3 * Declarations for the SimGear XML parser.
4 * Written by David Megginson, 2000-2001
5 * This file is in the Public Domain, and comes with NO WARRANTY of any kind.
11 #include <simgear/compiler.h>
12 #include <simgear/structure/exception.hxx>
22 typedef struct XML_ParserStruct* XML_Parser;
25 * Interface for XML attributes.
27 * This interface is used to provide a list of attributes to the
28 * application. The interface is a pure abstract class so that
29 * different implementations can be substituted for the sake of
32 * @see XMLAttributesDefault
47 virtual ~ XMLAttributes ();
51 * Get the number of attributes present.
53 * @return The number of attributes in the list (may be 0).
55 virtual int size () const = 0;
59 * Get the name of an attribute by index.
61 * The index must be less than the size of the list and greater
62 * than or equal to zero.
64 * @param i The index of the attribute (zero-based).
67 virtual const char * getName (int i) const = 0;
71 * Get the string value of an attribute by index.
73 * The index must be less than the size of the list and greater
74 * than or equal to zero.
76 * @param i The index of the attribute (zero-based).
79 virtual const char * getValue (int i) const = 0;
83 * Look up the index of an attribute by name.
85 * Attribute names must be unique. This method will return
86 * an index that can be used with the {@link #getValue(const char *)}
87 * method if the attribute is found.
89 * @param name The name of the attribute.
90 * @return The index of the attribute with the name specified,
91 * or -1 if no such attribute is present in the list.
93 virtual int findAttribute (const char * name) const;
97 * Test whether an attribute is present.
99 * @param name The name of the attribute.
100 * @return true if an attribute with the specified name is present
101 * in the attribute list, false otherwise.
103 virtual bool hasAttribute (const char * name) const;
107 * Look up the value of an attribute by name.
109 * This method provides a convenient short-cut to invoking
110 * {@link #findAttribute} and {@link #getValue(const char *)}.
112 * @param name The name of the attribute to look up.
113 * @return The attribute's value as a string, or 0 if no
114 * attribute was found with the name specified.
116 virtual const char * getValue (const char * name) const;
121 * Default mutable attributes implementation.
123 * This class provides a default implementation of the {@link
124 * XMLAttributes} interface. The implementation is mutable, so
125 * that it is possible to modify the attribute list when necessary.
126 * This class is particularly useful for taking a snapshot of
127 * an attribute list during parsing.
131 class XMLAttributesDefault : public XMLAttributes
136 * Default constructor.
138 XMLAttributesDefault ();
144 * This constructor is especially useful for taking a static
145 * snapshot of an attribute list for later use.
147 * @param atts The attribute list to copy.
149 XMLAttributesDefault (const XMLAttributes & atts);
155 virtual ~XMLAttributesDefault ();
159 * Count the attributes in the list.
161 virtual int size () const;
165 * Get the name of an attribute by index.
167 virtual const char * getName (int i) const;
171 * Get the value of an attribute by index.
173 virtual const char * getValue (int i) const;
177 * Add an attribute to an attribute list.
179 * The name is required to be unique in the list; the value is not.
181 * @param name The name of the attribute to add.
182 * @param value The value of the attribute to add.
184 virtual void addAttribute (const char * name, const char * value);
188 * Set an attribute name by index.
190 * This method will not extend the list; the attribute must
193 * @param i The index of the attribute (zero-based).
194 * @param name The new name.
196 virtual void setName (int i, const char * name);
200 * Set an attribute value by index.
202 * This method will not extend the list; the attribute must
205 * @param i The index of the attribute (zero-based).
206 * @param value The new value.
208 virtual void setValue (int i, const char * value);
212 * Set an attribute value by name.
214 * This method will not extend the list; the attribute must
217 * @param name The name of the attribute that will have the new
219 * @param value The new value.
221 virtual void setValue (const char * name, const char * value);
224 vector<string> _atts;
227 ////////////////////////////////////////////////////////////////////////
228 // Attribute list wrapper for Expat.
