libgedcom.so), to be linked in the
+application program, which implements the callback parsergedcom.h), to be used in the sources
+ of the application programgedcom-tags.h) that is also installed,
+ but that is automatically included via gedcom.hlibgedcom.so is also needed in this case, because the object model uses the callback parser internally):libgedcom.so), to be linked in the application
- programgedcom.h), to be used in the sources
- of the application programgedcom-tags.h) that is also installed,
-but that is automatically included via gedcom.hlibgedcom_gom.so), to be linked in the application program, which implements the C object modelgom.h), to be used in the sources of the application program$PREFIX/share/gedcom-parse
- that contains some additional stuff, but which is not immediately important
- at first. I'll leave the description of the data directory for later.$PREFIX/share/gedcom-parse
+ that contains some additional stuff, but which is not immediately
+ important at first. I'll leave the description of the data directory
+ for later.gedcom.h header is assumed, as everywhere
+in this manual):int result;
- ...
- result = gedcom_parse_file("myfamily.ged");
- - In the above piece of code,void my_message_handler (Gedcom_msg_type type, - char *msg)
- {
- ...
- }
- ...
- gedcom_set_message_handler(my_message_handler);
- ...
- result = gedcom_parse_file("myfamily.ged");
-
my_message_handler is the callback
- that will be called for errors (type=ERROR), warnings (
- type=WARNING) and messages (type=MESSAGE). The
- callback must have the signature as in the example. For errors, the
- msg passed to the callback will have the format:- Note that the entire string will be properly internationalized, and encoded - in UTF-8 (see "Why UTF-8?" LINK TBD). Also, no newline - is appended, so that the application program can use it in any way it wants. - Warnings are similar, but use "Warning" instead of "Error". Messages - are plain text, without any prefix.Error on line<lineno>: <actual_message>
-
printf
- is used in the message handler.gedcom.h and gom.h is required):int result;
+ ...
+ gedcom_init();
+ ...
+ result = gom_parse_file("myfamily.ged");
+ gom_parse_file will build the C object model, which is then a complete representation of the GEDCOM file.gedcom_init() should be one of the first calls
+in your program. The requirement is that it should come before the first
+call to iconv_open (part of the generic character set conversion
+feature) in the program, either by your program itself, or indirectly by
+the library calls it makes. Practically, it should e.g. come before
+ any calls to any GTK functions, because GTK uses iconv_open
+ in its initialization.-lgedcom option
+on the linking of the program as the last option, so that its initialization
+code is run first. In the case of using the C object model, the linking
+options should be: -lgedcom_gom -lgedcomGedcom_ctxt my_header_start_cb (int level, -
- - Gedcom_val xref,
- - char *tag,
- - char *raw_value,
- - int parsed_tag,
- - Gedcom_val parsed_value)
- {
- printf("The header starts\n");
- return (Gedcom_ctxt)1;
- }
-
- void my_header_end_cb (Gedcom_ctxt self)
- {
- printf("The header ends, context is %d\n", self); /* context - will print as "1" */
- }
-
- ...
- gedcom_subscribe_to_record(REC_HEAD, my_header_start_cb, - my_header_end_cb);
- ...
- result = gedcom_parse_file("myfamily.ged");
+ A typical piece of code would be (gom_parse_filewould be called in case the C object model is used):
+ +- Using thevoid my_message_handler (Gedcom_msg_type type, + char *msg)
+ {
+ ...
+ }
+ ...
+ gedcom_set_message_handler(my_message_handler);
+ ...
+ result = gedcom_parse_file("myfamily.ged");
gedcom_subscribe_to_recordfunction, the application - requests to use the specified callbacks as start and end callback. The -end callback is optional: you can passNULLif you are not -interested in the end callback. The identifiers to use as first argument -to the function (hereREC_HEAD) are described in the - interface details.
-
- From the name of the function it becomes clear that this function is -specific to complete records. For the separate elements in records -there is another function, which we'll see shortly. Again, the callbacks -need to have the signatures as shown in the example.
-
- TheGedcom_ctxttype that is used as a result of the start - callback and as an argument to the end callback is vital for passing context - necessary for the application. This type is meant to be opaque; in -fact, it's a void pointer, so you can pass anything via it. The important - thing to know is that the context that the application returns in the start - callback will be passed in the end callback as an argument, and as we will - see shortly, also to all the directly subordinate elements of the record.
