Syntactic Production Rules (seen before)
(Revised Notation)

R1: <i>j -> //as sequence of letters and/or digits that begins with a letter//

                			"i" for identifier


R2: <e>i -> <i>j			"e" for expression



R3: <s>, ->  <i>j := <e>i		"s" for statement


R4:	<e>i -> ( <e>j + <e>k )


R5:	<e>i -> ( <e>j * <e>k )


Example

ANS := (X + (Y * Z))

s1			R3:	s1 -> i2 := e3
i2 := e3		R1:	i2 -> ANS
ANS := e3		R4:	e3 -> (e4 + e5)
ANS := (e4 + e5)	R2:	e4 -> i6
ANS := (i6 + e5)	R1:	i6 -> X
ANS := (X + e5)		R5:	e5 -> (e7 * e8)
ANS := (X + (e7 * e8)	R2:	e7 -> i9
ANS := (X + (i9 * e8)	R1:	i9 -> Y
ANS := (X + (Y * e8)	R2:	e8 -> i10
ANS := (X + (Y * i10)	R1:	i10 -> Z
ANS := (X + (Y * Z))


NOTE:  Used simplified notation where, for example,  i2 means <i>2 and
2 is really a subscript.



Semantic Rules

SYNTAX				SEMANTICS

R1: <i>j -> w			M(<i>i) = w


R2: <e>i -> <i>j		M(<e>i) = M(<i>j)
				code (<e>i) = //nothing//
						(no code generated!)


R3: <s>k -> <i>j := <e>i	code (<s>k) =	code (<e>i)
						COPY AX,M(<e>i)
						COPY M(<i>j), AX


R4: <e>i -> (<e>j+<e>k)		M(<e>i) = createname
				code(<e>i) =	code (<e>j)
						code (<e>k)
						copy	ax, M(<e>j)
						add	ax,M(<e>k)
						copy	M(<e>i),ax


R5: <e>i -> (<e>j*<e>k)		M(<e>i) = createname
				code(<e>i) =	code (<e>j)
						code (<e>k)
						copy	ax, M(<e>j)
						mul	ax,M(<e>k)
						copy	M(<e>i),ax

MORE ADVANCED FEATURES: Looping (need 4 more rules)

sequence of statements:

R6: <q>i -> <s>j ;		code(<q>i) = code(<s>j)
	    <q>k			     code(<q>k)

R7: <q>i -> <s>j ;		code(<q>i) = code(<s>j)


compound statement:

R8: <c>i -> begin		code(<c>i) = code(<q>j)
	    <q>j
	    end


while statement:

R9: <s>i -> while <i>j < <e>k do	M(<s>i) = createname

	    <c>h			M'(<s>i) = createname
				code(<s>i) =  M(<s>i)	 code(<e>k)
							 COPY	AX, M(<i>j)
							 CMP	AX, M(<e>k)
							 JNB	M'(s<i>)
							 code(<c>h)
							 JMP	M(<s>i)
						M'(<s>i) NO-OP