cmark-gfm(3) Library Functions Manual cmark-gfm(3)

cmark-gfm - CommonMark parsing, manipulating, and rendering

char * cmark_markdown_to_html(const char *text, size_t len, int options)

Convert text (assumed to be a UTF-8 encoded string with length len) from CommonMark Markdown to HTML, returning a null-terminated, UTF-8-encoded string. It is the caller's responsibility to free the returned buffer.

typedef enum {
  /* Error status */
  CMARK_NODE_NONE = 0x0000,
  /* Block */
  CMARK_NODE_DOCUMENT       = CMARK_NODE_TYPE_BLOCK | 0x0001,
  CMARK_NODE_BLOCK_QUOTE    = CMARK_NODE_TYPE_BLOCK | 0x0002,
  CMARK_NODE_LIST           = CMARK_NODE_TYPE_BLOCK | 0x0003,
  CMARK_NODE_ITEM           = CMARK_NODE_TYPE_BLOCK | 0x0004,
  CMARK_NODE_CODE_BLOCK     = CMARK_NODE_TYPE_BLOCK | 0x0005,
  CMARK_NODE_HTML_BLOCK     = CMARK_NODE_TYPE_BLOCK | 0x0006,
  CMARK_NODE_CUSTOM_BLOCK   = CMARK_NODE_TYPE_BLOCK | 0x0007,
  CMARK_NODE_PARAGRAPH      = CMARK_NODE_TYPE_BLOCK | 0x0008,
  CMARK_NODE_HEADING        = CMARK_NODE_TYPE_BLOCK | 0x0009,
  CMARK_NODE_THEMATIC_BREAK = CMARK_NODE_TYPE_BLOCK | 0x000a,
  CMARK_NODE_FOOTNOTE_DEFINITION = CMARK_NODE_TYPE_BLOCK | 0x000b,
  /* Inline */
  CMARK_NODE_TEXT          = CMARK_NODE_TYPE_INLINE | 0x0001,
  CMARK_NODE_SOFTBREAK     = CMARK_NODE_TYPE_INLINE | 0x0002,
  CMARK_NODE_LINEBREAK     = CMARK_NODE_TYPE_INLINE | 0x0003,
  CMARK_NODE_CODE          = CMARK_NODE_TYPE_INLINE | 0x0004,
  CMARK_NODE_HTML_INLINE   = CMARK_NODE_TYPE_INLINE | 0x0005,
  CMARK_NODE_CUSTOM_INLINE = CMARK_NODE_TYPE_INLINE | 0x0006,
  CMARK_NODE_EMPH          = CMARK_NODE_TYPE_INLINE | 0x0007,
  CMARK_NODE_STRONG        = CMARK_NODE_TYPE_INLINE | 0x0008,
  CMARK_NODE_LINK          = CMARK_NODE_TYPE_INLINE | 0x0009,
  CMARK_NODE_IMAGE         = CMARK_NODE_TYPE_INLINE | 0x000a,
  CMARK_NODE_FOOTNOTE_REFERENCE = CMARK_NODE_TYPE_INLINE | 0x000b,
} cmark_node_type;
typedef enum {
  CMARK_NO_LIST,
  CMARK_BULLET_LIST,
  CMARK_ORDERED_LIST
} cmark_list_type;
typedef enum {
  CMARK_NO_DELIM,
  CMARK_PERIOD_DELIM,
  CMARK_PAREN_DELIM
} cmark_delim_type;

typedef struct cmark_mem {
  void *(*calloc)(size_t, size_t);
  void *(*realloc)(void *, size_t);
  void (*free)(void *);
} cmark_mem;

Defines the memory allocation functions to be used by CMark when parsing and allocating a document tree

cmark_mem * cmark_get_default_mem_allocator()

The default memory allocator; uses the system's calloc, realloc and free.

cmark_mem * cmark_get_arena_mem_allocator()

An arena allocator; uses system calloc to allocate large slabs of memory. Memory in these slabs is not reused at all.

void cmark_arena_reset(void)

Resets the arena allocator, quickly returning all used memory to the operating system.

typedef void(*cmark_free_func)

