FDF specifications

Specifications for FDF format and its processing by libFDF

Input lines are parsed and a token list is created. A token is:

* Any number of characters enclosed in a matching pair 
  of quotes (",',`). Embedded strings are not considered tokens.
  The quotes are removed by the parsing routine.

* A string of characters from the set [A-Z,a-z,0-9] of
  alphanumeric characters plus $%&@_.-*/^+~ (and any adjacent
      unmatched quotes, as in apostrophes)

* The character '<' by itself.

Examples:

MeshCutoff < "File.fdf"           3 tokens: MeshCutoff, <, File.fdf
System_Name  Devil's staircase    3 tokens: System_Name, Devil's, staircase
%block AtomicCoordinates %dump < coords.dat  5 tokens

The characters '#', ';', and '!' signal the beginning of a comment. Any remaining characters on the line are discarded.

Labels and directives (%block, %include, %endblock) are case-insensitive. Labels are also internal-separator-insensitive, by which it is understood that the characters '.', '_', and '-' are removed before any comparison is made. The following forms are then equivalent:

NumberOfPoints
number-of-points
NUMBER.of.Points
...

FDF data specifications

Label   [ Value ]

    This line assigns an optional Value to Label. Value could be
    a token or a sequence of tokens not including '<'. 
    'Numerical' routines such as fdf_integer will only use the first 
    token, but fdf_string will return the whole list.

%block Label 
  ...
  ...
  ...
# Optional comments
%endblock [ Label ]

    This construct specifies a block of data that is to be read
    by the calling program after a call to fdf_block. The contents
    of the block are dumped to fdf_out. %block and %endblock must
    be the first tokens in their respective lines.

%block Label  < Filename  [ %dump ]

    Opens Filename in order to read the block. If %dump appears
    at the *end* of the line, the contents of Filename are dumped
  to fdf_out.

%include  Filename  # Comments

    Opens Filename and continues reading from it.

Label   < Filename   # Comments

    Opens Filename and continues reading from it, ONLY if searching
    for Label.

    There is a maximum number of files that can be opened at the
    same time for fdf processing.

Debugging and logging.

By default, all the fdf requests are logged, printing the final value extracted (if it is the default value, it is identified as such).

No debugging is done, unless the "debug-level" is set to a value greater than zero. The most meaningful way to use this feature is to set the debugging level before the fdf data structures are built. This can be achieved by calling the routine fdf_setdebug with the appropriate level and file name before the call to fdf_init. This gives full control over the behavior.

Overview