utisam / gogtok

Toolkit for shell script used in go:generate

gogtok

Toolkit for shell script used in go:generate.

Getting started

go get -u github.com/utisam/gogtok/cmd/gogtok

1. gogtok new FILENAME to generate a new script file
2. Add //go:generate ./filename.sh in your code.
3. Write script to render source

Commands

• glue: Generate glue code
• import [packages...]: Generate import statement
• list funcs/values/types [files...]: Parse source files and show declarations
• list fields [file] [name]: Parse source files and show fields
• new [name]: Generate new script from boilerplate
• package name [dir]: Show package name of the directory
• package path [dir]: Show package path of the directory

Examples

Specify text/template

goimports cannot resolve package which has the same name with other packages. For example, template is matched with text/template and html/template, then you must specify package.

render_import() {
    gogtok import \
        "text/template" \
        "crypto/rand" \
        "$(gogtok package path ..)/config"
}

gogtok import generates a import block only if there are multiple packages. gogtok package rsespects GO111MODULE and parse go.mod in the parent directory.

Generate glue code

render_convert() {
    cat <<-EOS
    func convert(a *OtherStruct) *SomeStruct {
        return &SomeStruct{
    EOS
    gogtok list fields some.go SomeStruct | xargs gogtok glue a
    cat <<-EOS
        }
    }
    EOS
}

This function generates following code when SomeStruct has 4 fields W, X, Y, Z:

func convert(a *OtherStruct) *SomeStruct {
    return *SomeStruct{
        W: a.W,
        X: a.X,
        Y: a.Y,
        Z: a.Z,
    }
}

gogtok glue has options to customize glue code. See gogtok help glue.

List all reflect.Kind

source <(go env)
gogtok list values \
    --filter-decl-type Kind \
    "${GOROOT}/src/reflect/type.go"

List name, type and tags

name, type, tags and tag[key] can be used to --columns option.

gogtok list fields --print0 --columns 'name,type,tag[json]' file.go SomeStruct | \
    while IFS= read -r -d '' name && read -r -d '' type && read -r -d '' tag_json
do
    echo "name: $name, type: $type, tag[json]: $tag_json"
done

--print0 is usefull when you want to handle types and/or tags which contain space. Like find -print0, NULL chars are used to output. xargs -0 can be used to pass the regular commands.