Callback for freeing user data with a cmark_mem context.

typedef struct _cmark_llist
{
  struct _cmark_llist *next;
  void         *data;
} cmark_llist;

A generic singly linked list.

cmark_llist * cmark_llist_append(cmark_mem * mem, cmark_llist * head, void * data)

Append an element to the linked list, return the possibly modified head of the list.

void cmark_llist_free_full(cmark_mem * mem, cmark_llist * head, cmark_free_func free_func)

Free the list starting with head, calling free_func with the data pointer of each of its elements

void cmark_llist_free(cmark_mem * mem, cmark_llist * head)

Free the list starting with head

cmark_node * cmark_node_new(cmark_node_type type)

Creates a new node of type type. Note that the node may have other required properties, which it is the caller's responsibility to assign.

cmark_node * cmark_node_new_with_mem(cmark_node_type type, cmark_mem *mem)

Same as cmark_node_new, but explicitly listing the memory allocator used to allocate the node. Note: be sure to use the same allocator for every node in a tree, or bad things can happen.

void cmark_node_free(cmark_node *node)

Frees the memory allocated for a node and any children.

cmark_node * cmark_node_next(cmark_node *node)

Returns the next node in the sequence after node, or NULL if there is none.

cmark_node * cmark_node_previous(cmark_node *node)

Returns the previous node in the sequence after node, or NULL if there is none.

cmark_node * cmark_node_parent(cmark_node *node)

Returns the parent of node, or NULL if there is none.

cmark_node * cmark_node_first_child(cmark_node *node)

Returns the first child of node, or NULL if node has no children.

cmark_node * cmark_node_last_child(cmark_node *node)

Returns the last child of node, or NULL if node has no children.

An iterator will walk through a tree of nodes, starting from a root node, returning one node at a time, together with information about whether the node is being entered or exited. The iterator will first descend to a child node, if there is one. When there is no child, the iterator will go to the next sibling. When there is no next sibling, the iterator will return to the parent (but with a cmark_event_type of CMARK_EVENT_EXIT). The iterator will return CMARK_EVENT_DONE when it reaches the root node again. One natural application is an HTML renderer, where an ENTER event outputs an open tag and an EXIT event outputs a close tag. An iterator might also be used to transform an AST in some systematic way, for example, turning all level-3 headings into regular paragraphs.

void
usage_example(cmark_node *root) {
    cmark_event_type ev_type;
    cmark_iter *iter = cmark_iter_new(root);
    while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
        cmark_node *cur = cmark_iter_get_node(iter);
        // Do something with `cur` and `ev_type`
    }
    cmark_iter_free(iter);
}

Iterators will never return EXIT events for leaf nodes, which are nodes of type:

•
CMARK_NODE_HTML_BLOCK
•
CMARK_NODE_THEMATIC_BREAK
•
CMARK_NODE_CODE_BLOCK
•
CMARK_NODE_TEXT
•
CMARK_NODE_SOFTBREAK
•
CMARK_NODE_LINEBREAK
•
CMARK_NODE_CODE
•
CMARK_NODE_HTML_INLINE

Nodes must only be modified after an EXIT event, or an ENTER event for leaf nodes.

typedef enum {
  CMARK_EVENT_NONE,
  CMARK_EVENT_DONE,
  CMARK_EVENT_ENTER,
  CMARK_EVENT_EXIT
} cmark_event_type;

cmark_iter * cmark_iter_new(cmark_node *root)

Creates a new iterator starting at root. The current node and event type are undefined until cmark_iter_next is called for the first time. The memory allocated for the iterator should be released using cmark_iter_free when it is no longer needed.

void cmark_iter_free(cmark_iter *iter)

Frees the memory allocated for an iterator.

cmark_event_type cmark_iter_next(cmark_iter *iter)

Advances to the next node and returns the event type (CMARK_EVENT_ENTER, CMARK_EVENT_EXIT or CMARK_EVENT_DONE).

cmark_node * cmark_iter_get_node(cmark_iter *iter)

Returns the current node.

cmark_event_type cmark_iter_get_event_type(cmark_iter *iter)

Returns the current event type.

