<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><title>Using the GEDCOM parser library</title>
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<h1 align="center">Using the GEDCOM parser library</h1>
- <br>
-
+ <br>
+
<h2>Index</h2>
-
+
<ul>
- <li><a href="#anchor">Overview</a></li>
- <li><a href="#Error_handling">Error handling</a></li>
- <li><a href="#Data_callback_mechanism">Data callback mechanism</a></li>
-
+ <li><a href="#anchor">Overview</a></li>
+ <li><a href="#Error_handling">Error handling</a></li>
+ <li><a href="#Data_callback_mechanism">Data callback mechanism</a></li>
+
+ <ul>
+ <li><a href="#Start_and_end_callbacks">Start and end callbacks</a></li>
+ <li><a href="#Default_callbacks">Default callbacks</a></li>
+
+ </ul><li><a href="#Support_for_writing_GEDCOM_files">Support for writing GEDCOM files</a></li>
<ul>
- <li><a href="#Start_and_end_callbacks">Start and end callbacks</a></li>
- <li><a href="#Default_callbacks">Default callbacks</a></li>
-
+ <li><a href="#Opening_and_closing_files">Opening and closing files</a></li>
+ <li><a href="#Controlling_some_settings">Controlling some settings</a></li>
+ <li><a href="#Writing_data">Writing data</a><br>
+ </li>
</ul>
-
<li><a href="#Other_API_functions">Other API functions</a></li>
-
+<li><a href="#Other_API_functions">Other API functions</a></li>
+
<ul>
- <li><a href="#Debugging">Debugging</a></li>
- <li><a href="#Error_treatment">Error treatment</a></li>
- <li><a href="#Compatibility_mode">Compatibility mode</a></li>
-
- </ul><li><a href="#Converting_character_sets">Converting character sets</a></li><li><a href="#Support_for_configure.in">Support for configure.in</a><br>
- </li>
-
+ <li><a href="#Debugging">Debugging</a></li>
+ <li><a href="#Error_treatment">Error treatment</a></li>
+ <li><a href="#Compatibility_mode">Compatibility mode</a></li>
+
+ </ul>
+ <li><a href="#Converting_character_sets">Converting character sets</a></li>
+ <li><a href="#Support_for_configure.in">Development support</a><br>
+<br>
+ </li>
+ <li><a href="interface.html">Interface details of the callback parser</a></li><li><a href="gom.html">C object model</a><br>
+ </li>
- <li><a href="interface.html">Interface details</a><br>
- </li>
-
+
</ul>
-
-<hr width="100%" size="2">
+
+<hr width="100%" size="2">
<h2><a name="Overview"></a>Overview<br>
- </h2>
- The GEDCOM parser library is built as a callback-based parser (comparable
- to the SAX interface of XML). It comes with:<br>
-
+ </h2> The GEDCOM
+parser library provides two interfaces. At the one hand, it can be
+used as a callback-based parser (comparable to the SAX interface of
+XML); at the other hand, the parser can be used to convert the GEDCOM file
+into an object model (comparable to the DOM interface of XML). It comes
+with:<br>
+
<ul>
- <li>a library (<code>libgedcom.so</code>), to be linked in the application
- program</li>
- <li>a header file (<code>gedcom.h</code>), to be used in the sources
- of the application program</li>
- <li>a header file (<code>gedcom-tags.h</code>) that is also installed,
- but that is automatically included via <code>gedcom.h</code><br>
- </li>
-
-</ul>
- Next to these, there is also a data directory in <code>$PREFIX/share/gedcom-parse</code>
- that contains some additional stuff, but which is not immediately
-important at first. I'll leave the description of the data directory
-for later.<br>
- <br>
- The very simplest call of the gedcom parser is simply the following
-piece of code (include of the gedcom header is assumed, as everywhere in
-this manual):<br>
-
+ <li>a library (<code>libgedcom.so</code>), to be linked in the
+application program, which implements the callback parser</li>
+ <li>a header file (<code>gedcom.h</code>), to be used in the sources
+ of the application program</li>
+ <li>a header file (<code>gedcom-tags.h</code>) that is also installed,
+ but that is automatically included via <code>gedcom.h</code></li></ul>Additionally, if you want to use the GEDCOM C object model, the following should be used (note that <code>libgedcom.so</code> is also needed in this case, because the object model uses the callback parser internally):<br>
+<ul>
+ <li>a library (<code>libgedcom_gom.so</code>), to be linked in the application program, which implements the C object model</li>
+ <li>a header file (<code>gom.h</code>), to be used in the sources of the application program<br>
+ </li>
+
+
+</ul>There is a separate script to help with library and compilation flags, see the <a href="#Support_for_configure.in">development support</a>.<br>
+<br>
+Next to these, there is also a data directory in <code>$PREFIX/share/gedcom-parse</code>
+ that contains some additional stuff, but which is not immediately
+ important at first. I'll leave the description of the data directory
+ for later.<br>
+ <br>
+ The very simplest call of the gedcom callback parser is simply the following
+ piece of code (include of the <code>gedcom.h</code> header is assumed, as everywhere
+in this manual):<br>
+
<blockquote><code>int result;<br>
- ...<br>
- result = <b>gedcom_parse_file</b>("myfamily.ged");<br>
- </code> </blockquote>
- Although this will not provide much information, one thing it does
-is parse the entire file and return the result. The function returns
-0 on success and 1 on failure. No other information is available using
- this function only.<br>
- <br>
- The next sections will refine this to be able to have meaningful errors
- and the actual data that is in the file.<br>
-
- <hr width="100%" size="2">
- <h2><a name="Error_handling"></a>Error handling</h2>
- Since this is a relatively simple topic, it is discussed before the
-actual callback mechanism, although it also uses a callback...<br>
- <br>
- The library can be used in several different circumstances, both terminal-based
- as GUI-based. Therefore, it leaves the actual display of the error
- message up to the application. For this, the application needs to register
- a callback before parsing the GEDCOM file, which will be called by the library
- on errors, warnings and messages.<br>
- <br>
- A typical piece of code would be:<br>
-
- <blockquote><code>void <b>my_message_handler</b> (Gedcom_msg_type type,
- char *msg)<br>
- {<br>
- ...<br>
- }<br>
- ...<br>
- <b>gedcom_set_message_handler</b>(my_message_handler);<br>
- ...<br>
- result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
- </blockquote>
- In the above piece of code, <code>my_message_handler</code> is the callback
- that will be called for errors (<code>type=ERROR</code>), warnings (<code>type=WARNING</code>) and messages (<code>type=MESSAGE</code>). The
- callback must have the signature as in the example. For errors, the
- <code> msg</code> passed to the callback will have the format:<br>
-
- <blockquote><code>Error on line</code> <i><lineno></i>: <i><actual_message></i><br>
- </blockquote>
- Note that the entire string will be properly internationalized, and
-encoded in UTF-8 (<a href="encoding.html">Why UTF-8?</a>). 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.<br>
- <br>
- 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 <code>
-printf</code> is used in the message handler.<br>
+ ...<br>
+ <b>gedcom_init</b>();<br>
+ ...<br>
+ result = <b>gedcom_parse_file</b>("myfamily.ged");<br>
+ </code> </blockquote>
+ Although this will not provide much information, one thing it does
+ is parse the entire file and return the result. The function returns
+ 0 on success and 1 on failure. No other information is available
+using this function only.<br>
+<br>
+Alternatively, programs using the C object model should use the following (in this case, the inclusion of both <code>gedcom.h</code> and <code>gom.h</code> is required):<br>
+
+<blockquote><code>int result;<br>
+ ...<br>
+ <b>gedcom_init</b>();<br>
+ ...<br>
+ result = <b>gom_parse_file</b>("myfamily.ged");<br>
+ </code> </blockquote>
+The call to <code>gom_parse_file</code> will build the C object model, which is then a complete representation of the GEDCOM file.<br>
+<br>
+No matter which of the interfaces you use, the call to <code>gedcom_init</code>() should be one of the first calls
+in your program. The requirement is that it should come before the first
+call to <code>iconv_open</code> (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 <code>iconv_open</code>
+ in its initialization.<br>
+ <br>
+For the same reason it is also advised to put
+the <code>-lgedcom</code> 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: <code>-lgedcom_gom -lgedcom</code><br>
+ <br>The function <code>gedcom_init()</code> also initializes locale handling by calling <code>setlocale(LC_ALL, "")</code>, in case the application would not do this (it doesn't hurt for the application to do the same).<br>
+ <br>
+The next sections will refine this piece of code to be able to have
+ meaningful errors and the actual data that is in the file.<br>
+
+<hr width="100%" size="2">
+<h2><a name="Error_handling"></a>Error handling</h2>The library can be used in several different circumstances, both
+terminal-based as GUI-based. Therefore, it leaves the actual display
+of the error message up to the application. For this, the application
+needs to register a callback before parsing the GEDCOM file, which will
+be called by the library on errors, warnings and messages.<br>
+ <br>
+ A typical piece of code would be (<code>gom_parse_file</code> would be called in case the C object model is used):<br>
+
+<blockquote><code>void <b>my_message_handler</b> (Gedcom_msg_type type,
+ char *msg)<br>
+ {<br>
+ ...<br>
+ }<br>
+ ...<br>
+ <b>gedcom_set_message_handler</b>(my_message_handler);<br>
+ ...<br>
+ result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
+ </blockquote>
+ In the above piece of code, <code>my_message_handler</code> is the
+ callback that will be called for errors (<code>type=ERROR</code>), warnings
+ (<code>type=WARNING</code>) and messages (<code>type=MESSAGE</code>). The
+ callback must have the signature as in the example. For errors,
+the <code> msg</code> passed to the callback will have the format:<br>
- <hr width="100%" size="2">
- <h2><a name="Data_callback_mechanism"></a>Data callback mechanism</h2>
- The most important use of the parser is of course to get the data out
- of the GEDCOM file. As already mentioned, the parser uses a callback
- mechanism for that. In fact, the mechanism involves two levels.<br>
- <br>
- 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.<br>
- <br>
- 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.<br>
- <br>
- 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
+<blockquote><code>Error on line</code> <i><lineno></i>: <i><actual_message></i><br>
+ </blockquote>
+ Note that the entire string will be properly internationalized, and
+ encoded in UTF-8 (<a href="encoding.html">Why UTF-8?</a>). 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.<br>
+ <br>
+ 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 <code>
+ printf</code> is used in the message handler.<br>
+
+<hr width="100%" size="2">
+<h2><a name="Data_callback_mechanism"></a>Data callback mechanism</h2>
+ 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 <a href="gom.html">here</a> for the C object model). In fact, the mechanism involves two levels.<br>
+ <br>
+ 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 (note: see <a href="#Compatibility_mode">compatibility handling</a>).<br>
+ <br>
+ 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.<br>
+ <br>
+ 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.<br>
- <br>
- After this introduction, let's see what the API looks like...<br>
- <br>
-
- <h3><a name="Start_and_end_callbacks"></a>Start and end callbacks</h3>
-
- <h4><i>Callbacks for records</i> <br>
- </h4>
- 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:<br>
-
- <blockquote><code>Gedcom_ctxt <b>my_header_start_cb</b> (int level,
- <br>
-
- Gedcom_val xref, <br>
-
- char *tag, <br>
-
- char *raw_value,<br>
-
- int parsed_tag, <br>
-
- Gedcom_val parsed_value)<br>
- {<br>
- printf("The header starts\n");<br>
- return (Gedcom_ctxt)1;<br>
- }<br>
- <br>
- void <b>my_header_end_cb</b> (Gedcom_ctxt self)<br>
- {<br>
- printf("The header ends, context is %d\n", (int)self); /* context
- will print as "1" */<br>
- }<br>
- <br>
- ...<br>
- <b>gedcom_subscribe_to_record</b>(REC_HEAD, my_header_start_cb,
- my_header_end_cb);<br>
- ...<br>
- result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
- </blockquote>
- Using the <code>gedcom_subscribe_to_record</code> function, the application
- requests to use the specified callbacks as start and end callback. The end
- callback is optional: you can pass <code>NULL</code> if you are not interested
- in the end callback. The identifiers to use as first argument to
-the function (here <code>REC_HEAD</code>) are described in the <a href="interface.html#Record_identifiers">
- interface details</a>.<br>
- <br>
- 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.<br>
- <br>
- The <code>Gedcom_ctxt</code> type 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.<br>
- <br>
- The <code>tag</code> is the GEDCOM tag in string format, the <code>parsed_tag</code>
- is an integer, for which symbolic values are defined as <code>TAG_HEAD,</code>
- <code>TAG_SOUR,</code> <code>TAG_DATA,</code> ... and <code>USERTAG </code><code></code>
- for the application-specific tags. These values are defined in the
- header <code>gedcom-tags.h</code> that is installed, and included via <code>
- gedcom.h</code> (so no need to include <code>gedcom-tags.h</code> yourself).<br>
- <br>
- The example passes a simple integer as context, but an application could
- e.g. pass a <code>struct</code> (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 <code>struct</code> to put it in its database.<br>
- <br>
- (Note that the <code>Gedcom_val</code> type for the <code>xref</code>
- and <code>parsed_value</code> arguments was not discussed, see further
-for this)<br>
- <br>
-
- <h4><i>Callbacks for elements</i></h4>
- We will now retrieve the SOUR field (the name of the program that wrote
- the file) from the header:<br>
-
- <blockquote><code>Gedcom_ctxt <b>my_header_source_start_cb</b>(Gedcom_ctxt
- parent,<br>
-
- int
- level,<br>
-
- char*
- tag,<br>
-
- char*
- raw_value,<br>
-
- int
- parsed_tag,<br>
-
- Gedcom_val
- parsed_value)<br>
- {<br>
- char *source = GEDCOM_STRING(parsed_value);<br>
- printf("This file was written by %s\n", source);<br>
- return parent;<br>
- }<br>
- <br>
- void <b>my_header_source_end_cb</b>(Gedcom_ctxt parent,<br>
-
- Gedcom_ctxt self,<br>
-
- Gedcom_val parsed_value)<br>
- {<br>
- printf("End of the source description\n");<br>
- }<br>
- <br>
- ...<br>
- <b>gedcom_subscribe_to_element</b>(ELT_HEAD_SOUR,<br>
-
- my_header_source_start_cb,<br>
-
- my_header_source_end_cb);<br>
- ...<br>
- result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
- </blockquote>
- 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. the <code>struct</code> 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 <a href="interface.html#Element_identifiers">
- interface details</a> .<br>
- <br>
- 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.<br>
- <br>
- The <code>Gedcom_val</code> type 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 <a href="interface.html#Gedcom_val_types">
- interface details</a>. <br>
<br>
- Some extra notes:<br>
-
- <ul>
- <li>The <code>Gedcom_val</code> argument of the end callback
- is currently not used. It is there for future enhancements.</li>
- <li>There are also two <code>Gedcom_val</code> arguments in
-the start callback for records. The first one (<code>xref</code>) contains the <code>xref_value</code> corresponding to the cross-reference (or <code>NULL</code> if there isn't one), the second one (<code>parsed_value</code>) contains the value that is parsed from the <code>raw_value</code>. See the <a href="interface.html#Record_identifiers">interface details</a>.</li>
-
- </ul>
-
- <h3><a name="Default_callbacks"></a>Default callbacks<br>
- </h3>
- 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:<br>
-
- <blockquote><code>void <b>my_default_cb</b> (Gedcom_ctxt parent,
- int level, char* tag, char* raw_value, int parsed_tag)<br>
- {<br>
- ...<br>
- }<br>
+ After this introduction, let's see what the API looks like...<br>
+ <br>
+
+<h3><a name="Start_and_end_callbacks"></a>Start and end callbacks</h3>
+
+<h4><i>Callbacks for records</i> <br>
+ </h4>
+ 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:<br>
+
+<blockquote><code>Gedcom_ctxt <b>my_header_start_cb</b> (Gedcom_rec rec,<br>
+ int level, <br>
+
+ Gedcom_val xref, <br>
+
+ char *tag, <br>
+
+ char *raw_value,<br>
+
+ int parsed_tag, <br>
+
+ Gedcom_val parsed_value)<br>
+ {<br>
+ printf("The header starts\n");<br>
+ return (Gedcom_ctxt)1;<br>
+ }<br>
<br>
- ...<br>
- <b>gedcom_set_default_callback</b>(my_default_cb);<br>
- ...<br>
- result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
+ void <b>my_header_end_cb</b> (Gedcom_rec rec, Gedcom_ctxt self)<br>
+ {<br>
+ printf("The header ends, context is %d\n", (int)self);
+ /* context will print as "1" */<br>
+ }<br>
+ <br>
+ ...<br>
+ <b>gedcom_subscribe_to_record</b>(REC_HEAD, my_header_start_cb,
+ my_header_end_cb);<br>
+ ...<br>
+ result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
</blockquote>
- 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.<br>
+ Using the <code>gedcom_subscribe_to_record</code> function, the
+ application requests to use the specified callbacks as start and end
+callback. The end callback is optional: you can pass <code>NULL</code>
+ if you are not interested in the end callback. The identifiers
+to use as first argument to the function (here <code>REC_HEAD</code>)
+are described in the <a href="interface.html#Record_identifiers"> interface
+details</a> . These are also passed as first argument in the callbacks (the <code>Gedcom_rec</code> argument).<br>
<br>
- 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:<br>
-
- <blockquote><code>struct header {<br>
- char* source;<br>
- ...<br>
- char* extra_text;<br>
- };<br>
- <br>
- Gedcom_ctxt my_header_start_cb(int level, Gedcom_val xref, char* tag,
-char *raw_value,<br>
-
- int parsed_tag, Gedcom_val parsed_value)<br>
- {<br>
- struct header head = my_make_header_struct();<br>
- return (Gedcom_ctxt)head;<br>
- }<br>
+ 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.<br>
+ <br>
+ The <code>Gedcom_ctxt</code> type 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.<br>
+ <br>
+ The <code>tag</code> is the GEDCOM tag in string format, the <code>parsed_tag</code>
+ is an integer, for which symbolic values are defined as <code>TAG_HEAD,</code>
+ <code>TAG_SOUR,</code> <code>TAG_DATA,</code> ... and <code>USERTAG
+</code><code></code> for the application-specific tags. These values
+are defined in the header <code>gedcom-tags.h</code> that is installed,
+and included via <code> gedcom.h</code> (so no need to include <code>gedcom-tags.h</code>
+ yourself).<br>
+ <br>
+ The example passes a simple integer as context, but an application
+ could e.g. pass a <code>struct</code> (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
+<code> struct</code> to put it in its database.<br>
+ <br>
+ (Note that the <code>Gedcom_val</code> type for the <code>xref</code>
+ and <code>parsed_value</code> arguments was not discussed, see further
+ for this)<br>
+ <br>
+
+<h4><i>Callbacks for elements</i></h4>
+ We will now retrieve the SOUR field (the name of the program that
+wrote the file) from the header:<br>
+
+<blockquote><code>Gedcom_ctxt <b>my_header_source_start_cb</b>(Gedcom_elt elt,<br>
+
+ Gedcom_ctxt
+ parent,<br>
+
+ int
+ level,<br>
+
+ char*
+ tag,<br>
+
+ char*
+ raw_value,<br>
+
+ int
+ parsed_tag,<br>
+
+ Gedcom_val
+ parsed_value)<br>
+ {<br>
+ char *source = GEDCOM_STRING(parsed_value);<br>
+ printf("This file was written by %s\n", source);<br>
+ return parent;<br>
+ }<br>
<br>
- void my_default_cb(Gedcom_ctxt parent, int level, char* tag, char* raw_value,
- int parsed_tag)<br>
- {<br>
- struct header head = (struct header)parent;<br>
- my_header_add_to_extra_text(head, level, tag, raw_value);<br>
- }<br>
+ void <b>my_header_source_end_cb</b>(Gedcom_elt elt,<br>
+ Gedcom_ctxt parent,<br>
+
+ Gedcom_ctxt self,<br>
+
+ Gedcom_val parsed_value)<br>
+ {<br>
+ printf("End of the source description\n");<br>
+ }<br>
<br>
- gedcom_set_default_callback(my_default_cb);<br>
- gedcom_subscribe_to_record(REC_HEAD, my_header_start, NULL);<br>
- ...<br>
- result = gedcom_parse_file(filename);</code><br>
+ ...<br>
+ <b>gedcom_subscribe_to_element</b>(ELT_HEAD_SOUR,<br>
+
+ my_header_source_start_cb,<br>
+
+ my_header_source_end_cb);<br>
+ ...<br>
+ result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
</blockquote>
- 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 <code>parent</code> could be of different
-types, depending on the context).<br>
- <br>
-Note also that the default callback is not called when the parent context is <code>NULL</code><code></code>. This is e.g. the case if none of the "upper" tags has been subscribed upon.<br>
-
- <hr width="100%" size="2">
-
- <h2><a name="Other_API_functions"></a>Other API functions<br>
- </h2>
- 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.<br>
+ 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. the <code>struct</code>
+ 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 <a href="interface.html#Element_identifiers"> interface details</a> . Again, these are passed as first argument in the callback (the <code>Gedcom_elt</code> argument).<br>
+ <br>
+ 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.<br>
+ <br>
+ The <code>Gedcom_val</code> type 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 <a href="interface.html#Gedcom_val_types"> interface details</a>.
+ <br>
+ <br>
+ Some extra notes:<br>
+
+
+<ul>
+ <li>The <code>Gedcom_val</code> argument of the end callback
+ is used to pass 'complete' values, e.g. the full text of a note. See
+ the <a href="file:///home/verthezp/src/external/gedcom-parse/doc/interface.html#Record_identifiers">interface details</a>
+ for the exact type of this argument.</li>
+ <li>There are also two <code>Gedcom_val</code> arguments
+ in the start callback for records. The first one (<code>xref</code>
+ ) contains the <code>xref_value</code> corresponding to the cross-reference
+ (or <code>NULL</code> if there isn't one), the second one (<code>parsed_value</code>
+ ) contains the value that is parsed from the <code>raw_value</code>. See
+ the <a href="interface.html#Record_identifiers">interface details</a>
+ .</li>
+
+
+</ul>
+
+
+<h3><a name="Default_callbacks"></a>Default callbacks<br>
+ </h3>
+ 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:<br>
- <h3><a name="Debugging"></a>Debugging</h3>
- 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
+<blockquote><code>void <b>my_default_cb</b> (Gedcom_elt elt, Gedcom_ctxt parent, int level,
+ char* tag, char* raw_value, int parsed_tag)<br>
+ {<br>
+ ...<br>
+ }<br>
+ <br>
+ ...<br>
+ <b>gedcom_set_default_callback</b>(my_default_cb);<br>
+ ...<br>
+ result = <b>gedcom_parse_file</b>("myfamily.ged");</code><br>
+ </blockquote>
+ 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.<br>
+ <br>
+ 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:<br>
+
+<blockquote><code>struct header {<br>
+ char* source;<br>
+ ...<br>
+ char* extra_text;<br>
+ };<br>
+ <br>
+ Gedcom_ctxt my_header_start_cb(Gedcom_rec rec, int level, Gedcom_val xref, char* tag,
+ char *raw_value,<br>
+
+ int parsed_tag, Gedcom_val parsed_value)<br>
+ {<br>
+ struct header head = my_make_header_struct();<br>
+ return (Gedcom_ctxt)head;<br>
+ }<br>
+ <br>
+ void my_default_cb(Gedcom_elt elt, Gedcom_ctxt parent, int level, char* tag, char*
+raw_value, int parsed_tag)<br>
+ {<br>
+ struct header head = (struct header)parent;<br>
+ my_header_add_to_extra_text(head, level, tag, raw_value);<br>
+ }<br>
+ <br>
+ gedcom_set_default_callback(my_default_cb);<br>
+ gedcom_subscribe_to_record(REC_HEAD, my_header_start, NULL);<br>
+ ...<br>
+ result = gedcom_parse_file(filename);</code><br>
+ </blockquote>
+ 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 <code>parent</code> could be of different
+ types, depending on the context).<br>
+ <br>
+ Note also that the default callback is not called when the parent context
+ is <code>NULL</code><code></code>. This is e.g. the case if none
+ of the "upper" tags has been subscribed upon.<br>
+
+
+<hr width="100%" size="2"><br>
+<h2><a name="Support_for_writing_GEDCOM_files"></a>Support for writing GEDCOM files</h2>
+The Gedcom parser library also contains functions to writing GEDCOM files.
