update print functions

docs/src/manual/acOptimalPowerFlow.md

@@ -84,7 +84,7 @@ nothing # hide
 ---
 
 ##### Add Variables
-The user has the ability to easily add new variables to the defined AC optimal power flow model by using the [`@variable`](https://jump.dev/JuMP.jl/stable/api/JuMP/#JuMP.@variable) macro from the JuMP package. Here is an example:
+The user has the ability to easily add new variables to the defined AC optimal power flow model by using the [`@variable`](https://jump.dev/JuMP.jl/stable/api/JuMP/#JuMP.@variable) macro from the JuMP package:
 ```@example ACOptimalPowerFlow
 JuMP.@variable(analysis.method.jump, newVariable)
 nothing # hide

src/backend/utility.jl

@@ -380,15 +380,17 @@ function print(
 )
     for (key, idx) in label
         if haskey(obj, idx) && is_valid(owner_model(obj[idx]), obj[idx])
-            println(io::IO, key, ": ", obj[idx])
+            expr = constraint_string(MIME("text/plain"), obj[idx])
+            println(io::IO, key, ": ", simplifyExpression(expr))
         end
     end
 end
 
 function print(io::IO, obj::Dict{Int64, ConstraintRef})
     for key in sort(collect(keys(obj)))
         if is_valid(owner_model(obj[key]), obj[key])
-            println(io::IO, obj[key])
+            expr = constraint_string(MIME("text/plain"), obj[key])
+            println(io::IO, simplifyExpression(expr))
         end
     end
 end
@@ -419,6 +421,16 @@ function print(io::IO, obj::Dict{Int64, Vector{ConstraintRef}})
     end
 end
 
+function simplifyExpression(expr::String)
+    expr = replace(expr, r"[-]?0\.0\s*\*\s*(cos|sin)\(\s*[^()]*\s*\)" => "0")
+    expr = replace(expr, r"\(\s*[-]?0[.0]?\s*\)" => "")
+    expr = replace(expr, r"\(\s*[+]\s*\(" => "((")
+    expr = replace(expr, r"^\((.*)\)" => s"\1")
+
+    return expr
+end
+
+
 ##### Error Messages #####
 function errorVoltage(voltage::Vector{Float64})
     if isempty(voltage)