Question

Difference between s-attribute and l-attribute

Answer 1

S-attributed grammars are a class of attribute grammars characterized by having no inherited attributes, but only synthesized attributes
L-attributed grammars are a special type of attribute grammars. They allow theattributes to be evaluated in one depth-first left-to-right traversal of the abstract syntax tree

Answer 2

Answer:If a definition is S-attributed, then it is also L-attributed but NOT vice-versa.

Explanation:

S-attributed SDT :

• If  SDT uses only synthesized attributes, it is called as S-attributed SDT.
• S-attributed SDT are evaluated in bottom-up parsing, as the values of the parent nodes depend upon the values of the child nodes.
• Semantic actions are placed in right most place of RHS.

L-attributed SDT:

• If  SDT uses both synthesized attributes and inherited attributes with a restriction that inherited attribute can inherit values from left siblings only, it is called as L-attributed SDT.
• Attributes in L-attributed SDT are evaluated by depth-first and left-to-right parsing manner.
• Semantic actions are placed any where in RHS

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