What is predictive parser in compiler design?

A predictive parser is a recursive descent parser with no backtracking or backup. It is a top-down parser that does not require backtracking. At each step, the choice of the rule to be expanded is made upon the next terminal symbol.

What is LL parser in compiler design?

In computer science, an LL parser (Left-to-right, leftmost derivation) is a top-down parser for a restricted context-free language. It parses the input from Left to right, performing Leftmost derivation of the sentence. An LL parser is called an LL(k) parser if it uses k tokens of lookahead when parsing a sentence.

What is top down parsing with example?

Top-down parsing in computer science is a parsing strategy where one first looks at the highest level of the parse tree and works down the parse tree by using the rewriting rules of a formal grammar. LL parsers are a type of parser that uses a top-down parsing strategy.

What is the main operation of predictive parser?

Predictive parser is a recursive descent parser, which has the capability to predict which production is to be used to replace the input string. The predictive parser does not suffer from backtracking. To accomplish its tasks, the predictive parser uses a look-ahead pointer, which points to the next input symbols.

What are the different components of predictive parser?

Predictive parsing uses a stack and a parsing table to parse the input and generate a parse tree. Both the stack and the input contains an end symbol $to denote that the stack is empty and the input is consumed. The parser refers to the parsing table to take any decision on the input and stack element combination.

What are the different types of parsers in natural language processing?

Natural Language processing provides us with two basic parsing techniques viz; Top-Down and Bottom- Up. Their name describes the direction in which parsing process advances. We have a Basic-Top-Down parsing which is the fusion of top-down and bottom-up parsing.

What is the use of parser?

A parser is a software component that takes input data (frequently text) and builds a data structure – often some kind of parse tree, abstract syntax tree or other hierarchical structure, giving a structural representation of the input while checking for correct syntax.

Is LL 1 predictive parsing?

LL(1) grammar follows Top-down parsing method. For a class of grammars called LL(1) we can construct grammars predictive parser.

What is the difference between LL and LR parsers?

At a high level, the difference between LL parsing and LR parsing is that LL parsers begin at the start symbol and try to apply productions to arrive at the target string, whereas LR parsers begin at the target string and try to arrive back at the start symbol. An LL parse is a left-to-right, leftmost derivation.

How many top down parsers are there?

Parsing is classified into two categories, i.e. Top-Down Parsing, and Bottom-Up Parsing. Top-Down Parsing is based on Left Most Derivation whereas Bottom-Up Parsing is dependent on Reverse Right Most Derivation.

What is top-down and bottom-up parsing with example?

Top-down parsing : A parser can start with the start symbol and try to transform it to the input string. Example : LL Parsers. Bottom-up parsing : A parser can start with input and attempt to rewrite it into the start symbol. Example : LR Parsers.

What is a predictive parser?

A predictive parser is a recursive descent parser with no backtracking or backup. It is a top-down parser that does not require backtracking. At each step, the choice of the rule to be expanded is made upon the next terminal symbol.

What are the different types of parser in compiler design?

Types of Parsers in Compiler Design. 1 (i). Recursive descent parser: It is also known as Brute force parser or the with backtracking parser. It basically generates the parse tree by using 2 (ii). Non-recursive descent parser: It is also known as LL (1) parser or predictive parser or without backtracking parser or dynamic parser. It uses

Does the predictive parser suffer from backtracking?

The predictive parser does not suffer from backtracking. To accomplish its tasks, the predictive parser uses a look-ahead pointer, which points to the next input symbols. To make the parser back-tracking free, the predictive parser puts some constraints on the grammar and accepts only a class of grammar known as LL (k) grammar.

What is the difference between recursive descent and predictive parsing?

The parser refers to the parsing table to take any decision on the input and stack element combination. In recursive descent parsing, the parser may have more than one production to choose from for a single instance of input, whereas in predictive parser, each step has at most one production to choose.