The Gedcom parser library

The Gedcom parser library internals

The intention of this page is to provide some explanation of the gedcom parser, to aid development on and with it. First, some practical issues of testing with the parser will be explained.
-
+
+

Index

Testing

Basic testing
Preparing for further testing
Testing the parser with debugging
Testing the lexers separately
+

Structure of the parser

Character encoding
+

+
+

Testing
+

+ -

Basic testing
-

Basic testing
+ +

+ You should be able to perform a basic test using the commands:

./configure @@ -24,16 +42,16 @@ some practical issues of testing with the parser will be explained. make check

If everything goes OK, you'll see that some gedcom files are parsed, - and that each parse is successful. Note that the used gedcom files + and that each parse is successful. Note that some of the used gedcom files are made by Heiner Eichmann and are an excellent way to test gedcom parsers thoroughly.

-

Preparing for further testing

- The basic testing described above doesn't show anything else than -"Parse succeeded", which is nice, but not very interesting. Some + +

Preparing for further testing

+Some more detailed tests are possible, via the testgedcom program -that is generated by make test.
+that is generated by make.

However, since the output that testgedcom generates is in UTF-8 format (more on this later), some preparation is necessary @@ -66,12 +84,14 @@ the xterm coming with XFree86 4.0.x). UTF-8 capabilities and see the result.

-

Testing the parser with debugging

+ +

Testing the parser with debugging

+ Given the UTF-8 capable terminal, you can now let the testgedcom program print the values that it parses. An example of a command - line is (in the gedcom directory):
+ line is (in the top directory):
-

./testgedcom -dg t/ulhc.ged
+
./testgedcom -dg t/input/ulhc.ged

The -dg option instructs the parser to show its own debug messages (see ./testgedcom -h for the full set of options). @@ -80,47 +100,76 @@ containing a lot of special characters.

For the ANSEL test file (t/ansel.ged), you have to set the environment variable GCONV_PATH to the ansel - subdirectory of the gedcom directory:
+ subdirectory of the top directory:

export GCONV_PATH=./ansel - ./testgedcom -dg t/ansel.ged + ./testgedcom -dg t/input/ansel.ged
This is because for the ANSEL character set an extra module is needed for the iconv library (more on this later). But again, this should show a lot of special characters.

-
Testing the lexers separately
+ +
Testing the lexers separately
+ The lexers themselves can be tested separately. For the 1-byte lexer (i.e. supporting the encodings with 1 byte per characters, such as - ASCII, ANSI and ANSEL), the sequence of commands would be:
+ ASCII, ANSI and ANSEL), the command would be (in the gedcom subdirectory):
-
make clean - make test_1byte + make lexer_1byte - This will show all tokens in the t/allged.ged test file. - Similar tests can be done using make test_hilo and -make test_lohi (for the unicode lexers). + This will generate a lexer program that can process e.g. the t/input/allged.ged + test file. Simply cat the file through the lexer on standard input +and you should get all the tokens in the file. Similar tests can be +done using make lexer_hilo and +make lexer_lohi + (for the unicode lexers). In each of the cases you need to know +yourself which of the test files are appropriate to pass through the lexer. This concludes the testing setup. Now for some explanations... - + - Structure of the parser + Structure of the parser I see the structure of a program using the gedcom parser as follows: - TO BE COMPLETED... + The parser is based on lex/yacc, which means that a module generated by lex + takes the inputfile and determines the tokens in that file (i.e. the smallest +units, such as numbers, line terminators, GEDCOM tags, characters in GEDCOM +values...). These tokens are passed to the parser module, which is +generated by yacc, to parse the syntax of the file, i.e. whether the tokens +appear in a sequence that is valid. + +For each recognized statement in the GEDCOM file, the parser calls some callbacks, +which can be registered by the application to get the information out of +the file. + +This basic description ignores the problem of character encoding. + + Character encoding Refer to this page for some introduction on character encoding... + + +GEDCOM defines three standard encodings: + + ASCII + ANSEL + UNICODE (assumed to be UCS-2, either big-endian or little-endian: the GEDCOM spec doesn't specify this) + These are all supported by the parser, and converted into UTF-8 format. + + + + - $Id$ $Name$ + $Id$ $Name$

The Gedcom parser library

The Gedcom parser library internals

Index

Testing +

Basic testing -

Basic testing + +

Preparing for further testing

Preparing for further testing

Testing the parser with debugging

Testing the parser with debugging

Testing the lexers separately

Testing the lexers separately

Structure of the parser

Structure of the parser

Character encoding

Testing
+

Basic testing
-

Basic testing
+ +