L-attributed grammar
Template:More citations L-attributed grammars are a special type of attribute grammars.<ref name="Knuth1968">Template:Cite journal</ref> They allow the attributes to be evaluated in one depth-first left-to-right traversal of the abstract syntax tree. As a result, attribute evaluation in L-attributed grammars can be incorporated conveniently in top-down parsing.
A syntax-directed definition is L-attributed if each inherited attribute of <math>X_j</math> on the right side of <math>A \rightarrow X_1, X_2, \dots, X_n </math> depends only on
- the attributes of the symbols <math>X_1, X_2, \dots, X_{j-1}</math>
- the inherited attributes of <math>A</math> (but not its synthesized attributes)
Every S-attributed syntax-directed definition is also L-attributed.
Implementing L-attributed definitions in Bottom-Up parsers requires rewriting L-attributed definitions into translation schemes.
Many programming languages are L-attributed. Special types of compilers, the narrow compilers, are based on some form of L-attributed grammar. These are a strict superset of S-attributed grammars. Used for code synthesis.
Either "inherited attributes" or "synthesized attributes" associated with the occurrence of symbol <math>X_1,X_2, \dots, X_n</math>.