#LyX 1.1 created this file. For more info see http://www.lyx.org/ \lyxformat 2.16 \textclass article \language default \inputencoding latin1 \fontscheme default \graphics default \paperfontsize default \spacing single \papersize Default \paperpackage a4 \use_geometry 0 \use_amsmath 0 \paperorientation portrait \secnumdepth 3 \tocdepth 3 \paragraph_separation indent \defskip medskip \quotes_language english \quotes_times 2 \papercolumns 1 \papersides 1 \paperpagestyle default \layout Title Using Libical \layout Author Eric Busboom (eric@softwarestudio.org) \layout Date January 2001 \layout Standard \begin_inset LatexCommand \tableofcontents{} \end_inset \layout Section Introduction \layout Standard Libical is an Open Source implementation of the iCalendar protocols and protocol data units. The iCalendar specification describes how calendar clients can communicate with calendar servers so users can store their calendar data and arrange meetings with other users. \layout Standard Libical implements RFC2445, RFC2446 and some of RFC2447 and the CAP draft. \layout Standard This documentation assumes that you are familiar with the iCalendar standards RFC2445 and RFC2446. these specifications are online on the CALSCH webpage at: \layout LyX-Code http://www.imc.org/ietf-calendar/ \layout Subsection The libical project \layout Standard This code is under active development. If you would like to contribute to the project, you can contact me, Eric Busboom, at eric@softwarestudio.org. The project has a webpage at \layout LyX-Code http://softwarestudio.org/libical/index.html \layout Standard and a mailing list that you can join by sending the following mail: \layout LyX-Code To: minimalist@softwarestudio.org \layout LyX-Code Subject: subscribe libical \layout Subsection License \layout Standard The code and datafiles in this distribution are licensed under the Mozilla Public License. See http://www.mozilla.org/NPL/MPL-1.0.html for a copy of the license. Alternately, you may use libical under the terms of the GNU Library General Public License. See http://www.fsf.org/copyleft/lesser.html for a copy of the LGPL. \layout Standard This dual license ensures that the library can be incorporated into both proprietary code and GPL'd programs, and will benefit from improvements made by programmers in both realms. I will only accept changes into my version of the library if they are similarly dual-licensed. \layout Subsection Example Code \layout Standard A lot of the documentation for this library is in the form of example code. These examples are in the \begin_inset Quotes eld \end_inset examples \begin_inset Quotes erd \end_inset directory of the distribution. Also look in \begin_inset Quotes eld \end_inset src/test \begin_inset Quotes erd \end_inset for additional annotated examples. \layout Section Building and Installing the Library \layout Standard Libical uses autoconf to generate makefiles. It should built with no adjustments on Linux, FreeBSD and Solaris under gcc. Some version have been successfully been build on MacOS, Solaris, UnixWare, And Tru64 UNIX without gcc, but you may run into problems with a particular later version. \layout Standard For a more complete guide to building the library, see the README file in the distribution. \layout Standard \begin_inset Quotes eld \end_inset make install \begin_inset Quotes erd \end_inset will install the libraries and header files for three modules: libical, libicalss. and libicalvcal. If you build shared objects, then these files will be installed: \layout Itemize ical.h \layout Itemize libical.a \layout Itemize libical.so \layout Itemize icalss.h \layout Itemize libicalss.a \layout Itemize libicalss.so \layout Itemize icalvcal.h \layout Itemize libicalvcal.a \layout Itemize libicalvcal.so \layout Standard The header files ical.h and icalss.h are combined header files, generated by concatenating together all of the header files in src/libical and src/libica lss respectively. \layout Section Structure \layout Standard The iCal calendar model is based on four types of objects: components, propertie s, values and parameters. \layout Standard Properties are the fundamental unit of information in iCal, and they work a bit like a hash entry, with a constant key and a variable value. Properties may also have modifiers, called parameters. In the iCal content line \layout LyX-Code ORGANIZER;ROLE=CHAIR:MAILTO:mrbig@host.com \layout Standard The property name is \begin_inset Quotes eld \end_inset ORGANIZER, \begin_inset Quotes erd \end_inset the value of the property is \begin_inset Quotes eld \end_inset mrbig@host.com \begin_inset Quotes erd \end_inset and the \begin_inset Quotes eld \end_inset ROLE \begin_inset Quotes erd \end_inset parameter specifies that Mr Big is the chair of the meetings associated with this property. \layout Standard Components are groups of properties that represent the core objects of a calendar system, such as events or timezones. Components are delimited by \begin_inset Quotes eld \end_inset BEGIN \begin_inset Quotes erd \end_inset and \begin_inset Quotes eld \end_inset END \begin_inset Quotes erd \end_inset tags. \layout Standard \added_space_bottom 0.3cm When a component is sent across a network, if it is un-encrypted, it will look something like: \layout LyX-Code BEGIN:VCALENDAR \layout LyX-Code METHOD:REQUEST \layout LyX-Code PRODID: -//hacksw/handcal//NONSGML v1.0//EN \layout LyX-Code BEGIN:VEVENT \layout LyX-Code DTSTAMP:19980309T231000Z \layout LyX-Code UID:guid-1.host1.com \layout LyX-Code ORGANIZER;ROLE=CHAIR:MAILTO:mrbig@host.com \layout LyX-Code ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT;CUTYPE=GROUP: \layout LyX-Code MAILTO:employee-A@host.com \layout LyX-Code DESCRIPTION:Project XYZ Review Meeting \layout LyX-Code CATEGORIES:MEETING \layout LyX-Code CLASS:PUBLIC \layout LyX-Code CREATED:19980309T130000Z \layout LyX-Code SUMMARY:XYZ Project Review \layout LyX-Code DTSTART;TZID=US-Eastern:19980312T083000 \layout LyX-Code DTEND;TZID=US-Eastern:19980312T093000 \layout LyX-Code LOCATION:1CP Conference Room 4350 \layout LyX-Code END:VEVENT \layout LyX-Code END:VCALENDAR \layout Standard Note that components can be nested; this example has both a VCALENDAR and a VEVENT component, one nested inside the other. \layout Standard The main goal of Libical is to offer a structured, type-safe to create, access and manipulate components and their properties, values and parameters. \layout Subsection Core iCal classes \layout Standard Libical is an object-based, data-oriented library. There are no real-objects, but the way the routines are named and organized results in the same sort of encapsulations and abstraction that are major features of Object-Orieted languages. Nearly all of the routines in the library are associated with an opaque data types and perform some operation on that data type. For instnace, a Property is declared as: \layout LyX-Code icalproperty *prop; \layout Standard Icalproperty is typedef'd to void, so the only way to manipulate it is through the accessor