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package main
import (
"bytes"
"fmt"
"go/ast"
"go/format"
"go/parser"
"go/token"
"io/ioutil"
"log"
"os"
"strings"
)
const fileName = "enum.go"
const genName = "enum_gen.go"
type generator struct {
buf bytes.Buffer
caps []string
}
func (g *generator) writeHeader() {
g.buf.WriteString("// generated file; DO NOT EDIT - use go generate in directory with source\n")
g.buf.WriteString("\n")
g.buf.WriteString("package capability")
}
func (g *generator) writeStringFunc() {
g.buf.WriteString("\n")
g.buf.WriteString("func (c Cap) String() string {\n")
g.buf.WriteString("switch c {\n")
for _, cap := range g.caps {
fmt.Fprintf(&g.buf, "case %s:\n", cap)
fmt.Fprintf(&g.buf, "return \"%s\"\n", strings.ToLower(cap[4:]))
}
g.buf.WriteString("}\n")
g.buf.WriteString("return \"unknown\"\n")
g.buf.WriteString("}\n")
}
func (g *generator) writeListFunc() {
g.buf.WriteString("\n")
g.buf.WriteString("// List returns list of all supported capabilities\n")
g.buf.WriteString("func List() []Cap {\n")
g.buf.WriteString("return []Cap{\n")
for _, cap := range g.caps {
fmt.Fprintf(&g.buf, "%s,\n", cap)
}
g.buf.WriteString("}\n")
g.buf.WriteString("}\n")
}
func main() {
fs := token.NewFileSet()
parsedFile, err := parser.ParseFile(fs, fileName, nil, 0)
if err != nil {
log.Fatal(err)
}
var caps []string
for _, decl := range parsedFile.Decls {
decl, ok := decl.(*ast.GenDecl)
if !ok || decl.Tok != token.CONST {
continue
}
for _, spec := range decl.Specs {
vspec := spec.(*ast.ValueSpec)
name := vspec.Names[0].Name
if strings.HasPrefix(name, "CAP_") {
caps = append(caps, name)
}
}
}
g := &generator{caps: caps}
g.writeHeader()
g.writeStringFunc()
g.writeListFunc()
src, err := format.Source(g.buf.Bytes())
if err != nil {
fmt.Println("generated invalid Go code")
fmt.Println(g.buf.String())
log.Fatal(err)
}
fi, err := os.Stat(fileName)
if err != nil {
log.Fatal(err)
}
if err := ioutil.WriteFile(genName, src, fi.Mode().Perm()); err != nil {
log.Fatal(err)
}
}
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