cmark_node * cmark_iter_get_root(cmark_iter *iter)

Returns the root node.

void cmark_iter_reset(cmark_iter *iter, cmark_node *current, cmark_event_type event_type)

Resets the iterator so that the current node is current and the event type is event_type. The new current node must be a descendant of the root node or the root node itself.

void * cmark_node_get_user_data(cmark_node *node)

Returns the user data of node.

int cmark_node_set_user_data(cmark_node *node, void *user_data)

Sets arbitrary user data for node. Returns 1 on success, 0 on failure.

int cmark_node_set_user_data_free_func(cmark_node *node, cmark_free_func free_func)

Set free function for user data */

cmark_node_type cmark_node_get_type(cmark_node *node)

Returns the type of node, or CMARK_NODE_NONE on error.

const char * cmark_node_get_type_string(cmark_node *node)

Like cmark_node_get_type, but returns a string representation of the type, or "<unknown>".

const char * cmark_node_get_literal(cmark_node *node)

Returns the string contents of node, or an empty string if none is set. Returns NULL if called on a node that does not have string content.

int cmark_node_set_literal(cmark_node *node, const char *content)

Sets the string contents of node. Returns 1 on success, 0 on failure.

int cmark_node_get_heading_level(cmark_node *node)

Returns the heading level of node, or 0 if node is not a heading.

int cmark_node_set_heading_level(cmark_node *node, int level)

Sets the heading level of node, returning 1 on success and 0 on error.

cmark_list_type cmark_node_get_list_type(cmark_node *node)

Returns the list type of node, or CMARK_NO_LIST if node is not a list.

int cmark_node_set_list_type(cmark_node *node, cmark_list_type type)

Sets the list type of node, returning 1 on success and 0 on error.

cmark_delim_type cmark_node_get_list_delim(cmark_node *node)

Returns the list delimiter type of node, or CMARK_NO_DELIM if node is not a list.

int cmark_node_set_list_delim(cmark_node *node, cmark_delim_type delim)

Sets the list delimiter type of node, returning 1 on success and 0 on error.

int cmark_node_get_list_start(cmark_node *node)

Returns starting number of node, if it is an ordered list, otherwise 0.

int cmark_node_set_list_start(cmark_node *node, int start)

Sets starting number of node, if it is an ordered list. Returns 1 on success, 0 on failure.

int cmark_node_get_list_tight(cmark_node *node)

Returns 1 if node is a tight list, 0 otherwise.

int cmark_node_set_list_tight(cmark_node *node, int tight)

Sets the "tightness" of a list. Returns 1 on success, 0 on failure.

const char * cmark_node_get_fence_info(cmark_node *node)

Returns the info string from a fenced code block.

int cmark_node_set_fence_info(cmark_node *node, const char *info)

Sets the info string in a fenced code block, returning 1 on success and 0 on failure.

int cmark_node_set_fenced(cmark_node * node, int fenced, int length, int offset, char character)

Sets code blocks fencing details

int cmark_node_get_fenced(cmark_node *node, int *length, int *offset, char *character)

Returns code blocks fencing details

const char * cmark_node_get_url(cmark_node *node)

Returns the URL of a link or image node, or an empty string if no URL is set. Returns NULL if called on a node that is not a link or image.

int cmark_node_set_url(cmark_node *node, const char *url)

Sets the URL of a link or image node. Returns 1 on success, 0 on failure.

const char * cmark_node_get_title(cmark_node *node)

Returns the title of a link or image node, or an empty string if no title is set. Returns NULL if called on a node that is not a link or image.

int cmark_node_set_title(cmark_node *node, const char *title)

Sets the title of a link or image node. Returns 1 on success, 0 on failure.

const char * cmark_node_get_on_enter(cmark_node *node)

Returns the literal "on enter" text for a custom node, or an empty string if no on_enter is set. Returns NULL if called on a non-custom node.

int cmark_node_set_on_enter(cmark_node *node, const char *on_enter)

Sets the literal text to render "on enter" for a custom node. Any children of the node will be rendered after this text. Returns 1 on success 0 on failure.

const char * cmark_node_get_on_exit(cmark_node *node)

