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- /* U S E O F C H A R A C T E R C L A S S E S */
- /* As a starter, chars are divided into classes, according to which
- token they can be the start of.
- At present such a class number is supposed to fit in 4 bits.
- */
- #define class(ch) (tkclass[ch])
- /* Being the start of a token is, fortunately, a mutual exclusive
- property, so, as there are less than 16 classes they can be
- packed in 4 bits.
- */
- #define STSKIP 0 /* spaces and so on: skipped characters */
- #define STNL 1 /* newline character(s): update linenumber etc. */
- #define STGARB 2 /* garbage ascii character: not allowed */
- #define STSIMP 3 /* this character can occur as token */
- #define STCOMP 4 /* this one can start a compound token */
- #define STIDF 5 /* being the initial character of an identifier */
- #define STCHAR 6 /* the starter of a character constant */
- #define STSTR 7 /* the starter of a string */
- #define STNUM 8 /* the starter of a numeric constant */
- #define STEOI 9 /* End-Of-Information mark */
- /* But occurring inside a token is not, so we need 1 bit for each
- class. This is implemented as a collection of tables to speed up
- the decision whether a character has a special meaning.
- */
- #define in_idf(ch) ((unsigned)ch < 0177 && inidf[ch])
- #define is_dig(ch) ((unsigned)ch < 0177 && isdig[ch])
- extern char tkclass[];
- extern char inidf[], isdig[];
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