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EX-EV

A fully functional expression evaluator writtien in Ruby.

Usage

1. Prerequisites

  • Ruby, 3.0 and later, older versions might work.
  • A terminal (any would do so long as you've got Ruby installed)

Before you can run the project you must do

bundle install

In the root directory to install the needed gems

2. Running

To run in REPL mode you can just do

ruby ./main.rb
2.1 CLI arguments
  1. Turn the printing of the AST (abstract syntax tree) on for debugging purposes:
# You can use any of te following arguments to turn the AST printing on:
# --showTree, -st, --debugPrint, -dp
# So the command would look like so:

ruby ./main.rb --showTree

3. Testing

To start the tests you just do:

bundle exec rspec

In the root directory of the project

4. Linting

bundle exec rubocop

5. Debugging

When debugging you can print the current AST in a format similar to the linux tree command:

For exaple, say that in the command line you've entered the expression: ((11*22+33-44)**5)/((6**7)*8+9**9)*(69/420) and are running the REPL using --showTree, the output of the expression will be consist of the AST of the given expression and below that, the evaluated result:

> ((11*22+33-44)**5)/((6**7)*8+9**9)*(69/420)
└───BinaryExpression
    ├───BinaryExpression
    │   ├───ParenthesizedExpression
    │   │   ├───OpenParenthesisToken
    │   │   ├───BinaryExpression
    │   │   │   ├───ParenthesizedExpression
    │   │   │   │   ├───OpenParenthesisToken
    │   │   │   │   ├───BinaryExpression
    │   │   │   │   │   ├───BinaryExpression
    │   │   │   │   │   │   ├───BinaryExpression
    │   │   │   │   │   │   │   ├───
    │   │   │   │   │   │   │   │   └───NumberToken 11
    │   │   │   │   │   │   │   ├───StarToken
    │   │   │   │   │   │   │   └───
    │   │   │   │   │   │   │       └───NumberToken 22
    │   │   │   │   │   │   ├───PlusToken
    │   │   │   │   │   │   └───
    │   │   │   │   │   │       └───NumberToken 33
    │   │   │   │   │   ├───MinusToken
    │   │   │   │   │   └───
    │   │   │   │   │       └───NumberToken 44
    │   │   │   │   └───CloseParenthesisToken
    │   │   │   ├───DoubleStarToken
    │   │   │   └───
    │   │   │       └───NumberToken 5
    │   │   └───CloseParenthesisToken
    │   ├───SlashToken
    │   └───ParenthesizedExpression
    │       ├───OpenParenthesisToken
    │       ├───BinaryExpression
    │       │   ├───BinaryExpression
    │       │   │   ├───ParenthesizedExpression
    │       │   │   │   ├───OpenParenthesisToken
    │       │   │   │   ├───BinaryExpression
    │       │   │   │   │   ├───
    │       │   │   │   │   │   └───NumberToken 6
    │       │   │   │   │   ├───DoubleStarToken
    │       │   │   │   │   └───
    │       │   │   │   │       └───NumberToken 7
    │       │   │   │   └───CloseParenthesisToken
    │       │   │   ├───StarToken
    │       │   │   └───
    │       │   │       └───NumberToken 8
    │       │   ├───PlusToken
    │       │   └───BinaryExpression
    │       │       ├───
    │       │       │   └───NumberToken 9
    │       │       ├───DoubleStarToken
    │       │       └───
    │       │           └───NumberToken 9
    │       └───CloseParenthesisToken
    ├───StarToken
    └───ParenthesizedExpression
        ├───OpenParenthesisToken
        ├───BinaryExpression
        │   ├───
        │   │   └───NumberToken 69
        │   ├───SlashToken
        │   └───
        │       └───NumberToken 420
        └───CloseParenthesisToken

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