MarkupParser


Object Hierarchy:

Object hierarchy for MarkupParser

Description:

public struct MarkupParser

Any of the fields in MarkupParser 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, parse will report that error back to its caller.

Example: GMarkup-Parser:

public class MapParser : Object {
private const MarkupParser parser = {
visit_start,
visit_end,
visit_text,
visit_passthrough,
error
};

private MarkupParseContext context;

public MapParser () {
context = new MarkupParseContext (parser, 0, this, null);
}

// context.get_element_stack ().length () = O(n)
private int depth;


private string error_msg (string msg, ...) {
va_list va_list = va_list ();
int line_number;
int char_number;

StringBuilder pos = new StringBuilder ();
foreach (string lst in context.get_element_stack ()) {
if (pos.len != 0) {
pos.append_c ('.');
}
pos.append (lst);
}

context.get_position (out line_number, out char_number);
return "%s: %d.%d: %s".printf (pos.str, line_number, char_number, msg.vprintf (va_list));
}

// <name>
private void visit_start (MarkupParseContext context, string name, string[] attr_names, string[] attr_values) throws MarkupError {
// Use context.get_element_stack () to evaluate the state!

if (name == "map" && this.depth == 0) {
if (attr_names.length != 0) {
throw new MarkupError.UNKNOWN_ATTRIBUTE (error_msg ("Unexpected attribute': `map.%s'", name));
}
} else if (name == "entry" && this.depth == 1) {
unowned string key = null;
unowned string val = null;

for (int i = 0; attr_names[i] != null; i++) {
switch (attr_names[i]) {
case "key":
key = attr_values[i];
break;

case "value":
val = attr_values[i];
break;

default:
throw new MarkupError.UNKNOWN_ATTRIBUTE (error_msg ("Unexpected attribute': `entry.%s'", name));
}
}

if (key == null) {
throw new MarkupError.MISSING_ATTRIBUTE (error_msg ("Missing attribute': `entry.key'"));
} else if (val == null) {
throw new MarkupError.MISSING_ATTRIBUTE (error_msg ("Missing attribute': `entry.value'"));
}

print ("Entry: '%s' = '%s'\n", key, val);
} else {
throw new MarkupError.UNKNOWN_ELEMENT (error_msg ("Unexpected element: `%s'", name));
}

this.depth++;
}

// </foo>
private void visit_end (MarkupParseContext context, string name) throws MarkupError {
this.depth--;

if ((this.depth == 1 && name != "entry") || (this.depth == 0 && name != "map")) {
throw new MarkupError.PARSE (error_msg ("Missing element: `/%s'", name));
}
}

private void visit_text (MarkupParseContext context, string text, size_t text_len) throws MarkupError {
}

private void visit_passthrough () {
// process instructions, comments
}

private void error (MarkupParseContext context, Error error) {
}

public bool parse (string markup) throws MarkupError {
this.depth = 0;
return context.parse (markup, -1);
}

public static int main (string[] args) {
try {
MapParser parser = new MapParser ();
parser.parse ("""<map>
<entry key="method" value="printf" />
<entry key="field" value="errno" />
<entry key="constant" value="RED" />
</map>"""
);
} catch (Error e) {
print ("%s\n", e.message);
}
return 0;
}
}

valac --pkg glib-2.0 GLib.MarkupParser.vala


Namespace: GLib
Package: glib-2.0

Content:

Fields: