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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>
-
+
<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="#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>
+ <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="interface.html">Interface details</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 is built as a callback-based parser (comparable
+ to the SAX 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 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>$PREFIX/share/gedcom-parse</code>
- that contains some additional stuff, but which is not immediately important
- at first. I'll leave the description of the data directory for later.<br>
- <br>
- The very simplest call of the gedcom parser is simply the following piece
- of code (include of the gedcom header is assumed, as everywhere in this
-manual):<br>
-
+ Next to these, there is also a data directory in <code>$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>
+
<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">
+ ...<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>
-
+ 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>
-
+ 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 (see "Why UTF-8?" <i>LINK TBD</i>). 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">
+ </blockquote>
+ Note that the entire string will be properly internationalized, and
+encoded in UTF-8 (see "Why UTF-8?" <i>LINK TBD</i>). 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. 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 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>
-
+ 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
+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>
-
+ </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,
-Gedcom_val xref, char *tag)<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", 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 example passes a simple integer as context, but an application could
-e.g. pass a <code>struct</code> 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> argument
-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>
+ <br>
- int
- level,<br>
+ Gedcom_val xref, <br>
- char*
- tag,<br>
+ char *tag, <br>
- char*
- raw_value,<br>
+ char *raw_value,<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>
+ int parsed_tag, <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 (e.g. the <code>struct</code> that 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 <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 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.<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>
+ 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>
- Some extra notes:<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 is also a <code>Gedcom_val</code> argument in the
-start callback for records. This argument is currently a string value
-giving the pointer in string form.</li>
-
+ <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>
+ </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)<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>
+ 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(int level, Gedcom_val xref, char* tag)<br>
-{<br>
- struct header head = my_make_header_struct();<br>
- return (Gedcom_ctxt)head;<br>
-}<br>
- <br>
-void my_default_cb(Gedcom_ctxt parent, int level, char* tag, char* raw_value)<br>
-{<br>
- struct header head = (struct header)parent;<br>
- my_header_add_to_extra_text(head, level, tag, raw_value);<br>
-}<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>
+ <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>
+ <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>
-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>
- <hr width="100%" size="2">
+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>
+ </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>
+
<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>
+ 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>
+ 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>
+ <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>
+ 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>
+ 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>
+ 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>
+ <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>
+
+
</ul>
-This doesn't influence the generation of error or warning messages, only
-the behaviour of the parser and its return code.<br>
- <br>
+ 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>
+ </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>
+ (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>
+ <li>0: disable compatibility mode</li>
+ <li>1: allow compatibility mode (this is the default)<br>
+ </li>
+
+
</ul>
-Note that, currently, no actual compatibility code is present, but this is
-on the to-do list.<br>
- <hr width="100%" size="2">$Id: usage.html,v 1.1 2001/12/30
-22:45:43 verthezp Exp $<br>
- $Name$<br>
- <br>
-
- </body>
- </html>
+ Note that, currently, no actual compatibility code is present, but this
+ is on the to-do list.<br>
+
+
+ <hr width="100%" size="2">
+
+ <pre><font size="-1">$Id$<br>$Name$</font><br></pre>
+
+ <pre> </pre>
+
+
+ </body></html>
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