The C grammar[1] is not LL(1): The bottom part shows a parser that has digested the tokens "int v;main(){" and is about to choose a rule to derive the nonterminal "Stmt". Looking only at the first lookahead token "v", it cannot decide which of both alternatives for "Stmt" to choose, since two input continuations are possible. They can be discriminated by peeking at the second lookahead token (yellow background).
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 (hence LL, compared with LR parser that constructs a rightmost derivation). A language that has an LL grammar is known as an LL language. These form subsets of deterministic context-free grammars (DCFGs) and deterministic context-free languages (DCFLs), 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.
^Kernighan & Ritchie 1988, Appendix A.13 "Grammar", p.193 ff. The top image part shows a simplified excerpt in an EBNF-like notation..
In formal language theory, an LLgrammar is a context-free grammar that can be parsed by an LL parser, which parses the input from Left to right, and constructs...
An LL parser is called an LL(k) parser if it uses k tokens of lookahead when parsing a sentence. A grammar is called an LL(k) grammar if an LL(k) parser...
input. The LL(k) grammars therefore exclude all ambiguous grammars, as well as all grammars that contain left recursion. Any context-free grammar can be transformed...
class of grammars which are parsable in this way is known as the LLgrammars. LLgrammars are an even more restricted class of context-free grammars than...
and grammars than precedence parsers or top-down LL parsing. This is because the LR parser waits until it has seen an entire instance of some grammar pattern...
However, it differs because it takes parsing expression grammars (PEGs) as input rather than LLgrammars. In 1970, Alexander Birman laid the groundwork for...
Auckland Grammar School (often simplified to Auckland Grammar, or Grammar) is a state, day and boarding secondary school for boys in Epsom, Auckland, New...
some context-free grammars and parsing expression grammars Recursive descent parser: a top-down parser suitable for LL(k) grammars Shunting-yard algorithm:...
parentheses. (This is typically handled by a Chomsky Type 2 grammar, also termed a context-free grammar.) Context-free languages are a category of languages...
In computer science, a parsing expression grammar (PEG) is a type of analytic formal grammar, i.e. it describes a formal language in terms of a set of...
SLR grammars are the class of formal grammars accepted by a Simple LR parser. SLR grammars are a superset of all LR(0) grammars and a subset of all LALR(1)...
the grammar. The LALR(j) parsers are incomparable with LL(k) parsers: for any j and k both greater than 0, there are LALR(j) grammars that are not LL(k)...
context-free grammars there are well-known algorithms to generate efficient LL parsers and LR parsers to recognize the corresponding languages those grammars generate...
to declarations and scope. Often a subset of grammars is used to make parsing easier, such as by an LL parser. For example, the context-free language...
Dependency grammar (DG) is a class of modern grammatical theories that are all based on the dependency relation (as opposed to the constituency relation...
Estonian grammar is the grammar of the Estonian language. Estonian consonant gradation is a grammatical process that affects obstruent consonants at the...
The grammar of Modern Hebrew shares similarities with that of its Biblical Hebrew counterpart, but it has evolved significantly over time. Modern Hebrew...
in 1939. The alphabet, which contains 20 letters, was introduced in the grammar book developed by Lope K. Santos for the newly-designated national language...
Francis Llewellyn Harrison, FBA, better known as "Frank Harrison" or "Frank Ll. Harrison" (29 September 1905 – 29 December 1987) was one of the leading musicologists...
Chinnaya Suri wrote a simplified work on Telugu grammar called Bāla Vyākaraṇam (lit. Children's grammar), borrowing concepts and ideas from Nannayya, in...
hosted more than one future prime minister – Melbourne Grammar School (three), Sydney Grammar School (three), Wesley College, Melbourne (two), Abbotsholme...
given SGML document grammar forms an LL(1) language. ... The SGML document grammars by themselves are, however, not LL(1) grammars. The SGML standard does...
and l.l were used in the past for printing. Besides dialectal words, the "ḥ" is also used in some loanwords: ḥoquei (hockey). Asturian grammar is similar...
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