t i, end, skip;
  
  	while (level < size && level < 6 && data[level] == '#')
  		level++;
  
  	for (i = level; i < size && data[i] == ' '; i++);
  
  	for (end = i; end < size && data[end] != '\n'; end++);
  	skip = end;
  
  	while (end && data[end - 1] == '#')
  		end--;
  
  	while (end && data[end - 1] == ' ')
  		end--;
  
  	if (end > i) {
  		struct buf *work = rndr_newbuf(rndr, BUFFER_SPAN);
  
  		parse_inline(work, rndr, data + i, end - i);
  
  		if (rndr->cb.header)
  			rndr->cb.header(ob, work, (int)level, rndr->opaque);
  
  		rndr_popbuf(rndr, BUFFER_SPAN);
  	}
  
  	return skip;
  }
  
  
  /* htmlblock_end • checking end of HTML block : </tag>[ \t]*\n[ \t*]\n */
  /*	returns the length on match, 0 otherwise */
  static size_t
  htmlblock_end_tag(
  	const char *tag,
  	size_t tag_len,
  	struct sd_markdown *rndr,
  	uint8_t *data,
  	size_t size)
  {
  	size_t i, w;
  
  	/* checking if tag is a match */
  	if (tag_len + 3 >= size ||
  		strncasecmp((char *)data + 2, tag, tag_len) != 0 ||
  		data[tag_len + 2] != '>')
  		return 0;
  
  	/* checking white lines */
  	i = tag_len + 3;
  	w = 0;
  	if (i < size && (w = is_empty(data + i, size - i)) == 0)
  		return 0; /* non-blank after tag */
  	i += w;
  	w = 0;
  
  	if (i < size)
  		w = is_empty(data + i, size - i);
  
  	return i + w;
  }
  
  static size_t
  htmlblock_end(const char *curtag,
  	struct sd_markdown *rndr,
  	uint8_t *data,
  	size_t size,
  	int start_of_line)
  {
  	size_t tag_size = strlen(curtag);
  	size_t i = 1, end_tag;
  	int block_lines = 0;
  
  	while (i < size) {
  		i++;
  		while (i < size && !(data[i - 1] == '<' && data[i] == '/')) {
  			if (data[i] == '\n')
  				block_lines++;
  
  			i++;
  		}
  
  		/* If we are only looking for unindented tags, skip the tag
  		 * if it doesn't follow a newline.
  		 *
  		 * The only exception to this is if the tag is still on the
  		 * initial line; in that case it still counts as a closing
  		 * tag
  		 */
  		if (start_of_line && block_lines > 0 && data[i - 2] != '\n')
  			continue;
  
  		if (i + 2 + tag_size >= size)
  			break;
  
  		end_tag = htmlblock_end_tag(curtag, tag_size, rndr, data + i - 1, size - i + 1);
  		if (end_tag)
  			return i + end_tag - 1;
  	}
  
  	return 0;
  }
  
  
  /* parse_htmlblock • parsing of inline HTML block */
  static size_t
  parse_htmlblock(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int do_render)
  {
  	size_t i, j = 0, tag_end;
  	const char *curtag = NULL;
  	struct buf work = { data, 0, 0, 0 };
  
  	/* identification of the opening tag */
  	if (size < 2 || data[0] != '<')
  		return 0;
  
  	i = 1;
  	while (i < size && data[i] != '>' && data[i] != ' ')
  		i++;
  
  	if (i < size)
  		curtag = find_block_tag((char *)data + 1, (int)i - 1);
  
  	/* handling of special cases */
  	if (!curtag) {
  
  		/* HTML comment, laxist form */
  		if (size > 5 && data[1] == '!' && data[2] == '-' && data[3] == '-') {
  			i = 5;
  
  			while (i < size && !(data[i - 2] == '-' && data[i - 1] == '-' && data[i] == '>'))
  				i++;
  
  			i++;
  
  			if (i < size)
  				j = is_empty(data + i, size - i);
  
  			if (j) {
  				work.size = i + j;
  				if (do_render && rndr->cb.blockhtml)
  					rndr->cb.blockhtml(ob, &work, rndr->opaque);
  				return work.size;
  			}
  		}
  
