Context-Free  GRAMMARS

Context-Free GRAMMARS

A Context-Free Grammar is a quadruple that consists of terminals,non-terminals, start symbol and productions.   Terminals: These are the basic symbols from which strings are formed. Non-Terminals: These are the syntactic variables that denote a set of strings.…
Types of Parsing

Types of Parsing

Syntax analyzers follow production rules defined by means of context-free grammar. The way the production rules are implemented (derivation) divides parsing into two types : top-down parsing and bottom-up parsing.…
THE ROLE OF PARSER

THE ROLE OF PARSER

The parser or syntactic analyzer obtains a string of tokens from the lexical analyzer and verifies that the string can be generated by the grammar for the source language. It…
Syntax Analysis

Syntax Analysis

Syntax analysis or parsing is the second phase of a compiler. In this chapter, we shall learn the basic concepts used in the construction of a parser. We have seen…
Minimization of DFA

Minimization of DFA

DFA minimization stands for converting a given DFA to its equivalent DFA with minimum number of states. Minimization of DFASuppose there is a DFA D < Q, Σ, q0, δ,…
Regular Expressions

Regular Expressions

The lexical analyzer needs to scan and identify only a finite set of valid string/token/lexeme that belong to the language in hand. It searches for the pattern defined by the…
Finite Automata

Finite Automata

Finite automata is a state machine that takes a string of symbols as input and changes its state accordingly. Finite automata is a recognizer for regular expressions. When a regular…
RECOGNITION OF TOKENS

RECOGNITION OF TOKENS

Consider the following grammar fragment: stmt → if expr then stmt | if expr then stmt else stmt | ε expr → term relop term | term                            term →…
SPECIFICATION OF TOKENS

SPECIFICATION OF TOKENS

There are 3 specifications of tokens: 1)Strings 2) Language 3)Regular expression Strings and Languages ·         An alphabet or character class is a finite set of symbols. ·         A string over an alphabet is a finite sequence of…