yyparse
You call the function yyparse
to cause parsing to occur. This
function reads tokens, executes actions, and ultimately returns when it
encounters end-of-input or an unrecoverable syntax error. You can also
write an action which directs yyparse
to return immediately
without reading further.
The value returned by
yyparse
is 0 if parsing was successful (return is due to end-of-input).The value is 1 if parsing failed because of invalid input, i.e., input that contains a syntax error or that causes
YYABORT
to be invoked.The value is 2 if parsing failed due to memory exhaustion.
In an action, you can cause immediate return from yyparse
by using
these macros:
If you use a reentrant parser, you can optionally pass additional
parameter information to it in a reentrant way. To do so, use the
declaration %parse-param
:
Declare that an argument declared by the braced-code argument-declaration is an additional
yyparse
argument. The argument-declaration is used when declaring functions or prototypes. The last identifier in argument-declaration must be the argument name.
Here's an example. Write this in the parser:
%parse-param {int *nastiness} %parse-param {int *randomness}
Then call the parser like this:
{ int nastiness, randomness; ... /* Store proper data innastiness
andrandomness
. */ value = yyparse (&nastiness, &randomness); ... }
In the grammar actions, use expressions like this to refer to the data:
exp: ... { ...; *randomness += 1; ... }