  		/* HR, which is the only self-closing block tag considered */
  		if (size > 4 && (data[1] == 'h' || data[1] == 'H') && (data[2] == 'r' || data[2] == 'R')) {
  			i = 3;
  			while (i < size && data[i] != '>')
  				i++;
  
  			if (i + 1 < size) {
  				i++;
  				j = is_empty(data + i, size - i);
  				if (j) {
  					work.size = i + j;
  					if (do_render && rndr->cb.blockhtml)
  						rndr->cb.blockhtml(ob, &work, rndr->opaque);
  					return work.size;
  				}
  			}
  		}
  
  		/* no special case recognised */
  		return 0;
  	}
  
  	/* looking for an unindented matching closing tag */
  	/*	followed by a blank line */
  	tag_end = htmlblock_end(curtag, rndr, data, size, 1);
  
  	/* if not found, trying a second pass looking for indented match */
  	/* but not if tag is "ins" or "del" (following original Markdown.pl) */
  	if (!tag_end && strcmp(curtag, "ins") != 0 && strcmp(curtag, "del") != 0) {
  		tag_end = htmlblock_end(curtag, rndr, data, size, 0);
  	}
  
  	if (!tag_end)
  		return 0;
  
  	/* the end of the block has been found */
  	work.size = tag_end;
  	if (do_render && rndr->cb.blockhtml)
  		rndr->cb.blockhtml(ob, &work, rndr->opaque);
  
  	return tag_end;
  }
  
  static void
  parse_table_row(
  	struct buf *ob,
  	struct sd_markdown *rndr,
  	uint8_t *data,
  	size_t size,
  	size_t columns,
  	int *col_data,
  	int header_flag)
  {
  	size_t i = 0, col;
  	struct buf *row_work = 0;
  
  	if (!rndr->cb.table_cell || !rndr->cb.table_row)
  		return;
  
  	row_work = rndr_newbuf(rndr, BUFFER_SPAN);
  
  	if (i < size && data[i] == '|')
  		i++;
  
  	for (col = 0; col < columns && i < size; ++col) {
  		size_t cell_start, cell_end;
  		struct buf *cell_work;
  
  		cell_work = rndr_newbuf(rndr, BUFFER_SPAN);
  
  		while (i < size && _isspace(data[i]))
  			i++;
  
  		cell_start = i;
  
  		while (i < size && data[i] != '|')
  			i++;
  
  		cell_end = i - 1;
  
  		while (cell_end > cell_start && _isspace(data[cell_end]))
  			cell_end--;
  
  		parse_inline(cell_work, rndr, data + cell_start, 1 + cell_end - cell_start);
  		rndr->cb.table_cell(row_work, cell_work, col_data[col] | header_flag, rndr->opaque);
  
  		rndr_popbuf(rndr, BUFFER_SPAN);
  		i++;
  	}
  
  	for (; col < columns; ++col) {
  		struct buf empty_cell = { 0, 0, 0, 0 };
  		rndr->cb.table_cell(row_work, &empty_cell, col_data[col] | header_flag, rndr->opaque);
  	}
  
  	rndr->cb.table_row(ob, row_work, rndr->opaque);
  
  	rndr_popbuf(rndr, BUFFER_SPAN);
  }
  
  static size_t
  parse_table_header(
  	struct buf *ob,
  	struct sd_markdown *rndr,
  	uint8_t *data,
  	size_t size,
  	size_t *columns,
  	int **column_data)
  {
  	int pipes;
  	size_t i = 0, col, header_end, under_end;
  
  	pipes = 0;
  	while (i < size && data[i] != '\n')
  		if (data[i++] == '|')
  			pipes++;
  
  	if (i == size || pipes == 0)
  		return 0;
  
  	header_end = i;
  
  	while (header_end > 0 && _isspace(data[header_end - 1]))
  		header_end--;
  
  	if (data[0] == '|')
  		pipes--;
  
  	if (header_end && data[header_end - 1] == '|')
  		pipes--;
  
