basic

Tutorial on using flex/bison to build a BASIC interpreter

grammar

statements: /* empty */
| statement
| statements statement
;

statement: iStatement
| LINENUM iStatement
| LINENUM forStmt
| LINENUM nextStmt
| LINENUM endStmt
;

ids: ID
| ids ',' ID
;

exprs: expr
| exprs ',' expr
;

exprsAndLabels: exprOrLabel
| exprsAndLabels ',' exprOrLabel
;

exprOrLabel: expr
| STRING
;

expr: addend
| addend '+' addend
| addend '-' addend
;

addend: multiplicand
| multiplicand '*' multiplicand
| multiplicand '/' multiplicand
;

multiplicand: expt
| expt '^' expt
;

expt: NUM
| ID
| '(' expr ')'
;

letStmt: "LET" ID '=' expr;

readStmt: "READ" ids;

dataStmt: "DATA" exprs;

printStmt: "PRINT" exprsAndLabels;

gotoStmt: "GOTO" LINENUM;

ifStmt: "IF" relExpr "THEN" LINENUM;

forStmt: "FOR" ID '=' expr "TO" expr
| "FOR" ID '=' expr "TO" expr "STEP" expr
;

nextStmt: "NEXT" ID;

endStmt: "END";

Name		Name	Last commit message	Last commit date
Latest commit History 37 Commits
CMakeLists.txt		CMakeLists.txt
README.md		README.md
basic.cpp		basic.cpp
basic.h		basic.h
basic.l		basic.l
basic.y		basic.y
data.cpp		data.cpp
data.h		data.h
doubleexpression.cpp		doubleexpression.cpp
doubleexpression.h		doubleexpression.h
end.cpp		end.cpp
end.h		end.h
expression.cpp		expression.cpp
expression.h		expression.h
for.cpp		for.cpp
for.h		for.h
goto.cpp		goto.cpp
goto.h		goto.h
ifthen.cpp		ifthen.cpp
ifthen.h		ifthen.h
let.cpp		let.cpp
let.h		let.h
multiprogram.cpp		multiprogram.cpp
multiprogram.h		multiprogram.h
next.cpp		next.cpp
next.h		next.h
operatorexpression.cpp		operatorexpression.cpp
operatorexpression.h		operatorexpression.h
parenexpression.cpp		parenexpression.cpp
parenexpression.h		parenexpression.h
print.cpp		print.cpp
print.h		print.h
program.cpp		program.cpp
program.h		program.h
read.cpp		read.cpp
read.h		read.h
rem.cpp		rem.cpp
rem.h		rem.h
stringexpression.cpp		stringexpression.cpp
stringexpression.h		stringexpression.h
variableexpression.cpp		variableexpression.cpp
variableexpression.h		variableexpression.h