moisepan@gmail.com

Moises Pantoja

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Sacramento State Computer Science Sophomore

PL Assignment 4

Recursive Descent Parser Implementation

Grammar for Arithmatic Expression
EXP ::= EXP + TERM | EXP - TERM | TERM
TERM ::= TERM * FACTOR | TERM / FACTOR | FACTOR
FACTOR ::= (EXP) | DIGIT
DIGIT ::= 0|1|2|3|4|5|6|7|8|9

Example of some valid strings:
1-2*2$
(1-2)*3$
2/3$

Example of some invalid strings:
22-3$
2/$
(1+)$

Enter string using the numbers 0 to 9, and the
symbols +, -, *, /, (, and ).
Your end of string variable will be dollar sign ($).
When you click on 'submit', it will check whether entered string is valid or not for a given grammar.

Input String: Submit

output

Report:

I wrote this in Javascript because it is to my knowledge that Javascript is a necessity in modern web development. Also, everyone else appeared to be writing their interpreter in Javascript. I love it, the first language I learned was Java so any other language feels more intuitive and no where near as verbose. The assignment itself was straight forward with the pseudo code created in the beginning of the semester. Each function almost mirrored each definition. One of the best references for web development: moz://a. I also wanted to add that people should be using Visual Studio code as their editor because of the plug-ins and the vast library to help you develop. Microsoft Edge's developer tool is better than Chrome's.

PL Assignment 1

• Syntax:

  The syntax of a language is a set of rules that define how a language is to be used. It defines the combinations of symbols that are considered to be a correctly structured document or fragment in that language.
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• Semantics:

  In computer science, the term is frequently used to differentiate the meaning of an instruction from its format. The format, which covers the spelling of language components and the rules controlling how components are combined, is called the language's syntax.
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• Lexical Scanning:

  Breaking down High level input program into a sequence of Tokens.
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• Parsing

  Parsing is the process of analyzing a string of symbols, conforming to the rules of a formal grammar.
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• Parser

  A parser takes input in the form of a sequence of tokens or program instructions and usually builds a data structure in the form of a parse tree or an abstract syntax tree.
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