3.1.2 Format for Keyword Entries

The second input file format section contains lines of keywords and any associated attributes you might supply. A line beginning with ‘#’ in the first column is considered a comment. Everything following the ‘#’ is ignored, up to and including the following newline. A line beginning with ‘%’ in the first column is an option declaration and must not occur within the keywords section.

The first field of each non-comment line is always the keyword itself. It can be given in two ways: as a simple name, i.e., without surrounding string quotation marks, or as a string enclosed in double-quotes, in C syntax, possibly with backslash escapes like \" or \234 or \xa8. In either case, it must start right at the beginning of the line, without leading whitespace. In this context, a “field” is considered to extend up to, but not include, the first blank, comma, or newline. Here is a simple example taken from a partial list of C reserved words:

# These are a few C reserved words, see the c.gperf file 
# for a complete list of ANSI C reserved words.
unsigned
sizeof
switch
signed
if
default
for
while
return

Note that unlike flex or bison the first ‘%%’ marker may be elided if the declaration section is empty.

Additional fields may optionally follow the leading keyword. Fields should be separated by commas, and terminate at the end of line. What these fields mean is entirely up to you; they are used to initialize the elements of the user-defined struct provided by you in the declaration section. If the ‘-t’ option (or, equivalently, the ‘%struct-type’ declaration) is not enabled these fields are simply ignored. All previous examples except the last one contain keyword attributes.