-
- Thetagis the GEDCOM tag in string format, theparsed_tag- is an integer, for which symbolic values are defined asTAG_HEAD,-TAG_SOUR,TAG_DATA,... andUSERTAG- for the application-specific tags. These values are defined in the -headergedcom-tags.hthat is installed, and included via- gedcom.h(so no need to includegedcom-tags.hyourself).
-
- The example passes a simple integer as context, but an application could - e.g. pass astructthat will contain the information for the - header. In the end callback, the application could then e.g. do some - finalizing operations on thestructto put it in its database.
-
- (Note that theGedcom_valtype for thexref- andparsed_valuearguments was not discussed, see further -for this)
-
+ In the above piece of code,my_message_handleris the + callback that will be called for errors (type=ERROR), warnings + (type=WARNING) and messages (type=MESSAGE). The + callback must have the signature as in the example. For errors, +themsgpassed to the callback will have the format:
-Callbacks for elements
- We will now retrieve the SOUR field (the name of the program that wrote - the file) from the header:
- -+ Using theGedcom_ctxt my_header_source_start_cb(Gedcom_ctxt - parent,
- - int - level,
- - char* - tag,
- - char* - raw_value,
- - int - parsed_tag,
- - Gedcom_val - parsed_value)
- {
- char *source = GEDCOM_STRING(parsed_value);
- printf("This file was written by %s\n", source);
- return parent;
- }
++ Note that the entire string will be properly internationalized, and + encoded in UTF-8 (Why UTF-8?). Also, +no newline is appended, so that the application program can use it in any +way it wants. Warnings are similar, but use "Warning" instead of "Error". + Messages are plain text, without any prefix.Error on line<lineno>: <actual_message>
+
+
+ With this in place, the resulting code will already show errors and + warnings produced by the parser, e.g. on the terminal if a simple+ printfis used in the message handler.
+ +
+Data callback mechanism
+ The most important use of the parser is of course to get the data +out of the GEDCOM file. This section focuses on the callback mechanism (see the next section for the C object model). In fact, the mechanism involves two levels.
+
+ The primary level is that each of the sections in a GEDCOM file is + notified to the application code via a "start element" callback and an + "end element" callback (much like in a SAX interface for XML), i.e. when + a line containing a certain tag is parsed, the "start element" callback + is called for that tag, and when all its subordinate lines with their +tags have been processed, the "end element" callback is called for the +original tag. Since GEDCOM is hierarchical, this results in properly +nested calls to appropriate "start element" and "end element" callbacks.
+
+ However, it would be typical for a genealogy program to support only + a subset of the GEDCOM standard, certainly a program that is still under + development. Moreover, under GEDCOM it is allowed for an application + to define its own tags, which will typically not be supported by +another application. Still, in that case, data preservation is important; + it would hardly be accepted that information that is not understood by + a certain program is just removed.
+
+ Therefore, the second level of callbacks involves a "default callback". + An application needs to subscribe to callbacks for tags it does support, + and need to provide a "default callback" which will be called for tags +it doesn't support. The application can then choose to just store +the information that comes via the default callback in plain textual format.
+
+ After this introduction, let's see what the API looks like...
- void my_header_source_end_cb(Gedcom_ctxt parent,
+ +Start and end callbacks
+ +Callbacks for records
+ As a simple example, we will get some information from the header +of a GEDCOM file. First, have a look at the following piece of code:
+
+ +- The subscription mechanism for elements is similar, only the signatures - of the callbacks differ. The signature for the start callback shows - that the context of the parent line (e.g. theGedcom_ctxt my_header_start_cb (Gedcom_rec rec,
+ int level,
- Gedcom_ctxt self,
+ Gedcom_val xref,
- Gedcom_val parsed_value)
- {
- printf("End of the source description\n");
- }
-
- ...
- gedcom_subscribe_to_element(ELT_HEAD_SOUR,
+ char *tag,
- my_header_source_start_cb,
+ char *raw_value,
- my_header_source_end_cb);
- ...
- result = gedcom_parse_file("myfamily.ged");
-structthat describes - the header) is passed to this start callback. The callback itself -returns here the same context, but this can be its own context object of -course. The end callback is called with both the context of the parent -and the context of itself, which will be the same in the example. Again, - the list of identifiers to use as a first argument for the subscription -function are detailed in the -interface details .
-
- If we look at the other arguments of the start callback, we see the level - number (the initial number of the line in the GEDCOM file), the tag (e.g. - "SOUR"), and then a raw value, a parsed tag and a parsed value. The -raw value is just the raw string that occurs as value on the line next to -the tag (in UTF-8 encoding). The parsed value is the meaningful value -that is parsed from that raw string. The parsed tag is described in -the section for record callbacks.
-
- TheGedcom_valtype is meant to be an opaque type. The - only thing that needs to be known about it is that it can contain specific - data types, which have to be retrieved from it using pre-defined macros. - These data types are described in the - interface details.
+ int parsed_tag,
+ + Gedcom_val parsed_value)
+ {
+ printf("The header starts\n");
+ return (Gedcom_ctxt)1;
+ }
+
+ void my_header_end_cb (Gedcom_rec rec, Gedcom_ctxt self)
+ {
+ printf("The header ends, context is %d\n", (int)self); + /* context will print as "1" */
+ }
+
+ ...
+ gedcom_subscribe_to_record(REC_HEAD, my_header_start_cb, + my_header_end_cb);
+ ...
+ result = gedcom_parse_file("myfamily.ged");
+gedcom_subscribe_to_recordfunction, the + application requests to use the specified callbacks as start and end +callback. The end callback is optional: you can passNULL+ if you are not interested in the end callback. The identifiers +to use as first argument to the function (hereREC_HEAD) +are described in the interface +details . These are also passed as first argument in the callbacks (theGedcom_recargument).
+
+ From the name of the function it becomes clear that this function +is specific to complete records. For the separate elements in records + there is another function, which we'll see shortly. Again, the callbacks + need to have the signatures as shown in the example.
+
+ TheGedcom_ctxttype that is used as a result of the +start callback and as an argument to the end callback is vital for passing +context necessary for the application. This type is meant to be opaque; +in fact, it's a void pointer, so you can pass anything via it. The +important thing to know is that the context that the application returns +in the start callback will be passed in the end callback as an argument, +and as we will see shortly, also to all the directly subordinate elements +of the record.
- Some extra notes:
- --
- -- The
-Gedcom_valargument of the end callback - is currently not used. It is there for future enhancements.- There is also a
- -Gedcom_valargument in the - start callback for records. This argument is currently a string value - giving the pointer in string form.Default callbacks
- As described above, an application doesn't always implement the entire - GEDCOM spec, and application-specific tags may have been added by other -applications. To preserve this extra data anyway, a default callback -can be registered by the application, as in the following example:
-
- -- This callback has a similar signature as the previous ones, -but it doesn't contain a parsed value. However, it does contain the -parent context, that was returned by the application for the most specific -containing tag that the application supported.void my_default_cb (Gedcom_ctxt parent, - int level, char* tag, char* raw_value, int parsed_tag)
- {
- ...
- }
-
- ...
- gedcom_set_default_callback(my_default_cb);
- ...
- result = gedcom_parse_file("myfamily.ged");
-
-
- Suppose e.g. that this callback is called for some tags in the header -that are specific to some other application, then our application could -make sure that the parent context contains the struct or object that represents -the header, and use the default callback here to add the level, tag and raw_value - as plain text in a member of that struct or object, thus preserving the -information. The application can then write this out when the data -is saved again in a GEDCOM file. To make it more specific, consider -the following example:
- -- Note that the default callback will be called for any tag that isn't specifically - subscribed upon by the application, and can thus be called in various contexts. - For simplicity, the example above doesn't take this into account (the -struct header {
- char* source;
- ...
- char* extra_text;
- };
-
- Gedcom_ctxt my_header_start_cb(int level, Gedcom_val xref, char* tag, -char *raw_value,
+ Thetagis the GEDCOM tag in string format, theparsed_tag+ is an integer, for which symbolic values are defined asTAG_HEAD,+TAG_SOUR,TAG_DATA,... andUSERTAG +for the application-specific tags. These values +are defined in the headergedcom-tags.hthat is installed, +and included viagedcom.h(so no need to includegedcom-tags.h+ yourself).
