A GEDCOM Grammar

The following LALR(1) grammar can be used to parse GEDCOM 5.5 files generated by a variety of programs. If desired, pointer strings must be manually trimmed to remove prefix and suffix characters ('@'). Embedded escape sequences in value strings (if used) must also be manually extracted.

ALNUM: // an alphanumeric character

[a-z_A-Z0-9]

WHITE: // any whitespace character

[ \t\v\b\f\a]

ANY: // any character except newline

[^\n]

POINTER: // a pointer string

@ALNUM[^@]*@

BOM8: // a UTF-8 byte order mark

\xEF\xBB\xBF

UBOM: // a Unicode byte order mark

\xFF\xFE

NEWLINE:

\n

SPACE:

' ' // single space character (0x20)

TAG:

ALNUM+

LEVEL:

0|([1-9][0-9]*)

VALUE:

ANY+

%ignore%:

BOM8 // UTF-8 byte order mark

UBOM // Unicode byte order mark

WHITE* // leading whitespace

file:

line

file line

line:

LEVEL SPACE TAG

LEVEL SPACE TAG line_value NEWLINE

LEVEL SPACE POINTER SPACE TAG

LEVEL SPACE POINTER SPACE TAG line_value NEWLINE

line_value:

VALUE

POINTER