expression processing: fixed error if expression contained nested unary operators such as log(sqrt(4))

package/src/ExpressionProcessing.jl

@@ -9,6 +9,8 @@ export ExpressionElement
 @enum Operator ADD=1 SUBTRACT=2 MULTIPLY=3 DIVIDE=4 POWER=5 ABS=6 LOG=7 EXP=8 SQRT=9
 @enum ElementType EMPTY=0 FLOAT32=1 OPERATOR=2 INDEX=3
 
+const unary_operators = [ABS, LOG, EXP, SQRT]
+
 struct ExpressionElement
 	Type::ElementType
 	Value::Int32 # Reinterpret the stored value to type "ElementType" when using it
@@ -46,7 +48,7 @@ function expr_to_postfix(expr::Expr)::PostfixType
 	end
 
 	# For the case this expression has an operator that only takes in a single value like "abs(x)"
-	if length(postfix) == 1
+	if operator in unary_operators 
 		push!(postfix, convert_to_ExpressionElement(operator))
 	end
 	return postfix

package/test/InterpreterTests.jl

@@ -132,8 +132,8 @@ end
 
 	# var set 1
 	@test isapprox(result[1,1], 37.32, atol=0.01) # expr1
-	@test isapprox(result[1,2], 64.74, atol=0.01) # expr2
+	@test isapprox(result[1,2], 64.75, atol=0.01) # expr2
 	# var set 2
 	@test isapprox(result[2,1], 37.32, atol=0.01) # expr1
-	@test isapprox(result[2,2], -83.65, atol=0.01) # expr2
+	@test isapprox(result[2,2], -83.66, atol=0.01) # expr2
 end

package/test/TranspilerTests.jl

@@ -6,7 +6,7 @@ expressions = Vector{Expr}(undef, 3)
 variables = Matrix{Float32}(undef, 5, 4)
 parameters = Vector{Vector{Float32}}(undef, 3)
 
-expressions[1] = :(1 + 3 * 5 / 7 - sqrt(4))
+expressions[1] = :(1 + 3 * 5 / 7 - sqrt(log(4)))
 expressions[2] = :(5 + x1 + 1 * x2 + p1 + p2 + x1^x3)
 expressions[3] = :(log(x1) / x2 * sqrt(p1) + x3^x4 - exp(x5))
 
@@ -46,10 +46,10 @@ parameters[3][1] = 16.0
 
 	# dump(expressions[3]; maxdepth=10)
 	# Expr 1:
-	@test isapprox(results[1,1], 1.14286)
-	@test isapprox(results[2,1], 1.14286)
-	@test isapprox(results[3,1], 1.14286)
-	@test isapprox(results[4,1], 1.14286)
+	@test isapprox(results[1,1], 1.96545)
+	@test isapprox(results[2,1], 1.96545)
+	@test isapprox(results[3,1], 1.96545)
+	@test isapprox(results[4,1], 1.96545)
 	#Expr 2:
 	@test isapprox(results[1,2], 16.0)
 	@test isapprox(results[2,2], 25.0)