+
+ The example passes a simple integer as context, but an application + could e.g. pass astruct(or an object in a C++ application) + that will contain the information for the header. In the end callback, + the application could then e.g. do some finalizing operations on the +structto put it in its database.
+
+ (Note that theGedcom_valtype for thexref+ andparsed_valuearguments was not discussed, see further + for this)
+
+ +Callbacks for elements
+ We will now retrieve the SOUR field (the name of the program that +wrote the file) from the header:
+ ++ The subscription mechanism for elements is similar, only the signatures + of the callbacks differ. The signature for the start callback shows + that the context of the parent line (here e.g. theGedcom_ctxt my_header_source_start_cb(Gedcom_elt elt,
- int parsed_tag, Gedcom_val parsed_value)
- {
- struct header head = my_make_header_struct();
- return (Gedcom_ctxt)head;
- }
+ Gedcom_ctxt + parent,
+ + int + level,
+ + char* + tag,
+ + char* + raw_value,
+ + int + parsed_tag,
+ + Gedcom_val + parsed_value)
+ {
+ char *source = GEDCOM_STRING(parsed_value);
+ printf("This file was written by %s\n", source);
+ return parent;
+ }
+
+ void my_header_source_end_cb(Gedcom_elt elt,
+ Gedcom_ctxt parent,
+ + Gedcom_ctxt self,
+ + Gedcom_val parsed_value)
+ {
+ printf("End of the source description\n");
+ }
+
+ ...
+ gedcom_subscribe_to_element(ELT_HEAD_SOUR,
+ + my_header_source_start_cb,
+ + my_header_source_end_cb);
+ ...
+ result = gedcom_parse_file("myfamily.ged");
+struct+ that describes the header) is passed to this start callback. The + callback itself returns here in this example the same context, but this +can be its own context object of course. The end callback is called +with both the context of the parent and the context of itself, which in this +example will be the same. Again, the list of identifiers to use as +a first argument for the subscription function are detailed in the interface details . Again, these are passed as first argument in the callback (theGedcom_eltargument).
+
+ If we look at the other arguments of the start callback, we see the + level number (the initial number of the line in the GEDCOM file), the tag + (e.g. "SOUR"), and then a raw value, a parsed tag and a parsed value. The + raw value is just the raw string that occurs as value on the line next +to the tag (in UTF-8 encoding). The parsed value is the meaningful +value that is parsed from that raw string. The parsed tag is described +in the section for record callbacks above.
+
+ TheGedcom_valtype is meant to be an opaque type. The + only thing that needs to be known about it is that it can contain specific + data types, which have to be retrieved from it using pre-defined macros. + These data types are described in the interface details. +
- void my_default_cb(Gedcom_ctxt parent, int level, char* tag, char* raw_value, -int parsed_tag)
- {
- struct header head = (struct header)parent;
- my_header_add_to_extra_text(head, level, tag, raw_value);
- }
+ Some extra notes:
+ + ++
+ + +- The
+Gedcom_valargument of the end callback + is currently not used. It is there for future enhancements.- There are also two
+ + +Gedcom_valarguments + in the start callback for records. The first one (xref+ ) contains thexref_valuecorresponding to the cross-reference + (orNULLif there isn't one), the second one (parsed_value+ ) contains the value that is parsed from theraw_value. See + the interface details + .Default callbacks
+ As described above, an application doesn't always implement the entire + GEDCOM spec, and application-specific tags may have been added by other + applications. To preserve this extra data anyway, a default callback + can be registered by the application, as in the following example:
+
+ ++ This callback has a similar signature as the previous ones, + but it doesn't contain a parsed value. However, it does contain the + parent context, that was returned by the application for the most specific + containing tag that the application supported.void my_default_cb (Gedcom_elt elt, Gedcom_ctxt parent, int level, + char* tag, char* raw_value, int parsed_tag)
+ {
+ ...
+ }
+
+ ...
+ gedcom_set_default_callback(my_default_cb);
+ ...