Returns the literal "on exit" text for a custom node, or an empty string if no on_exit is set. Returns NULL if called on a non-custom node.

int cmark_node_set_on_exit(cmark_node *node, const char *on_exit)

Sets the literal text to render "on exit" for a custom node. Any children of the node will be rendered before this text. Returns 1 on success 0 on failure.

int cmark_node_get_start_line(cmark_node *node)

Returns the line on which node begins.

int cmark_node_get_start_column(cmark_node *node)

Returns the column at which node begins.

int cmark_node_get_end_line(cmark_node *node)

Returns the line on which node ends.

int cmark_node_get_end_column(cmark_node *node)

Returns the column at which node ends.

void cmark_node_unlink(cmark_node *node)

Unlinks a node, removing it from the tree, but not freeing its memory. (Use cmark_node_free for that.)

int cmark_node_insert_before(cmark_node *node, cmark_node *sibling)

Inserts sibling before node. Returns 1 on success, 0 on failure.

int cmark_node_insert_after(cmark_node *node, cmark_node *sibling)

Inserts sibling after node. Returns 1 on success, 0 on failure.

int cmark_node_replace(cmark_node *oldnode, cmark_node *newnode)

Replaces oldnode with newnode and unlinks oldnode (but does not free its memory). Returns 1 on success, 0 on failure.

int cmark_node_prepend_child(cmark_node *node, cmark_node *child)

Adds child to the beginning of the children of node. Returns 1 on success, 0 on failure.

int cmark_node_append_child(cmark_node *node, cmark_node *child)

Adds child to the end of the children of node. Returns 1 on success, 0 on failure.

void cmark_consolidate_text_nodes(cmark_node *root)

Consolidates adjacent text nodes.

void cmark_node_own(cmark_node *root)

Ensures a node and all its children own their own chunk memory.

Simple interface:

cmark_node *document = cmark_parse_document("Hello *world*", 13,
                                            CMARK_OPT_DEFAULT);

Streaming interface:

cmark_parser *parser = cmark_parser_new(CMARK_OPT_DEFAULT);
FILE *fp = fopen("myfile.md", "rb");
while ((bytes = fread(buffer, 1, sizeof(buffer), fp)) > 0) {
	   cmark_parser_feed(parser, buffer, bytes);
	   if (bytes < sizeof(buffer)) {
	       break;
	   }
}
document = cmark_parser_finish(parser);
cmark_parser_free(parser);

cmark_parser * cmark_parser_new(int options)

Creates a new parser object.

cmark_parser * cmark_parser_new_with_mem(int options, cmark_mem *mem)

Creates a new parser object with the given memory allocator

void cmark_parser_free(cmark_parser *parser)

Frees memory allocated for a parser object.

void cmark_parser_feed(cmark_parser *parser, const char *buffer, size_t len)

Feeds a string of length len to parser.

cmark_node * cmark_parser_finish(cmark_parser *parser)

Finish parsing and return a pointer to a tree of nodes.

cmark_node * cmark_parse_document(const char *buffer, size_t len, int options)

Parse a CommonMark document in buffer of length len. Returns a pointer to a tree of nodes. The memory allocated for the node tree should be released using cmark_node_free when it is no longer needed.

cmark_node * cmark_parse_file(FILE *f, int options)

Parse a CommonMark document in file f, returning a pointer to a tree of nodes. The memory allocated for the node tree should be released using cmark_node_free when it is no longer needed.

char * cmark_render_xml(cmark_node *root, int options)

Render a node tree as XML. It is the caller's responsibility to free the returned buffer.

char * cmark_render_xml_with_mem(cmark_node *root, int options, cmark_mem *mem)

As for cmark_render_xml, but specifying the allocator to use for the resulting string.

char * cmark_render_html(cmark_node *root, int options, cmark_llist *extensions)

Render a node tree as an HTML fragment. It is up to the user to add an appropriate header and footer. It is the caller's responsibility to free the returned buffer.

char * cmark_render_html_with_mem(cmark_node *root, int options, cmark_llist *extensions, cmark_mem *mem)

As for cmark_render_html, but specifying the allocator to use for the resulting string.

