enum GMarkupError

typedef enum
{
  G_MARKUP_ERROR_BAD_UTF8,
  G_MARKUP_ERROR_EMPTY,
  G_MARKUP_ERROR_PARSE,
  /* The following are primarily intended for specific GMarkupParser
   * implementations to set.
   */
  G_MARKUP_ERROR_UNKNOWN_ELEMENT,
  G_MARKUP_ERROR_UNKNOWN_ATTRIBUTE,
  G_MARKUP_ERROR_INVALID_CONTENT,
  G_MARKUP_ERROR_MISSING_ATTRIBUTE
} GMarkupError;

Error codes returned by markup parsing.

G_MARKUP_ERROR

#define G_MARKUP_ERROR g_markup_error_quark ()

Error domain for markup parsing. Errors in this domain will be from the GMarkupError enumeration. See GError for information on error domains.

enum GMarkupParseFlags

typedef enum
{
  G_MARKUP_DO_NOT_USE_THIS_UNSUPPORTED_FLAG = 1 << 0,
  G_MARKUP_TREAT_CDATA_AS_TEXT              = 1 << 1,
  G_MARKUP_PREFIX_ERROR_POSITION            = 1 << 2
} GMarkupParseFlags;

Flags that affect the behaviour of the parser.

GMarkupParseContext

typedef struct _GMarkupParseContext GMarkupParseContext;

A parse context is used to parse a stream of bytes that you expect to contain marked-up text. See g_markup_parse_context_new(), GMarkupParser, and so on for more details.

GMarkupParser

typedef struct {
  /* Called for open tags <foo bar="baz"> */
  void (*start_element)  (GMarkupParseContext *context,
                          const gchar         *element_name,
                          const gchar        **attribute_names,
                          const gchar        **attribute_values,
                          gpointer             user_data,
                          GError             **error);

  /* Called for close tags </foo> */
  void (*end_element)    (GMarkupParseContext *context,
                          const gchar         *element_name,
                          gpointer             user_data,
                          GError             **error);

  /* Called for character data */
  /* text is not nul-terminated */
  void (*text)           (GMarkupParseContext *context,
                          const gchar         *text,
                          gsize                text_len,  
                          gpointer             user_data,
                          GError             **error);

  /* Called for strings that should be re-saved verbatim in this same
   * position, but are not otherwise interpretable.  At the moment
   * this includes comments and processing instructions.
   */
  /* text is not nul-terminated. */
  void (*passthrough)    (GMarkupParseContext *context,
                          const gchar         *passthrough_text,
                          gsize                text_len,  
                          gpointer             user_data,
                          GError             **error);

  /* Called on error, including one set by other
   * methods in the vtable. The GError should not be freed.
   */
  void (*error)          (GMarkupParseContext *context,
                          GError              *error,
                          gpointer             user_data);
} GMarkupParser;

Any of the fields in GMarkupParser can be NULL, in which case they will be ignored. Except for the error function, any of these callbacks can set an error; in particular the G_MARKUP_ERROR_UNKNOWN_ELEMENT, G_MARKUP_ERROR_UNKNOWN_ATTRIBUTE, and G_MARKUP_ERROR_INVALID_CONTENT errors are intended to be set from these callbacks. If you set an error from a callback, g_markup_parse_context_parse() will report that error back to its caller.

g_markup_escape_text ()

gchar*              g_markup_escape_text                (const gchar *text,
                                                         gssize length);

Escapes text so that the markup parser will parse it verbatim. Less than, greater than, ampersand, etc. are replaced with the corresponding entities. This function would typically be used when writing out a file to be parsed with the markup parser.

Note that this function doesn't protect whitespace and line endings from being processed according to the XML rules for normalization of line endings and attribute values.

Note also that if given a string containing them, this function will produce character references in the range of &x1; .. &x1f; for all control sequences except for tabstop, newline and carriage return. The character references in this range are not valid XML 1.0, but they are valid XML 1.1 and will be accepted by the GMarkup parser.

g_markup_printf_escaped ()

gchar*              g_markup_printf_escaped             (const char *format,
                                                         ...);

Formats arguments according to format, escaping all string and character arguments in the fashion of g_markup_escape_text(). This is useful when you want to insert literal strings into XML-style markup output, without having to worry that the strings might themselves contain markup.

const char *store = "Fortnum & Mason";
const char *item = "Tea";
char *output;
 
output = g_markup_printf_escaped ("<purchase>"
                                  "<store>%s</store>"
                                  "<item>%s</item>"
                                  "</purchase>",
                                  store, item);

Since 2.4

g_markup_vprintf_escaped ()

gchar*              g_markup_vprintf_escaped            (const char *format,
                                                         va_list args);

Formats the data in args according to format, escaping all string and character arguments in the fashion of g_markup_escape_text(). See g_markup_printf_escaped().

