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In simple applications, such as evaluation of arithmetic expressions, attribute grammar may be used to describe the entire task to be performed besides parsing in straightforward way; in complicated systems, for instance, when constructing a language translation tool, such as a compiler, it may be used to validate semantic checks associated ...
L-attributed grammars are a special type of attribute grammars. [1] 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 .
W-grammars are two-level grammars: they are defined by a pair of grammars, that operate on different levels: the hypergrammar is an attribute grammar, i.e. a set of context-free grammar rules in which the nonterminals may have attributes; and; the metagrammar is a context-free grammar defining possible values for these attributes.
S-attributed grammars are a class of attribute grammars characterized by having no inherited attributes, but only synthesized attributes.Inherited attributes, which must be passed down from parent nodes to children nodes of the abstract syntax tree during the semantic analysis of the parsing process, are a problem for bottom-up parsing because in bottom-up parsing, the parent nodes of the ...
They are a subset of the L-attributed grammars, where the attributes can be evaluated in one left-to-right traversal of the abstract syntax tree. They are a superset of the S-attributed grammars, 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 ...
Depending on the presence of empty derivations, a LL(1) grammar can be equal to a SLR(1) or a LALR(1) grammar. If the LL(1) grammar has no empty derivations it is SLR(1) and if all symbols with empty derivations have non-empty derivations it is LALR(1). If symbols having only an empty derivation exist, the grammar may or may not be LALR(1). [12]
ECLR-attributed grammars are a special type of attribute grammars. They are a variant of LR-attributed grammars where an equivalence relation on inherited attributes is used to optimize attribute evaluation. EC stands for equivalence class. Rie is based on ECLR-attributed grammars.
Compiler-compilers exist in many flavors, including bottom-up rewrite machine generators (see JBurg) used to tile syntax trees according to a rewrite grammar for code generation, and attribute grammar parser generators (e.g. ANTLR can be used for simultaneous type checking, constant propagation, and more during the parsing stage).