'Leftmost derivations' diaporamas de présentation

Compiler Construction Parsing Part I

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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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Applied Computer Science II Chapter 2 : Context-free languages

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The Parser

The Parser. Its job: Check and verify syntax based on specified syntax rules Report errors Build IR Good news the process can be automated. Parsing. The scanner recognizes words The parser recognizes syntactic units Can we use regular expressions?

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Parse Trees

Parse Trees. Definitions Relationship to Left- and Rightmost Derivations Ambiguity in Grammars. Parse Trees. Parse trees are trees labeled by symbols of a particular CFG. Leaves : labeled by a terminal or ? . Interior nodes : labeled by a variable.

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Parse Trees

Parse Trees. Definitions Relationship to Left- and Rightmost Derivations Ambiguity in Grammars. Parse Trees. Parse trees are trees labeled by symbols of a particular CFG. Leaves : labeled by a terminal or ? . Interior nodes : labeled by a variable.

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5. Context-Free Grammars and Languages

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Chapter 3 - 2

Chapter 3 - 2. Construction Techniques. Section 3.3 Grammars. A grammar is a finite set of rules, called productions, that are used to describe the strings of a language.

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Introduction to Parsing

Introduction to Parsing. The Front End. Parser Checks the stream of words and their parts of speech (produced by the scanner) for grammatical correctness Determines if the input is syntactically well formed Guides checking at deeper levels than syntax

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Chapter 3

Chapter 3. Context-Free Grammars. Context-Free Grammars and Languages. Defn. 3.1.1 A context-free grammar is a quadruple ( V , ?, P , S ), where V is a finite set of variables ( non-terminals ) ?, the alphabet , is a finite set of terminal symbols

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Lexical and Syntactic Analysis

Lexical and Syntactic Analysis. Here, we look at two of the tasks involved in the compilation process Given source code, we need to first break it into meaningful units (lexical analysis) and then parse these lexical components into their syntactic uses (syntactic analysis)

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Discrete Structure

Discrete Structure. Li Tak Sing( 李德成 ). From grammar to inductive definition. Consider the following grammar: S |aB B b|bB Basis: , abL(G) Induction: if ay  L(G), then aby  L(G). Constructing grammars. {a n |n N} S|aS {a n b n |n N} S |aSb {(ab) n |nN} S |abS.

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