  	*columns = pipes + 1;
  	*column_data = calloc(*columns, sizeof(int));
  
  	/* Parse the header underline */
  	i++;
  	if (i < size && data[i] == '|')
  		i++;
  
  	under_end = i;
  	while (under_end < size && data[under_end] != '\n')
  		under_end++;
  
  	for (col = 0; col < *columns && i < under_end; ++col) {
  		size_t dashes = 0;
  
  		while (i < under_end && data[i] == ' ')
  			i++;
  
  		if (data[i] == ':') {
  			i++; (*column_data)[col] |= MKD_TABLE_ALIGN_L;
  			dashes++;
  		}
  
  		while (i < under_end && data[i] == '-') {
  			i++; dashes++;
  		}
  
  		if (i < under_end && data[i] == ':') {
  			i++; (*column_data)[col] |= MKD_TABLE_ALIGN_R;
  			dashes++;
  		}
  
  		while (i < under_end && data[i] == ' ')
  			i++;
  
  		if (i < under_end && data[i] != '|')
  			break;
  
  		if (dashes < 3)
  			break;
  
  		i++;
  	}
  
  	if (col < *columns)
  		return 0;
  
  	parse_table_row(
  		ob, rndr, data,
  		header_end,
  		*columns,
  		*column_data,
  		MKD_TABLE_HEADER
  	);
  
  	return under_end + 1;
  }
  
  static size_t
  parse_table(
  	struct buf *ob,
  	struct sd_markdown *rndr,
  	uint8_t *data,
  	size_t size)
  {
  	size_t i;
  
  	struct buf *header_work = 0;
  	struct buf *body_work = 0;
  
  	size_t columns;
  	int *col_data = NULL;
  
  	header_work = rndr_newbuf(rndr, BUFFER_SPAN);
  	body_work = rndr_newbuf(rndr, BUFFER_BLOCK);
  
  	i = parse_table_header(header_work, rndr, data, size, &columns, &col_data);
  	if (i > 0) {
  
  		while (i < size) {
  			size_t row_start;
  			int pipes = 0;
  
  			row_start = i;
  
  			while (i < size && data[i] != '\n')
  				if (data[i++] == '|')
  					pipes++;
  
  			if (pipes == 0 || i == size) {
  				i = row_start;
  				break;
  			}
  
  			parse_table_row(
  				body_work,
  				rndr,
  				data + row_start,
  				i - row_start,
  				columns,
  				col_data, 0
  			);
  
  			i++;
  		}
  
  		if (rndr->cb.table)
  			rndr->cb.table(ob, header_work, body_work, rndr->opaque);
  	}
  
  	free(col_data);
  	rndr_popbuf(rndr, BUFFER_SPAN);
  	rndr_popbuf(rndr, BUFFER_BLOCK);
  	return i;
  }
  
  /* parse_block • parsing of one block, returning next uint8_t to parse */
  static void
  parse_block(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
  {
  	size_t beg, end, i;
  	uint8_t *txt_data;
  	beg = 0;
  
  	if (rndr->work_bufs[BUFFER_SPAN].size +
  		rndr->work_bufs[BUFFER_BLOCK].size > rndr->max_nesting)
  		return;
  
  	while (beg < size) {
  		txt_data = data + beg;
  		end = size - beg;
  
  		if (is_atxheader(rndr, txt_data, end))
  			beg += parse_atxheader(ob, rndr, txt_data, end);
  
  		else if (data[beg] == '<' && rndr->cb.blockhtml &&
  				(i = parse_htmlblock(ob, rndr, txt_data, end, 1)) != 0)
  			beg += i;
  
  		else if ((i = is_empty(txt_data, end)) != 0)
  			beg += i;
  
  		else if (is_hrule(txt_data, end)) {
  			if (rndr->cb.hrule)
  				rndr->cb.hrule(ob, rndr->opaque);
  