routines, all of which have a form similar to: \layout LyX-Code char* icalproperty_as_ical_string(icalproperty* prop); \layout Standard That is, the name of the 'class' is the first word in the routine name, and the first parameter is a pointer to the 'object.' \layout Standard Although the library does not actually have classes, we will use those terms since the behavior of these associations of data and routines is very similar to a class. \layout Subsubsection Properties \layout LyX-Code icalproperty *prop; \layout Standard Properties are represented with the icalproperty class and its many \begin_inset Quotes eld \end_inset derived \begin_inset Quotes erd \end_inset classes with on \begin_inset Quotes eld \end_inset derived \begin_inset Quotes erd \end_inset class per property type in RFC2445. Again, there is no actual inheritance relations, but there are clusters of routines that make this term useful. A property is a container for a single value and a set of parameters. \layout Subsubsection Components \layout LyX-Code icalcomponent *comp; \layout Standard In libical, components are represented with the icalcomponent class. Icalcomponent is a container for a set of other components and properties. \layout Subsubsection Values \layout LyX-Code icalvalue *value; \layout Standard Values are represented in a similar way to properties; a base class and many \begin_inset Quotes eld \end_inset derived \begin_inset Quotes eld \end_inset classes. A value is essentially a abstract handle on a single fundamental type, a structure or a union. You probably will never use a value directly, since for most operations you can get to its data through the property that holds it. \layout Subsubsection Parameters \layout LyX-Code icalparameter *param; \layout Standard Parameters are represetned in a similar way to properties, except that they contain only one value \layout Subsection Other elements of libical \layout Standard In addition to the core iCal classes, libical has many other types, structures, classes that aid in creating and using iCal components. \layout Subsubsection Enumerations and types \layout Standard Libical is strongly typed, so every component, property, parameter, and value type has an enumeration, and some have an associated structure or union. \layout Subsubsection The parser \layout Standard The libical parser offers a variety of ways to convert RFC2445 text into a libical iinsteral component structure. the parser can parse blocks of text as a string, or it can parse lin-by-line. \layout Subsubsection Error objects \layout Standard Libical has a substantial error reporting system for both programming errors and component usage errors. \layout Subsubsection Memory Management \layout Standard Since many of libicals interfaces return strings, the library has its own memory management system to elimiate the need to free every string returned from the libraru. \layout Subsubsection Storage classes \layout Standard The library also offers several classes to store components to flies, memory or databases. \layout Section Differences From RFCs \layout Standard Libical has been designed to follow the standards as closely as possible, so that the key objects in the standards are also key objects in the library. However, there are a few areas where the specifications are (arguably) irregular, and following them exactly would result in an unfriendly interface. These deviations make libical easier to use by maintaining a self-similar interface. \layout Subsection Pseudo Components \layout Standard Libical defines components for groups of properties that look and act like components, but are not defined as components in the specification. XDAYLIGHT and XSTANDARD are notable examples. These pseudo components group properties within the VTIMEZONE components. For instanace, the timezone properties associated with daylight savings time starts with \begin_inset Quotes eld \end_inset BEGIN:DAYLIGHT \begin_inset Quotes erd \end_inset and ends with \begin_inset Quotes eld \end_inset END:DAYLIGHT, just like other components, but is not defined as a component in RFC2445. ( See RFC2445, page 61 ) In Libical,this grouping is represented by the XDAYLIGHT component. Standard iCAL components all start with the letter \begin_inset Quotes eld \end_inset V, \begin_inset Quotes erd \end_inset while pseudo components start with \begin_inset Quotes erd \end_inset X. \begin_inset Quotes erd \end_inset \layout Standard There are also pseudo components that are conceptually derived classes of VALARM. RFC2446 defines what properties may be included in each component, and for VALARM, the set of properties it may have depends on the value of the ACTION property. \layout Standard For instance, if a VALARM component has an ACTION property with the value of \begin_inset Quotes eld \end_inset AUDIO, \begin_inset Quotes erd \end_inset the component must also have an \begin_inset Quotes eld \end_inset ATTACH \begin_inset Quotes erd \end_inset property. However, if the ACTION value is \begin_inset Quotes eld \end_inset DISPLAY, \begin_inset Quotes erd \end_inset the component must have a DESCRIPTION property. \layout Standard To handle these various, complex restrictions, libical has pseudo components for each type of alarm: XAUDIOALARM, XDISPLAYALARM, XEMAILALARM and XPROCEDUREA LARM. \layout Subsection Combined Values \layout Standard Many values can take more than one type. TRIGGER, for instance, can have a value type of with DURATION or of DATE-TIME. These multiple types make it difficult to create routines to return the value associated with a property. \layout Standard It is natural to have interfaces that would return the value of a property, but it is cumbersome for a single routine to return multiple types. So, in libical, properties that can have multiple types are given a single type that is the union of their RFC2445 types. For instance, in libical, the value of the TRIGGER property resolves to struct icaltriggertype. This type is a union of a DURATION and a DATE-TIME. \layout Subsection Multi-Valued Properties \layout Standard Some properties, such as CATEGORIES have only one value type, but each CATEGORIE S property can have multiple value instances. This also results in a cumbersome interface -- CATEGORIES accessors would have to return a list while all other accessors returned a single value. In libical, all properties have a single value, and multi-valued properties are broken down into multiple single valued properties during parsing. That is, an input line like, \layout LyX-Code CATEGORIES: work, home \layout Standard becomes in libical's internal representation \layout LyX-Code CATEGORIES: work \layout LyX-Code CATEGORIES: home \layout Standard Oddly, RFC2445 allows some multi-valued properties ( like FREEBUSY ) to exist as both a multi-values property and as multiple single value properties, while others ( like CATEGORIES ) can only exist as single multi-valued properties. This makes the internal representation for CATEGORIES illegal. However when you convert