Parsec

Usage

Add to your Gemfile

gem 'parsecs'

Tests

gem build parsec.gemspec
gem install ./parsecs-VERSION.gem (e.g.: gem install ./parsecs-0.9.3.gem)
ruby -Ilib -Iext/libnativemath test/test_parsec.rb

You can then eval equations in your code

parser = Parsec::Parsec
parser.eval_equation('5 + 1')
parser.eval_equation('(3 + 3) * (5 * 2)')

And also validate the syntax of the equations

parser = Parsec::Parsec
parser.validate_syntax!('4 + 4') # return => true
parser.validate_syntax!('4 + ') # raise SyntaxError with message: Unexpected end of expression found at position 4.
parser.validate_syntax!('(4 + 3) + ( 4 + 2)') # return => true
parser.validate_syntax!('(4 + 3) + ( 4 + 2') # raise SyntaxError with message: Missing parenthesis.
parser.validate_syntax!('4==4 ? true : false') # return => true
parser.validate_syntax!('4==4 ? true') # raise SyntaxError with message: If-then-else operator is missing an else clause.
parser.validate_syntax!('4==4 ^ true : false') # raise SyntaxError with message: Misplaced colon at position 12.

Here are examples of equations which are accepted by the parser

parser = Parsec::Parsec
# Simple Math equations
parser.eval_equation('(5 + 1) + (6 - 2)') # result => 10
parser.eval_equation('4 + 4 * 3') # result => 16
parser.eval_equation('10.5 / 5.25') # result => 2
parser.eval_equation('abs(-5)') # result => 5
parser.eval_equation('sqrt(16) + cbrt(8)') # result => 6
parser.eval_equation('log10(10)') # result => 1
parser.eval_equation('round(4.4)') # result => 4
parser.eval_equation('(3^3)^2') # result => 729
parser.eval_equation('3^(3^(2))') # result => 19683
parser.eval_equation('10!') # result => 3628800
parser.eval_equation('string(10)') # result => "10"
# Complex Math equations
parser.eval_equation('log10(10) + ln(e) + log(10)') # result => 4.30259
parser.eval_equation('sin(1) + cos(0) + tan(0.15722)') # result => 2.0
parser.eval_equation('max(1, 2) + min(3, 4) + sum(5, 6)') # result => 16
parser.eval_equation('avg(9, 9.8, 10)') # result => 9.6
parser.eval_equation('pow(2, 3)') # result => 8
parser.eval_equation('round_decimal(4.559, 2)') # result => 4.56
# IF THEN ELSE equations
parser.eval_equation('4 > 2 ? "bigger" : "smaller"') # result => "bigger"
parser.eval_equation('2 == 2 ? true : false') # result => true
parser.eval_equation('2 != 2 ? true : false') # result => false
parser.eval_equation('"this" == "this" ? "yes" : "no"') # result => "yes"
parser.eval_equation('"this" != "that" ? "yes" : "no"') # result => "yes"
# Logic equations
parser.eval_equation('true and false') # result => false
parser.eval_equation('true or false') # result => true
parser.eval_equation('(3==3) and (3!=3)') # result => false
parser.eval_equation('exp(1) == e') # result => true
# String equations
parser.eval_equation('length("test string")') # result => 11
parser.eval_equation('toupper("test string")') # result => "TEST STRING"
parser.eval_equation('tolower("TEST STRING")') # result => "test string"
parser.eval_equation('concat("Hello ", "World")') # result => "Hello World"
parser.eval_equation('link("Title", "http://foo.bar")') # result => "<a href="http://foo.bar">Title</a>"
parser.eval_equation('str2number("5")') # result => 5
parser.eval_equation('left("Hello World", 5)') # result => "Hello"
parser.eval_equation('right("Hello World", 5)') # result => "World"
parser.eval_equation('number("5")') # result => 5
# Date equations (return the difference in days)
parsec.eval_equation("current_date()")) # result => "2018-10-03"
parsec.eval_equation('daysdiff(current_date(), "2018-10-04")') # result => 1
parsec.eval_equation('daysdiff("2018-01-01", "2018-12-31")') # result => 364
# DateTime equations (return the difference in hours)
parsec.eval_equation('hoursdiff("2018-01-01", "2018-01-02")') # result => 24
parsec.eval_equation('hoursdiff("2019-02-01T08:00", "2019-02-01T12:00")') # result => 4
parsec.eval_equation('hoursdiff("2019-02-01T08:20", "2019-02-01T12:00")') # result => 3.67
parsec.eval_equation('hoursdiff("2018-01-01", "2018-01-01")') # result => 0

The following functions can be used