/
function.go
191 lines (169 loc) · 3.77 KB
/
function.go
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package main
import (
"bytes"
"fmt"
"go/ast"
"go/format"
"go/printer"
"go/token"
"log"
"strings"
"text/template"
"unicode"
"golang.org/x/tools/imports"
"github.com/Masterminds/sprig"
)
func FunctionFromDecl(decl *ast.FuncDecl, fset *token.FileSet) Function {
a := Function{Name: decl.Name.Name}
for _, e := range decl.Type.Params.List {
a.Params = append(a.Params, Param{
Name: e.Names[0].Name,
Type: NodeAsString(fset, e.Type),
})
}
for _, e := range decl.Type.Results.List {
a.Returns = append(a.Returns, Return{
Type: NodeAsString(fset, e.Type),
})
}
if decl.Recv != nil && len(decl.Recv.List) > 0 {
a.Recv.Type = NodeAsString(fset, decl.Recv.List[0].Type)
if len(decl.Recv.List[0].Names) > 0 {
a.Recv.Name = NodeAsString(fset, decl.Recv.List[0].Names[0])
} else {
a.Recv.Name = "_recv"
}
}
return a
}
func NodeAsString(fset *token.FileSet, v interface{}) string {
var b bytes.Buffer
printer.Fprint(&b, fset, v)
br := b.String()
return br
}
func NodeAsStringFunc(fset *token.FileSet) func(v interface{}) string {
return func(v interface{}) string {
return NodeAsString(fset, v)
}
}
type Param struct {
Name string
Type string
}
func (p Param) Variadic() string {
if strings.HasPrefix(p.Type, "...") {
return "..."
}
return ""
}
type Params []Param
func (p Params) String() string {
str, err := WithTemplate(`{{range $i, $e := .}}{{.Name}} {{.Type}},{{end}}`, p)
if err != nil {
return ""
}
return str
}
type Return struct {
Name string
Type string
}
type Returns []Return
func (p Returns) String() string {
str, err := WithTemplate(`{{range $i, $e := .}}{{.Name}} {{.Type}},{{end}}`, p)
if err != nil {
return ""
}
return str
}
type Reciever struct {
Type string
Name string
}
func (f Reciever) String() string {
if f.Type == "" {
return ""
}
str, err := WithTemplate(`({{.Name}} {{.Type}})`, f)
if err != nil {
panic(err)
}
return str
}
type Function struct {
Name string
Body string
Comment string
Recv Reciever
Params Params
Returns Returns
}
func (f Function) IsExported() bool {
if len(f.Name) == 0 {
return false
}
return unicode.IsUpper(rune(f.Name[0]))
}
func (f Function) String() string {
str, err := WithTemplate(`{{.Comment}}
func {{.Recv}}{{.Name}}({{.Params}})({{.Returns}}){
{{.Body}}
}
`, f)
if err != nil {
panic(err)
}
return formatCode(str)
}
func WithTemplate(tmplstr string, data interface{}, funcs ...interface{}) (string, error) {
funcmap := sprig.FuncMap()
err := extraFuncs(funcmap, funcs...)
if err != nil {
return "", err
}
tmpl, err := template.New("").
Funcs(map[string]interface{}(funcmap)).
Parse(tmplstr)
if err != nil {
return "", err
}
var buf bytes.Buffer
if err := tmpl.Execute(&buf, data); err != nil {
return "", err
}
return buf.String(), err
}
func extraFuncs(m map[string]interface{}, funcs ...interface{}) error {
if len(funcs)%2 != 0 {
return fmt.Errorf("extra funcs should be even with form ['funcname', func...]")
}
for i := 0; i < len(funcs)-1; i += 2 {
key, ok := funcs[i].(string)
if !ok {
return fmt.Errorf("key of wrong type, key should be string type")
}
val := funcs[i+1]
m[key] = val
}
return nil
}
// importCode returns the gofmt-ed contents of the Generator's buffer.
func importCode(buf string) (string, error) {
src, err := imports.Process("", []byte(buf), nil)
if err != nil {
return "", err
}
return string(src), nil
}
func formatCode(buf string) string {
src, err := format.Source([]byte(buf))
if err != nil {
// Should never happen, but can arise when developing this code.
// The user can compile the output to see the error.
log.Printf("warning: internal error: invalid Go generated: %s", err)
log.Printf("warning: compile the package to analyze the error")
return buf
}
return string(src)
}