229 ////////////////////////////////////////////////////////////////////////
231 class ExpatAtts : public XMLAttributes
234 ExpatAtts (const char ** atts) : _atts(atts) {}
236 virtual int size () const;
237 virtual const char * getName (int i) const;
238 virtual const char * getValue (int i) const;
240 virtual const char * getValue (const char * name) const;
247 * Visitor class for an XML document.
249 * This interface uses the Visitor pattern. The XML parser walks
250 * through the XML document and invokes the appropriate method in
251 * this visitor for each piece of markup it finds. By default,
252 * the methods do nothing; the application must subclass the visitor
253 * and override the methods for the events it's interested in.
254 * All applications are required to provide an implementation
255 * for the {@link #error} callback.
261 XMLVisitor() : parser(0), line(-1), column(-1) {}
264 * Virtual destructor.
266 virtual ~XMLVisitor () {}
270 * Callback for the start of an XML document.
272 * The XML parser will invoke this method once, at the beginning of
273 * the XML document, before any other methods are invoked. The
274 * application can use this callback to set up data structures,
279 virtual void startXML () {}
283 * Callback for the end of an XML document.
285 * The XML parser will invoke this method once, at the end of the
286 * XML document, after all other methods are invoked, and only
287 * if there have been no parsing errors. The application can use
288 * this callback to close or write files, finalize data structures,
289 * and so on, but the application will need to be prepared to
290 * clean up any resources without this callback in the event of
296 virtual void endXML () {}
300 * Callback for the start of an XML element.
302 * The XML parser will invoke this method at the beginning of every
303 * XML element. Start and end element calls will be balanced
304 * and properly nested: every element has both a start and end
305 * callback (even if it was specified with an XML empty element tag),
306 * there is exactly one root element, and every element must end
307 * before its parent does. Elements may not overlap.
308 * Note that the attribute list provided is volatile; it's contents
309 * are not guaranteed to persist after the end of the callback.
310 * If the application needs to keep a copy of the attribute list,
311 * it can make the copy with the {@link XMLAttributesDefault} class.
313 * @param name The name of the element that is starting (not null).
314 * @param atts The element's attributes (not null).
317 virtual void startElement (const char * name, const XMLAttributes &atts) {}
321 * Callback for the end of an XML element.
323 * The XML parser will invoke this method at the end of every XML element.
325 * @param name The name of the element that is ending (not null).
328 virtual void endElement (const char * name) {}
332 * Callback for a chunk of character data.
334 * The XML parser will invoke this method once for every chunk of
335 * character data in the XML document, including whitespace
336 * separating elements (as required by the XML recommendation).
337 * Note that character data may be chunked arbitrarily: the
338 * character data content of an element may be returned in one
339 * large chunk or several consecutive smaller chunks.
341 * @param s A pointer to the beginning of the character data (not null).
342 * @param length The number of characters in the chunk (may
345 virtual void data (const char * s, int length) {}
349 * Callback for an XML processing instruction.
351 * The XML parser will invoke this method once for every processing
352 * instruction in the XML document. Note that the XML declaration
353 * and the Text declaration are NOT PROCESSING INSTRUCTIONS and
354 * will not be reported through this callback. Processing
355 * instructions are not all that useful, but the XML recommendation
356 * requires that they be reported. Most applications can safely
357 * ignore this callback and use the empty default implementation.
359 * @param target The processing instruction target (not null).
360 * @param data The processing instruction data (not null).
362 virtual void pi (const char * target, const char * data) {}
366 * Callback for an XML parsing warning.
368 * The XML parser will use this callback to report any non-fatal warnings
369 * during parsing. It is the responsibility of the application to
370 * deal with the warning in some appropriate way.
372 * @param message The warning message from the parser.
373 * @param line The number of the line that generated the warning.
374 * @param column The character position in the line that generated
377 virtual void warning (const char * message, int line, int column) {}
379 /** Set the path to the file that is parsed.
