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/* ntp_scanner.h
*
* The header file for a simple lexical analyzer.
*
* Written By: Sachin Kamboj
* University of Delaware
* Newark, DE 19711
* Copyright (c) 2006
*/
#ifndef NTP_SCANNER_H
#define NTP_SCANNER_H
#include "ntp_config.h"
/*
* ntp.conf syntax is slightly irregular in that some tokens such as
* hostnames do not require quoting even if they might otherwise be
* recognized as T_ terminal tokens. This hand-crafted lexical scanner
* uses a "followed by" value associated with each keyword to indicate
* normal scanning of the next token, forced scanning of the next token
* alone as a T_String, or forced scanning of all tokens to the end of
* the command as T_String.
* In the past the identifiers for this functionality ended in _ARG:
*
* NO_ARG -> FOLLBY_TOKEN
* SINGLE_ARG -> FOLLBY_STRING
* MULTIPLE_ARG -> FOLLBY_STRINGS_TO_EOC
*
* Note that some tokens use FOLLBY_TOKEN even though they sometimes
* are followed by strings. FOLLBY_STRING is used only when needed to
* avoid the keyword scanner matching a token where a string is needed.
*
* FOLLBY_NON_ACCEPT is an overloading of this field to distinguish
* non-accepting states (where the state number does not match a T_
* value).
*/
typedef enum {
FOLLBY_TOKEN = 0,
FOLLBY_STRING,
FOLLBY_STRINGS_TO_EOC,
FOLLBY_NON_ACCEPTING
} follby;
#define MAXLINE 1024 /* maximum length of line */
#define MAXINCLUDELEVEL 5 /* maximum include file levels */
/* STRUCTURES
* ----------
*/
/*
* Define a structure to hold the FSA for the keywords.
* The structure is actually a trie.
*
* To save space, a single u_int32 encodes four fields, and a fifth
* (the token completed for terminal states) is implied by the index of
* the rule within the scan state array, taking advantage of the fact
* there are more scan states than the highest T_ token number.
*
* The lowest 8 bits hold the character the state matches on.
* Bits 8 and 9 hold the followedby value (0 - 3). For non-accepting
* states (which do not match a completed token) the followedby
* value 3 (FOLLBY_NONACCEPTING) denotes that fact. For accepting
* states, values 0 - 2 control whether the scanner forces the
* following token(s) to strings.
* Bits 10 through 20 hold the next state to check not matching
* this state's character.
* Bits 21 through 31 hold the next state to check matching the char.
*/
#define S_ST(ch, fb, match_n, other_n) ( \
(u_char)((ch) & 0xff) | \
((u_int32)(fb) << 8) | \
((u_int32)(match_n) << 10) | \
((u_int32)(other_n) << 21) \
)
#define SS_CH(ss) ((char)(u_char)((ss) & 0xff))
#define SS_FB(ss) (((u_int)(ss) >> 8) & 0x3)
#define SS_MATCH_N(ss) (((u_int)(ss) >> 10) & 0x7ff)
#define SS_OTHER_N(ss) (((u_int)(ss) >> 21) & 0x7ff)
typedef u_int32 scan_state;
struct LCPOS {
int nline;
int ncol;
};
/* Structure to hold a filename, file pointer and positional info.
* Instances are dynamically allocated, and the file name is copied by
* value into a dynamic extension of the 'fname' array. (Which *must* be
* the last field for that reason!)
*/
struct FILE_INFO {
struct FILE_INFO * st_next; /* next on stack */
FILE * fpi; /* File Descriptor */
int force_eof; /* locked or not */
int backch; /* ungetch buffer */
struct LCPOS curpos; /* current scan position */
struct LCPOS bakpos; /* last line end for ungetc */
struct LCPOS tokpos; /* current token position */
struct LCPOS errpos; /* error position */
char fname[1]; /* (formal only) buffered name */
};
/* SCANNER GLOBAL VARIABLES
* ------------------------
*/
extern config_tree cfgt; /* Parser output stored here */
/* VARIOUS EXTERNAL DECLARATIONS
* -----------------------------
*/
extern int old_config_style;
/* VARIOUS SUBROUTINE DECLARATIONS
* -------------------------------
*/
extern const char *keyword(int token);
extern char *quote_if_needed(char *str);
int yylex(void);
/* managing the input source stack itself */
extern int/*BOOL*/ lex_init_stack(const char * path, const char * mode);
extern void lex_drop_stack(void);
extern int/*BOOL*/ lex_flush_stack(void);
/* add/remove a nested input source */
extern int/*BOOL*/ lex_push_file(const char * path, const char * mode);
extern int/*BOOL*/ lex_pop_file(void);
/* input stack state query functions */
extern size_t lex_level(void);
extern int/*BOOL*/ lex_from_file(void);
extern struct FILE_INFO * lex_current(void);
#endif /* NTP_SCANNER_H */
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