  			while (beg < size && data[beg] != '\n')
  				beg++;
  
  			beg++;
  		}
  
  		else if ((rndr->ext_flags & MKDEXT_FENCED_CODE) != 0 &&
  			(i = parse_fencedcode(ob, rndr, txt_data, end)) != 0)
  			beg += i;
  
  		else if ((rndr->ext_flags & MKDEXT_TABLES) != 0 &&
  			(i = parse_table(ob, rndr, txt_data, end)) != 0)
  			beg += i;
  
  		else if (prefix_quote(txt_data, end))
  			beg += parse_blockquote(ob, rndr, txt_data, end);
  
  		else if (prefix_code(txt_data, end))
  			beg += parse_blockcode(ob, rndr, txt_data, end);
  
  		else if (prefix_uli(txt_data, end))
  			beg += parse_list(ob, rndr, txt_data, end, 0);
  
  		else if (prefix_oli(txt_data, end))
  			beg += parse_list(ob, rndr, txt_data, end, MKD_LIST_ORDERED);
  
  		else
  			beg += parse_paragraph(ob, rndr, txt_data, end);
  	}
  }
  
  
  
  /*********************
   * REFERENCE PARSING *
   *********************/
  
  /* is_ref • returns whether a line is a reference or not */
  static int
  is_ref(const uint8_t *data, size_t beg, size_t end, size_t *last, struct link_ref **refs)
  {
  /*	int n; */
  	size_t i = 0;
  	size_t id_offset, id_end;
  	size_t link_offset, link_end;
  	size_t title_offset, title_end;
  	size_t line_end;
  
  	/* up to 3 optional leading spaces */
  	if (beg + 3 >= end) return 0;
  	if (data[beg] == ' ') { i = 1;
  	if (data[beg + 1] == ' ') { i = 2;
  	if (data[beg + 2] == ' ') { i = 3;
  	if (data[beg + 3] == ' ') return 0; } } }
  	i += beg;
  
  	/* id part: anything but a newline between brackets */
  	if (data[i] != '[') return 0;
  	i++;
  	id_offset = i;
  	while (i < end && data[i] != '\n' && data[i] != '\r' && data[i] != ']')
  		i++;
  	if (i >= end || data[i] != ']') return 0;
  	id_end = i;
  
  	/* spacer: colon (space | tab)* newline? (space | tab)* */
  	i++;
  	if (i >= end || data[i] != ':') return 0;
  	i++;
  	while (i < end && data[i] == ' ') i++;
  	if (i < end && (data[i] == '\n' || data[i] == '\r')) {
  		i++;
  		if (i < end && data[i] == '\r' && data[i - 1] == '\n') i++; }
  	while (i < end && data[i] == ' ') i++;
  	if (i >= end) return 0;
  
  	/* link: whitespace-free sequence, optionally between angle brackets */
  	if (data[i] == '<')
  		i++;
  
  	link_offset = i;
  
  	while (i < end && data[i] != ' ' && data[i] != '\n' && data[i] != '\r')
  		i++;
  
  	if (data[i - 1] == '>') link_end = i - 1;
  	else link_end = i;
  
  	/* optional spacer: (space | tab)* (newline | '\'' | '"' | '(' ) */
  	while (i < end && data[i] == ' ') i++;
  	if (i < end && data[i] != '\n' && data[i] != '\r'
  			&& data[i] != '\'' && data[i] != '"' && data[i] != '(')
  		return 0;
  	line_end = 0;
  	/* computing end-of-line */
  	if (i >= end || data[i] == '\r' || data[i] == '\n') line_end = i;
  	if (i + 1 < end && data[i] == '\n' && data[i + 1] == '\r')
  		line_end = i + 1;
  
  	/* optional (space|tab)* spacer after a newline */
  	if (line_end) {
  		i = line_end + 1;
  		while (i < end && data[i] == ' ') i++; }
  
