LL parser

• is a top-down parser
• for subset of context-free languages.
• It parses the input from Left to right
• performing Leftmost derivation of the sentence.
• LL(k) grammar
• An LL parser is called an LL(k) parser 
• if it uses k tokens of lookahead when parsing a sentence.
• If such a parser exists for a certain grammar and it can parse sentences of this grammar without backtracking then it is called an LL(k) grammar.
• LL parsers can only parse languages that have 
• LL(k) grammars without ε-rules.
• LL(k) grammars without ε-rules can generate more languages the higher the number k of lookahead tokens.
• LL(*) parser
• An LL-regular parser.
• if it is not restricted to a finite k tokens of lookahead,
• but can make parsing decisions by recognizing whether the following tokens belong to a regular language
• e.g.
• by means of Deterministic Finite Automaton.
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