https://github.com/hacsoc/expr

An expression calculator example.
https://github.com/hacsoc/expr

Last synced: about 2 months ago
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An expression calculator example.

• Host: GitHub
• URL: https://github.com/hacsoc/expr
• Owner: hacsoc
• License: other
• Created: 2015-09-02T20:47:55.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2015-09-03T00:10:41.000Z (over 9 years ago)
• Last Synced: 2024-04-15T01:10:51.116Z (10 months ago)
• Language: Java
• Size: 207 KB
• Stars: 0
• Watchers: 5
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Expr

By Tim Henderson

## What?

A simple expression calculator for integer math. You give it an expression:

    $ expr '1 + 2'

    (+ 1 2)

    3

It will calculate the result and additionally give you back your expression as

an s-expression.

## Why?

To demonstrate gradle, testing, lexing and recursive descent parsing.

## Install

You must have java 1.7+ and git on your system. Get those first!

    $ git clone https://github.com/hacsoc/expr.git

    ## some output

    $ cd expr

    $ ./gradlew test installApp

    ## bunch of output

    $ ./build/install/expr/bin/expr '1+2'

    (+ 1 2)

    3

To make it available for this session run

    $ export PATH=$(pwd)/build/install/expr/bin:$PATH

Now you can just run

    $ expr '4 * 3/5'

    (/ (* 4 3) 5)

    2

To "install" permanently do

    $ echo "export PATH=$(pwd)/build/install/expr/bin:$PATH" >> .bashrc