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+Gedcom object model in C
+
+
+
+
+Gedcom object model in C
+
+
+Index
+
+
+
+
+
+Main functions
+
+
+There are two ways to start with a GEDCOM object model (after having called gedcom_init): either by starting from scratch, or by starting from a given GEDCOM file. This is done via the following two functions:
+int gom_parse_file (const char* file_name)
+
+ This initializes the object model by parsing the GEDCOM file given by file_name. It returns 0 on success and 1 on failure.
+
+
+int gom_new_model ()
+
+ This starts an empty model. Actually, this is done by processing the file "new.ged" in the gedcom-parse data directory.
+
+
+In the GEDCOM object model, all the data is immediately available after calling gom_parse_file() or gom_new_model(). For this, an entire model based on C structs is used. These structs are documented here,
+and follow the GEDCOM syntax quite closely. Each of the records in
+a GEDCOM file are modelled by a separate struct, and some common sub-structures
+have their own struct definition.
+
+
+The following functions are available to get at these structs:
+
+ - First, there are two functions to get the header record and the submission
+record (there can be only one of them in a GEDCOM file):
+ struct header* gom_get_header();
+struct submission* gom_get_submission();
+
+
+ - Further, for each of the other records, there are two functions, one
+to get the first of such records, and one to get a record via its cross-reference
+tag in the GEDCOM file:
+ struct XXX* gom_get_first_XXX();
+struct XXX* gom_get_XXX_by_xref(char* xref);
+
+
+
+The XXX stands for one of the following: family, individual, multimedia, note, repository, source, submitter, user_rec.
+
+Object model structure
+
+
+
+All records of a certain type are linked together in a linked list. The
+above functions only give access to the first record of each linked list.
+ The others can be accessed by traversing the linked list via the next member of the structs. This means that e.g. the following piece of code will traverse the linked list of family records:
+struct family* fam;
+
+for (fam = gom_get_first_family() ; fam ; fam = fam->next) {
+ ...
+}
+
+The next member of the last element in the list is guaranteed to have the NULL value.
+
+Actually, the linked list is a doubly-linked list: each record also has a previous member. But for implementation reasons the behaviour of this previous member on the edges of the linked list will not be guaranteed, i.e. it can be circular or terminated with NULL, no assumptions can be made in the application code.
+
+This linked-list model applies also to all sub-structures of the main record structs, i.e. each struct that has a next and previous
+member following the above conventions. This means that the following
+piece of code traverses all children of a family (see the details of the
+different structs here):
+struct family* fam = ...;
+
+struct xref_list* xrl;
+for (xrl = fam->children ; xrl ; xrl = xrl->next) {
+ ...
+}
+
+Note that all character strings in the object model are encoded in UTF-8 (Why UTF-8?).
+User data
+
+Each of the structs has an extra member called extra (of type struct user_data*).
+ This gathers all non-standard GEDCOM tags within the scope of the struct
+in a flat linked list, no matter what the internal structure of the non-standard
+tags is. Each element of the linked list has:
+
+ - a level: the level number in the GEDCOM file
+ - a tag: the tag given in the GEDCOM file
+ - a value: the value, which can be a string value or a cross-reference value (one of the two will be non-NULL)
+
+
+This way, none of the information in the GEDCOM file is lost, even the non-standard information.
+
+
+$Id$
$Name$
+
+
+
+
+
+
+
+
+
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