  	/* optional title: any non-newline sequence enclosed in '"()
  					alone on its line */
  	title_offset = title_end = 0;
  	if (i + 1 < end
  	&& (data[i] == '\'' || data[i] == '"' || data[i] == '(')) {
  		i++;
  		title_offset = i;
  		/* looking for EOL */
  		while (i < end && data[i] != '\n' && data[i] != '\r') i++;
  		if (i + 1 < end && data[i] == '\n' && data[i + 1] == '\r')
  			title_end = i + 1;
  		else	title_end = i;
  		/* stepping back */
  		i -= 1;
  		while (i > title_offset && data[i] == ' ')
  			i -= 1;
  		if (i > title_offset
  		&& (data[i] == '\'' || data[i] == '"' || data[i] == ')')) {
  			line_end = title_end;
  			title_end = i; } }
  
  	if (!line_end || link_end == link_offset)
  		return 0; /* garbage after the link empty link */
  
  	/* a valid ref has been found, filling-in return structures */
  	if (last)
  		*last = line_end;
  
  	if (refs) {
  		struct link_ref *ref;
  
  		ref = add_link_ref(refs, data + id_offset, id_end - id_offset);
  		if (!ref)
  			return 0;
  
  		ref->link = bufnew(link_end - link_offset);
  		bufput(ref->link, data + link_offset, link_end - link_offset);
  
  		if (title_end > title_offset) {
  			ref->title = bufnew(title_end - title_offset);
  			bufput(ref->title, data + title_offset, title_end - title_offset);
  		}
  	}
  
  	return 1;
  }
  
  static void expand_tabs(struct buf *ob, const uint8_t *line, size_t size)
  {
  	size_t  i = 0, tab = 0;
  
  	while (i < size) {
  		size_t org = i;
  
  		while (i < size && line[i] != '\t') {
  			i++; tab++;
  		}
  
  		if (i > org)
  			bufput(ob, line + org, i - org);
  
  		if (i >= size)
  			break;
  
  		do {
  			bufputc(ob, ' '); tab++;
  		} while (tab % 4);
  
  		i++;
  	}
  }
  
  /**********************
   * EXPORTED FUNCTIONS *
   **********************/
  
  struct sd_markdown *
  sd_markdown_new(
  	unsigned int extensions,
  	size_t max_nesting,
  	const struct sd_callbacks *callbacks,
  	void *opaque)
  {
  	struct sd_markdown *md = NULL;
  
  	assert(max_nesting > 0 && callbacks);
  
  	md = malloc(sizeof(struct sd_markdown));
  	if (!md)
  		return NULL;
  
  	memcpy(&md->cb, callbacks, sizeof(struct sd_callbacks));
  
  	stack_init(&md->work_bufs[BUFFER_BLOCK], 4);
  	stack_init(&md->work_bufs[BUFFER_SPAN], 8);
  
  	memset(md->active_char, 0x0, 256);
  
  	if (md->cb.emphasis || md->cb.double_emphasis || md->cb.triple_emphasis) {
  		md->active_char['*'] = MD_CHAR_EMPHASIS;
  		md->active_char['_'] = MD_CHAR_EMPHASIS;
  		if (extensions & MKDEXT_STRIKETHROUGH)
  			md->active_char['~'] = MD_CHAR_EMPHASIS;
  	}
  
  	if (md->cb.codespan)
  		md->active_char['`'] = MD_CHAR_CODESPAN;
  
  	if (md->cb.linebreak)
  		md->active_char['\n'] = MD_CHAR_LINEBREAK;
  
  	if (md->cb.image || md->cb.link)
  		md->active_char['['] = MD_CHAR_LINK;
  
  	md->active_char['<'] = MD_CHAR_LANGLE;
  	md->active_char['\\'] = MD_CHAR_ESCAPE;
  	md->active_char['&'] = MD_CHAR_ENTITITY;
  
  	if (extensions & MKDEXT_AUTOLINK) {
  		md->active_char[':'] = MD_CHAR_AUTOLINK_URL;
  	}
  
  	if (extensions & MKDEXT_SUPERSCRIPT)
  		md->active_char['^'] = MD_CHAR_SUPERSCRIPT;
  
