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