added test for converting AST to postfix

package/src/ExpressionProcessing.jl

@@ -7,20 +7,27 @@ export SymbolTable64
 
 const SymbolTable64 = Dict{Tuple{Expr, Symbol},Float64}
 
-# Maybe switch from Array{String} to Array{Union{Float64, String}}?
-function expr_to_postfix(expr::Expr)::Array{String}
-	postfix = Array{String,1}()
+# Maybe switch from Array{String} to Array{Union{Float64, Symbol}}?
+function expr_to_postfix(expr::Expr)::Array{Union{Float64,String}}
+	postfix = Array{Union{Float64,String},1}()
 	operator = String(expr.args[1])
 
-	push!(postfix, expr.args[2], expr.args[3], operator)
-	for i in 4:length(expr.args)
+	# push!(postfix, expr.args[2], expr.args[3], operator)
+	for i in 2:length(expr.args)
 		arg = expr.args[i]
 		if typeof(arg) === Expr
-			push!(postfix, expr_to_postfix(ex))
+			append!(postfix, expr_to_postfix(arg))
+		elseif typeof(arg) === Symbol
+			push!(postfix, String(arg))
 		else
-			push!(postfix, string(arg), operator)
+			push!(postfix, convert(Float64, arg))
+		end
+		if length(postfix) >= 2
+			push!(postfix, operator)
 		end
 	end
+
+	return postfix
 end
 
 "Replaces all the variables and parameters of the given expression with their corresponding value stored in the symtable
@@ -34,7 +41,6 @@ function replace_variables!(ex::Expr, symtable::SymbolTable64, originalExpr::Exp
 		if typeof(arg) === Expr
 			replace_variables!(arg, symtable, originalExpr)
 		elseif haskey(symtable, (originalExpr,arg)) # We found a variable/parameter and can replace it with the actual value
-			println("Replacing")
 			ex.args[i] = symtable[(originalExpr,arg)]
 		end
 	end

package/test/ExpressionProcessing.jl

@@ -22,10 +22,16 @@ end
 
 @testset "Test variable replacement in expression" begin
 	symtable = ExpressionExecutorCuda.ExpressionProcessing.construct_symtable(expressions, variables, parameters)
-	println(keys(symtable))
 	exprCopy = deepcopy(expressions[1])
 	ExpressionExecutorCuda.ExpressionProcessing.replace_variables!(exprCopy, symtable, expressions[1])
 
-	dump(exprCopy)
 	@test eval(exprCopy) == 10 # If it can be evaluated, it means all variables have been replaced, as there are no globally defined variables
+end
+
+@testset "Test conversion to postfix" begin
+	reference = Array{Union{Float64,String},1}()
+	append!(reference, ["x1", 1.0, "x2", "*", "+", "p1", "+"])
+	postfix = ExpressionExecutorCuda.ExpressionProcessing.expr_to_postfix(expressions[1])
+
+	@test isequal(reference, postfix)
 end