Let the attribute 'val' give the value of a binary number generated by S in the following grammar:
S - L . L
S - L...

Question

Let the attribute 'val' give the value of a binary number generated by S in the following grammar:
  S -> L . L
  S -> L
  L -> L B
  L -> B
  B -> 0
  B -> 1
For example, an input 101.101 gives S.val = 5.625.
Construct a syntax directed translation scheme using only synthesized attributes, to determine S.val.

Accepted Answer

SDTS with synthesized attributes:
B -> 0 { B.val = 0 }
B -> 1 { B.val = 1 }
L -> B { L.val = B.val; L.len = 1 }
L -> L1 B { L.val = L1.val*2 + B.val; L.len = L1.len+1 }
S -> L { S.val = L.val }
S -> L1 . L2 { S.val = L1.val + L2.val / 2^(L2.len) } We have a grammar that generates binary numbers with an optional decimal point (like 101.101). We need to write semantic rules (using only synthesized attributes — values computed from children) to compute the numeric value of such a binary number. The example 101.101 = 5 + 0.625 = 5.625.

Let the attribute 'val' give the value of a binary number generated by S in the following grammar: S -> L . L S -> L L -> L B L -> B B -> 0 B -> 1 For example, an input 101.101 gives S.val = 5.625. Construct a syntax directed translation scheme using only synthesized attributes, to determine S.val.