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SYNTAX DIRECTED TRANSLATION

SYNTAX DIRECTED TRANSLATION. COMPILERS 29 TH OCTOBER 2013. SDD. Semantic Rule. A.x = f ( X 1 .a, X 2 .b, X 3 .c ). A  X 1 X 2 X 3. SDT. Embedded. A  X 1 X 2 { A.x = f( X 1 .a, X 2 .b) } X 3. S – attributed SDD SDT A  X 1 X 2 X 3 {a}

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SYNTAX DIRECTED TRANSLATION

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  1. SYNTAX DIRECTED TRANSLATION COMPILERS29TH OCTOBER 2013

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

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

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

  5. We have the stackX1X2X3  symbols and statesX1.a, X2.b, X3.c  values

  6. After ReductionA  replaces X1X2X3A.x evaluated by the functionf( X1.a, X2.b, X3.c )

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

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

  10. 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 ruleFor predictive parsers, for each non-terminal, we have a function

  11. E.G : Recursive Descent ParserA  X1X2X3A() { if ( a == X1 ) move to next symbolif ( X1 is a NT) X1() }

  12. This function invokes the functions of the body of the productionTo implement predictive parsing, we need to implement those functions

  13. Made By : Mohit Bhura11CS30019

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