+ Similar as for the parsing itself, there are two interfaces: an interface
+which is very basic, and requires you to call a function for each line in
+the GEDCOM file, and an interface which just dumps the Gedcom object model
+to a file in one shot (if you use the Gedcom object model).<br>
+<br>
+Again, this section focuses on the basic interface, the Gedcom object model interface is described <a href="gom.html#Writing_the_object_model_to_file">here</a>.<br>
+<br>
+<h3><a name="Opening_and_closing_files"></a>Opening and closing files</h3>
+The basic functions for opening and closing Gedcom files for writing are the following:<br>
+<code></code>
+<blockquote><code>Gedcom_write_hndl <b>gedcom_write_open</b> (const char* filename);<br>
+int <b>gedcom_write_close</b> (Gedcom_write_hndl hndl, int* total_conv_fails);<br></code></blockquote>
+The function <code>gedcom_write_open</code> takes a parameter the name of
+the file to write, and returns a write handle, which needs to be used in
+subsequent functions. It returns <code>NULL</code> in case of errors.<br>
+<br>
+The function <code>gedcom_write_close</code> takes, next to the write handle,
+an integer pointer as parameter. If you pass an actual pointer for
+this, the function will write in it the total number of conversion failures;
+you can pass <code>NULL</code> if you're not interested. The function returns 0 in case of success, non-zero in case of failure.<br>
+<br>
+<h3><a name="Controlling_some_settings"></a>Controlling some settings<br>
+</h3>
+Note that by default the file is written in the same encoding as the read file was in. You can change
+this by calling the following function <i>before</i> calling <code>gedcom_write_open</code>, i.e. it affects all files that are opened after it is being called:<code></code><code><br>
+</code>
+<blockquote><code>int <b>gedcom_write_set_encoding</b> (Enc_from from, const char* charset, Encoding width, Enc_bom bom);<br></code></blockquote>The <code>from</code> parameter indicates how you want the encoding to be set:<br>
+<ul>
+ <li><b><code>ENC_FROM_FILE</code></b>: The same as the read file was in (this is the default).</li>
+ <li><b><code>ENC_FROM_SYS</code></b>: Not a valid value here, see below for <code>gedcom_write_set_terminator</code><br>
+ </li>
+ <li><b><code>ENC_MANUAL</code></b>: From the values given in the following parameters.</li>
+</ul>
+When <code>ENC_FROM_FILE</code><b> </b>is selected, the other parameters in the function are ignored (they can be passed as 0). When <code>ENC_MANUAL</code> is chosen, the meaning of the other parameters is as follows:<br>
+<br>
+The valid <code>charset</code> values are given in the first column in the file <code>gedcom.enc</code> in the data directory of gedcom-parse (<code>$PREFIX/share/gedcom-parse</code>).
+ The character sets UNICODE, ASCII and ANSEL are always supported (these
+are standard for GEDCOM), as well as ANSI (not standard), but there may be
+others.<br>
+<br>
+The <code>width</code> parameter takes one of the following values:<br>
+<ul>
+</ul>
+<ul>
+ <li><code><b>ONE_BYTE</b></code>: This should be used for all character sets except UNICODE.</li>
+ <li><code><b>TWO_BYTE_HILO</b></code>: High-low encoding for UNICODE (i.e. big-endian)</li>
+ <li><code><b>TWO_BYTE_LOHI</b></code>: Low-high encoding for UNICODE (i.e. little-endian)</li>
+</ul>
+The <code>bom</code> parameter determines whether a byte-order-mark should
+be written in the file in case of UNICODE encoding (usually preferred because
+it then clearly indicates the byte ordering). It takes one of the following
+values:<br>
+<ul>
+ <li><code><b>WITHOUT_BOM</b></code></li>
+ <li><code><b>WITH_BOM</b></code></li>
+</ul> For both these parameters you can pass 0 for non-UNICODE encodings,
+since that corresponds to the correct values (and is ignored anyway). The
+function returns 0 in case of success, non-zero in case of error. Note
+that you still need to pass the correct charset value for the HEAD.CHAR tag,
+otherwise you will get a warning, and the value will be forced to the correct
+value.<br>
+<br>
+Further, it is possible to control the kind of line terminator that is used, via the following function (also to be used before <code>gedcom_write_open</code>):<br>
+<blockquote><code>int <b>gedcom_write_set_line_terminator</b> (Enc_from from, Enc_line_end end);<br></code></blockquote>The values for the <code>from</code> parameter are given above. The value <b><code>ENC_FROM_SYS</code></b>
+is valid here, and means that the normal terminator for the current system
+is used (the second parameter of the function is then ignored). This
+is the default for this setting.<br>
+<br>
+The <code>end</code> parameter takes one of the following values:<br>
+<ul>
+ <li><b><code>END_CR</code></b>: only carriage return ("/r") (system value for Macintosh)</li>
+ <li><b><code>END_LF</code></b>: only line feed ("/n") (system value for Unix, Mac OS X)</li>
+ <li><b><code>END_CR_LF</code></b>: first carriage return, then line feed ("/r/n") (system value for DOS, Windows)</li>
+ <li><b><code>END_LF_CR</code></b>: first line feed, then carriage return ("/n/r")</li>
+</ul>
+By default, this is set to the appropriate line terminator on the current
+platform, so it only needs to be changed if there is some special reason
+for it.<br>
+<h3><a name="Writing_data"></a>Writing data<br>
+</h3>
+For actually writing the data, the principle is that every line in the GEDCOM
+file to write corresponds to a call to one of the following functions, except
+that CONT/CONC lines can be automatically taken care of. Note that
+the resulting GEDCOM file should conform to the GEDCOM standard. Several
+checks are built in already, and more will follow, to force this. There
+is no compatibility mode for writing GEDCOM files (and probably never will be).<br>
+<br>
+In general, each of the following functions expect their input in UTF-8 encoding (see also <a href="#Converting_character_sets">here</a>). If this is not the case, errors will be returned.<br>
+<br>
+Note that for examples of using these functions you can look at the sources for the Gedcom object model (e.g. the function <code>write_header</code> in <code>gom/header.c</code>).<br>
+<h4>Records</h4>
+For writing lines corresponding to records (i.e. on level 0), the following function is available:
+<blockquote><code>int <b>gedcom_write_record_str</b> (Gedcom_write_hndl hndl, Gedcom_rec rec, const char* xrefstr, const char* value);<br></code></blockquote>
+The <code>hndl</code> parameter is the write handle that was returned by <code>gedcom_write_open</code>. The <code>rec</code> parameter is one of the identifiers given in the first column in <a href="interface.html#Record_identifiers">this table</a> (except <code>REC_USER</code>: see below). The <code>xrefstr</code> and <code>val</code> parameters are respectively the cross-reference key of the record (something like '<code>@FAM01@</code>'), and the value of the record line, which should be <code>NULL</code> for some record types, according to the same table.<br>
+<h4>Elements</h4>
+For writing lines corresponding to elements (inside records, i.e. on a level
+bigger than 0), the following functions are available, depending on the data
+type:
+<blockquote><code>int <b>gedcom_write_element_str</b> (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag, <br>
+
+ int parent_rec_or_elt, const char* value);<br>
+i</code><code>nt <b>gedcom_write_element_xref</b> (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag, <br>
+
+ int parent_rec_or_elt, const struct xref_value*
+value);</code><br>
+ <code>int <b>gedcom_write_element_date</b> (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag, <br>
+
+ int parent_rec_or_elt, const struct date_value*
+value);</code><br>
+ <code>i</code><code>nt <b>gedcom_write_element_age </b> (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag, <br>
+
+ int parent_rec_or_elt, const struct age_value*
+value);</code><br>
+</blockquote>
+<blockquote><code></code></blockquote>
+These functions only differ in the type of the last argument, which is the value of the element.<br>
+<br>
+The <code>hndl</code> parameter is again the write handle returned by <code>gedcom_write_open</code>. The <code>elt</code> parameter is one of the identifiers given in the first column in <a href="interface.html#Element_identifiers">this table</a> (except <code>ELT_USER</code>: see below). The <code>parent_rec_or_elt</code> is the corresponding <code>rec</code> or <code>elt</code>
+identifier of the logically enclosing statement: this will determine the
+level number written on the line, as the level number of the parent + 1.<br>
+<br>
+Some of the identifiers can actually stand for different tags. For this reason, the <code>parsed_tag</code> has to be passed for some of them. This parsed tag is the same as was returned by the callback functions defined <a href="#Start_and_end_callbacks">above</a>, and is an identifier of the form <code>TAG_<i>name</i></code>. This parameter is needed whenever the second column in <a href="interface.html#Element_identifiers">this table</a> shows several possible tags (this is e.g. the case for <code>ELT_SUB_FAM_EVT</code>).<br>
+<br>
+Note that for writing a date value, the given value should be valid, i.e.
