boolexp.c File Reference

Handle boolean expressions. More...

#include "config.h"
#include "constants.h"
#include "typedefs.h"
#include "macros.h"
#include "externs.h"
#include "prototypes.h"
#include <stdbool.h>
#include <ctype.h>

Include dependency graph for boolexp.c:

Functions
bool	check_attr (dbref player, dbref lockobj, ATTR *attr, char *key)
	indicate if attribute ATTR on player passes key when checked by the object lockobj More...
BOOLEXP *	alloc_boolexp (void)
	Prepare a BOOLEXP item. More...
void	free_boolexp (BOOLEXP *b)
	Free a BOOLEXP item. More...
bool	eval_boolexp (dbref player, dbref thing, dbref from, BOOLEXP *b)
	Evaluate a boolean expression. More...
bool	eval_boolexp_atr (dbref player, dbref thing, dbref from, char *key)
	Evaluate attribute's boolean expression. More...
void	skip_whitespace (char **pBuf)
	Skip over whitespace in a string. More...
BOOLEXP *	test_atr (char *s, dbref parse_player)
	Test attriutes. More...
BOOLEXP *	parse_boolexp_L (char **pBuf, dbref parse_player, bool parsing_internal)
	L -> (E); L -> object identifier. More...
BOOLEXP *	parse_boolexp_F (char **pBuf, dbref parse_player, bool parsing_internal)
	F -> !F; F -> @L; F -> =L; F -> +L; F -> $L. More...
BOOLEXP *	parse_boolexp_T (char **pBuf, dbref parse_player, bool parsing_internal)
	T -> F; T -> F & T. More...
BOOLEXP *	parse_boolexp_E (char **pBuf, dbref parse_player, bool parsing_internal)
	E -> T; E -> T | E. More...
BOOLEXP *	parse_boolexp (dbref player, const char *buf, bool internal)
	Parse a boolean expression. More...

Detailed Description

Handle boolean expressions.

Author

TinyMUSH development team (https://github.com/TinyMUSH)

Version

3.3

Date

2020-12-24

Copyright

Copyright (C) 1989-2021 TinyMUSH development team. You may distribute under the terms the Artistic License, as specified in the COPYING file.

Function Documentation

alloc_boolexp()

BOOLEXP * alloc_boolexp

(

void

)

Prepare a BOOLEXP item.

Returns

BOOLEXP* Initialized BOOLEXP item.

check_attr()

bool check_attr	(	dbref	player,
		dbref	lockobj,
		ATTR *	attr,
		char *	key
	)

indicate if attribute ATTR on player passes key when checked by the object lockobj

Parameters

player	DBref of player
lockobj	DBref of locked object
attr	Attribute
key	Key

Returns

bool

We can see control locks... else we'd break zones

eval_boolexp()

bool eval_boolexp	(	dbref	player,
		dbref	thing,
		dbref	from,
		BOOLEXP *	b
	)

Evaluate a boolean expression.

Parameters

player	DBref of player
thing	DBref of thing
from	DBref from
b	Boolean expression

Returns

bool

BOOLEXP_INDIR (i.e. @) is a unary operation which is replaced at evaluation time by the lock of the object whose number is the argument of the operation.

no such attribute

First check the object itself, then its contents

no such attribute

If an object check, do that

Nope, do an attribute check

If an object check, do that

Nope, do an attribute check

bad type

eval_boolexp_atr()

bool eval_boolexp_atr	(	dbref	player,
		dbref	thing,
		dbref	from,
		char *	key
	)

Evaluate attribute's boolean expression.

Parameters

player	DBref of player
thing	DBref of thing
from	DBref from
key	Attribute's key

Returns

bool

free_boolexp()

void free_boolexp

(

BOOLEXP *

b

)

Free a BOOLEXP item.

Parameters

b	BOOLEXP item.

parse_boolexp()

BOOLEXP * parse_boolexp	(	dbref	player,
		const char *	buf,
		bool	internal
	)

Parse a boolean expression.

Parameters

player	DBref of player
buf	Attribute buffer
internal	Internal check?

Returns

BOOLEXP* Boolean expression result

parse_boolexp_E()

BOOLEXP * parse_boolexp_E	(	char **	pBuf,
		dbref	parse_player,
		bool	parsing_internal
	)

E -> T; E -> T | E.

Parameters

pBuf	Attribute buffer
parse_player	DBref of player
parsing_internal	Engine or player triggered?

Returns

BOOLEXP* Boolean expression result

parse_boolexp_F()

BOOLEXP * parse_boolexp_F	(	char **	pBuf,
		dbref	parse_player,
		bool	parsing_internal
	)

F -> !F; F -> @L; F -> =L; F -> +L; F -> $L.

The argument L must be type BOOLEXP_CONST

Parameters

pBuf	Attribute buffer
parse_player	DBref of player
parsing_internal	Engine or player triggered?

Returns

BOOLEXP* Boolean expression result

parse_boolexp_L()

BOOLEXP * parse_boolexp_L	(	char **	pBuf,
		dbref	parse_player,
		bool	parsing_internal
	)

L -> (E); L -> object identifier.

Parameters

pBuf	Attribute buffer
parse_player	DBref of player
parsing_internal	Engine or player triggered?

Returns

BOOLEXP* Boolean expression result

must have hit an object ref. Load the name into our buffer

check for an attribute

Do the match. If we are parsing a boolexp that was a stored lock then we know that object refs are all dbrefs, so we skip the expensive match code.

parse_boolexp_T()

BOOLEXP * parse_boolexp_T	(	char **	pBuf,
		dbref	parse_player,
		bool	parsing_internal
	)

T -> F; T -> F & T.

Parameters

pBuf	Attribute buffer
parse_player	DBref of player
parsing_internal	Engine or player triggered?

Returns

BOOLEXP* Boolean expression result

skip_whitespace()

void skip_whitespace

(

char **

pBuf

)

Skip over whitespace in a string.

Attention

If the parser returns TRUE_BOOLEXP, you lose TRUE_BOOLEXP cannot be typed in by the user; use @unlock instead

Parameters

pBuf	Buffer to skip whitespace in

test_atr()

BOOLEXP * test_atr	(	char *	s,
		dbref	parse_player
	)

Test attriutes.

Parameters

s	Attribute to test
parse_player	DBref of player triggering the test

Returns

BOOLEXP* Boolean expression with the result of the test

See if left side is valid attribute. Access to attr is checked on eval. Also allow numeric references to attributes. It can't hurt us, and lets us import stuff that stores attr locks by number instead of by name.

Only #1 can lock on numbers

made it now make the parse tree node