Matching mathematical operations in scala using regex - regex

Question

I am trying to match mathematical operations using a match in scala. So the function will be able to match any string like "5+2" or "log10" or "10^5" etc. However the match keeps failing for the individual types of expressions
def isValid(expression:String):Boolean={
val number = """((\-|\+)?[0-9]+\.?[0-9])*"""
val operation = """([\+,\-,*,/,C,P])"""
val functions = """(log|ln|sin|cos|tan|arc sin|arc cos|arc tan|sec|csc|cot)"""
val powers = """\^"""+number
val arithmeticExpression = (number + operation + number).r
val functionExpression = (functions + number).r
val powerOperation = (number + powers).r
val stringToTest: Regex = ("""(""" +arithmeticExpression+"""|"""+functionExpression+"""|"""+powerOperation+""")""").r
expression match {
case arithmeticExpression(s) => true
case functionExpression(s) => true
case powerOperation(s)=>true
case _ => false
}
}
println(isValid("1+4").toString)
However if I match for a general expression I get the expected output:
def isValid(expression:String):Boolean={
val number = """(\-|\+)?[0-9]+\.?[0-9]*"""
val operation = """[\+,\-,*,/,C,P]"""
val functions = """(log|ln|sin|cos|tan|arc sin|arc cos|arc tan|sec|csc|cot)"""
val power = """\^"""+number
val arithmeticExpression = number+operation+number
val functionExpression = functions+number
val powerExpression = number+power
val validExpression = """(""" +arithmeticExpression+"""|"""+functionExpression+"""|"""+powerExpression+""")"""
validExpression.r.findFirstIn(expression) match {
case Some(`expression`) => true
case None => false
}

Answer 1

You're not doing numbers correctly:
scala> arithmeticExpression.findFirstIn("1+4")
res2: Option[String] = Some(+)
scala> arithmeticExpression.unapplySeq("1+4")
res3: Option[List[String]] = None
scala> arithmeticExpression.unapplySeq("11+14")
res4: Option[List[String]] = Some(List(11, null, +, 14, null))
Since you're requiring two digits.

Answer 2

The "()" in the regular expression for numbers was affecting the result. Also /^ needed to wrapped in (). This ended up working for me.
def isValid(expression:String):Boolean={
val number = """[\-,\+]?[0-9]+\.?[0-9]*"""
val operation = """([\+,\-,*,/,C,P])"""
val functions = """(log|ln|sin|cos|tan|arc sin|arc cos|arc tan|sec|csc|cot)"""
val powers = """(\^)"""+number
val arithmeticExpression = (""""""+number + operation + number+"""""").r
val functionExpression = (functions + number).r
val powerOperation = (number + powers).r
val stringToTest: Regex = ("""(""" +arithmeticExpression+"""|"""+functionExpression+"""|"""+powerOperation+""")""").r
expression match {
case arithmeticExpression(s) => {
println("Arithmetic Match")
true
}
case functionExpression(s) => {
println("Function Match")
true
}
case powerOperation(s)=>{
println("Power Match")
true
}
case _ => false
}
}
Thanks for the help!