Editing L-attributed grammar (section)

{{More citations|date=July 2020}}
'''L-attributed grammars''' are a special type of [[attribute grammar]]s.<ref name="Knuth1968">{{cite journal |last1=Knuth |first1=Donald E. |authorlink1=Donald Knuth |date=June 1968 |title=Semantics of context-free languages |journal=[[Mathematical Systems Theory]] |volume=2 |issue=2 |pages=127–145 |citeseerx=10.1.1.455.1434 |doi=10.1007/BF01692511 |issn=0025-5661 |s2cid=5182310 |id={{QID|56672530}}}}</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 [[compiler]]s, the narrow compilers, are based on some form of L-attributed grammar. These are a strict superset of [[S-attributed grammar]]s. 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>.