a component to a string, the library will collect all of the CATEGORIES properties into one. \layout Section Using libical \layout Subsection Creating Components \layout Standard There are three ways to create components in Libical: \layout Itemize Create individual components, properties and parameters and assemble them into structures \layout Itemize Build complete components with nested vaargs calls \layout Itemize Parse bits of text \layout Itemize Parse entire files \layout Subsubsection Constructor Interfaces \layout Standard Using constructor interfaces, you create each of the objects separately and then assemble them in to components: \layout LyX-Code icalcomponent *event; \layout LyX-Code icalproperty *prop; \layout LyX-Code icalparameter *param; \layout LyX-Code struct icaltimetype atime; \layout LyX-Code \layout LyX-Code event = icalcomponent_new(ICAL_VEVENT_COMPONENT); \layout LyX-Code prop = icalproperty_new_dtstamp(atime); \layout LyX-Code icalcomponent_add_property(event, prop); \layout LyX-Code \layout LyX-Code prop = icalproperty_new_uid(''guid-1.host1.com'') ); \layout LyX-Code icalcomponent_add_property(event,prop); \layout LyX-Code \layout LyX-Code prop=icalproperty_new_organizer(''mrbig@host.com''); \layout LyX-Code param = icalparameter_new_role(ICAL_ROLE_CHAIR) \layout LyX-Code icalproperty_add_parameter(prop, param); \layout LyX-Code \layout LyX-Code icalcomponent_add_property(event,prop); \layout Standard Notice that libical uses a semi-object-oriented style of interface. Most things you work with are objects, that are instantiated with a constructor that has \begin_inset Quotes eld \end_inset new \begin_inset Quotes erd \end_inset in the name. Also note that, other than the object reference, most structure data is passed in to libical routines by value. Libical has some complex but very regular memory handling rules. These are detailed in section \begin_inset LatexCommand \ref{sec:memory} \end_inset . \layout Standard If any of the constructors fail, they will return 0. If you try to insert 0 into a property or component, or use a zero-valued object reference, libical will either silently ignore the error or will abort with an error message. This behavior is controlled by a compile time flag (ICAL_ERRORS_ARE_FATAL), and will abort by default. \layout Subsubsection vaargs Constructors \layout Standard There is another way to create complex components, which is arguably more elegant, if you are not horrified by varargs. The varargs constructor interface allows you to create intricate components in a single block of code. Here is the previous examples in the vaargs style. \layout LyX-Code calendar = \layout LyX-Code icalcomponent_vanew( \layout LyX-Code ICAL_VCALENDAR_COMPONENT, \layout LyX-Code icalproperty_new_version(''2.0''), \layout LyX-Code icalproperty_new_prodid( \layout LyX-Code ''-//RDU Software//NONSGML HandCal//EN''), \layout LyX-Code icalcomponent_vanew( \layout LyX-Code ICAL_VEVENT_COMPONENT, \layout LyX-Code icalproperty_new_dtstamp(atime), \layout LyX-Code icalproperty_new_uid(''guid-1.host1.com''), \layout LyX-Code icalproperty_vanew_organizer( \layout LyX-Code ''mrbig@host.com''), \layout LyX-Code icalparameter_new_role(ICAL_ROLE_CHAIR), \layout LyX-Code 0 \layout LyX-Code ), \layout LyX-Code icalproperty_vanew_attendee( \layout LyX-Code ''employee-A@host.com'', \layout LyX-Code icalparameter_new_role( \layout LyX-Code ICAL_ROLE_REQPARTICIPANT), \layout LyX-Code icalparameter_new_rsvp(1), \layout LyX-Code icalparameter_new_cutype(ICAL_CUTYPE_GROUP), \layout LyX-Code 0 \layout LyX-Code ), \layout LyX-Code icalproperty_new_location( \layout LyX-Code "1CP Conference Room 4350"), \layout LyX-Code 0 \layout LyX-Code ), \layout LyX-Code 0 \layout LyX-Code ); \layout Standard This form is similar to the constructor form , except that the constructors have \begin_inset Quotes eld \end_inset vanew \begin_inset Quotes erd \end_inset instead of \begin_inset Quotes eld \end_inset new \begin_inset Quotes erd \end_inset in the name. The arguments are similar too, except that the component constructor can have a list of properties, and the property constructor can have a list of parameters. Be sure to terminate every list with a '0', or your code will crash, if you are lucky. \layout Subsubsection Parsing Text \layout Standard Several routines are available for generating objects from text. For properties, use: \layout LyX-Code icalproperty* p; \layout LyX-Code p = icalproperty_new_from_string("DTSTART:19970101T120000Z \backslash n"); \layout Standard For parameters, use: \layout LyX-Code icalparameter *param \layout LyX-Code param = icalparameter_new_from_string("PARTSTAT=ACCEPTED"); \layout Standard The final way to create components will probably be the most common; you can create components from RFC2445 compliant text. If you have the string in memory, use \layout LyX-Code icalcomponent* icalcomponent_new_from_string(char* str); \layout Standard If the string contains only one component, the routine will return the component in libical form. If the string contains multiple components, the multiple components will be returned as the children of an ICAL_XROOT_COMPONENT component. This routine is identical to ( and actually uses ) icalparser_parse_string(char * str). \layout Standard Parsing a whole string may seem wasteful if you want to pull a large component off of the network or from a file; you may prefer to parse the component line by line. This is possible too by using: \layout LyX-Code icalparser* icalparser_new(); \layout LyX-Code void icalparser_free(icalparser* parser); \layout LyX-Code icalparser_get_line(parser,read_stream); \layout LyX-Code icalparser_add_line(parser,line); \layout LyX-Code icalparser_set_gen_data(parser,stream) \layout Standard These routines will construct a parser object to which you can add lines of input and retrieve any components that the parser creates from the input. These routines work by specifing an adaptor routine to get string data from a source. For an example: \layout LyX-Code char* read_stream(char *s, size_t size, void *d) \layout LyX-Code { \layout LyX-Code char *c = fgets(s,size, (FILE*)d); \layout LyX-Code return c; \layout LyX-Code } \layout LyX-Code main() { \layout LyX-Code char* line; \layout LyX-Code icalcomponent *c; \layout LyX-Code icalparser *parser = icalparser_new(); \layout LyX-Code FILE* stream = fopen(argv[1],"r"); \layout LyX-Code icalparser_set_gen_data(parser,stream); \layout LyX-Code do{ \layout LyX-Code line = icalparser_get_line(parser,read_stream); \layout LyX-Code c = icalparser_add_line(parser,line); \layout LyX-Code if (c != 0){ \layout LyX-Code printf("%s",icalcomponent_as_ical_string(c)); \layout LyX-Code icalparser_claim(parser); \layout LyX-Code printf(" \backslash n--------------- \backslash n"); \layout LyX-Code icalcomponent_free(c); \layout LyX-Code } \layout LyX-Code } while ( line != 0); \layout LyX-Code } \layout Standard The parser object parameterizes the routine used to get input lines with icalparser_set_gen_data() and \emph on \emph default icalparser_get_line(). In this example, the routine read_stream() will fetch the next line from a stream, with the stream passed in as the void* parameter d. The parser calls read_stream() from icalparser_get_line(), but it also needs to know what stream to use. This is set by the call to icalparser_set_gen_data(). By using a different routine for read_stream or passing in different data with icalparser_set_gen_data, you can connect to any data source. \layout Standard Using the same mechanism, other implementations could read from memory buffers, sockets or other interfaces. \layout Standard Since the example code is a very common way to use the parser, there is a convenience routine; \layout LyX-Code icalcomponent* icalparser_parse(icalparser *parser, \layout LyX-Code char* (*line_gen_func)(char *s, size_t size, void* d)) \layout Standard To use this routine, you still must construct the parser object and pass in a reference to a line reading routine. If the parser can create a single component from the input, it will return a pointer to the newly constructed component. If the parser can construct multiple components from the input, it will return a reference to an XROOT component ( of type ICAL_XROOT_COMPONENT.) This XROOT component will hold all of the components constructed from the input as children. \layout Subsection Accessing Components \layout Standard Given a reference to a component, you probably will want to access the propertie s, parameters and values inside. Libical interfaces let you find sub-components, add and remove sub-components, and do the same three operations on properties. \layout Subsubsection Finding Components \layout Standard To find a sub-component of a component, use: \layout LyX-Code icalcomponent* icalcomponent_get_first_component( \layout LyX-Code icalcomponent* component, \layout LyX-Code icalcomponent_kind kind); \layout Standard This routine will return a reference to the first component of the type 'kind.' The key kind values, listed in icalenums.h are: \layout LyX-Code ICAL_ANY_COMPONENT \layout LyX-Code ICAL_VEVENT_COMPONENT \layout LyX-Code ICAL_VTODO_COMPONENT \layout LyX-Code ICAL_VJOURNAL_COMPONENT \layout LyX-Code ICAL_VCALENDAR_COMPONENT \layout LyX-Code ICAL_VFREEBUSY_COMPONENT \layout LyX-Code ICAL_VALARM_COMPONENT \layout Standard These are only the most common components; there are many more listed in icalenums.h. \layout Standard As you might guess, if there is more than one subcomponent of the type you have chosen, this routine will return only the first. to get at the others, you need to iterate through the component. \layout Subsubsection Iterating Through Components \layout Standard Iteration requires a second routine to get the next subcomponent after the first: \layout LyX-Code icalcomponent* icalcomponent_get_next_component( \layout LyX-Code icalcomponent* component, \layout LyX-Code icalcomponent_kind kind); \layout Standard With the 'first' and 'next' routines, you can create a for loop to iterate through all of a components subcomponents \layout LyX-Code for(c = icalcomponent_get_first_component(comp,ICAL_ANY_COMPONENT); \layout LyX-Code c != 0; \layout LyX-Code c = icalcomponent_get_next_component(comp,ICAL_ANY_COMPONENT)) \layout LyX-Code { \layout LyX-Code do_something(c); \layout LyX-Code } \layout Standard This code bit wil iterate through all of the subcomponents in 'comp' but you can select a specific type of component by changing ICAL_ANY_COMPONENT to another component type. \layout Subsubsection Using Component Iterators \layout Standard The iteration model in the previous section requires the component to keep the state of the iteration. So, you could not use this model to perform a sorting operations, since you'd need two iterators and there is only space for one. If you ever call icalcomponent_get_first_component() when an iteration is in progress, the pointer will be reset to the beginning. \layout Standard To solve this problem, there are also external iterators for components. The routines associated with these external iterators are: \layout LyX-Code icalcompiter icalcomponent_begin_component(icalcomponent* component, icalcompone nt_kind kind); \layout LyX-Code icalcompiter icalcomponent_end_component(icalcomponent* component, icalcomponent _kind kind); \layout LyX-Code icalcomponent* icalcompiter_next(icalcompiter* i); \layout LyX-Code icalcomponent* icalcompiter_prior(icalcompiter* i); \layout LyX-Code icalcomponent* icalcompiter_deref(icalcompiter* i); \layout Standard The _begin_() and _end_() routines return a new iterator that points to the beginning and ending of the list of subcomponent for the given component, and the kind argument works like the kind argument for internal iterators. \layout Standard After creating an iterators, use _next_() and _prior_() to step forward and backward through the list and get the component that the iterator points to, and use _deref() to return the component that the iterator points to without moving the iterator. All routines will return 0 when they move to point off the end of the list. \layout Standard Here is an example of a loop using these routines: \layout LyX-Code for( \layout LyX-Code i = icalcomponent_begin_component(impl->cluster,ICAL_ANY_COMPONENT); \layout LyX-Code icalcompiter_deref(&i)!= 0; \layout LyX-Code icalcompiter_next(&i) \layout LyX-Code ) { \layout LyX-Code icalcomponent *this = icalcompiter_deref(&i); \layout LyX-Code } \layout Subsubsection Removing Components \layout Standard Removing an element from a list while iterating through the list with the internal iterators can cause problems, since you will probably be removing the element that the internal iterator points to. The _remove() routine will keep the iterator valid by moving it to the next component, but in a normal loop, this will result in two advances per iteration, and you will remove only every other component. To avoid the problem, you will need to step the iterator ahead of the element you are going to remove, like this: \layout LyX-Code for(c = icalcomponent_get_first_component(parent_comp,ICAL_ANY_COMPONENT); \layout LyX-Code c != 0; \layout LyX-Code c = next \layout LyX-Code { \layout LyX-Code next = icalcomponent_get_next_component(parent_comp,ICAL_ANY_COMPONENT); \layout LyX-Code icalcomponent_remove_component(parent_comp,c); \layout LyX-Code } \layout Standard Another way to remove components is to rely on the side effect of icalcomponent_ remove_component: if component iterator in the parent component is pointing to the child that will be removed, it will move the iterator to the component after the child. The following code will exploit this behavior: \layout LyX-Code icalcomponent_get_first_component(parent_comp,ICAL_VEVENT_COMPONENT); \layout LyX-Code while((c=icalcomponent_get_current_component(c)) != 0 ){ \layout LyX-Code if(icalcomponent_isa(c) == ICAL_VEVENT_COMPONENT){ \layout LyX-Code icalcomponent_remove_component(parent_comp,inner); \layout LyX-Code } else { \layout LyX-Code