go-types-internals

Get access to runtime implementation of go types

For any supported type you can get its internal representation with help of functions:

func GetMapStruct(value any) MapStruct  
func GetSliceStruct(value any) SliceStruct

Each type's struct has a form of this struct:

type TypeStruct struct {
	InitialValue interface{}
	Type         TypeT
	Value        ValueT
}

and has its own handy methods (for example for printing map info)

Content:
1. Map
2. Slice
_. Empty Interface

2. Map:

Initialize some map:

package main

import (
	"github.com/rostislaved/go-types-internals/maptype"
)

func main() {
        m := make(map[int]int)

	for i := 1; i < 10; i++ {
		m[i] = i
	}

	mapStruct := maptype.GetMapStruct(m)
}

type MapStruct struct {
	InitialValue  interface{} // map itself
	Type          Maptype     // type info
	Value         Hmap        // map data
}

There are some handy functions:

1. Print general map info: [# elements], [# buckets], [LoadFactor]:

mapStruct.PrintMapInfo()

// Elements | Buckets | LoadFactor
//        9 |       2 | 4.5

2. Print Buckets(and OldBuckets): key:value

mapStruct.PrintBuckets()

// Alternative to previous func in case the value type is not supported
maptype.PrintBucketsGeneric[int64](mapStruct)

// Buckets:
//	Bucket: 0
//	   Element: [0] = 1
//	   Element: [1] = 2
//	   Element: [2] = 6
//	   Element: [3] = 8
//	   Element: [4] = 0
//	   Element: [5] = 0
//	   Element: [6] = 0
//	   Element: [7] = 0
//	Bucket: 1
//	   Element: [0] = 3
//	   Element: [1] = 4
//	   Element: [2] = 5
//	   Element: [3] = 7
//	   Element: [4] = 9
//	   Element: [5] = 0
//	   Element: [6] = 0
//	   Element: [7] = 0
//	OldBuckets:
//	[]

3. Get buckets [][][]unsafe.Pointer

buckets := mapStruct.GetBuckets()

2. Slice:

package main

import (
	"github.com/rostislaved/go-types-internals/slicetype"
    "fmt"
)

func main() {
	s := []int{1, 2, 3}

	ss := slicetype.GetSliceStruct(s)

	fmt.Println(ss.Value.Len)
	fmt.Println(ss.Value.Cap)
	fmt.Println(ss.Value.Array)

	fmt.Println(ss.Type.Elem.Align)
}

no handy methods yet :) only access to fields

_. Empty Interface:

iFace := GetEmptyInterface(anyValue)

it is used mainly for others function, but I left it exported

type Iface struct { 
	Itab unsafe.Pointer
	Data unsafe.Pointer
}