Simple Lexer Parser

A simple lexer and parser that can compute simple mathematical operations using the most basic operators +, -, *, / and can correctly handle parentheses () and floating point operations (decimal numbers). It can NOT currently handle negative numbers or unary operations.

It is implemented as a Drupal 8 service module and provides a text field formatter.

The formatter currently displays errors inline.

Requirements

• Drupal 8

Installation

Download, install and enable as you normally install a Drupal 8 module hosted on github.

cd modules/contrib
git clone git@github.com:GiorgosK/simple_lexer_parser.git
drush en simple_lexer_parser

Usage

After enabling the module create a text field in your content type and choose Simple lexer parser formatter as a formatter at admin/structure/types/manage/CONTENT_TYPE/display

The formatter will display both the expression and the result (or error message)

(1 + 2) * 4  = 12

The result will be revealed on hover with a delayed css animation

Unit testing

Run test cases for this module using phpunit (tested with phpunit 6.5)

cd web
../vendor/bin/phpunit -c core/phpunit.xml.dist modules/contrib/simple_lexer_parser/tests/src/Calculator/CalculatorTest.php

You should get 10 tests and 10 assertions

if phpnunit is not in the bin folder try with ../vendor/phpunit/phpunit/phpunit instead