.\"
.\" Copyright (c) 2009 - 2016 Natacha Porté <natacha@instinctive.eu>
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.Dd September 12, 2016
.Dt SOLDOUT_MARKDOWN 3
.Os
.Sh NAME
.Nm soldout_markdown ,
.Nm markdown
.Nd parse markdown document
.Sh SYNOPSIS
.In markdown.h
.Pp
.Fd "#define MKD_CELL_ALIGN_DEFAULT"
.Fd "#define MKD_CELL_ALIGN_LEFT"
.Fd "#define MKD_CELL_ALIGN_RIGHT"
.Fd "#define MKD_CELL_ALIGN_CENTER"
.Fd "#define MKD_CELL_ALIGN_MASK"
.Fd "#define MKD_CELL_HEAD"
.Fd "#define MKD_LIST_ORDERED"
.Fd "#define MKD_LI_BLOCK"
.Ft void
.Fo markdown
.Fa "struct buf *ob"
.Fa "struct buf *ib"
.Fa "const struct mkd_renderer *rndr"
.Fc
.Sh DESCRIPTION
The
.Fn markdown
function parses the input buffer
.Fa ib
and renders it into the output buffer
.Fa ob ;
.Fa rndr
is a pointer to the renderer structure.
.Pp
The following describes a general parse sequence:
.Bl -enum
.It
Create output, input buffers by
.Fn bufnew
function.
.It
Fill input buffer by
.Fn bufput
function.
.It
Create
.Vt "struct mkd_renderer"
or use provided renderer.
.It
Call
.Fn markdown
function.
.It
Process output buffer.
.It
Call
.Fn bufrelease
function to clean up buffers.
.El
.Sh REFERENCE
This section documents the functions, types, definitions available via
.In markdown.h .
.Ss Types
.Bl -ohang
.It Vt "enum mkd_autolink"
type of autolink:
.Bl -tag -width Ds
.It MKDA_NORMAL
normal http/https/ftp link.
.It MKDA_EXPLICIT_EMAIL
e-mail link with explicit mailto.
.It MKDA_IMPLICIT_EMAIL
e-mail link without mailto.
.El
.It Vt "struct mkd_renderer"
has this form:
.Bd -literal -offset indent
struct mkd_renderer {
	/* document level callbacks */
	void (*prolog)(struct buf *ob, void *opaque);
	void (*epilog)(struct buf *ob, void *opaque);

	/* block level callbacks - NULL skips the block */
	void (*blockcode)(struct buf *ob,
	    struct buf *text,
	    void *opaque);
	void (*blockquote)(struct buf *ob,
	    struct buf *text,
	    void *opaque);
	void (*blockhtml)(struct buf *ob,
	    struct buf *text,
	    void *opaque);
	void (*header)(struct buf *ob,
	    struct buf *text, int level,
	    void *opaque);
	void (*hrule)(struct buf *ob, void *opaque);
	void (*list)(struct buf *ob,
	    struct buf *text, int flags,
	    void *opaque);
	void (*listitem)(struct buf *ob,
	    struct buf *text, int flags,
	    void *opaque);
	void (*paragraph)(struct buf *ob,
	    struct buf *text,
	    void *opaque);
	void (*table)(struct buf *ob,
	    struct buf *head_row, struct buf *rows,
	    void *opaque);
	void (*table_cell)(struct buf *ob,
	    struct buf *text, int flags,
	    void *opaque);
	void (*table_row)(struct buf *ob,
	    struct buf *cells, int flags,
	    void *opaque);

	/* span level callbacks - NULL or return 0 prints the span verbatim */
	int (*autolink)(struct buf *ob,
	    struct buf *link, enum mkd_autolink type,
	    void *opaque);
	int (*codespan)(struct buf *ob,
	    struct buf *text,
	    void *opaque);
	int (*emphasis)(struct buf *ob,
	    struct buf *text, char c,
	    void *opaque);
	int (*double_emphasis)(struct buf *ob,
	    struct buf *text, char c,
	    void *opaque);
	int (*triple_emphasis)(struct buf *ob,
	    struct buf *text, char c,
	    void *opaque);
	int (*image)(struct buf *ob,
	    struct buf *link, struct buf *title, struct buf *alt,
	    void *opaque);
	int (*linebreak)(struct buf *ob, void *opaque);
	int (*link)(struct buf *ob,
	    struct buf *link, struct buf *title, struct buf *content,
	    void *opaque);
	int (*raw_html_tag)(struct buf *ob,
	    struct buf *tag,
	    void *opaque);