char * cmark_render_man(cmark_node *root, int options, int width)

Render a node tree as a groff man page, without the header. It is the caller's responsibility to free the returned buffer.

char * cmark_render_man_with_mem(cmark_node *root, int options, int width, cmark_mem *mem)

As for cmark_render_man, but specifying the allocator to use for the resulting string.

char * cmark_render_commonmark(cmark_node *root, int options, int width)

Render a node tree as a commonmark document. It is the caller's responsibility to free the returned buffer.

char * cmark_render_commonmark_with_mem(cmark_node *root, int options, int width, cmark_mem *mem)

As for cmark_render_commonmark, but specifying the allocator to use for the resulting string.

char * cmark_render_plaintext(cmark_node *root, int options, int width)

Render a node tree as a plain text document. It is the caller's responsibility to free the returned buffer.

char * cmark_render_plaintext_with_mem(cmark_node *root, int options, int width, cmark_mem *mem)

As for cmark_render_plaintext, but specifying the allocator to use for the resulting string.

char * cmark_render_latex(cmark_node *root, int options, int width)

Render a node tree as a LaTeX document. It is the caller's responsibility to free the returned buffer.

char * cmark_render_latex_with_mem(cmark_node *root, int options, int width, cmark_mem *mem)

As for cmark_render_latex, but specifying the allocator to use for the resulting string.

#define CMARK_OPT_DEFAULT 0

Default options.

#define CMARK_OPT_SOURCEPOS (1 << 1)

Include a data-sourcepos attribute on all block elements.

#define CMARK_OPT_HARDBREAKS (1 << 2)

Render softbreak elements as hard line breaks.

#define CMARK_OPT_SAFE (1 << 3)

CMARK_OPT_SAFE is defined here for API compatibility, but it no longer has any effect. "Safe" mode is now the default: set CMARK_OPT_UNSAFE to disable it.

#define CMARK_OPT_UNSAFE (1 << 17)

Render raw HTML and unsafe links (javascript:, vbscript:, file:, and data:, except for image/png, image/gif, image/jpeg, or image/webp mime types). By default, raw HTML is replaced by a placeholder HTML comment. Unsafe links are replaced by empty strings.

#define CMARK_OPT_NOBREAKS (1 << 4)

Render softbreak elements as spaces.

#define CMARK_OPT_NORMALIZE (1 << 8)

Legacy option (no effect).

#define CMARK_OPT_VALIDATE_UTF8 (1 << 9)

Validate UTF-8 in the input before parsing, replacing illegal sequences with the replacement character U+FFFD.

#define CMARK_OPT_SMART (1 << 10)

Convert straight quotes to curly, --- to em dashes, -- to en dashes.

#define CMARK_OPT_GITHUB_PRE_LANG (1 << 11)

Use GitHub-style tags for code blocks instead of .

#define CMARK_OPT_LIBERAL_HTML_TAG (1 << 12)

Be liberal in interpreting inline HTML tags.

#define CMARK_OPT_FOOTNOTES (1 << 13)

Parse footnotes.

#define CMARK_OPT_STRIKETHROUGH_DOUBLE_TILDE (1 << 14)

Only parse strikethroughs if surrounded by exactly 2 tildes. Gives some compatibility with redcarpet.

#define CMARK_OPT_TABLE_PREFER_STYLE_ATTRIBUTES (1 << 15)

Use style attributes to align table cells instead of align attributes.

#define CMARK_OPT_FULL_INFO_STRING (1 << 16)

Include the remainder of the info string in code blocks in a separate attribute.

int cmark_version(void)

The library version as integer for runtime checks. Also available as macro CMARK_VERSION for compile time checks.

•
Bits 16-23 contain the major version.
•
Bits 8-15 contain the minor version.
•
Bits 0-7 contain the patchlevel.

In hexadecimal format, the number 0x010203 represents version 1.2.3.

const char * cmark_version_string(void)

The library version string for runtime checks. Also available as macro CMARK_VERSION_STRING for compile time checks.

John MacFarlane, Vicent Marti, Kārlis Gaņģis, Nick Wellnhofer.

April 8, 2019 LOCAL