keelar/exprk

A simple mathematical expression evaluator for Kotlin and Java, written in Kotlin.

exprk's Issues

Parse error when BigDecimal contains scientific notation

This unit test:

    @Test
    fun `test that scientific notation BigDecimals are parsed and equivalent to the plain representation`() {
        val expr = Expressions()
        val scival = BigDecimal("1E+7")
        expr.define("SCIVAL", scival)
        assertEquals(scival.toPlainString(), expr.eval("SCIVAL").toPlainString())
    }

Produces this result:

com.github.keelar.exprk.ExpressionException: Expected end of expression, found 'E'

	at com.github.keelar.exprk.internal.Parser.parse(Parser.kt:15)
	at com.github.keelar.exprk.Expressions.parse(Expressions.kt:173)
	at com.github.keelar.exprk.Expressions.parse(Expressions.kt:169)
	at com.github.keelar.exprk.Expressions.define(Expressions.kt:141)
	at com.github.keelar.exprk.Expressions.define(Expressions.kt:135)
	at com.github.keelar.exprk.TestExpressions.test that scientific notation BigDecimals are parsed and equivalent to the plain representation(TestExpressions.kt:13)

How to use this library ?

Hi,

How to import this library with gradle for my android project ?

Define value via eval function

E.g:
Instead of using define("x",2), I need to use eval("x=2")

🐛 Exponential operator(^) does not throw exception about overflow

First of all, thanks for your code.
I found a bug, and would like to report it

It's about exponential(^) operation between two bigDecimal number.
I think that a calculation which expected to take a long time to calculate must throw exception about overflow.
e.g.
Expressions().eval("34^3.0E+24")
Expressions().eval("34^3.0E+2451223111")

The code above throw exception about overflow.
But below is not
34^3.0E+2451223

I think it has to have some validation about each power calculation.
Thank you

Undefined variable

Hi
Is it possible to define string expression:

e.g:
expressions.define("x", "durim")

Evaluator should be public

It should be possible to obtain and configure an Evaluator separately from Expressions, so different functions/constants/etc. can be configured.

(This will also require Expr and its various subclasses, probably Parser, and likely other interfaces and classes to be made public. I honestly don't see much reason to restrict visibility of much in the library, it's already nice and tight. IMO the easiest fix is just to make everything public.)

Change arguments.min()!! and arguments.max()!! with arguments.minOrNull()!! and arguments.maxAndNull() in Expressions.kt

arguments.min()!! and arguments.max()!! throw error in recent kotlin versions. Consider changing it with arguments.minOrNull()!! and arguments.maxAndNull()!! in

Replace this part of the code:

Expressions.kt

 evaluator.addFunction("min", object : Function() {
            override fun call(arguments: List<BigDecimal>): BigDecimal {
                if (arguments.isEmpty()) throw ExpressionException(
                        "min requires at least one argument")

                return arguments.min()!!
            }
        })

        evaluator.addFunction("max", object : Function() {
            override fun call(arguments: List<BigDecimal>): BigDecimal {
                if (arguments.isEmpty()) throw ExpressionException(
                        "max requires at least one argument")

                return arguments.max()!!
            }
        })

with this:

Expressions.kt

 evaluator.addFunction("min", object : Function() {
            override fun call(arguments: List<BigDecimal>): BigDecimal {
                if (arguments.isEmpty()) throw ExpressionException(
                        "min requires at least one argument")

                return arguments.minOrNull()!!
            }
        })

        evaluator.addFunction("max", object : Function() {
            override fun call(arguments: List<BigDecimal>): BigDecimal {
                if (arguments.isEmpty()) throw ExpressionException(
                        "max requires at least one argument")

                return arguments.maxOrNull()!!
            }
        })

Can i configure exponential usage in result?

first of all, Thank you for your code!

my question is that how can i configure exponential result?
for example, the result is 10.01+E3 for 10000+10. I want to use exponential only for much larger numbers.

Thank you again.