+ result = gedcom_parse_file("myfamily.ged");
+
+
+ Suppose e.g. that this callback is called for some tags in the header + that are specific to some other application, then our application could + make sure that the parent context contains the struct or object that represents + the header, and use the default callback here to add the level, tag and + raw_value as plain text in a member of that struct or object, thus preserving + the information. The application can then write this out when the +data is saved again in a GEDCOM file. To make it more specific, consider + the following example:
+ ++ Note that the default callback will be called for any tag that isn't + specifically subscribed upon by the application, and can thus be called + in various contexts. For simplicity, the example above doesn't take + this into account (thestruct header {
+ char* source;
+ ...
+ char* extra_text;
+ };
+
+ Gedcom_ctxt my_header_start_cb(Gedcom_rec rec, int level, Gedcom_val xref, char* tag, + char *raw_value,
+ + int parsed_tag, Gedcom_val parsed_value)
+ {
+ struct header head = my_make_header_struct();
+ return (Gedcom_ctxt)head;
+ }
+
+ void my_default_cb(Gedcom_elt elt, Gedcom_ctxt parent, int level, char* tag, char* +raw_value, int parsed_tag)
+ {
+ struct header head = (struct header)parent;
+ my_header_add_to_extra_text(head, level, tag, raw_value);
+ }
+
+ gedcom_set_default_callback(my_default_cb);
+ gedcom_subscribe_to_record(REC_HEAD, my_header_start, NULL);
+ ...
+ result = gedcom_parse_file(filename);
+parentcould be of different + types, depending on the context).
- gedcom_set_default_callback(my_default_cb);
- gedcom_subscribe_to_record(REC_HEAD, my_header_start, NULL);
- ...
- result = gedcom_parse_file(filename);
-parentcould be of different types, depending -on the context).
+ Note also that the default callback is not called when the parent context + isNULL. This is e.g. the case if none + of the "upper" tags has been subscribed upon.
+ + +
+C object model
+In the GEDCOM object model, all the data is immediately available after callinggom_parse_file(). 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.
+
+Main functions
+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
+nextmember of the structs. This means that e.g. the following piece of code will traverse the linked list of family records:
++Thestruct family* fam;
+
+for (fam = gom_get_first_family() ; fam ; fam = fam->next) {
+ ...
+}
+nextmember of the last element in the list is guaranteed to have theNULLvalue.
+
+Actually, the linked list is a doubly-linked list: each record also has apreviousmember. But for implementation reasons the behaviour of thispreviousmember on the edges of the linked list will not be guaranteed, i.e. it can be circular or terminated withNULL, 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 anextandprevious+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):
++Note that all character strings in the object model are encoded in UTF-8 (Why UTF-8?).struct family* fam = ...;
+
+struct xref_list* xrl;
+for (xrl = fam->children ; xrl ; xrl = xrl->next) {
+ ...
+}
+
+User data
+Each of the structs has an extra member calledextra(of typestruct 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:
++
+This way, none of the information in the GEDCOM file is lost, even the non-standard information.- 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)
+
+
+
+ +Other API functions
+ + Although the above describes the basic interface of the gedcom parser, there + are some other functions that allow to customize the behaviour of the library. + These will be explained in the current section.
+
+ + +Debugging
+ The library can generate various debugging output, not only from itself, + but also the debugging output generated by the yacc parser. By default, + no debugging output is generated, but this can be customized using the +following function:
+ + ++ Thevoid gedcom_set_debug_level (int level, FILE* +trace_output)
+levelcan be one of the following values:
+ + ++
+ If the- 0: no debugging information (this is the + default)
+- 1: only debugging information from libgedcom + itself
+- 2: debugging information from libgedcom + and yacc
+ + +trace_outputisNULL, debugging information + will be written tostderr, otherwise the given file handle + is used (which must be open).