+all its struct fields filled in properly and consistent. This can be
+done by calling <code>gedcom_normalize_date</code> (see <a href="interface.html#date">here</a>).<br>
+<h4>User-defined tags</h4>
+For user-defined tags (tags starting with an underscore), there are separate functions, again depending on the data type:<code></code>
+<blockquote><code>int <b>gedcom_write_user_str</b> (Gedcom_write_hndl hndl, int level, const char* tag, const char* xrefstr,<br>
+ const char* value);<br>
+i</code><code>nt <b>gedcom_write_user_xref</b> (Gedcom_write_hndl hndl, </code><code>int level, const char* tag, const char* xrefstr,</code><br>
+ <code>
+
+ const struct xref_value* value);</code><br>
+ <code></code></blockquote>
+In the case of user-defined tags, the level and tag string are passed verbatim
+(not controlled by the library). This allows to write any extra data
+that doesn't use a standard tag, but is only allowed for tags starting with
+an underscore.<br>
+<hr width="100%" size="2">
+
+<h2><a name="Other_API_functions"></a>Other API functions<br>
+ </h2>
+
+ 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.<br>
+
+
+<h3><a name="Debugging"></a>Debugging</h3>
+ 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:<br>
-
- <blockquote><code>void <b>gedcom_set_debug_level</b> (int level,
- FILE* trace_output)</code><br>
- </blockquote>
- The <code>level</code> can be one of the following values:<br>
-
- <ul>
- <li>0: no debugging information (this is the
-default)</li>
- <li>1: only debugging information from libgedcom
- itself</li>
- <li>2: debugging information from libgedcom and
- yacc</li>
-
- </ul>
- If the <code>trace_output</code> is <code>NULL</code>, debugging information
- will be written to <code>stderr</code>, otherwise the given file handle
-is used (which must be open).<br>
- <br>
-
- <h3><a name="Error_treatment"></a>Error treatment</h3>
- 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:<br>
-
- <blockquote><code>void <b>gedcom_set_error_handling</b> (Gedcom_err_mech
- mechanism)</code><br>
- </blockquote>
- The <code>mechanism</code> can be one of:<br>
-
- <ul>
- <li><code>IMMED_FAIL</code>: immediately fail the
-parsing on an error (this is the default)</li>
- <li><code>DEFER_FAIL</code>: continue parsing after
- an error, but return a failure code eventually</li>
- <li><code>IGNORE_ERRORS</code>: continue parsing
-after an error, return success always</li>
+
+<blockquote><code>void <b>gedcom_set_debug_level</b> (int level, FILE*
+trace_output)</code><br>
+ </blockquote>
+ The <code>level</code> can be one of the following values:<br>
-
- </ul>
- This doesn't influence the generation of error or warning messages, only
- the behaviour of the parser and its return code.<br>
- <br>
+
+<ul>
+ <li>0: no debugging information (this is the
+ default)</li>
+ <li>1: only debugging information from libgedcom
+ itself</li>
+ <li>2: debugging information from libgedcom
+ and yacc</li>
-
- <h3><a name="Compatibility_mode"></a>Compatibility mode<br>
- </h3>
- 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:<br>
+
+</ul>
+ If the <code>trace_output</code> is <code>NULL</code>, debugging information
+ will be written to <code>stderr</code>, otherwise the given file handle
+ is used (which must be open).<br>
+ <br>
-
- <blockquote><code>void <b>gedcom_set_compat_handling</b>
- (int enable_compat)</code><br>
- </blockquote>
- The argument can be:<br>
+
+<h3><a name="Error_treatment"></a>Error treatment</h3>
+ 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:<br>
-
- <ul>
- <li>0: disable compatibility mode</li>
- <li>1: allow compatibility mode (this is the default)<br>
- </li>
+
+<blockquote><code>void <b>gedcom_set_error_handling</b> (Gedcom_err_mech
+ mechanism)</code><br>
+ </blockquote>
+ The <code>mechanism</code> can be one of:<br>
-
- </ul>
- Note that, currently, no actual compatibility code is present, but this
- is on the to-do list.<br>
- <hr width="100%" size="2">
- <h2><a name="Converting_character_sets"></a>Converting character sets</h2>
-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.<br>
- <br>
-The most common case is that the output character set is controlled by the <code>locale</code> mechanism (i.e. via the <code>LANG</code>, <code>LC_ALL</code> or <code>LC_CTYPE</code> environment variables), which also controls the <code>gettext</code>
- mechanism in the application. <br>
- <br>
- <br>
-
-
+
+<ul>
+ <li><code>IMMED_FAIL</code>: immediately fail
+the parsing on an error (this is the default)</li>
+ <li><code>DEFER_FAIL</code>: continue parsing
+after an error, but return a failure code eventually</li>
+ <li><code>IGNORE_ERRORS</code>: continue parsing
+ after an error, return success always</li>
-
- The source distribution of <code>gedcom-parse</code> contains an example implementation (<code>utf8-locale.c</code> and <code>utf8-locale.h</code>
- in 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).
