Intel XENIX 286 Programmers Guide (86) - Tenox.tc

XENIX Programming yacc: Compiler-Compiler
Old Features
This section mentions synonyms and features supported for historical continuity, but
that, for various reasons, are not encouraged.
• Literals may also be delim ited by double quotation marks (").
• Literals may be more than one character long. If all the characters are
alphabetic, nu meric, or underscore, the type number of the literal is defined, just
as if the literal did not have the quotation marks around it. Otherwise, it is
difficult to find the value for such literals. The use of multicharacter literals is
likely to mislead those unfamiliar with yacc, since it suggests that yacc is doing a
job that must be actually done by the lexical analyzer.
• Most places where % is legal, backslash {\) may be used. In particular, the double
backslash {\ \} is the same as 9696, \left the same as 96left, etc.
• There are a number of other synonyms:
96< is the same as 96left
96> is the same as %right
%binary and 962 are the same as 96nonassoc
960 and 96term are the same as %token
96= is the same as 96prec
• Actions may also have the form
= { .
.. }
and the curly braces can be dropped if the action is a single C statement.
• C code between 96{ and 96} used to be permitted at the head of the rules section,
as well as in the declaration section.
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