Syntax-directed definition-inherited attributes Syntax directed definition of simple desk calculator O Terminals have synthesized attributes which are the lexical values (denoted by lexval) generated by the lexical analyzer. O The non terminal concerned must be in the head of production. O Attributes values are confined to the children of node and by itself. O It is defined by the semantic rule associated with the production at the node. O The non-terminal concerned must be in the body of the production. O Attributes values are confined to the parent of node, its siblings and by itself. O It is defined by the semantic rule associated with the production at the parent of node. O It is performed in connection with bottom up parsing. O It performs translation during parsing itself. It can occur anywhere in a production but usually at the end of production. They are usually enclosed within curly braces (). Semantic actions are fragments of code which are embedded within production bodies by syntax directed translation. Computing values of attributes at each node by visiting the nodes of syntax tree.The process of syntax directed translation is two-fold: It is a context free grammar with attributes and rules together which are associated with grammar symbols and productions respectively. Syntax directed definition specifies the values of attributes by associating semantic rules with the grammar productions.
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