icalcomponent_get_next_component(parent_comp,ICAL_VEVENT_COMPONENT); \layout LyX-Code } \layout LyX-Code } \layout Subsubsection Working with properties and parameters \layout Standard Finding, iterating and removing properties works the same as it does for components, using the property-specific or parameter-specific interfaces: \layout LyX-Code icalproperty* icalcomponent_get_first_property( \layout LyX-Code icalcomponent* component, \layout LyX-Code icalproperty_kind kind); \layout LyX-Code icalproperty* icalcomponent_get_next_property( \layout LyX-Code icalcomponent* component, \layout LyX-Code icalproperty_kind kind); \layout LyX-Code void icalcomponent_add_property( \layout LyX-Code icalcomponent* component, \layout LyX-Code icalproperty* property); \layout LyX-Code void icalcomponent_remove_property( \layout LyX-Code icalcomponent* component, \layout LyX-Code icalproperty* property); \layout Standard For parameters: \layout LyX-Code icalparameter* icalproperty_get_first_parameter( \layout LyX-Code icalproperty* prop, \layout LyX-Code icalparameter_kind kind); \layout LyX-Code icalparameter* icalproperty_get_next_parameter( \layout LyX-Code icalproperty* prop, \layout LyX-Code icalparameter_kind kind); \layout LyX-Code void icalproperty_add_parameter( \layout LyX-Code icalproperty* prop, \layout LyX-Code icalparameter* parameter); \layout LyX-Code void icalproperty_remove_parameter( \layout LyX-Code icalproperty* prop, \layout LyX-Code icalparameter_kind kind); \layout Standard Note that since there should be only one parameter of each type in a property, you will rarely need to use icalparameter_get_nect_paameter. \layout Subsubsection Working with values \layout Standard Values are typically part of a property, although they can exist on their own. You can manipulate them either as part of the property or independently. \layout Standard The most common way to work with values to is to manipulate them from they properties that contain them. This involves fewer routine calls and intermediate variables than working with them independently, and it is type-safe. \layout Standard For each property, there are a _get_ and a _set_ routine that access the internal value. For instanace, for the UID property, the routines are: \layout LyX-Code void icalproperty_set_uid(icalproperty* prop, const char* v) \layout LyX-Code const char* icalproperty_get_uid(icalproperty* prop) \layout Standard For multi-valued properties, like ATTACH, the value type is usually a struct or union that holds both possible types. \layout Standard If you want to work with the underlying value object, you can get and set it with: \layout LyX-Code icalvalue* icalproperty_get_value (icalproperty* prop) \layout LyX-Code void icalproperty_set_value(icalproperty* prop, icalvalue* value); \layout Standard Icalproperty_get_value() will return a reference that you can manipulate with other icalvalue routines. Most of the time, you will have to know what the type of the value is. For instance, if you know that the value is a DATETIME type, you can manipulate it with: \layout LyX-Code struct icaltimetype icalvalue_get_datetime(icalvalue* value); \layout LyX-Code void icalvalue_set_datetime(icalvalue* value, struct icaltimetype v); \layout Standard When working with an extension property or value (and X-PROPERTY or a property that has the parameter VALUE=x-name ) the value type is always a string. To get and set the value, use: \layout LyX-Code void icalproperty_set_x(icalproperty* prop, char* v); \layout LyX-Code char* icalproperty_get_x(icalproperty* prop); \layout Standard All X properties have the type of ICAL_X_PROPERTY, so you will need these routines to get and set the name of the property: \layout LyX-Code char* icalproperty_get_x_name(icalproperty* prop) \layout LyX-Code void icalproperty_set_x_name(icalproperty* prop, char* name); \layout Subsubsection Checking Component Validity \layout Standard RFC 2446 defines rules for what properties must exist in a component to be used for transferring scheduling data. Most of these rules relate to the existence of properties relative to the METHOD property, which declares what operation a remote receiver should use to process a component. For instance, if the METHOD is REQUEST and the component is a VEVENT, the sender is probably asking the receiver to join in a meeting. In this case, RFC2446 says that the component must specify a start time (DTSTART) and list the receiver as an attendee (ATTENDEE). \layout Standard Libical can check these restrictions with the routine: \layout LyX-Code int icalrestriction_check(icalcomponent* comp); \layout Standard This routine returns 0 if the component does not pass RFC2446 restrictions, or if the component is malformed. The component you pass in \emph on must \emph default be a VCALENDAR, with one or more children, like the examples in RFC2446. \layout Standard When this routine runs, it will insert new properties into the component to indicate any errors it finds. See section 6.5.3, X-LIC-ERROR for more information about these error properties. \layout Subsubsection Converting Components to Text \layout Standard To create an RFC2445 compliant text representation of an object, use one of the *_as_ical_string() routines: \layout LyX-Code char* icalcomponent_as_ical_string (icalcomponent* component) \layout LyX-Code char* icalproperty_as_ical_string (icalproperty* property) \layout LyX-Code char* icalparameter_as_ical_string (icalparameter* parameter) \layout LyX-Code char* icalvalue_as_ical_string (icalvalue* value) \layout Standard In most cases, you will only use icalcomponent_as_ical_string (), since it will cascade and convert all of the parameters, properties and values that are attached to the root component. \layout Standard Icalproperty_as_ical_string() will terminate each line with the RFC2445 specified line terminator \begin_inset Quotes eld \end_inset \backslash \backslash n \begin_inset Quotes erd \end_inset However, if you compile with the symbol ICAL_UNIX_NEWLINE undefined, ( it is defined by default) it will terminate lines with \begin_inset Quotes eld \end_inset \backslash \backslash n \backslash \backslash r \begin_inset Quotes erd \end_inset \layout Standard Remember that the string returned by these routines is owned by the library, and will eventually be re-written. You should copy it if you want to preserve it. \layout Subsection Time \layout Subsubsection Time structure \layout Standard LIbical defines it's own time structure for storing all dates and times. It would have been nice to re-use the C library's \emph on struct tm, \emph default but that structure does not differentiate between dates and times, and between local time and UTC. The libical structure is: \layout LyX-Code struct icaltimetype { \layout LyX-Code int year; \layout LyX-Code int month; \layout LyX-Code int day; \layout LyX-Code int hour; \layout LyX-Code int minute; \layout LyX-Code int second; \layout LyX-Code int is_utc; /* 1-> time is in UTC timezone */ \layout LyX-Code int is_date; /* 1 -> interpret this as date. */ }; \layout Standard The year, month, day, hour, minute and second fields hold the broken-out time values. The is_utc field distinguishes between times in UTC and a local time zone. The is_date field indicates if the time should be interpreted only as a date. If it is a date, the hour, minute and second fields are assumed to be zero, regardless of their actual vaules. \layout Subsubsection Creating time structures \layout Standard There are several ways to create a new icaltimetype structure: \layout LyX-Code struct icaltimetype icaltime_from_string(const char* str); \layout LyX-Code struct icaltimetype icaltime_from_timet(time_t v, int is_date); \layout LyX-Code \layout Standard Icaltime_from_string takes any RFC2445 compliant time string: \layout LyX-Code struct icaltimetype tt = icaltime_from_string("19970101T103000"); \layout Standard Icaltime_from_timet takes a timet value, representing seconds past the POSIX epoch, and a flag to indicate if the time is a date. Dates have an identical structure to a time, but the time portion ( hours, minuts and seconds ) is always 00:00:00. Dates act differently in sorting an comparision, and they have a different string representation in RFC2445. \layout Subsubsection Time manipulating routines \layout Standard The null time value is used to indicate that the data in the structure is not a valid time. \layout LyX-Code struct icaltimetype icaltime_null_time(void); \layout LyX-Code int icaltime_is_null_time(struct icaltimetype t); \layout Standard It is sensible for the broken-out time fields to contain values that are not permitted in an ISO compliant time string. For instance, the seconds field can hold values greater than 59, and the hours field can hold values larger than 24. The excessive values will be rolled over into the next larger field when the structure is normalized. \layout LyX-Code struct icaltimetype icaltime_normalize(struct icaltimetype t); \layout Standard Normalizing allows you to do arithmetic operations on time values. \layout LyX-Code struct icaltimetype tt = icaltime_from_string( \begin_inset Quotes eld \end_inset 19970101T103000 \begin_inset Quotes erd \end_inset ); \layout LyX-Code tt.days +=3 \layout LyX-Code tt.second += 70; \layout LyX-Code tt = icaltime_normalize(tt); \layout Standard There are several routines to get the day of the week or month, etc, from a time structure. \layout LyX-Code short icaltime_day_of_year(struct icaltimetype t); \layout LyX-Code struct icaltimetype icaltime_from_day_of_year(short doy, short year); \layout LyX-Code short icaltime_day_of_week(struct icaltimetype t); \layout LyX-Code short icaltime_start_doy_of_week(struct icaltimetype t); \layout LyX-Code short icaltime_week_number(short day_of_month, short month, short year); \layout LyX-Code struct icaltimetype icaltime_from_week_number(short week_number, short year); \layout LyX-Code short icaltime_days_in_month(short month,short year); \layout Standard Two routines convert time structures to and from the number of seconds since the POSIX epoch. The is_date field indicates whether or not the hour, minute and second fields should be used in the conversion. \layout LyX-Code struct icaltimetype icaltime_from_timet(time_t v, int is_date); \layout LyX-Code time_t icaltime_as_timet(struct icaltimetype); \layout Standard The compare routine works exactly like strcmp, but on time structures. \layout LyX-Code int icaltime_compare(struct icaltimetype a,struct icaltimetype b); \layout Standard The following routines convert between UTC and a named timezone. The tzid field must be a timezone name from the Olsen database, such as \begin_inset Quotes eld \end_inset America/Los_Angeles. \begin_inset Quotes erd \end_inset \layout Standard The utc_offset routine returns the offset of the named time zone from UTC, in seconds. \layout Standard The tt parameter in the following routines indicates the date on which the conversion should be made. The tt parameter is necessary because timezones have many different rules for when daylight savings time is used, and these rules can change over time. So, for a single timezone one year may have daylight savings time on March 15, but for other years March 15 may be standard time, and some years may have standard time all year. \layout LyX-Code int icaltime_utc_offset(struct icaltimetype tt, char* tzid); \layout LyX-Code int icaltime_local_utc_offset(); \layout LyX-Code struct icaltimetype icaltime_as_utc(struct icaltimetype tt,char* tzid); \layout LyX-Code struct icaltimetype icaltime_as_zone(struct icaltimetype tt,char* tzid); \layout LyX-Code struct icaltimetype icaltime_as_local(struct icaltimetype tt); \layout Subsection Storing Objects \layout Standard The libical distribution includes a separate library, libicalss, that allows you to store iCal component data to disk in a variety of ways. This library also includes code to implement the CSTP protocol of CAP and has some routines for deciphering incomming messages. \layout Standard The file storage routines are organized in an inheritance heirarchy that is rooted in icalset, with the derived class icalfileset and icaldirset. Icalfileset stores components to a file, while icaldirset stores components to multiple files, one per month based on DTSTAMP. Other storages classess, for storage to a heap or a mysql database are planned for the future. \layout Standard All of the icalset derived classes have the same interface: \layout LyX-Code \layout LyX-Code icaldirset* icaldirset_new(const char* path); \layout LyX-Code void icaldirset_free(icaldirset* store); \layout LyX-Code const char* icaldirset_path(icaldirset* store); \layout LyX-Code void icaldirset_mark(icaldirset* store); \layout LyX-Code icalerrorenum icaldirset_commit(icaldirset* store); \layout LyX-Code icalerrorenum icaldirset_add_component(icaldirset* store, icalcomponent* comp); \layout LyX-Code icalerrorenum icaldirset_remove_component(icaldirset* store, icalcomponent* comp); \layout LyX-Code int icaldirset_count_components(icaldirset* store, icalcomponent_kind kind); \layout LyX-Code icalerrorenum icaldirset_select(icaldirset* store, icalcomponent* gauge); \layout LyX-Code void icaldirset_clear(icaldirset* store); \layout LyX-Code icalcomponent* icaldirset_fetch(icaldirset* store, const char* uid); \layout LyX-Code int icaldirset_has_uid(icaldirset* store, const char* uid); \layout LyX-Code icalcomponent* icaldirset_fetch_match(icaldirset* set, icalcomponent *c); \layout LyX-Code icalerrorenum icaldirset_modify(icaldirset* store, icalcomponent *oldc, icalcomponent *newc); \layout LyX-Code icalcomponent* icaldirset_get_current_component(icaldirset* store); \layout LyX-Code icalcomponent* icaldirset_get_first_component(icaldirset* store); \layout LyX-Code icalcomponent* icaldirset_get_next_component(icaldirset* store); \layout Subsubsection Creating a new set \layout Standard You can create a new set from either the base class or the direved class. From the base class use one of: \layout LyX-Code icalset* icalset_new_file(const char* path); \layout LyX-Code