lex.h

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * Source input, lexer and parser
 */

/* $Id: lex.h,v 1.4 1994/05/31 13:34:34 michael Exp $ */

#define	IDENT	64

typedef struct source Source;
struct source {
	const char *str;	/* input pointer */
	int	type;		/* input type */
	const char *start;	/* start of current buffer */
	union {
		char **strv;	/* string [] */
		struct shf *shf; /* shell file */
		struct tbl *tblp; /* alias (SALIAS) */
		char *freeme;	/* also for SREREAD */
	} u;
	char	ugbuf[2];	/* buffer for ungetsc() (SREREAD) and
				 * alias (SALIAS) */
	int	line;		/* line number */
	int	errline;	/* line the error occured on (0 if not set) */
	const char *file;	/* input file name */
	int	flags;		/* SF_* */
	Area	*areap;
	XString	xs;		/* input buffer */
	Source *next;		/* stacked source */
};

/* Source.type values */
#define	SEOF		0	/* input EOF */
#define	SFILE		1	/* file input */
#define SSTDIN		2	/* read stdin */
#define	SSTRING		3	/* string */
#define	SWSTR		4	/* string without \n */
#define	SWORDS		5	/* string[] */
#define	SWORDSEP	6	/* string[] seperator */
#define	SALIAS		7	/* alias expansion */
#define SREREAD		8	/* read ahead to be re-scanned */

/* Source.flags values */
#define SF_ECHO		BIT(0)	/* echo input to shlout */
#define SF_ALIAS	BIT(1)	/* faking space at end of alias */
#define SF_ALIASEND	BIT(2)	/* faking space at end of alias */
#define SF_TTY		BIT(3)	/* type == SSTDIN & it is a tty */

/*
 * states while lexing word
 */
#define	SBASE	0		/* outside any lexical constructs */
#define	SWORD	1		/* implicit quoting for substitute() */
#ifdef KSH
#define	SLETPAREN 2		/* inside (( )), implicit quoting */
#endif /* KSH */
#define	SSQUOTE	3		/* inside '' */
#define	SDQUOTE	4		/* inside "" */
#define	SBRACE	5		/* inside ${} */
#define	SCSPAREN 6		/* inside $() */
#define	SBQUOTE	7		/* inside `` */
#define	SASPAREN 8		/* inside $(( )) */
#define SHEREDELIM 9		/* parsing <<,<<- delimiter */
#define SHEREDQUOTE 10		/* parsing " in <<,<<- delimiter */
#define SPATTERN 11		/* parsing *(...|...) pattern (*+?@!) */
#define STBRACE 12		/* parsing ${..[#%]..} */

typedef union {
	int	i;
	char   *cp;
	char  **wp;
	struct op *o;
	struct ioword *iop;
} YYSTYPE;

/* If something is added here, add it to tokentab[] in syn.c as well */
#define	LWORD	256
#define	LOGAND	257		/* && */
#define	LOGOR	258		/* || */
#define	BREAK	259		/* ;; */
#define	IF	260
#define	THEN	261
#define	ELSE	262
#define	ELIF	263
#define	FI	264
#define	CASE	265
#define	ESAC	266
#define	FOR	267
#define SELECT	268
#define	WHILE	269
#define	UNTIL	270
#define	DO	271
#define	DONE	272
#define	IN	273
#define	FUNCTION 274
#define	TIME	275
#define	REDIR	276
#ifdef KSH
#define MDPAREN	277		/* (( )) */
#endif /* KSH */
#define BANG	278		/* ! */
#define DBRACKET 279		/* [[ .. ]] */
#define COPROC	280		/* |& */
#define	YYERRCODE 300

/* flags to yylex */
#define	CONTIN	BIT(0)		/* skip new lines to complete command */
#define	ONEWORD	BIT(1)		/* single word for substitute() */
#define	ALIAS	BIT(2)		/* recognize alias */
#define	KEYWORD	BIT(3)		/* recognize keywords */
#define LETEXPR	BIT(4)		/* get expression inside (( )) */
#define VARASN	BIT(5)		/* check for var=word */
#define ARRAYVAR BIT(6)		/* parse x[1 & 2] as one word */
#define ESACONLY BIT(7)		/* only accept esac keyword */
#define CMDWORD BIT(8)		/* parsing simple command (alias related) */
#define HEREDELIM BIT(9)	/* parsing <<,<<- delimiter */

#define	HERES	10		/* max << in line */

EXTERN	Source *source;		/* yyparse/yylex source */
EXTERN	YYSTYPE	yylval;		/* result from yylex */
EXTERN	struct ioword *heres [HERES], **herep;
EXTERN	char	ident [IDENT+1];

#ifdef HISTORY
# define HISTORYSIZE	128	/* size of saved history */

EXTERN	char  **history;	/* saved commands */
EXTERN	char  **histptr;	/* last history item */
EXTERN	int	histsize;	/* history size */
#endif /* HISTORY */