Optimize serialization

[sisyphusSmiling]

Related: #80

Description

• Updates Serialize.cdc & SerializeMetadata.cdc by replacing .concat with String.join <- credit to @bluesign for the suggestion
  • See these transactions comparing .concat (2167 gas) and String.join (7 gas) to join 500 strings without looping
• Removes previewnet from flow.json

---

For contributor use:

• Targeted PR against main branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the standards mentioned here.
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 95.45455% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.73%. Comparing base (02aab3f) to head (fae3977).
Report is 156 commits behind head on main.

Files with missing lines	Patch %	Lines
cadence/contracts/utils/SerializeMetadata.cdc	93.33%	2 Missing ⚠️
cadence/contracts/utils/Serialize.cdc	97.22%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #132      +/-   ##
==========================================
+ Coverage   86.19%   86.73%   +0.53%     
==========================================
  Files          18       18              
  Lines         884      965      +81     
==========================================
+ Hits          762      837      +75     
- Misses        122      128       +6     

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[joshuahannan]

Looks fine to me, but I'm probably not the best one to approve this. Would be good to get Austin or Deniz to take a look too

[bluesign]

I think switch can be optimized with isInstance or better if let

fun tryToJSONString(_ value: AnyStruct): String? {
        // Recursively serialize array & return
        if value.getType().isSubtype(of: Type<[AnyStruct]>()) {
            return arrayToJSONString(value as! [AnyStruct])
        }
        // Recursively serialize map & return
        if value.getType().isSubtype(of: Type<{String: AnyStruct}>()) {
            return dictToJSONString(dict: value as! {String: AnyStruct}, excludedNames: nil)
        }
        
        if let v=value as? String {
          return String.join(["\"", v , "\"" ], separator: "")
        }
        if let v=value as? Number {
          return String.join(["\"", v.toString() , "\"" ], separator: "")
        }
        if let v=value as? Character {
          return String.join(["\"", v.toString() , "\"" ], separator: "")
        }
        if let v=value as? Bool {
          return String.join(["\"", v?"true":"false" , "\"" ], separator: "")
        }
        if let v=value as? Address {
          return String.join(["\"", v.toString() , "\"" ], separator: "")
        }
        

        if value==nil{
          return "\"nil\""
        }
        
        return nil
       
    }

[sisyphusSmiling]

Thanks for the suggestions @bluesign. Some quick comparisons indicate there doesn't seem to be much of a difference between switch and if let and isInstance seems to be less efficient if I understood you suggestion correctly.

[bluesign]

Yeah they are pretty much same, but less code basically, I think switch is converting to if else technically but not sure