- <br>
- <br>
-
-Its interface is:<br>
- <blockquote><pre><code>char *<b>convert_utf8_to_locale</b> (char *input, int *conv_failures);<br>char *<b>convert_locale_to_utf8</b> (char *input);<br></code></pre></blockquote>
+
+</ul>
+ This doesn't influence the generation of error or warning messages,
+ only the behaviour of the parser and its return code.<br>
+ <br>
+
+
+<h3><a name="Compatibility_mode"></a>Compatibility mode<br>
+ </h3>
+ 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:<br>
+
+
+<blockquote><code>void <b>gedcom_set_compat_handling</b> (int enable_compat)</code><br>
+ </blockquote>
+ The argument can be:<br>
+
+
+<ul>
+ <li>0: disable compatibility mode</li>
+ <li>1: allow compatibility mode (this is the
+default)<br>
+ </li>
+
+
+</ul>
+ Currently, there is (some) compatibility for:<br>
+<ul>
+ <li>ftree</li>
+ <li>Lifelines (3.0.2)</li>
+ <li>Personal Ancestral File (PAF), version 2, 4 and 5</li>
+ <li>Family Origins</li>
+ <li>EasyTree</li>
+</ul>
+The following function allows to set some options for the compatibility handling:<br>
+<blockquote><code>void <b>gedcom_set_compat_options</b> (Gedcom_compat options)</code><br>
+ </blockquote>
+The parameter can be an OR'ed combination of the following options:<br>
+<ul>
+ <li><code>COMPAT_ALLOW_OUT_OF_CONTEXT</code></li>
+</ul>
+<blockquote>
+ <blockquote>In some compatibility cases, tags are coming out-of-order,
+i.e. their start element callback would have to come after the end element
+callback of the parent tag. E.g. instead of the standard GEDCOM<br>
+ <blockquote><code>1 DATE ...<br>
+2 TIME ...</code><br>
+ </blockquote>
+the genealogy program has generated something like:<br>
+ <blockquote><code>1 DATE ...<br>
+1 TIME ...</code><br>
+ </blockquote>
+This can give a problem if your end element callbacks free some resources. <br>
+ <br>
+If your program can handle elements out of context, you can enable this option.
+ By default it is disabled, and so the values of these out-of-context
+tags are lost (the parser generates a warning if this is the case). The Gedcom object model in C has this option enabled.<br>
+ </blockquote>
+</blockquote>
+<br>
-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 <code>setlocale</code> function (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. <br>
- <br>
-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 pass <code>NULL</code> if you are not interested (note that usually, the interesting information is just whether there <i>were</i>
- 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.<br>
- <br>
+
+<hr width="100%" size="2">
+<h2><a name="Converting_character_sets"></a>Converting character sets</h2>
+ 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.<br>
+ <br>
+ The most common case is that the output character set is controlled by
+the <code>locale</code> mechanism (i.e. via the <code>LANG</code>, <code>
+ LC_ALL</code> or <code>LC_CTYPE</code> environment variables), which also
+controls the <code>gettext</code> mechanism in the application. <br>
+ <br>With<code>
+gedcom-parse</code> comes a library implementing help functions for UTF-8 encoding (<code></code>see
+the <a href="utf8tools.html">documentation</a> for this library).<br>
+
+
+<hr width="100%" size="2">
+
+<h2><a name="Support_for_configure.in"></a>Development support</h2>
+<h3>Macro for configure.in<br>
+</h3>
+There
+is a macro available for use in configure.in for applications that are using
+autoconf to configure their sources. The following macro checks whether
+the Gedcom parser library is available and whether its version is high enough:<br>
+<blockquote><code>AM_PATH_GEDCOM_PARSER([<i>min_version</i>,[<i>action_if_found</i>,[<i>action_if_not_found,</i>[<i>modules</i>]]]])</code><br>
+</blockquote>
+All the arguments are optional and default to 0. E.g. to check for
+version 1.34.2, you would put in configure.in the following statement:<br>
+<blockquote><code>AM_PATH_GEDCOM_PARSER(1.34.2)</code><br>
+</blockquote>Note that version numbers now contains three parts (since version
+0.20.0: this is also the first version in which this macro is available).<br>
+<br>
+The macro also sets the variables <code>GEDCOM_CFLAGS</code> and <code>GEDCOM_LIBS</code> for use in Makefiles. Typically, this would be done as follows in a Makefile.am:<br>
+<blockquote><code>bin_programs = myprg</code><br>
+ <code>myprg_SOURCES = myprg.c foo.c bar.c<br>
+INCLUDES = @GEDCOM_CFLAGS@<br>
+LDADD = @GEDCOM_LIBS@</code></blockquote>
+If your program uses some extra modules, they can be passed as fourth argument
+in the macro, so that the CFLAGS and LIBS are correctly filled in. Currently,
+the only available module is <code>gom</code> (the Gedcom object model). For example:<br>
+<blockquote><code>AM_PATH_GEDCOM_PARSER(0.21.2, , ,gom)</code><br>
+</blockquote>
+To be able to use this macro in the sources of your application, you have three options:<br>
+<ul>
+ <li>Put the file <code>m4/gedcom.m4</code> in your autoconf data directory (i.e. the path given by '<code>aclocal --print-ac-dir</code>', usually <code>/usr/share/aclocal</code>). You can do this automatically by going into the m4 subdirectory and typing '<code>make install-m4</code>'.<br>
+ <br>
+ </li>
+ <li>If you're using autoconf, but not automake, copy the contents of <code>m4/gedcom.m4</code> in the <code>aclocal.m4</code> file in your sources.<br>
+ <br>
+ </li>
+ <li>If you're using automake, copy the contents of <code>m4/gedcom.m4</code> in the <code>acinclude.m4</code> file in your sources.<br>
+ </li>
+</ul>
+<br>
+There are three preprocessor symbols defined for version checks in the
+ header (but their direct use is deprecated: please use the macro above):<br>
+
+<ul>
+ <li><code>GEDCOM_PARSE_VERSION_MAJOR</code></li>
+ <li><code>GEDCOM_PARSE_VERSION_MINOR</code></li>
+ <li><code>GEDCOM_PARSE_VERSION</code><br>
+ </li>
+
+</ul>
+ The last one is equal to <code>(GEDCOM_PARSE_VERSION_MAJOR * 1000) + GEDCOM_PARSE_VERSION_MINOR.</code> As you see, this only checked the major and minor version, not the patch number, so this is obsolete.<br>
+<br>
+<h3>Compilation and linking flags</h3>
