X-Git-Url: https://git.dlugolecki.net.pl/?a=blobdiff_plain;f=doc%2Fusage.html;h=39a0cb3594f58e5ca6cfeb0a30d3c1e99c09f371;hb=0ed444394c30a2e3983fb551e7f788804116a8b4;hp=ee3e248bae1331b1f9d175c2320c416ef024881d;hpb=7372fd1bb10934271adbb12fe27f45df8ea225d2;p=gedcom-parse.git diff --git a/doc/usage.html b/doc/usage.html index ee3e248..39a0cb3 100644 --- a/doc/usage.html +++ b/doc/usage.html @@ -17,15 +17,14 @@
  • Start and end callbacks
  • Default callbacks
    • -
  • C object model
    • +
  • Support for writing GEDCOM files
    • - -
  • Other API functions
    • +
  • Other API functions
  • Converting character sets
    • -
  • Support for configure.in
    +
  • Development support

    • -
  • Interface details of the callback parser
  • C object model details
    +
  • Interface details of the callback parser
  • C object model
    • @@ -65,9 +64,9 @@ application program, which implements the callback parser - - - Next to these, there is also a data directory in $PREFIX/share/gedcom-parse +There is a separate script to help with library and compilation flags, see the development support.
    +
    +Next to these, there is also a data directory in $PREFIX/share/gedcom-parse that contains some additional stuff, but which is not immediately important at first.  I'll leave the description of the data directory for later.
    @@ -110,8 +109,9 @@ the -lgedcom option on the linking of the program as the last option, so that its initialization code is run first.  In the case of using the C object model, the linking options should be: -lgedcom_gom -lgedcom
    -
    - The next sections will refine this piece of code to be able to have +
    The function gedcom_init() also initializes locale handling by calling setlocale(LC_ALL, ""), in case the application would not do this (it doesn't hurt for the application to do the same).
    + 
    +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.
    @@ -154,7 +154,7 @@ way it wants.  Warnings are similar, but use "Warning" instead of "Error"

    Data callback mechanism

    The most important use of the parser is of course to get the data -out of the GEDCOM file.  This section focuses on the callback mechanism (see the next section for the C object model).  In fact, the mechanism involves two levels.
    +out of the GEDCOM file.  This section focuses on the callback mechanism (see here for the C object model).  In fact, the mechanism involves two levels.

    The primary level is that each of the sections in a GEDCOM file is notified to the application code via a "start element" callback and an @@ -420,71 +420,135 @@ raw_value, int parsed_tag)

    -

    C object model

    -In the GEDCOM object model, all the data is immediately available after calling gom_parse_file().  For this, an entire model based on C structs is used.  These structs are documented here, -and follow the GEDCOM syntax quite closely.  Each of the records in -a GEDCOM file are modelled by a separate struct, and some common sub-structures -have their own struct definition.
    +

    Support for writing GEDCOM files

    +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).
    +
    +Again, this section focuses on the basic interface, the Gedcom object model interface is described here.

    -

    Main functions
    +

    Opening and closing files

    +The basic functions for opening and closing Gedcom files for writing are the following:
    + +
    Gedcom_write_hndl gedcom_write_open (const char* filename);
    +int               gedcom_write_close (Gedcom_write_hndl hndl, int* total_conv_fails);
    +The function gedcom_write_open 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 NULL in case of errors.
    +
    +The function gedcom_write_close 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 NULL if you're not interested.  The function returns 0 in case of success, non-zero in case of failure.
    +
    +

    Controlling some settings

    -The following functions are available to get at these structs:
    +Note that by default the file is written in ASCII encoding (and hence e.g. +accented characters will cause a conversion failure).  You can change +this by calling the following function before calling gedcom_write_open, i.e. it affects all files that are opened after it is being called:
    +     +
    int gedcom_write_set_encoding (const char* charset, Encoding width, Enc_bom bom);
    +The valid charset values are given in the first column in the file gedcom.enc in the data directory of gedcom-parse ($PREFIX/share/gedcom-parse). + 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.
    +
    +The width parameter takes one of the following values:
    -
    The XXX stands for one of the following: family, individual, multimedia, note, repository, source, submitter, user_rec.
    -
    -