  	/* Extension data */
  	md->ext_flags = extensions;
  	md->opaque = opaque;
  	md->max_nesting = max_nesting;
  	md->in_link_body = 0;
  
  	return md;
  }
  
  void
  sd_markdown_render(struct buf *ob, const uint8_t *document, size_t doc_size, struct sd_markdown *md)
  {
  #define MARKDOWN_GROW(x) ((x) + ((x) >> 1))
  	static const char UTF8_BOM[] = {0xEF, 0xBB, 0xBF};
  
  	struct buf *text;
  	size_t beg, end;
  
  	text = bufnew(64);
  	if (!text)
  		return;
  
  	/* Preallocate enough space for our buffer to avoid expanding while copying */
  	bufgrow(text, doc_size);
  
  	/* reset the references table */
  	memset(&md->refs, 0x0, REF_TABLE_SIZE * sizeof(void *));
  
  	/* first pass: looking for references, copying everything else */
  	beg = 0;
  
  	/* Skip a possible UTF-8 BOM, even though the Unicode standard
  	 * discourages having these in UTF-8 documents */
  	if (doc_size >= 3 && memcmp(document, UTF8_BOM, 3) == 0)
  		beg += 3;
  
  	while (beg < doc_size) /* iterating over lines */
  		if (is_ref(document, beg, doc_size, &end, md->refs))
  			beg = end;
  		else { /* skipping to the next line */
  			end = beg;
  			while (end < doc_size && document[end] != '\n' && document[end] != '\r')
  				end++;
  
  			/* adding the line body if present */
  			if (end > beg)
  				expand_tabs(text, document + beg, end - beg);
  
  			while (end < doc_size && (document[end] == '\n' || document[end] == '\r')) {
  				/* add one \n per newline */
  				if (document[end] == '\n' || (end + 1 < doc_size && document[end + 1] != '\n'))
  					bufputc(text, '\n');
  				end++;
  			}
  
  			beg = end;
  		}
  
  	/* pre-grow the output buffer to minimize allocations */
  	bufgrow(ob, MARKDOWN_GROW(text->size));
  
  	/* second pass: actual rendering */
  	if (md->cb.doc_header)
  		md->cb.doc_header(ob, md->opaque);
  
  	if (text->size) {
  		/* adding a final newline if not already present */
  		if (text->data[text->size - 1] != '\n' &&  text->data[text->size - 1] != '\r')
  			bufputc(text, '\n');
  
  		parse_block(ob, md, text->data, text->size);
  	}
  
  	if (md->cb.doc_footer)
  		md->cb.doc_footer(ob, md->opaque);
  
  	/* clean-up */
  	bufrelease(text);
  	free_link_refs(md->refs);
  
  	assert(md->work_bufs[BUFFER_SPAN].size == 0);
  	assert(md->work_bufs[BUFFER_BLOCK].size == 0);
  }
  
  void
  sd_markdown_free(struct sd_markdown *md)
  {
  	size_t i;
  
  	for (i = 0; i < (size_t)md->work_bufs[BUFFER_SPAN].asize; ++i)
  		bufrelease(md->work_bufs[BUFFER_SPAN].item[i]);
  
  	for (i = 0; i < (size_t)md->work_bufs[BUFFER_BLOCK].asize; ++i)
  		bufrelease(md->work_bufs[BUFFER_BLOCK].item[i]);
  
  	stack_free(&md->work_bufs[BUFFER_SPAN]);
  	stack_free(&md->work_bufs[BUFFER_BLOCK]);
  
  	free(md);
  }
  
  void
  sd_version(int *ver_major, int *ver_minor, int *ver_revision)
  {
  	*ver_major = SUNDOWN_VER_MAJOR;
  	*ver_minor = SUNDOWN_VER_MINOR;
  	*ver_revision = SUNDOWN_VER_REVISION;
  }
  
  /* vim: set filetype=c: */
  