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In formal language theory, an LL grammar is a context-free grammar that can be parsed by an LL parser, which parses the input from Left to right, and constructs a Leftmost derivation of the sentence. A language that has an LL grammar is known as an LL language. These form subsets of deterministic context-free grammars and deterministic context-free languages , respectively. One says that a given grammar or language "is an LL grammar/language" or simply "is LL" to indicate that it is in this class.
LL parsers are table-based parsers, similar to LR parsers. LL grammars can alternatively be characterized as precisely those that can be parsed by a predictive parser – a recursive descent parser without backtracking – and these can be readily written by hand. This article is about the formal properties of LL grammars; for parsing, see LL parser or recursive descent parser.