    Object model structure
    + +The bom 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:
    + 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.
    +
    +Further, it is possible to control the kind of line terminator that is used, via the following function (also to be used before gedcom_write_open):
    +
    int gedcom_write_set_line_terminator (Enc_line_end end);
    +The end parameter takes one of the following values:
    + +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.
    +

    Writing data

    -All records of a certain type are linked together in a linked list.  The -above functions only give access to the first record of each linked list. - The others can be accessed by traversing the linked list via the next member of the structs.  This means that e.g. the following piece of code will traverse the linked list of family records:
    -
    struct family* fam;
    -
    -for (fam = gom_get_first_family() ; fam ; fam = fam->next) {
    -  ...
    -}
    -
    -The next member of the last element in the list is guaranteed to have the NULL value.
    +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 (currently) no compatibility mode for writing GEDCOM files.

    -Actually, the linked list is a doubly-linked list: each record also has a previous member.  But for implementation reasons the behaviour of this previous member on the edges of the linked list will not be guaranteed, i.e. it can be circular or terminated with NULL, no assumptions can be made in the application code.
    +In general, each of the following functions expect their input in UTF-8 encoding (see also here).  If this is not the case, errors will be returned.

    -This linked-list model applies also to all sub-structures of the main record structs, i.e. each struct that has a next and previous -member following the above conventions.  This means that the following -piece of code traverses all children of a family (see the details of the -different structs here):
    -
    struct family* fam = ...;
    -
    -struct xref_list* xrl;
    -for (xrl = fam->children ; xrl ; xrl = xrl->next) {
    -  ...
    -}
    +Note that for examples of using these functions you can look at the sources for the Gedcom object model (e.g. the function write_header in gom/header.c).
    +

    Records

    +For writing lines corresponding to records (i.e. on level 0), the following function is available: +
    int gedcom_write_record_str (Gedcom_write_hndl hndl, Gedcom_rec rec, char* xrefstr, char* value);
    +The hndl parameter is the write handle that was returned by gedcom_write_open.  The rec parameter is one of the identifiers given in the first column in this table (except REC_USER: see below).  The xrefstr and val parameters are respectively the cross-reference key of the record (something like '@FAM01@'), and the value of the record line, which should be NULL for some record types, according to the same table.
    +

    Elements

    +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: +
    int gedcom_write_element_str  (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag,
    +                      +         int parent_rec_or_elt, char* value);
    +i    nt gedcom_write_element_xref (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag,
    +                      +         int parent_rec_or_elt, struct xref_value* +value);
    + int gedcom_write_element_date (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag,
    +                      +         int parent_rec_or_elt, struct date_value* +value);
    + int gedcom_write_element_age  (Gedcom_write_hndl hndl, Gedcom_elt elt, int parsed_tag,
    +                      +         int parent_rec_or_elt, struct age_value* +value);
    -Note that all character strings in the object model are encoded in UTF-8 (Why UTF-8?).
    -

    User data

    -Each of the structs has an extra member called extra (of type struct user_data*). - This gathers all non-standard GEDCOM tags within the scope of the struct -in a flat linked list, no matter what the internal structure of the non-standard -tags is.  Each element of the linked list has:
    - -This way, none of the information in the GEDCOM file is lost, even the non-standard information.
    +
    +These functions only differ in the type of the last argument, which is the value of the element.
    +
    +The hndl parameter is again the write handle returned by gedcom_write_open.  The elt parameter is one of the identifiers given in the first column in this table (except ELT_USER: see below).  The parent_rec_or_elt is the corresponding rec or elt +identifier of the logically enclosing statement: this will determine the +level number written on the line, as the level number of the parent + 1.
    +
    +Some of the identifiers can actually stand for different tags.  For this reason, the parsed_tag has to be passed for some of them.  This parsed tag is the same as was returned by the callback functions defined above, and is an identifier of the form TAG_name.  This parameter is needed whenever the second column in this table shows several possible tags (this is e.g. the case for ELT_SUB_FAM_EVT).
    +
    +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 gedcom_normalize_date (see here).
    +

    User-defined tags

    +For user-defined tags (tags starting with an underscore), there are separate functions, again depending on the data type: +
    int gedcom_write_user_str  (Gedcom_write_hndl hndl, int level, char* tag, char* xrefstr,
    +                            char* value);
    +i    nt gedcom_write_user_xref (Gedcom_write_hndl hndl, int level, char* tag, char* xrefstr,
    + +                            struct xref_value* value);
    +
    +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.