Since 2.4

g_markup_parse_context_end_parse ()

gboolean            g_markup_parse_context_end_parse    (GMarkupParseContext *context,
                                                         GError **error);

Signals to the GMarkupParseContext that all data has been fed into the parse context with g_markup_parse_context_parse(). This function reports an error if the document isn't complete, for example if elements are still open.

g_markup_parse_context_free ()

void                g_markup_parse_context_free         (GMarkupParseContext *context);

Frees a GMarkupParseContext. Can't be called from inside one of the GMarkupParser functions. Can't be called while a subparser is pushed.

g_markup_parse_context_get_position ()

void                g_markup_parse_context_get_position (GMarkupParseContext *context,
                                                         gint *line_number,
                                                         gint *char_number);

Retrieves the current line number and the number of the character on that line. Intended for use in error messages; there are no strict semantics for what constitutes the "current" line number other than "the best number we could come up with for error messages."

g_markup_parse_context_get_element ()

const gchar*        g_markup_parse_context_get_element  (GMarkupParseContext *context);

Retrieves the name of the currently open element.

If called from the start_element or end_element handlers this will give the element_name as passed to those functions. For the parent elements, see g_markup_parse_context_get_element_stack().

Since 2.2

g_markup_parse_context_get_element_stack ()

const GSList*       g_markup_parse_context_get_element_stack
                                                        (GMarkupParseContext *context);

Retrieves the element stack from the internal state of the parser. The returned GSList is a list of strings where the first item is the currently open tag (as would be returned by g_markup_parse_context_get_element()) and the next item is its immediate parent.

This function is intended to be used in the start_element and end_element handlers where g_markup_parse_context_get_element() would merely return the name of the element that is being processed.

Since 2.16

g_markup_parse_context_get_user_data ()

gpointer            g_markup_parse_context_get_user_data
                                                        (GMarkupParseContext *context);

Returns the user_data associated with context. This will either be the user_data that was provided to g_markup_parse_context_new() or to the most recent call of g_markup_parse_context_push().

Since 2.18

g_markup_parse_context_new ()

GMarkupParseContext* g_markup_parse_context_new         (const GMarkupParser *parser,
                                                         GMarkupParseFlags flags,
                                                         gpointer user_data,
                                                         GDestroyNotify user_data_dnotify);

Creates a new parse context. A parse context is used to parse marked-up documents. You can feed any number of documents into a context, as long as no errors occur; once an error occurs, the parse context can't continue to parse text (you have to free it and create a new parse context).

g_markup_parse_context_parse ()

gboolean            g_markup_parse_context_parse        (GMarkupParseContext *context,
                                                         const gchar *text,
                                                         gssize text_len,
                                                         GError **error);

Feed some data to the GMarkupParseContext. The data need not be valid UTF-8; an error will be signaled if it's invalid. The data need not be an entire document; you can feed a document into the parser incrementally, via multiple calls to this function. Typically, as you receive data from a network connection or file, you feed each received chunk of data into this function, aborting the process if an error occurs. Once an error is reported, no further data may be fed to the GMarkupParseContext; all errors are fatal.

g_markup_parse_context_push ()

void                g_markup_parse_context_push         (GMarkupParseContext *context,
                                                         GMarkupParser *parser,
                                                         gpointer user_data);

Temporarily redirects markup data to a sub-parser.

This function may only be called from the start_element handler of a GMarkupParser. It must be matched with a corresponding call to g_markup_parse_context_pop() in the matching end_element handler (except in the case that the parser aborts due to an error).

All tags, text and other data between the matching tags is redirected to the subparser given by parser. user_data is used as the user_data for that parser. user_data is also passed to the error callback in the event that an error occurs. This includes errors that occur in subparsers of the subparser.

The end tag matching the start tag for which this call was made is handled by the previous parser (which is given its own user_data) which is why g_markup_parse_context_pop() is provided to allow "one last access" to the user_data provided to this function. In the case of error, the user_data provided here is passed directly to the error callback of the subparser and g_markup_parse_context() should not be called. In either case, if user_data was allocated then it ought to be freed from both of these locations.

This function is not intended to be directly called by users interested in invoking subparsers. Instead, it is intended to be used by the subparsers themselves to implement a higher-level interface.

