Parsec

A parser for Math equations using a lighter, faster and more complete version of muparserx C++ library

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

• Use Ruby version 2.5.1

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

• Math trigonometric functions: sin, cos, tan, sinh, cosh, tanh, asin, acos, atan, asinh, acosh, atanh
• Math logarithm functions: ln, log, log10
• Math standard functions: abs, sqrt, cbrt, pow, exp, round, round_decimal
• Number functions: string
• Math constants: e, pi
• Unlimited number of arguments: min, max, sum, avg
• String functions: concat, length, toupper, tolower, left, right, str2number, number, link
• Complex functions: real, imag, conj, arg, norm
• Array functions: sizeof, eye, ones, zeros
• Date functions: current_date, daysdiff, hoursdiff
• Extra functions: default_value