    Other API functions
    @@ -585,207 +649,52 @@ default)
    the locale mechanism (i.e. via the LANG, LC_ALL or LC_CTYPE environment variables), which also controls the gettext mechanism in the application.  
    -
    -
    - - The source distribution of -gedcom-parse contains an example implementation (utf8-locale.c - and utf8-locale.h in the "t" subdirectory of the top directory).  - Feel free to use it in your source code (it is not part of the library, -and it isn't installed anywhere, so you need to take over the source and -header file in your application).  
    -
    - Its interface is:
    - -
    - 
    char *convert_utf8_to_locale (char *input, int *conv_failures);
    char *convert_locale_to_utf8 (char *input);
    -
    - 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 setlocale 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. -  
    -
    - 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 NULL if you are not interested -(note that usually, the interesting information is just whether there -were conversion failures or not, which is then given by the integer -being bigger than zero or not).  The second function doesn't need this, -because any locale can be converted to UTF-8.
    -
    - You can change the "?" that is output for characters that can't be converted - to any string you want, using the following function before the conversion - calls:
    - -
    - 
    void convert_set_unknown (const char *unknown);
    -
    -
    - If you want to have your own functions for it instead of this example -implementation, the following steps need to be taken by the application -(more detailed info can be found in the info file of the GNU libc library -in the "Generic Charset Conversion" section under "Character Set Handling" -or online - here):
    - - - -
    -
    - 
    #include <locale.h>    /* for setlocale */
    #include <langinfo.h>  /* for nl_langinfo */
    #include <iconv.h>     /* for iconv_* functions */
    -
    -
    - - - -
    -
    - 
    setlocale(LC_ALL, "");
    -
    -
    - - - -
    -
    - 
    iconv_t iconv_handle;
    ...
    iconv_handle = iconv_open(nl_langinfo(CODESET), "UTF-8");
    if (iconv_handle == (iconv_t) -1)
      /* signal an error */
    -
    -
    - - - -
    -
    - 
    /* char* in_buf is the input buffer,    size_t in_len is its length */
    /* char* out_buf is the output buffer,  size_t out_len is its length */

    size_t nconv;
    char *in_ptr = in_buf;
    char *out_ptr = out_buf;
    nconv = iconv(iconv_handle, &in_ptr, &in_len, &out_ptr, &out_len);
    -
    -
    - -
    If the output buffer is not big enough, iconv will - return -1 and set errno to E2BIG.  Also, -the in_ptr and out_ptr will point just after -the last successfully converted character in the respective buffers, and -the in_len and out_len will be updated to show -the remaining lengths.  There can be two strategies here:
    - -
      -
    • Make sure from the beginning - that the output buffer is big enough.  However, it's difficult to find - an absolute maximum length in advance, even given the length of the input - string.
      -
      -
      • -
    • Do the conversion in several - steps, growing the output buffer each time to make more space, and calling - iconv consecutively until the conversion is complete. -  This is the preferred way (a function could be written to encapsulate - all this).
      • - -
    - Another error case is when the conversion was unsuccessful (if one of -the characters can't be represented in the target character set).  The - iconv function will then also return -1 and set errno - to EILSEQ; the in_ptr will point to the character - that couldn't be converted.  In that case, again two strategies are -possible:
    - -
      -
    • Just fail the conversion, -and show an error.  This is not very user friendly, of course.
      -
      -
      • -
    • Skip over the character that - can't be converted and append a "?" to the output buffer, then call - iconv again.  Skipping over a UTF-8 character is fairly simple, - as follows from the encoding rules - :
      • - -
    - -
      - -
        -
      1. if the first byte is in -binary 0xxxxxxx, then the character is only one byte long, just skip over -that byte
        -
        -
        2. -
      2. if the first byte is in -binary 11xxxxxx, then skip over that byte and all bytes 10xxxxxx that follow.
        -
        3. - -
      - -
    -
    - - - -
    -
    - 
    iconv_close(iconv_handle);
    -
    -
    - The example implementation - mentioned above grows the output buffer dynamically and outputs "?" for characters - that can't be converted.
    +
    With +gedcom-parse comes a library implementing help functions for UTF-8 encoding (see +the documentation for this library).
    -