As an example, see the following implementation of a simple parser that counts the number of tags encountered.

typedef struct
{
  gint tag_count;
} CounterData;

static void
counter_start_element (GMarkupParseContext  *context,
                       const gchar          *element_name,
                       const gchar         **attribute_names,
                       const gchar         **attribute_values,
                       gpointer              user_data,
                       GError              **error)
{
  CounterData *data = user_data;

  data->tag_count++;
}

static void
counter_error (GMarkupParseContext *context,
               GError              *error,
               gpointer             user_data)
{
  CounterData *data = user_data;

  g_slice_free (CounterData, data);
}

static GMarkupParser counter_subparser =
{
  counter_start_element,
  NULL,
  NULL,
  NULL,
  counter_error
};

In order to allow this parser to be easily used as a subparser, the following interface is provided:

void
start_counting (GMarkupParseContext *context)
{
  CounterData *data = g_slice_new (CounterData);

  data->tag_count = 0;
  g_markup_parse_context_push (context, &counter_subparser, data);
}

gint
end_counting (GMarkupParseContext *context)
{
  CounterData *data = g_markup_parse_context_pop (context);
  int result;

  result = data->tag_count;
  g_slice_free (CounterData, data);

  return result;
}

The subparser would then be used as follows:

static void start_element (context, element_name, ...)
{
  if (strcmp (element_name, "count-these") == 0)
    start_counting (context);

  /* else, handle other tags... */
}

static void end_element (context, element_name, ...)
{
  if (strcmp (element_name, "count-these") == 0)
    g_print ("Counted %d tags\n", end_counting (context));

  /* else, handle other tags... */
}

Since 2.18

g_markup_parse_context_pop ()

gpointer            g_markup_parse_context_pop          (GMarkupParseContext *context);

Completes the process of a temporary sub-parser redirection.

This function exists to collect the user_data allocated by a matching call to g_markup_parse_context_push(). It must be called in the end_element handler corresponding to the start_element handler during which g_markup_parse_context_push() was called. You must not call this function from the error callback -- the user_data is provided directly to the callback in that case.

This function is not intended to be directly called by users interested in invoking subparsers. Instead, it is intended to be used by the subparsers themselves to implement a higher-level interface.

Since 2.18

enum GMarkupCollectType

typedef enum
{
  G_MARKUP_COLLECT_INVALID,
  G_MARKUP_COLLECT_STRING,
  G_MARKUP_COLLECT_STRDUP,
  G_MARKUP_COLLECT_BOOLEAN,
  G_MARKUP_COLLECT_TRISTATE,

  G_MARKUP_COLLECT_OPTIONAL = (1 << 16)
} GMarkupCollectType;

A mixed enumerated type and flags field. You must specify one type (string, strdup, boolean, tristate). Additionally, you may optionally bitwise OR the type with the flag G_MARKUP_COLLECT_OPTIONAL.

It is likely that this enum will be extended in the future to support other types.

g_markup_collect_attributes ()

gboolean            g_markup_collect_attributes         (const gchar *element_name,
                                                         const gchar **attribute_names,
                                                         const gchar **attribute_values,
                                                         GError **error,
                                                         GMarkupCollectType first_type,
                                                         const gchar *first_attr,
                                                         ...);

Collects the attributes of the element from the data passed to the GMarkupParser start_element function, dealing with common error conditions and supporting boolean values.

This utility function is not required to write a parser but can save a lot of typing.

The element_name, attribute_names, attribute_values and error parameters passed to the start_element callback should be passed unmodified to this function.

Following these arguments is a list of "supported" attributes to collect. It is an error to specify multiple attributes with the same name. If any attribute not in the list appears in the attribute_names array then an unknown attribute error will result.

The GMarkupCollectType field allows specifying the type of collection to perform and if a given attribute must appear or is optional.

The attribute name is simply the name of the attribute to collect.

The pointer should be of the appropriate type (see the descriptions under GMarkupCollectType) and may be NULL in case a particular attribute is to be allowed but ignored.

This function deals with issuing errors for missing attributes (of type G_MARKUP_ERROR_MISSING_ATTRIBUTE), unknown attributes (of type G_MARKUP_ERROR_UNKNOWN_ATTRIBUTE) and duplicate attributes (of type G_MARKUP_ERROR_INVALID_CONTENT) as well as parse errors for boolean-valued attributes (again of type G_MARKUP_ERROR_INVALID_CONTENT). In all of these cases FALSE will be returned and error will be set as appropriate.

Since 2.16