381 * This method will be called to store the path to the parsed file. Note that
382 * the XML parser makes no use of this copy of the path. The intent is
383 * to be capable of refering to the path to the parsed file if needed.
385 * @param _path The path to the parsed file.
388 void setPath(const string& _path) { path = _path; }
390 /** Get the path to the parsed file.
392 * This method will be called if the application needs to access the path to
393 * the parsed file. This information is typically needed if an error is found
394 * so the file where it occurred can be retrieved to help the user locate the
397 * @return the path to the parsed file.
400 const string& getPath(void) const { return path; }
402 /** Save the current position in the parsed file.
404 * This method will be called to save the position at which the file is
405 * currently parsed. Note that the XML parser makes no use of that
406 * information. The intent is to be capable of refering to the position in
407 * the parsed file if needed.
412 void savePosition(void);
414 /** Get the saved column number in the parsed file.
416 * This method will be called if the application needs to get the column
417 * number that has been saved during the last call to savePosition(). This
418 * information is typically needed if an error is found so the position at
419 * which it occurred can be retrieved to help the user locate the error.
421 * @return the save column number.
424 int getColumn(void) const { return column; }
426 /** Get the saved line number in the parsed file.
428 * This method will be called if the application needs to get the line
429 * number that has been saved during the last call to savePosition(). This
430 * information is typically needed if an error is found so the position at
431 * which it occurred can be retrieved to help the user locate the error.
433 * @return the save line number.
436 int getLine(void) const { return line; }
438 /** Set the XML parser.
440 * This method will be called so the #XMLVisitor instance can internally use
441 * the XML parser for its housekeeping. The intent is that #XMLVisitor will
442 * only call the reporting functions of the XML parser and will not interfer
443 * with the XML parser current state. Doing otherwise will result in an
444 * unpredictable behavior of the XML parser.
446 * @param _parser the XML parser
448 void setParser(XML_Parser _parser) { parser = _parser; }
457 * @relates XMLVisitor
458 * Read an XML document.
460 * This function reads an XML document from the input stream provided,
461 * and invokes the callback methods in the visitor object to pass the
462 * parsing events back to the application. When this function
463 * returns, the parser will have reported all of the data in the XML
464 * document to the application through the visitor callback methods,
465 * and XML processing will be complete.
467 * @param input The byte input stream containing the XML document.
468 * @param visitor An object that contains callbacks for XML parsing
470 * @param path A string describing the original path of the resource.
471 * @exception Throws sg_io_exception or sg_xml_exception if there
472 * is a problem reading the file.
475 extern void readXML (istream &input, XMLVisitor &visitor,
476 const string &path="");
480 * @relates XMLVisitor
481 * Read an XML document.
483 * This function reads an XML document from the input stream provided,
484 * and invokes the callback methods in the visitor object to pass the
485 * parsing events back to the application. When this function
486 * returns, the parser will have reported all of the data in the XML
487 * document to the application through the visitor callback methods,
488 * and XML processing will be complete.
490 * @param path The file name of the XML resource.
491 * @param visitor An object that contains callbacks for XML parsing
493 * @exception Throws sg_io_exception or sg_xml_exception if there
494 * is a problem reading the file.
497 extern void readXML (const string &path, XMLVisitor &visitor);
501 * @relates XMLVisitor
502 * Read an XML document.
504 * This function reads an XML document from the buffer provided,
505 * and invokes the callback methods in the visitor object to pass the
506 * parsing events back to the application. When this function
507 * returns, the parser will have reported all of the data in the XML
508 * document to the application through the visitor callback methods,
509 * and XML processing will be complete.
511 * @param buf The xml data buffer.
512 * @param size The size of the data buffer in bytes
513 * @param visitor An object that contains callbacks for XML parsing
515 * @exception Throws sg_io_exception or sg_xml_exception if there
516 * is a problem reading the file.
519 extern void readXML (const char *buf, const int size, XMLVisitor &visitor);
522 #endif // __EASYXML_HXX