+
+ + +Error treatment
+ One of the previous sections already described the callback to be +registered to get error messages. The library also allows to customize +what happens on an error, using the following function:
+ + ++ Thevoid gedcom_set_error_handling (Gedcom_err_mech + mechanism)
+mechanismcan be one of:
+ + ++
+ This doesn't influence the generation of error or warning messages, + only the behaviour of the parser and its return code.- +
IMMED_FAIL: immediately fail +the parsing on an error (this is the default)- +
DEFER_FAIL: continue parsing +after an error, but return a failure code eventually- + + +
IGNORE_ERRORS: continue parsing + after an error, return success always
+
+ + +Compatibility mode
+ Applications are not necessarily true to the GEDCOM spec (or use a +different version than 5.5). The intention is that the library is +resilient to this, and goes in compatibility mode for files written by specific +programs (detected via the HEAD.SOUR tag). This compatibility mode +can be enabled and disabled via the following function:
+
+ + ++ The argument can be:void gedcom_set_compat_handling (int enable_compat)
+
+ + ++
+ Currently, there is a beginning for compatibility for ftree and Lifelines (3.0.2).- 0: disable compatibility mode
+- 1: allow compatibility mode (this is the +default)
+ + +
+
+ +
+Converting character sets
+ All strings passed by the GEDCOM parser to the application are in UTF-8 + encoding. Typically, an application needs to convert this to something + else to be able to display it.
+
+ The most common case is that the output character set is controlled by +thelocalemechanism (i.e. via theLANG,+ LC_ALLorLC_CTYPEenvironment variables), which also +controls thegettextmechanism in the application.
+
+
+ + The source distribution of+gedcom-parsecontains an example implementation (utf8-locale.c+ andutf8-locale.hin the "t" subdirectory of the top directory). + Feel free to use it in your source code (it is not part of the library, +and it isn't installed anywhere, so you need to take over the source and +header file in your application).
+
+ Its interface is:
+ +++ Both functions return a pointer to a static buffer that is overwritten + on each call. To function properly, the application must first set +the locale using the+char *convert_utf8_to_locale (char *input, int *conv_failures);
char *convert_locale_to_utf8 (char *input);setlocalefunction (the second step detailed + below). All other steps given below, including setting up and closing + down the conversion handles, are transparantly handled by the two functions. +
+
+ If you pass a pointer to an integer to the first function, it will be +set to the number of conversion failures, i.e. characters that couldn't +be converted; you can also just passNULLif you are not interested +(note that usually, the interesting information is just whether there +were conversion failures or not, which is then given by the integer +being bigger than zero or not). The second function doesn't need this, +because any locale can be converted to UTF-8.
+
+ You can change the "?" that is output for characters that can't be converted + to any string you want, using the following function before the conversion + calls:
+ ++++void convert_set_unknown (const char *unknown);
+ If you want to have your own functions for it instead of this example +implementation, the following steps need to be taken by the application +(more detailed info can be found in the info file of the GNU libc library +in the "Generic Charset Conversion" section under "Character Set Handling" +or online + here):
+ ++
+ +- inclusion of some headers:
+ +++ ++++#include <locale.h> /* for setlocale */
#include <langinfo.h> /* for nl_langinfo */
#include <iconv.h> /* for iconv_* functions */+
+ +- set the program's current locale to what +the user configured in the environment:
+ +++ ++++setlocale(LC_ALL, "");+
+ +- open a conversion handle for conversion + from UTF-8 to the character set of the current locale (once for the entire + program):
+ +++ ++++iconv_t iconv_handle;
...
iconv_handle = iconv_open(nl_langinfo(CODESET), "UTF-8");
if (iconv_handle == (iconv_t) -1)
/* signal an error */+
+ +- then, every string can be converted + using the following:
+ +++ ++++/* char* in_buf is the input buffer, size_t in_len is its length */
/* char* out_buf is the output buffer, size_t out_len is its length */
size_t nconv;
char *in_ptr = in_buf;
char *out_ptr = out_buf;
nconv = iconv(iconv_handle, &in_ptr, &in_len, &out_ptr, &out_len);If the output buffer is not big enough,+ +iconvwill + return -1 and seterrnotoE2BIG. Also, +thein_ptrandout_ptrwill point just after +the last successfully converted character in the respective buffers, and +thein_lenandout_lenwill be updated to show +the remaining lengths. There can be two strategies here:
-
- -Other API functions
- Although the above describes the basic interface of libgedcom, there are - some other functions that allow to customize the behaviour of the library. - These will be explained in the current section.
-
++
+ Another error case is when the conversion was unsuccessful (if one of +the characters can't be represented in the target character set). The +- Make sure from the beginning + that the output buffer is big enough. However, it's difficult to find + an absolute maximum length in advance, even given the length of the input + string.