icalset* icalset_new_dir(const char* path); \layout LyX-Code icalset* icalset_new_heap(void); \layout LyX-Code icalset* icalset_new_mysql(const char* path); \layout Standard You can also create a new set based on the derived class, For instance, with icalfileset: \layout LyX-Code icalfileset* icalfileset_new(const char* path); \layout LyX-Code icalfileset* icalfileset_new_open(const char* path, int flags, mode_t mode); \layout Standard Icaset_new_file is identical to icalfileset_new. BOth routines will open an existing file for readinga and writing, or create a new file if it does not exist. Icalfilset_new_open takes the same arguments as the open() system routine and behaves in the same way. \layout Standard The icalset and icalfilset objects are somewhat interchangable -- you can use an icalfileset* as an argument to any of the icalset routines. \layout Standard The following examples will all use icalfileset routines; using the other icalset derived classess will be similar. \layout Subsubsection Adding, Finding and Removing Components \layout Standard To add components to a set, use: \layout LyX-Code icalerrorenum icalfileset_add_component(icalfileset* cluster, icalcomponent* child); \layout Standard The fileset keeps an inmemory copy of the components, and this set must be written back to the file ocassionally. There are two routines to manage this: \layout LyX-Code void icalfileset_mark(icalfileset* cluster); \layout LyX-Code icalerrorenum icalfileset_commit(icalfileset* cluster); \layout Standard Icalfileset_mark indicates that the in-memory components have changed. Calling the _add_component routine will call _mark automatically, but you may need to call it yourself if you have made a change to an existing component. The _commit routine writes the data base to disk, but only if it is marked. The _commit routine is called automatically when the icalfileset is freed. \layout Standard To iterate through the components in a set, use: \layout LyX-Code icalcomponent* icalfileset_get_first_component(icalfileset* cluster); \layout LyX-Code icalcomponent* icalfileset_get_next_component(icalfileset* cluster); \layout LyX-Code icalcomponent* icalfileset_get_current_component (icalfileset* cluster); \layout Standard These routines work like the corresponding routines from icalcomponent, except that their output is filtered through a gauge. A gauge is a test for the properties within a components; only components that pass the test are returned. A gauge can be constructed from a MINSQL string with: \layout LyX-Code icalgauge* icalgauge_new_from_sql(char* sql); \layout Standard Then, you can add the gauge to the set with : \layout LyX-Code icalerrorenum icalfileset_select(icalfileset* store, icalgauge* gauge); \layout Standard Here is an example that puts all of these routines together: \layout LyX-Code \latex no_latex void test_fileset() \layout LyX-Code \latex no_latex { \layout LyX-Code \latex no_latex icalfileset *fs; \layout LyX-Code \latex no_latex icalcomponent *c; \layout LyX-Code \latex no_latex int i; \layout LyX-Code \latex no_latex char *path = "test_fileset.ics"; \layout LyX-Code \latex no_latex icalgauge *g = icalgauge_new_from_sql( \layout LyX-Code \latex no_latex "SELECT * FROM VEVENT WHERE DTSTART > '20000103T120000Z' AND DTSTART <= '20000106T120000Z'"); \layout LyX-Code \latex no_latex \layout LyX-Code \latex no_latex fs = icalfileset_new(path); \layout LyX-Code \layout LyX-Code \latex no_latex for (i = 0; i!= 10; i++){ \layout LyX-Code \latex no_latex c = make_component(i); \latex default /* Make a new component where DTSTART has month of i */ \layout LyX-Code \latex no_latex icalfileset_add_component(fs,c); \layout LyX-Code \latex no_latex } \layout LyX-Code \layout LyX-Code \latex no_latex icalfileset_commit(fs); \latex default /* Write to disk */ \layout LyX-Code \layout LyX-Code \latex no_latex icalfileset_select(fs,g); \latex default /* Set the gauge to filter components */ \layout LyX-Code \latex no_latex \layout LyX-Code \latex no_latex for (c = icalfileset_get_first_component(fs); \layout LyX-Code \latex no_latex c != 0; \layout LyX-Code \latex no_latex c = icalfileset_get_next_component(fs)){ \layout LyX-Code \latex no_latex struct icaltimetype t = icalcomponent_get_dtstart(c); \layout LyX-Code \latex no_latex \layout LyX-Code \latex no_latex printf("%s \backslash n",icaltime_as_ctime(t)); \layout LyX-Code \latex no_latex } \layout LyX-Code \latex no_latex icalfileset_free(fs); \layout LyX-Code \latex no_latex } \layout Subsubsection Other routines \layout Standard There are several other routines in the icalset interface, but they not fully implemented yet. \layout Subsection \begin_inset LatexCommand \label{sec:memory} \end_inset Memory Management \layout Standard Libical relies heavily on dynamic allocation for both the core objects and for the strings used to hold values. Some of this memory the library caller owns and must free, and some of the memory is managed by the library. Here is a summary of the memory rules. \layout Description 1) If the function name has "new" in it, the caller gets control of the memory. ( such as icalcomponent_new(), or icalproperty_new_clone() ) \layout Description 2) If you got the memory from a routine with new in it, you must call the corresponding *_free routine to free the memory. ( Use icalcomponent_free() to free objects created with icalcomponent_new()) \layout Description 3) If the function name has "add" in it, the caller is transferring control of the memory to the routine. ( icalproperty_add_parameter() ) \layout Description 4) If the function name has "remove" in it, the caller passes in a pointer to an object and after the call returns, the caller owns the object. So, before you call icalcomponent_remove_property(comp,foo), you do not own "foo" and after the call returns, you do. \layout Description 5) If the routine returns a string, libical owns the memory and will put it on a ring buffer to reclaim later. For example, icalcomponent_as_ical_string(). You'd better strdup() it if you want to keep it, and you don't have to delete it. \layout Subsection Error Handling \layout Standard Libical has several error handling mechanisms for the various types of programmi ng, semantic and syntactic errors you may encounter. \layout Subsubsection Return values \layout Standard Many library routines signal errors through their return values. All routines that return a pointer, such as icalcomponent_new(), will return 0 ( zero ) on a fatal error. Some routines will return a value of enum icalerrorenum. \layout Subsubsection icalerrno \layout Standard Most routines will set the global error value icalerrno on errors. This variable is an enumeration; permissible values can be found in libical/ica lerror.h. If the routine returns an enum icalerrorenum, then the return value will be the same as icalerrno. You can use icalerror_strerror() to get a string that describes the error. The enumerations are: \layout Standard \added_space_top 0.3cm \added_space_bottom 0.3cm \align center \LyXTable