'Next input symbol' diaporamas de présentation

PushDown Automata

PushDown Automata. What is a stack?. A stack is a Last In First Out data structure where I only have access to the last element inserted in the stack. In order to access other elements I have to remove those that are on top one by one. Stack. Stack. Stack. Stack. Stack. Stack. Stack.

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C O N T E X T - F R E E LANGUAGES ( use a grammar to describe a language)

C O N T E X T - F R E E LANGUAGES ( use a grammar to describe a language). Context-free grammars. Ch.1 introduced two different, though equivalent, methods of describing languages: finite automata and regular expressions .

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C O N T E X T - F R E E LANGUAGES ( use a grammar to describe a language)

C O N T E X T - F R E E LANGUAGES ( use a grammar to describe a language). Context-free grammars. Ch.1 introduced two different, though equivalent, methods of describing languages: finite automata and regular expressions .

686 views • 55 slides

LR-Grammars

LR-Grammars. LR(0), LR(1), and LR(K). Deterministic Context-Free Languages. DCFL A family of languages that are accepted by a Deterministic Pushdown Automaton (DPDA) Many programming languages can be described by means of DCFLs. Prefix and Proper Prefix. Prefix (of a string)

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LESSON 18

LESSON 18. Overview of Previous Lesson(s). Over View. In our compiler model, the parser obtains a string of tokens from the lexical analyzer & verifies that the string of token names can be generated by the grammar for the source language. Over View. Trivial Approach: No Recovery

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Top-Down Parsing

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Lecture Three: Finite Automata

Lecture Three: Finite Automata. Amjad Ali. DFA: Deterministic Finite Automaton. An informal definition (formal version later): A diagram with a finite number of states represented by circles An arrow points to one of the states, the unique start state

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6.1 ?? ?? ??

6.1 ?? ?? ??. How to check whether an input string is a sentence of a grammar and how to construct a parse tree for the string.

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LL(1) Parsing

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LL(1) Parsing

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Evolution ary Programming

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Parsing

( a, a/aa ). (b, a/ ? ). (a, Z 0 /aZ 0 ). (b, a/ ? ). ( ? , Z 0 /Z 0 ). start. Parsing. For a given CFG G, parsing a string w is to check if w ? L(G) and, if it is, to find a sequence of production rules which derive w.

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Exercise: construct the SLR parsing table for grammar: S->L=R, S->R L->*R L->id R->L The grammar can have

Exercise: construct the SLR parsing table for grammar: S->L=R, S->R L->*R L->id R->L The grammar can have shift/reduce conflict or reduce/reduce conflict. What about shift/shift conflict?.

1.1k views • 7 slides