1. SYNTAX DIRECTED TRANSLATION
COMPILERS 29TH OCTOBER 2013

2. SDD
Semantic Rule
A  X1X2X3
A.x = f ( X1.a, X2.b, X3.c )

3. SDT
A  X1X2{A.x = f( X1.a, X2.b) }X3
Embedded

4. When we perform reduction, we evaluate the attribute to get the result
S – attributed SDD SDT
A  X1X2X3 {a}
When we perform reduction, we evaluate the attribute to get the result

5. We have the stack X1X2X3  symbols and states X1. a, X2. b, X3
We have the stack X1X2X3  symbols and states X1.a, X2.b, X3.c  values

6. After Reduction A  replaces X1X2X3 A
After Reduction A  replaces X1X2X3 A.x  evaluated by the function f( X1.a, X2.b, X3.c )

7. L  E { Print (E. val) } E  E + T { E. val = E. val + T
L  E { Print (E.val) } E  E + T { E.val = E.val + T.val } E  T {E.val = T.val} T  T * F { T.val = T.val * F.val } T  F { T.val = F.val } F  id { F.val = id }

8. Stack Symbol Stack Value Input String Syntax Action $ 3*4 $ 3 $3 *4
Semantic Action $
3*4
$ 3 $3 *4
F  id
F.val = id
$ F
T  F
T.Val = F.val
$ T
Shift
$ T *
$ 3* 4
$ T*4
$ 3*4
$ T*F
T  T * F
T.Val = T.val * F.val
$ 12

9. To evaluate T. val = T. val. F
To evaluate T.val = T.val * F.val , we need the two values; which we get form the value stack.

10. L – attributed SDD is suitable for top-down parsing LL (1)  synthesized attributes  inherited attributes

11. A non-terminal can have multiple inherited attributes ; for each will have some defined action In case of synthesize attribute, we append it to the end of the rule For predictive parsers, for each non-terminal, we have a function

12. E. G : Recursive Descent Parser A  X1X2X3 A(). {. if ( a == X1 )
E.G : Recursive Descent Parser A  X1X2X3 A() { if ( a == X1 ) move to next symbol if ( X1 is a NT) X1() }

13. This function invokes the functions of the body of the production To implement predictive parsing, we need to implement those functions

14. Made By : Mohit Bhura 11CS30019