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Reference.org
LR-attributed grammar
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<p>LR-attributed grammars are a special type of <a href="/facts/Attribute_grammar/N4yuxaoR">attribute grammars</a>. They allow the attributes to be evaluated on <a href="/facts/LR_parser/bpMod8K0">LR parsing</a>. As a result, attribute evaluation in LR-attributed grammars can be incorporated conveniently in bottom-up parsing. zyacc is based on LR-attributed grammars. They are a subset of the <a href="/facts/L-attributed_grammar/57hpIYH0">L-attributed grammars</a>, where the attributes can be evaluated in one left-to-right traversal of the abstract syntax tree. They are a superset of the <a href="/facts/S-attributed_grammar/9HUfcgDW">S-attributed grammars</a>, which allow only synthesized attributes. In yacc, a common hack is to use global variables to simulate some kind of inherited attributes and thus LR-attribution. </p>