• Input file parser
  • FDF - Flexible Data Format


0.6.6, September 2007


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.


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 punctuation-insensitive, by which it is understood that the characters ., _, and - are removed before any comparison is made.

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). In MPI operation, only the master node does the logging, unless the output-level is set to a value ≥2. This can be done directly in the FDF file:

fdf-output 2  # Turn on logging for all nodes
fdf-output 0  # Turn off logging completely

No debugging is done, unless the debug-level is set to a value >0. 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.

Alternatively, if the library is compiled with the pre-processor symbol FDF_DEBUG defined, it will set the debug level to 2 (exhaustive) for all nodes in the system. (It will also set the output level to 2 (all nodes)).

If the debugging level (≥2) is only specified in the FDF file itself, the library will provide a print-out of the final data structure generated (in all nodes).