    Support for configure.in

    - Programs using the GEDCOM parser library and using autoconf to configure - their sources can use the following statements in configure.in (the example - is checking for gedcom-parse, version 1.34):
    - -
    AC_CHECK_LIB(gedcom, gedcom_parse_file,,
    -              AC_MSG_ERROR(Cannot - find libgedcom: Please install gedcom-parse))
    - AC_MSG_CHECKING(for libgedcom version)
    - AC_TRY_RUN([
    - #include <stdio.h>
    - #include <stdlib.h>
    - #include <gedcom.h>
    - int
    - main()
    - {
    - if (GEDCOM_PARSE_VERSION >= 1034) exit(0);
    - exit(1);
    - }],
    - ac_gedcom_version_ok='yes',
    - ac_gedcom_version_ok='no',
    - ac_gedcom_version_ok='no')
    - if test "$ac_gedcom_version_ok" = 'yes' ; then
    -   AC_MSG_RESULT(ok)
    - else
    -   AC_MSG_RESULT(not ok)
    -   AC_MSG_ERROR(You need at least version 1.34 of gedcom-parse)
    - fi
    -
    - There are three preprocessor symbols defined for version checks in the - header:
    +

    Development support

    +

    Macro for configure.in
    +

    +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:
    +
    AM_PATH_GEDCOM_PARSER([min_version,[action_if_found,[action_if_not_found,[modules]]]])
    +
    +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:
    +
    AM_PATH_GEDCOM_PARSER(1.34.2)
    +
    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).
    +
    +The macro also sets the variables GEDCOM_CFLAGS and GEDCOM_LIBS for use in Makefiles.  Typically, this would be done as follows in a Makefile.am:
    +
    bin_programs   = myprg
    + myprg_SOURCES  = myprg.c foo.c bar.c
    +INCLUDES       = @GEDCOM_CFLAGS@
    +LDADD          = @GEDCOM_LIBS@
    +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 gom (the Gedcom object model).  For example:
    +
    AM_PATH_GEDCOM_PARSER(0.21.2, , ,gom)
    +
    +To be able to use this macro in the sources of your application, you have three options:
    + +
    +There are three preprocessor symbols defined for version checks in the + header (but their direct use is deprecated: please use the macro above):
    - The last one is equal to (GEDCOM_PARSE_VERSION_MAJOR * 1000) + GEDCOM_PARSE_VERSION_MINOR.
    + The last one is equal to (GEDCOM_PARSE_VERSION_MAJOR * 1000) + GEDCOM_PARSE_VERSION_MINOR. As you see, this only checked the major and minor version, not the patch number, so this is obsolete.
    +
    +

    Compilation and linking flags

    +Similar to other libraries, the GEDCOM parse library installs a script gedcom-config to help with compilation and linking flags for programs that don't use autoconf/automake.
    +
    +To get compilation flags for your program, use (depending on whether you +only use the callback parser, or also the GEDCOM object model): +
    gedcom-config --cflags
    +gedcom-config --cflags gom
    +
    +Similarly, to get linking flags, use one of the following: +
    gedcom-config --libs
    +gedcom-config --libs gom
    +
    + +
    @@ -804,6 +728,14 @@ handle needs to be closed (when the program exits):
    +
    +
    +
    +
    +
    +
    +
    +


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