+Similar to other libraries, the GEDCOM parse library installs a script <code>gedcom-config</code> to help with compilation and linking flags for programs that don't use autoconf/automake.<br>
+<br>
+To get compilation flags for your program, use (depending on whether you
+only use the callback parser, or also the GEDCOM object model):
+<blockquote><code>gedcom-config --cflags<br>
+gedcom-config --cflags gom</code><br>
+</blockquote>
+Similarly, to get linking flags, use one of the following:
+<blockquote><code>gedcom-config --libs<br>
+gedcom-config --libs gom</code><br>
+</blockquote>
-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:<br>
- <blockquote><pre><code>void <b>convert_set_unknown</b> (const char *unknown);</code></pre></blockquote>
- <br>
-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 <a href="http://www.gnu.org/manual/glibc-2.2.3/html_chapter/libc_6.html#SEC99">here</a>):<br>
- <ul>
- <li>inclusion of some headers:</li>
- </ul>
- <blockquote>
- <blockquote>
- <pre><code>#include <locale.h> /* for setlocale */<br>#include <langinfo.h> /* for nl_langinfo */<br>#include <iconv.h> /* for iconv_* functions */<br></code></pre>
- </blockquote>
- </blockquote>
- <ul>
- <li>set the program's current locale to what the user configured in the environment:</li>
- </ul>
- <blockquote>
- <blockquote>
- <pre><code>setlocale(LC_ALL, "");</code><br></pre>
- </blockquote>
- </blockquote>
- <ul>
- <li>open a conversion handle for conversion from UTF-8 to the character set of the current locale (once for the entire program):</li>
- </ul>
- <blockquote>
- <blockquote>
- <pre><code>iconv_t iconv_handle;<br>...<br>iconv_handle = iconv_open(nl_langinfo(CODESET), "UTF-8");</code><br>if (iconv_handle == (iconv_t) -1)<br> /* signal an error */<br></pre>
- </blockquote>
- </blockquote>
- <ul>
- <li>then, every string can be converted using the following:</li>
- </ul>
- <blockquote>
- <blockquote>
- <pre><code>/* char* in_buf is the input buffer, size_t in_len is its length */<br>/* char* out_buf is the output buffer, size_t out_len is its length */<br><br>size_t nconv;<br>char *in_ptr = in_buf;<br>char *out_ptr = out_buf;<br>nconv = iconv(iconv_handle, &in_ptr, &in_len, &out_ptr, &out_len);</code></pre>
- </blockquote>
- </blockquote>
- <blockquote>If the output buffer is not big enough, <code>iconv</code> will return -1 and set <code>errno</code> to <code>E2BIG</code>. Also, the <code>in_ptr</code> and <code>out_ptr</code> will point just after the last successfully converted character in the respective buffers, and the <code>in_len</code> and <code>out_len</code> will be updated to show the remaining lengths. There can be two strategies here:<br>
- <ul>
- <li>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.<br>
- <br>
- </li>
- <li>Do the conversion in several steps, growing the output buffer each time to make more space, and calling <code>iconv</code>
- consecutively until the conversion is complete. This is the preferred
-way (a function could be written to encapsulate all this).</li>
- </ul>
-Another error case is when the conversion was unsuccessful (if one of the
-characters can't be represented in the target character set). The <code>iconv</code> function will then also return -1 and set <code>errno</code> to <code>EILSEQ</code>; the <code>in_ptr</code> will point to the character that couldn't be converted. In that case, again two strategies are possible:<br>
- <ul>
- <li>Just fail the conversion, and show an error. This is not very user friendly, of course.<br>
- <br>
- </li>
- <li>Skip over the character that can't be converted and append a "?" to the output buffer, then call <code>iconv</code> again. Skipping over a UTF-8 character is fairly simple, as follows from the <a href="http://www.cl.cam.ac.uk/%7Emgk25/unicode.html#utf-8">encoding rules</a>:</li>
- </ul>
- <ol>
- <ol>
- <li>if the first byte is in binary 0xxxxxxx, then the character is only one byte long, just skip over that byte<br>
- <br>
- </li>
- <li>if the first byte is in binary 11xxxxxx, then skip over that byte and all bytes 10xxxxxx that follow.<br>
- </li>
- </ol>
- </ol>
- </blockquote>
- <ul>
- <li>eventually, the conversion handle needs to be closed (when the program exits):<br>
- </li>
- </ul>
- <blockquote>
- <blockquote>
- <pre><code>iconv_close(iconv_handle);<br></code></pre>
- </blockquote>
- </blockquote>
- The example implementation
-mentioned above grows the output buffer dynamically and outputs "?" for characters
-that can't be converted.<br>
-
- <hr width="100%" size="2">
- <h2><a name="Support_for_configure.in"></a>Support for configure.in</h2>
-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):<br>
- <blockquote><code>AC_CHECK_LIB(gedcom, gedcom_parse_file,,<br>
- AC_MSG_ERROR(Cannot find libgedcom: Please install gedcom-parse))<br>
-AC_CACHE_CHECK(for libgedcom version, ac_cv_gedcom_version_ok,<br>
-[AC_TRY_RUN([<br>
-#include <stdio.h><br>
-#include <stdlib.h><br>
-#include <gedcom.h><br>
-int<br>
-main()<br>
-{<br>
-if (GEDCOM_PARSE_VERSION >= 1034) exit(0);<br>
-exit(1);<br>
-}],<br>
-ac_cv_gedcom_version_ok='yes',<br>
-ac_cv_gedcom_version_ok='no')])<br>
-if test "$ac_cv_gedcom_version_ok" = 'yes' ; then<br>
- AC_MSG_RESULT(ok)<br>
-else<br>
- AC_MSG_RESULT(not ok)<br>
- AC_MSG_ERROR(You need at least version 1.34 of gedcom-parse)<br>
-fi</code><br>
- </blockquote>
-There are three preprocessor symbols defined for version checks in the header:<br>
- <ul>
- <li><code>GEDCOM_PARSE_VERSION_MAJOR</code></li>
- <li><code>GEDCOM_PARSE_VERSION_MINOR</code></li>
- <li><code>GEDCOM_PARSE_VERSION</code><br>
- </li>
- </ul>
-The last one is equal to <code>(GEDCOM_PARSE_VERSION_MAJOR * 1000) + GEDCOM_PARSE_VERSION_MINOR.</code><br>
-<hr width="100%" size="2">
-
- <pre><font size="-1">$Id$<br>$Name$</font><br></pre>
-
- <pre> </pre>
+
+<hr width="100%" size="2">
+
+<pre><font size="-1">$Id$<br>$Name$</font><br></pre>
-
- </body></html>
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+
+<pre> </pre>
+
+
+<br>
+<br>
+<br>
+<br>
+<br>
+<br>
+<br>
+<br>
+<br>
+<br>
+<br>
+<br>
+</body></html>
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