go2flow

go2flow is a tool written in Go that generates Flow type definitions given a file with Go types.

It relies on the JSON encoding of a Go struct (defined in struct field tags), generating Flow type definitions to be used in the consumer's JS code base.

Development

Run the Proof of Concept on the sample file

go run main.go -f samples/kube_types_sample.go

Print usage

go run main.go -h

Run the tests

go test

TODO

• Examples of use
• More sample files
• Test output (return a string instead of printing)
• Document the decisions made for translation from Go type --> JSON output --> Flow definition
• Accept CLI args

Rules

We handle the following TypeSpec definitions:

ast.StructType A struct type definition.

Example Go Code:

type MyStruct struct {
    field1: bool,
    field2: string,
}

Rule: For each of the fields defined in this struct, handle them according to the rules of struct fields (below).

Generated Flow Code:

type MyStruct = {
    field1: boolean,
    field2: string,
}

ast.Ident A type definition, typically an alias.

Example Go Code:

type MyStruct string
type MyStruct2 AnotherType

Rule: Create a flow alias to whatever the type is. If it exists in the map of go types to flow types, use that mapping. Else, use the name of the custom type.

Generated Flow Code:

type MyStruct = string;
type MyStruct2 = AnotherType;

ast.ArrayType A type definition, typically an alias, that is an array of another type.

Example Go Code:

type MyStruct []string
type MyStruct2 []*AnotherType

Rule: Create a flow alias to an array of whatever the included type is. If it exists in the map of go types to flow types, use that mapping. Else, use the name of the custom type. If the type is a pointer, the pointer will either resolve to JSON or nil (it won't exist), so ignore the pointer value and use the type.

Generated Flow Code:

type MyStruct = Array<string>;
type MyStruct2 = Array<AnotherType>;

ast.MapType A type definition, typically an alias, that is a map.

Example Go Code:

type MyStruct map[bool]AnotherType

Rule: Create a flow alias to a map of the appropriate types, using the following rules: If it exists in the map of go types to flow types, use that mapping. Else, use the name of the custom type. If the type is a pointer, the pointer will either resolve to JSON or nil (it won't exist), so ignore the pointer value and use the type.

Generated Flow Code:

type MyStruct = {
    [boolean]: AnotherType,
}