magic

magic is an auto-parsing library and competitive coding helper package with batteries included. You just need to initialize it with a SrcProvider (e.g. a string, file, stream, etc.) and subsequently wish a type to auto-parse. The library takes care of allocating and populating your memory. The sequence of inputs is defined by the memory layout of the reading-type.

Under no circumstances should you use this package for production code. Use it only during competetive coding, when coding time matters and input parsing is trivial. I originally built this for the Catalysts Coding Contest (codingcontest.org)

Installation

To install magic, simly run:

$ go get -u github.com/harwoeck/magic

Quick start

1. Create a SrcProvider

   src := bufio.NewScanner(strings.NewReader("INPUT"))
   
   f, _ := os.Open("/path/to/file.txt")
   src := bufio.NewScanner(f)

2. Create a new Manager instance

   m := magic.NewManager(src)

3. Read, either primitive and complex types, from the manager

   parsedBool := m.ReadBool()
   parsedInt := m.ReadInt()
   parsedFloat := m.ReadFloat32()
   parsedString := m.ReadString()
   
   parsedStructList := m.Read([]myStruct).([]myStruct)

Complete example

In the following example a complex type (slice of structs) is read and auto-parsed. Within the main struct there are uncaped slices. In these situations magic will dynamically try to infer the size by reading an integer from the SrcProvider and incremting the cursor position accordingly.

type tx struct {
    id        int64
    authority string
    from      []txpart
    to        []txpart
}

type txpart struct {
    origin string
    amount float64
}

func main() {
    src := bufio.NewScanner(strings.NewReader(
        // Image the strings below are single lines within an input-file
        "1 FINANCE_MINISTRY 1 YourBankAccount 100 1 MyBankAccount 100\n" +
        "2 FINANCE_MINISTRY_DE 2 YourBusinessAcount1 50 YourBusinessAcount2 150 1 MyBusinessAcount 200\n"
    ))

    m := magic.NewManager(src)

    for _, item := range m.Read([]tx{}).([]tx) {
        fmt.Printf("%d %s\n", item.id, item.authority)
    }
}