Email	Print Reprint
	add to:
	Del.icio.us Digg Google Furl	Slashdot Y! MyWeb Blink

Grammar Fragment	English Explanation	Formal IL (Allison)	TBIL (Pittman)
line::=	Tiny Basic reads lines	GETLINE	GL
number	possibly with a line number in front	TSTL <label>	BN <label>
--	insert numbered statement into program	INSERT	IL
*	repeat as needed	JMP <label>	BR <label>
statement	do whatever the statement rule says to do	STMT: <label>	:STMT
PRINT	is this keyword "PRINT"?	TST S8,'PRINT'	BC SKIP "PR"
expr-list::=	this is what you can print…	--
string	quoted string	TST S7,'"'; PRS	BC P7 '"'; PQ
expression	do the expression evaluation rule	CALL EXPR	JS EXPR
--	print the resulting value	PRN	PN
IF	is this keyword "IF"?	TST S9,'IF'	BC INPT "IF"
relop	do compare operator rule	CALL RELOP	JS RELO
THEN	error if this in not keyword "THEN"?	TST S17,'THEN'	BC I1 "THEN"
statement	do whatever the statement rule says to do	JMP STMT	J STMT
GOTO	is this keyword "GOTO"? if not, try another	TST S3,'GO'; TST S2,'TO'	BC PRNT "GO"; BC GOSB "TO"
expression	do the expression evaluation rule	CALL EXPR	JS EXPR
--	error if not end of statement	DONE	BE *
--	find that line in the program, do it next	XPER	GO
LET	is this keyword "LET"? if not, try another	TST S1,'LET'	BC GOTO "LET"
var	save variable name; error if none	TSTV S17	BV *
=	error if there is no "=" here	TST S17,'='	BC * "="
expression	do the expression evaluation rule	CALL EXPR	JS EXPR
--	error if not end of statement	DONE	BE *
--	store the value into the variable	STORE	SV
--	resume with next line	XPER	NX

Table 1: Partial correlation between Grammar, English pseudocode, and Interpreter Language. Grammar elements in the left column, represented by English pseudocode in the next column, then IL equivalents in the last two columns, Allison's then mine.

Previous Page | 1 | 2 | 3

RELATED ARTICLES Logging In C++ : Part 2 OutSystems Updates Agile Platform SDK, .NET Controls Released for Communications Enabling Web Pages Welcome To the World of Cryptographic Voting recls 100% .NET		TOP 5 ARTICLES No Top Articles.