PROP_INGEST(3)          NetBSD Library Functions Manual         PROP_INGEST(3)

NAME
     prop_ingest_context_alloc, prop_ingest_context_free,
     prop_ingest_context_error, prop_ingest_context_type,
     prop_ingest_context_key, prop_ingest_context_private,
     prop_dictionary_ingest -- Ingest a dictionary into an arbitrary binary
     format

SYNOPSIS
     #include <prop/proplib.h>

     prop_ingest_context_t
     prop_ingest_context_alloc(void *private);

     void
     prop_ingest_context_free(prop_ingest_context_t ctx);

     prop_ingest_error_t
     prop_ingest_context_error(prop_ingest_context_t ctx);

     prop_type_t
     prop_ingest_context_type(prop_ingest_context_t ctx);

     const char *
     prop_ingest_context_key(prop_ingest_context_t ctx);

     void *
     prop_ingest_context_private(prop_ingest_context_t ctx);

     bool
     prop_dictionary_ingest(prop_dictionary_t dict,
         const prop_ingest_table_entry rules[], prop_ingest_context_t ctx);

     typedef bool
     (*prop_ingest_handler_t)(prop_ingest_context_t, prop_object_t);

DESCRIPTION
     The prop_dictionary_ingest function provides a convenient way to convert
     a property list into an arbitrary binary format or to extract values from
     dictionaries in a way that is convenient to an application (for
     configuration files, for example).

     prop_dictionary_ingest is driven by a table of rules provided by the
     application.  Each rule consists of three items:

     o   A C string containing a key to be looked up in the dictionary.

     o   The expected property type of the object associated with the key (or
         PROP_TYPE_UNKNOWN to specify that any type is allowed).

     o   A callback function of type prop_ingest_handler_t that will perform
         the translation for the application.

     The table is constructed using a series of macros as follows:

     static const prop_ingest_table_entry ingest_rules[] = {
             PROP_INGEST("file-name", PROP_TYPE_STRING, ingest_filename),
             PROP_INGEST("count", PROP_TYPE_NUMBER, ingest_count),
             PROP_INGEST_OPTIONAL("required", PROP_TYPE_BOOL, ingest_required),
             PROP_INGEST_OPTIONAL("extra", PROP_TYPE_UNKNOWN, ingest_extra),
             PROP_INGEST_END
     };

     The PROP_INGEST macro specifies that the key is required to be present in
     the dictionary.  The PROP_INGEST_OPTIONAL macro specifies that the pres-
     ence of the key in the dictionary is optional.  The PROP_INGEST_END macro
     marks the end of the rules table.

     In each case, prop_dictionary_ingest looks up the rule's key in the dic-
     tionary.  If an object is present in the dictionary at that key, its type
     is checked against the type specified in the rule.  A type specification
     of PROP_TYPE_UNKNOWN allows the object to be of any type.  If the object
     does not exist and the rule is not marked as optional, then an error is
     returned.  Otherwise, the handler specified in the rule is invoked with
     the ingest context and the object (or NULL if the key does not exist in
     the dictionary).  The handler should return false if the value of the
     object is invalid to indicate failure and true otherwise.

     The ingest context contains several pieces of information that are useful
     during the ingest process.  The context also provides specific error
     information should the ingest fail.

     prop_ingest_context_alloc(void *private)
            Allocate an ingest context.  The argument private may be used to
            pass application-specific context to the ingest handlers.  Note
            that an ingest context can be re-used to perform multiple ingests.
            Returns NULL on failure.

     prop_ingest_context_free(prop_ingest_context_t ctx)
            Free an ingest context.

     prop_ingest_context_error(prop_ingest_context_t ctx)
            Returns the code indicating the error encountered during ingest.
            The following error codes are defined:

            PROP_INGEST_ERROR_NO_ERROR        No error was encountered during
                                              ingest.
            PROP_INGEST_ERROR_NO_KEY          A non-optional key was not found
                                              in the dictionary.
            PROP_INGEST_ERROR_WRONG_TYPE      An object in the dictionary was
                                              not the same type specifed in
                                              the rules.
            PROP_INGEST_ERROR_HANDLER_FAILED  An object's handler returned
                                              false.

     prop_ingest_context_type(prop_ingest_context_t ctx)
            Returns the type of the last object visited during an ingest.
            When called by an ingest handler, it returns the type of the
            object currently being processed.

     prop_ingest_context_key(prop_ingest_context_t ctx)
            Returns the last dictionary key looked up during an ingest.  When
            called by an ingest handler, it returns the dictionary key corre-
            sponding to the object currently being processed.

     prop_ingest_context_private(prop_ingest_context_t ctx)
            Returns the private data set when the context was allocated with
            prop_ingest_context_alloc().

SEE ALSO
     prop_dictionary(3), proplib(3)

HISTORY
     The proplib property container object library first appeared in
     NetBSD 4.0.

NetBSD 5.0_STABLE              January 21, 2008              NetBSD 5.0_STABLE
