Syntax-Directed Definitions A syntax-directed definition is a generalization of a context-free grammar in which: -Each grammar symbol is associated with a set of attributes. This set of attributes for a grammar symbol is partitioned into two subsets called synthesized and inherited attributes of that grammar symbol. Each production rule is associated with a set of semantic rules. Semantic rules set up dependencies between attributes which can be represented by a dependency graph. This dependency graph determines the evaluation order of these semantic rules. Evaluation of a semantic rule defines the value of an attribute.But a semantic rule may also have some side effects such as printing a value. CS308 Compiler TheorySyntax-Directed Definitions • A syntax-directed definition is a generalization of a context-free grammar i hi h n whi c h: – Each grammar symbol is associated with a set of attributes. – This set of attributes for a grammar symbol is partitioned into two subsets called This set of attributes for a grammar symbol is partitioned into two subsets called synthesized and inherited attributes of that grammar symbol. – Each production rule is associated with a set of semantic rules. • Semantic rules set up dependencies between attributes which can be represented by a dependency graph. • This dependency graph determines the evaluation order of these semantic rules. • Evaluation of a semantic rule defines the value of an attribute. But a semantic rule may also have some side effects such as printing a value. CS308 Compiler Theory 4