multicol5 12 2 0 0 -1 -1 -1 -1 1 1 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 1 0 0 2 1 0 "" "" 2 1 1 "" "" 0 8 1 0 0 0 0 "" "" 0 8 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" \newline \newline ICAL_BADARG_ERROR \newline One of the argument to a routine was bad. Typically for a null pointer. \newline ICAL_NEWFAILED_ERROR \newline A new() or malloc() failed \newline ICAL_MALFORMEDDATA_ERROR \newline An input string was not in the correct format \newline ICAL_PARSE_ERROR \newline the parser failed to parse an incomming component \newline ICAL_INTERNAL_ERROR \newline Largely equivalent to an assert; it indicates a bug in the libical code \newline ICAL_FILE_ERROR \newline A file operation failed. Check errno for more detai \newline ICAL_ALLOCATION_ERROR \newline \newline ICAL_NO_ERROR \newline No error has occurred \newline ICAL_TIMEDOUT_ERROR \newline Failed to acquire a lock on a file, or the CSTP protocol timed out. \newline ICAL_MULTIPLEINCLUSION_ERROR \newline \newline ICAL_UNKNOWN_ERROR \newline \layout Subsubsection X-LIC-ERROR and X-LIC-INVALID-COMPONENT \layout Standard The library handles semantic and syntactic errors in components by inserting errors properties into the components. If the parser cannot parse incoming text ( a syntactic error ) or if the icalrestriction_check() routine indicates that the component does not meet the requirements of RFC2446 ( a semantic error) the library will insert properties of the type X-LIC-ERROR to describe the error. Here is an example of the error property: \layout LyX-Code X-LIC-ERROR;X-LIC-ERRORTYPE=INVALID_ITIP :Failed iTIP restrictions for property DTSTART. \layout LyX-Code Expected 1 instances of the property and got 0 \layout Standard This error resulted from a call to icalrestriction_check(), which discovered that the component does not have a DTSTART property, as required by RFC2445. \layout Standard There are a few routines to manipulate error properties: \layout Standard \LyXTable multicol5 10 2 0 0 -1 -1 -1 -1 1 1 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 1 0 0 0 1 1 0 0 1 0 0 0 1 1 0 0 1 1 0 2 1 1 "" "" 2 1 1 "3in" "" 0 2 1 1 0 0 0 "" "" 0 8 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 1 0 1 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 1 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 1 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 1 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 1 1 0 1 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 1 1 0 1 "" "" 0 2 1 0 0 0 0 "" "" 0 2 1 1 0 0 1 "" "" Routine \newline Purpose \newline void icalrestriction_check() \newline Check a component against RFC2446 and insert \newline \newline error properties to indicate non compliance \newline int icalcomponent_count_errors() \newline Return the number of error properties \newline \newline in a component \newline void icalcomponent_strip_errors() \newline Remove all error properties in as \newline \newline component \newline void icalcomponent_convert_errors() \newline Convert some error properties into \newline \newline REQUESTS-STATUS proprties to indicate the inability to \newline \newline process the component as an iTIP request. \layout Standard The types of errors are listed in icalerror.h. They are: \layout LyX-Code ICAL_XLICERRORTYPE_COMPONENTPARSEERROR \layout LyX-Code ICAL_XLICERRORTYPE_PARAMETERVALUEPARSEERROR \layout LyX-Code ICAL_XLICERRORTYPE_PARAMETERNAMEPARSEERROR \layout LyX-Code ICAL_XLICERRORTYPE_PROPERTYPARSEERROR \layout LyX-Code ICAL_XLICERRORTYPE_VALUEPARSEERROR \layout LyX-Code ICAL_XLICERRORTYPE_UNKVCALPROP \layout LyX-Code ICAL_XLICERRORTYPE_INVALIDITIP \layout Standard The libical parser will generate the error that end in PARSEERROR when it encounters garbage in the input steam. ICAL_XLICERRORTYPE_INVALIDITIP is inserted by icalrestriction_check(), and ICAL_XLICERRORTYPE_UNKVCALPROP is generated by icalvcal_convert() when it encounters a vCal property that it cannot convert or does not know about. \layout Standard Icalcomponent_convert_errors() converts some of the error properties in a component into REQUEST-STATUS properties that indicate a failure. As of libical version0.18, this routine only convert *PARSEERROR errors and it always generates a 3.x ( failure ) code. This makes it more of a good idea than a really useful bit of code. \layout Subsubsection ICAL_ERRORS_ARE_FATAL and icalerror_errors_are_fatal \layout Standard If the global variable icalerror_errors_are_fatal is set to 1, then any error condition will cause the program to abort. The abort occurs in icalerror_set_errno(), and is done with an assert(0) if NDEBUG is undefined, and with icalerror_crash_here if NDEBUG is defined. The default value of icalerror_errors_are_fatal is 1 when ICAL_ERRORS_ARE_FATAL is defined, and 0 otherwise. Since ICAL_ERRORS_ARE_FATAL is defined by default, icalerror_errors_are_fatal is also defined by default. \layout Subsection Naming Standard \layout Standard Structures that you access with the \begin_inset Quotes eld \end_inset struct \begin_inset Quotes erd \end_inset keyword, such as \begin_inset Quotes eld \end_inset struct icaltimetype \begin_inset Quotes erd \end_inset are things that you are allowed to see inside and poke at. \layout Standard Structures that you access though a typedef, such as \begin_inset Quotes eld \end_inset icalcomponent \begin_inset Quotes erd \end_inset are things where all of the data is hidden. \layout Standard Component names that start with \begin_inset Quotes eld \end_inset V \begin_inset Quotes erd \end_inset are part of RFC 2445 or another iCal standard. Component names that start with \begin_inset Quotes eld \end_inset X \begin_inset Quotes erd \end_inset are also part of the spec, but they are not actually components in the spec. However, they look and act like components, so they are components in libical. Names that start with \begin_inset Quotes eld \end_inset XLIC \begin_inset Quotes erd \end_inset or \begin_inset Quotes eld \end_inset X-LIC \begin_inset Quotes erd \end_inset are not part of any iCal spec. They are used internally by libical. \layout Standard Enums that identify a component, property, value or parameter end with \begin_inset Quotes eld \end_inset _COMPONENT, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset _PROPERTY, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset _VALUE, \begin_inset Quotes erd \end_inset or \begin_inset Quotes eld \end_inset _PARAMETER \begin_inset Quotes erd \end_inset s \layout Standard Enums that identify a parameter value have the name of the parameter as the second word. For instance: ICAL_ROLE_REQPARTICIPANT or ICAL_PARTSTAT_ACCEPTED. \layout Standard The enums for the parts of a recurarance rule and request statuses are irregular. \layout Section Hacks and Bugs \layout Standard There are a lot of hacks in the library -- bits of code that I am not proud of and should probably be changed. These are marked with the comment string \begin_inset Quotes eld \end_inset HACK. \begin_inset Quotes erd \end_inset \the_end