+
+
+- Do the conversion in several + steps, growing the output buffer each time to make more space, and calling +
-iconvconsecutively until the conversion is complete. + This is the preferred way (a function could be written to encapsulate + all this).Debugging
- The library can generate various debugging output, not only from itself, - but also the debugging output generated by the yacc parser. By default, - no debugging output is generated, but this can be customized using the following - function:
+iconvfunction will then also return -1 and seterrno+ toEILSEQ; thein_ptrwill point to the character + that couldn't be converted. In that case, again two strategies are +possible:
-- Thevoid gedcom_set_debug_level (int level, - FILE* trace_output)
-levelcan be one of the following values:
++
+ +- Just fail the conversion, +and show an error. This is not very user friendly, of course.
+
+
+- Skip over the character that + can't be converted and append a "?" to the output buffer, then call
+ ++ iconvagain. Skipping over a UTF-8 character is fairly simple, + as follows from the encoding rules + :-
+ + +-
- If the- 0: no debugging information (this is the default)
-- 1: only debugging information from libgedcom - itself
-- 2: debugging information from libgedcom and - yacc
++
- if the first byte is in +binary 0xxxxxxx, then the character is only one byte long, just skip over +that byte
+
+
+- if the first byte is in +binary 11xxxxxx, then skip over that byte and all bytes 10xxxxxx that follow.
-
+trace_outputisNULL, debugging information - will be written tostderr, otherwise the given file handle is - used (which must be open).
-
++
+ +- eventually, the conversion +handle needs to be closed (when the program exits):
+ +
+++ The example implementation + mentioned above grows the output buffer dynamically and outputs "?" for characters + that can't be converted.+++iconv_close(iconv_handle);
+ + +
+ +Support for configure.in
+ Programs using the GEDCOM parser library and using autoconf to configure + their sources can use the following statements in configure.in (the example + is checking for gedcom-parse, version 1.34):
+ ++ There are three preprocessor symbols defined for version checks in the + header:AC_CHECK_LIB(gedcom, gedcom_parse_file,,
+ AC_MSG_ERROR(Cannot + find libgedcom: Please install gedcom-parse))
+ AC_MSG_CHECKING(for libgedcom version)
+ AC_TRY_RUN([
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <gedcom.h>
+ int
+ main()
+ {
+ if (GEDCOM_PARSE_VERSION >= 1034) exit(0);
+ exit(1);
+ }],
+ ac_gedcom_version_ok='yes',
+ ac_gedcom_version_ok='no',
+ ac_gedcom_version_ok='no')
+ if test "$ac_gedcom_version_ok" = 'yes' ; then
+ AC_MSG_RESULT(ok)
+ else
+ AC_MSG_RESULT(not ok)
+ AC_MSG_ERROR(You need at least version 1.34 of gedcom-parse)
+ fi
+
-Error treatment
- One of the previous sections already described the callback to be registered - to get error messages. The library also allows to customize what happens - on an error, using the following function:
++
- +
GEDCOM_PARSE_VERSION_MAJOR- +
GEDCOM_PARSE_VERSION_MINOR- -
GEDCOM_PARSE_VERSION
+- Thevoid gedcom_set_error_handling (Gedcom_err_mech - mechanism)
-mechanismcan be one of:
- --
- This doesn't influence the generation of error or warning messages, only - the behaviour of the parser and its return code.- -
IMMED_FAIL: immediately fail the -parsing on an error (this is the default)- -
DEFER_FAIL: continue parsing after - an error, but return a failure code eventually- - -
IGNORE_ERRORS: continue parsing after - an error, return success always
-
- -Compatibility mode
- Applications are not necessarily true to the GEDCOM spec (or use a different - version than 5.5). The intention is that the library is resilient to - this, and goes in compatibility mode for files written by specific programs - (detected via the HEAD.SOUR tag). This compatibility mode can be enabled - and disabled via the following function:
-
- -- The argument can be:void gedcom_set_compat_handling - (int enable_compat)
-
- --
- Note that, currently, no actual compatibility code is present, but this - is on the to-do list.- 0: disable compatibility mode
-- 1: allow compatibility mode (this is the default)
- -
-
- -
- -$Id$- -
$Name$+
(GEDCOM_PARSE_VERSION_MAJOR * 1000) + GEDCOM_PARSE_VERSION_MINOR.$Id$+ + +
$Name$
- - - + +