Name the widely used Language Processor Development Tools (LPDTs).

Widely used Language processor development tools are:

Lex - A Lexical Analyzer Generator

Lex assists write programs whose control flow is directed through instances of regular expressions in the input stream. This is well fine for editor-script type transformations and for segmenting input into preparation for a parsing routine.

Lex source: It is a table of regular expressions and consequent program fragments. The table is translated to a program that reads an input stream, copying this to an output stream and partitioning the input in strings that match the specified expressions. Since each such string is recognized the consequent program fragment is executed. The recognition of the expressions is performed through a deterministic finite automaton generated through Lex. The program fragments written through the user are executed in the order wherein the corresponding regular expressions arise in the input stream.

YACC: It is Yet another Compiler-Compiler

Computer program input usually has some structure; actually, every computer program which does input can be thought of as defining an ''input language'' that it accept. An input language may be as complex like a programming language, or as easy as a sequence of numbers. Unluckily, usual input facilities are restricted, difficult to utilize, and for validity frequently are lax about checking their inputs.

YACC gives a general tool for describing the input to a computer program. The Yet another Compiler-Compiler user specifies the structures of his input, mutually with code to be invoked as each that structure is recognized. Yet another Compiler-Compiler turns such a specification in a subroutine that handles the input process; often, this is convenient and suitable to have most of the flow of control in the user's application handled through this subroutine.