feat(ps-gen): create param set generator (#6)

Author: plastikfan

.golangci.yml

@@ -69,8 +69,6 @@ linters:
         linters:
           - revive
         text: 'dot-imports'
-      # errcheck: We need to temporarily disable checking of auto generated
-      # code, until the new generator has been created
       - path: '-auto\.go'
         linters:
           - errcheck

.vscode/settings.json

@@ -71,6 +71,7 @@
     "stylecheck",
     "subosito",
     "thelper",
+    "tmpl",
     "toplevel",
     "tparallel",
     "typecheck",

Taskfile.yml

@@ -146,6 +146,12 @@ tasks:
       - go tool cover -html=./coverage.out -o {{.COVER_HTML_PATH}}
       - open {{.COVER_HTML_PATH}}
 
+  # === ps-gen (param set generator) =========================
+
+  ps-gen:
+    cmds:
+      - go run ./cmd/ps-gen/main.go
+
   # === i18n =================================================
 
   clear:

assist/param-set-auto.go

@@ -0,0 +1,245 @@
+// ps-gen generates the file param-set-auto.go which contains all the
+// Bind* methods on ParamSet[N]. To regenerate, run:
+//
+//	go run ./cmd/ps-gen/main.go
+//
+// The output is written to: assist/param-set-auto.go
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/format"
+	"log"
+	"os"
+	"text/template"
+)
+
+// outputPath is the destination file relative to the working directory from
+// which you invoke `go run`.  Adjust this to match your repository layout.
+const outputPath = "assist/param-set-auto.go"
+
+// typeSpec describes a single Bind* method (or Bind*Slice pair).
+type typeSpec struct {
+	// GoType is the Go type name used in the method signature, e.g. "bool",
+	// "int32", "net.IPMask".
+	GoType string
+
+	// FlagType is the pflag method suffix, e.g. "Bool", "Int32", "IPMask".
+	// For BindEnum this differs from the method name.
+	FlagType string
+
+	// MethodName overrides the generated Bind<MethodName> name when it differs
+	// from FlagType (only needed for BindEnum).
+	MethodName string
+
+	// HasSlice indicates whether a Bind*Slice variant should also be generated.
+	HasSlice bool
+
+	// SliceGoType overrides the slice element type when it differs from GoType
+	// (not currently needed, but kept for extensibility).
+	SliceGoType string
+
+	// Comment is the doc-comment body (the part after "binds ").
+	Comment string
+
+	// SliceComment is the doc-comment body for the slice variant.
+	SliceComment string
+}
+
+func (s typeSpec) Resolve() typeSpec {
+	if s.MethodName == "" {
+		s.MethodName = s.FlagType
+	}
+	if s.SliceGoType == "" {
+		s.SliceGoType = s.GoType
+	}
+	return s
+}
+
+var specs = []typeSpec{
+	{
+		GoType:       "bool",
+		FlagType:     "Bool",
+		HasSlice:     true,
+		Comment:      "bool slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]bool slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:       "time.Duration",
+		FlagType:     "Duration",
+		HasSlice:     true,
+		Comment:      "time.Duration slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]time.Duration slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:     "string",
+		FlagType:   "String",
+		MethodName: "Enum",
+		HasSlice:   false,
+		Comment:    "enum slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:       "float32",
+		FlagType:     "Float32",
+		HasSlice:     true,
+		Comment:      "float32 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]float32 slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:       "float64",
+		FlagType:     "Float64",
+		HasSlice:     true,
+		Comment:      "float64 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]float64 slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:       "int",
+		FlagType:     "Int",
+		HasSlice:     true,
+		Comment:      "int slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]int slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:   "int16",
+		FlagType: "Int16",
+		HasSlice: false,
+		Comment:  "int16 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:       "int32",