	/* low level callbacks - NULL copies input directly into the output */
	void (*entity)(struct buf *ob,
	    struct buf *entity,
	    void *opaque);
	void (*normal_text)(struct buf *ob,
	    struct buf *text,
	    void *opaque);

	/* renderer data */
	int max_work_stack; /* prevent arbitrary deep recursion, cf README */
	const char *emph_chars; /* chars that trigger emphasis rendering */
	void *opaque; /* opaque data send to every rendering callback */
};
.Ed
.Pp
The first argument of a renderer function is always the output buffer,
where the function is supposed to write its output.
The last argument of a renderer function is always
a private pointer, which is
.Va opaque
member of
.Vt struct mkd_renderer .
libsoldout itself never does nothing with this data.
.Pp
Function pointers in
.Vt "struct mkd_renderer"
can be
.Dv NULL .
A null block-level callback will make the corresponding block
disappear from the output, as if the callback was an empty function.
A null span-level callback will cause the corresponding element
to be treated as normal characters, copied verbatim to the output.
Moreover, span-level callbacks return an integer, which tells
whether the renderer accepts to render the item (non-zero return value)
or whether it should be copied verbatim (zero return value).
.Pp
.Fa flags
of the
.Va list
and
.Va listitem
function callbacks are:
.Dv MKD_LIST_ORDERED ,
.Dv MKD_LI_BLOCK .
.Pp
.Fa flags
of the
.Va table_cell
and
.Va table_row
function callbacks are:
.Dv MKD_CELL_ALIGN_DEFAULT ,
.Dv MKD_CELL_ALIGN_LEFT ,
.Dv MKD_CELL_ALIGN_RIGHT ,
.Dv MKD_CELL_ALIGN_CENTER ,
.Dv MKD_CELL_ALIGN_MASK ,
.Dv MKD_CELL_HEAD .
.Pp
The
.Va normal_text
callback should perform whatever escape is needed
to have the output looking like the input data.
.Pp
.Va emph_chars
is a zero-terminated string which contains
the set of characters that trigger emphasis.
In regular markdown, emphasis is only
triggered by
.Sq _
and
.Sq * ,
but in some extensions it might be useful to
add other characters to this list.
The character that triggered the emphasis is then passed to
.Va emphasis , double_emphasis
and
.Va triple_emphasis
function callbacks through the parameter
.Fa c .
.El
.Sh EXAMPLES
Simple example that uses first argument as a markdown string,
converts it to an HTML and outputs it to stdout.
.Bd -literal
#include <stdio.h>

#include <buffer.h>
#include <markdown.h>
#include <renderers.h>

#define INPUT_UNIT  1024
#define OUTPUT_UNIT 64

int
main(int argc, char *argv[])
{
  struct buf *ib, *ob;

  /* Make sure we have enough arguments. */
  if (argc != 2) {
    return 1;
  }

  ib = bufnew(INPUT_UNIT);
  ob = bufnew(OUTPUT_UNIT);

  /* bufputs() is a wrapper over bufput() for nil-terminated string. */
  bufputs(ib, argv[1]);

  markdown(ob, ib, &mkd_html);

  /* Note the resulted data is not nil-terminated string;
   * to make it use bufnullterm(). */
  printf("%.*s", (int)ob->size, ob->data);

  bufrelease(ib);
  bufrelease(ob);
  return 0;
}
.Ed
.Sh SEE ALSO
.Xr soldout_array 3 ,
.Xr soldout_buffer 3 ,
.Xr soldout_renderers 3 ,
.Lk http://daringfireball.net/projects/markdown/ John Gruber's markdown format
.Sh AUTHORS
.An -nosplit
The
.Nm soldout
library was written by
.An Natasha Qo Kerensikova Qc Porte Aq Mt natacha@instinctive.eu .
Manual page was originally written by
.An Massimo Manghi Aq Mt mxmanghi@apache.org ,
and rewritten to mdoc format by
.An Svyatoslav Mishyn Aq Mt juef@openmailbox.org .