Convert to templates

Signed-off-by: jolheiser <john.olheiser@gmail.com>

data/entity/gen_entity.go

@@ -6,24 +6,56 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"go/ast"
-	"go/format"
-	"go/token"
 	"net/http"
 	"os"
-	"reflect"
-	"strconv"
+	"text/template"
 
 	"github.com/iancoleman/strcase"
 )
 
 const (
 	infoURL = "https://raw.githubusercontent.com/PrismarineJS/minecraft-data/master/data/pc/1.17/entities.json"
+	//language=gohtml
+	entityTmpl = `// Code generated by gen_entity.go DO NOT EDIT.
+// Package entity stores information about entities in Minecraft.
+package entity
+// ID describes the numeric ID of an entity.
+type ID uint32
+
+// Entity describes information about a type of entity.
+type Entity struct {
+ID          ID
+InternalID  uint32
+DisplayName string
+Name        string
+Width  float64
+Height float64
+Type     string
+}
+
+var (
+	{{- range .}}
+	{{.CamelName}} = Entity{
+		ID: {{.ID}},
+		InternalID: {{.InternalID}},
+		DisplayName: "{{.DisplayName}}",
+		Name: "{{.Name}}",
+		Width: {{.Width}},
+		Height: {{.Height}},
+		Type: "{{.Type}}",
+	}{{end}}
+)
+
+// ByID is an index of minecraft entities by their ID.
+var ByID = map[ID]*Entity{ {{range .}}
+	{{.ID}}: &{{.CamelName}},{{end}}
+}`
 )
 
 type Entity struct {
 	ID          uint32 `json:"id"`
 	InternalID  uint32 `json:"internalId"`
+	CamelName   string `json:"-"`
 	DisplayName string `json:"displayName"`
 	Name        string `json:"name"`
 
@@ -33,121 +65,39 @@ type Entity struct {
 	Type string `json:"type"`
 }
 
-func downloadInfo() ([]Entity, error) {
+func downloadInfo() ([]*Entity, error) {
 	resp, err := http.Get(infoURL)
 	if err != nil {
 		return nil, err
 	}
 	defer resp.Body.Close()
 
-	var data []Entity
+	var data []*Entity
 	if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
 		return nil, err
 	}
-	return data, nil
-}
-
-func makeEntityDeclaration(entities []Entity) *ast.DeclStmt {
-	out := &ast.DeclStmt{Decl: &ast.GenDecl{Tok: token.VAR}}
-
-	for _, e := range entities {
-		t := reflect.TypeOf(e)
-		fields := make([]ast.Expr, t.NumField())
-
-		for i := 0; i < t.NumField(); i++ {
-			ft := t.Field(i)
-
-			var val ast.Expr
-			switch ft.Type.Kind() {
-			case reflect.Uint32, reflect.Int:
-				val = &ast.BasicLit{Kind: token.INT, Value: fmt.Sprint(reflect.ValueOf(e).Field(i))}
-			case reflect.Float64:
-				val = &ast.BasicLit{Kind: token.FLOAT, Value: fmt.Sprint(reflect.ValueOf(e).Field(i))}
-			case reflect.String:
-				val = &ast.BasicLit{Kind: token.STRING, Value: strconv.Quote(reflect.ValueOf(e).Field(i).String())}
-			case reflect.Bool:
-				val = &ast.BasicLit{Kind: token.IDENT, Value: fmt.Sprint(reflect.ValueOf(e).Field(i).Bool())}
-
-			case reflect.Slice:
-				val = &ast.CompositeLit{
-					Type: &ast.ArrayType{
-						Elt: &ast.BasicLit{Kind: token.IDENT, Value: ft.Type.Elem().Name()},
-					},
-				}
-				v := reflect.ValueOf(e).Field(i)
-				switch ft.Type.Elem().Kind() {
-				case reflect.Uint32, reflect.Int:
-					for x := 0; x < v.Len(); x++ {
-						val.(*ast.CompositeLit).Elts = append(val.(*ast.CompositeLit).Elts, &ast.BasicLit{
-							Kind:  token.INT,
-							Value: fmt.Sprint(v.Index(x)),
-						})
-					}
-				}
-			}
-
-			fields[i] = &ast.KeyValueExpr{
-				Key:   &ast.Ident{Name: ft.Name},
-				Value: val,
-			}
-		}
-
-		out.Decl.(*ast.GenDecl).Specs = append(out.Decl.(*ast.GenDecl).Specs, &ast.ValueSpec{
-			Names: []*ast.Ident{{Name: strcase.ToCamel(e.Name)}},
-			Values: []ast.Expr{
-				&ast.CompositeLit{
-					Type: &ast.Ident{Name: reflect.TypeOf(e).Name()},
-					Elts: fields,
-				},
-			},
-		})
+	for _, d := range data {
+		d.CamelName = strcase.ToCamel(d.Name)
 	}
-
-	return out
+	return data, nil
 }
 
 //go:generate go run $GOFILE
 //go:generate go fmt entity.go
 func main() {
+	fmt.Println("generating entity.go")
 	entities, err := downloadInfo()
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
-		os.Exit(1)
+		panic(err)
 	}
 
 	f, err := os.Create("entity.go")
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
-		os.Exit(1)
+		panic(err)
 	}
 	defer f.Close()
 
-	fmt.Fprintln(f, `// Code generated by gen_entity.go DO NOT EDIT.
-// Package entity stores information about entities in Minecraft.
-package entity
-// ID describes the numeric ID of an entity.
-type ID uint32
-
-// Entity describes information about a type of entity.
-type Entity struct {
-	ID          ID
-	InternalID  uint32
-	DisplayName string
-	Name        string
-	Width  float64
-	Height float64
-	Type     string
-}`)
-	format.Node(f, token.NewFileSet(), makeEntityDeclaration(entities))
-
-	fmt.Fprintln(f)
-	fmt.Fprintln(f)
-	fmt.Fprintln(f, "// ByID is an index of minecraft entities by their ID.")
-	fmt.Fprintln(f, "var ByID = map[ID]*Entity{")
-	for _, e := range entities {
-		fmt.Fprintf(f, "  %d: &%s,\n", e.ID, strcase.ToCamel(e.Name))
+	if err := template.Must(template.New("").Parse(entityTmpl)).Execute(f, entities); err != nil {
+		panic(err)
 	}
-	fmt.Fprintln(f, "}")
-
-	fmt.Fprintln(f)
 }