+		FlagType:     "Int32",
+		HasSlice:     true,
+		Comment:      "int32 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]int32 slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:       "int64",
+		FlagType:     "Int64",
+		HasSlice:     true,
+		Comment:      "int64 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]int64 slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:   "int8",
+		FlagType: "Int8",
+		HasSlice: false,
+		Comment:  "int8 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:   "net.IPMask",
+		FlagType: "IPMask",
+		HasSlice: false,
+		Comment:  "net.IPMask slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:   "net.IPNet",
+		FlagType: "IPNet",
+		HasSlice: false,
+		Comment:  "net.IPNet slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:       "string",
+		FlagType:     "String",
+		HasSlice:     true,
+		Comment:      "string slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]string slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+	{
+		GoType:   "uint16",
+		FlagType: "Uint16",
+		HasSlice: false,
+		Comment:  "uint16 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:   "uint32",
+		FlagType: "Uint32",
+		HasSlice: false,
+		Comment:  "uint32 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:   "uint64",
+		FlagType: "Uint64",
+		HasSlice: false,
+		Comment:  "uint64 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:   "uint8",
+		FlagType: "Uint8",
+		HasSlice: false,
+		Comment:  "uint8 slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+	},
+	{
+		GoType:       "uint",
+		FlagType:     "Uint",
+		HasSlice:     true,
+		Comment:      "uint slice flag with a shorthand if\n// 'info.Short' has been set otherwise binds without a short name.",
+		SliceComment: "[]uint slice flag with a shorthand if 'info.Short' has been set\n// otherwise binds without a short name.",
+	},
+}
+
+const tmplSrc = `// Code generated by gen-param-set; DO NOT EDIT.
+
+package assist
+
+import (
+	"net"
+	"time"
+)
+{{range .}}{{$s := .}}
+// Bind{{$s.MethodName}} binds {{$s.Comment}}
+func (params *ParamSet[N]) Bind{{$s.MethodName}}(info *FlagInfo, to *{{$s.GoType}}) *ParamSet[N] {
+	flagSet := params.ResolveFlagSet(info)
+	if info.Short == "" {
+		flagSet.{{$s.FlagType}}Var(to, info.FlagName(), info.Default.({{$s.GoType}}), info.Usage)
+	} else {
+		flagSet.{{$s.FlagType}}VarP(to, info.FlagName(), info.Short, info.Default.({{$s.GoType}}), info.Usage)
+	}
+
+	return params
+}
+{{if $s.HasSlice}}
+// Bind{{$s.MethodName}}Slice binds {{$s.SliceComment}}
+func (params *ParamSet[N]) Bind{{$s.MethodName}}Slice(info *FlagInfo, to *[]{{$s.SliceGoType}}) *ParamSet[N] {
+	flagSet := params.ResolveFlagSet(info)
+	if info.Short == "" {
+		flagSet.{{$s.FlagType}}SliceVar(to, info.FlagName(), info.Default.([]{{$s.SliceGoType}}), info.Usage)
+	} else {
+		flagSet.{{$s.FlagType}}SliceVarP(to, info.FlagName(), info.Short, info.Default.([]{{$s.SliceGoType}}), info.Usage)
+	}
+
+	return params
+}
+{{end}}{{end}}`
+
+func main() {
+	// Resolve all specs (fill in derived fields).
+	resolved := make([]typeSpec, len(specs))
+	for i, s := range specs {
+		resolved[i] = s.Resolve()
+	}
+
+	tmpl, err := template.New("param-set-auto").Parse(tmplSrc)
+	if err != nil {
+		log.Fatalf("parse template: %v", err)
+	}
+
+	var buf bytes.Buffer
+	if err = tmpl.Execute(&buf, resolved); err != nil {
+		log.Fatalf("execute template: %v", err)
+	}
+
+	// Run through gofmt so the output is canonical.
+	formatted, err := format.Source(buf.Bytes())
+	if err != nil {
+		// Emit the raw output to make debugging easier.
+		fmt.Fprintf(os.Stderr, "--- raw output ---\n%s\n--- end ---\n", buf.String())
+		log.Fatalf("gofmt: %v", err)
+	}
+
+	if err := os.WriteFile(outputPath, formatted, 0o644); err != nil { //nolint:gosec // ok
+		log.Fatalf("write %s: %v", outputPath, err)
+	}
+
+	fmt.Printf("wrote %s\n", outputPath)
+}