/
codegen.go
418 lines (371 loc) · 11.9 KB
/
codegen.go
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// Package main is a tool to automate the creation of code init function.
// Inspired by `github.com/golang/tools/cmd/stringer`.
package main
import (
"bytes"
"flag"
"fmt"
"go/ast"
"go/constant"
"go/format"
"go/token"
"go/types"
"html/template"
"io/ioutil"
"log"
"os"
"path/filepath"
"regexp"
"strings"
"golang.org/x/tools/go/packages"
)
var errCodeDocPrefix = `# 错误码
错误码列表,由 {{.}}codegen -type=int -doc{{.}} 命令生成,不要对此文件做任何更改。
## 错误码列表
错误码列表如下:
| Identifier | Code | HTTP Code | Description |
| ---------- | ---- | --------- | ----------- |
`
var (
typeNames = flag.String("type", "", "comma-separated list of type names; must be set")
output = flag.String("output", "", "output file name; default srcdir/<type>_string.go")
trimprefix = flag.String("trimprefix", "", "trim the `prefix` from the generated constant names")
buildTags = flag.String("tags", "", "comma-separated list of build tags to apply")
doc = flag.Bool("doc", false, "if true only generate error code documentation in markdown format")
)
// Usage is a replacement usage function for the flags package.
func Usage() {
fmt.Fprintf(os.Stderr, "Usage of codegen:\n")
fmt.Fprintf(os.Stderr, "\tcodegen [flags] -type T [directory]\n")
fmt.Fprintf(os.Stderr, "\tcodegen [flags] -type T files... # Must be a single package\n")
fmt.Fprintf(os.Stderr, "Flags:\n")
flag.PrintDefaults()
}
func main() {
log.SetFlags(0)
log.SetPrefix("codegen: ")
flag.Usage = Usage
flag.Parse()
if len(*typeNames) == 0 {
flag.Usage()
os.Exit(2)
}
types := strings.Split(*typeNames, ",")
var tags []string
if len(*buildTags) > 0 {
tags = strings.Split(*buildTags, ",")
}
// We accept either one directory or a list of files. Which do we have?
args := flag.Args()
if len(args) == 0 {
// Default: process whole package in current directory.
args = []string{"."}
}
// Parse the package once.
var dir string
g := Generator{
trimPrefix: *trimprefix,
}
// TODO(suzmue): accept other patterns for packages (directories, list of files, import paths, etc).
if len(args) == 1 && isDirectory(args[0]) {
dir = args[0]
} else {
if len(tags) != 0 {
log.Fatal("-tags option applies only to directories, not when files are specified")
}
dir = filepath.Dir(args[0])
}
g.parsePackage(args, tags)
if !*doc {
// Print the header and package clause.
g.Printf("// Code generated by \"codegen %s\"; DO NOT EDIT.\n", strings.Join(os.Args[1:], " "))
g.Printf("\n")
g.Printf("package %s", g.pkg.name)
g.Printf("\n")
}
// Run generate for each type.
var src []byte
for _, typeName := range types {
if *doc {
g.generateDocs(typeName)
src = g.buf.Bytes()
} else {
g.generate(typeName)
// Format the output.
src = g.format()
}
}
// Write to file.
outputName := *output
if outputName == "" {
absDir, _ := filepath.Abs(dir)
baseName := fmt.Sprintf("%s_generated.go", strings.ReplaceAll(filepath.Base(absDir), "-", "_"))
if len(flag.Args()) == 1 {
baseName = fmt.Sprintf(
"%s_generated.go",
strings.ReplaceAll(filepath.Base(strings.TrimSuffix(flag.Args()[0], ".go")), "-", "_"),
)
}
outputName = filepath.Join(dir, strings.ToLower(baseName))
}
err := ioutil.WriteFile(outputName, src, 0o600)
if err != nil {
log.Fatalf("writing output: %s", err)
}
}
// isDirectory reports whether the named file is a directory.
func isDirectory(name string) bool {
info, err := os.Stat(name)
if err != nil {
log.Fatal(err)
}
return info.IsDir()
}
// Generator holds the state of the analysis. Primarily used to buffer
// the output for format.Source.
type Generator struct {
buf bytes.Buffer // Accumulated output.
pkg *Package // Package we are scanning.
trimPrefix string
}
// Printf like fmt.Printf, but add the string to g.buf.
func (g *Generator) Printf(format string, args ...interface{}) {
fmt.Fprintf(&g.buf, format, args...)
}
// File holds a single parsed file and associated data.
type File struct {
pkg *Package // Package to which this file belongs.
file *ast.File // Parsed AST.
// These fields are reset for each type being generated.
typeName string // Name of the constant type.
values []Value // Accumulator for constant values of that type.
trimPrefix string
}
// Package defines options for package.
type Package struct {
name string
defs map[*ast.Ident]types.Object
files []*File
}
// parsePackage analyzes the single package constructed from the patterns and tags.
// parsePackage exits if there is an error.
func (g *Generator) parsePackage(patterns []string, tags []string) {
cfg := &packages.Config{
// nolint: staticcheck
Mode: packages.LoadSyntax,
// TODO: Need to think about constants in test files. Maybe write type_string_test.go
// in a separate pass? For later.
Tests: false,
BuildFlags: []string{fmt.Sprintf("-tags=%s", strings.Join(tags, " "))},
}
pkgs, err := packages.Load(cfg, patterns...)
if err != nil {
log.Fatal(err)
}
if len(pkgs) != 1 {
log.Fatalf("error: %d packages found", len(pkgs))
}
g.addPackage(pkgs[0])
}
// addPackage adds a type checked Package and its syntax files to the generator.
func (g *Generator) addPackage(pkg *packages.Package) {
g.pkg = &Package{
name: pkg.Name,
defs: pkg.TypesInfo.Defs,
files: make([]*File, len(pkg.Syntax)),
}
for i, file := range pkg.Syntax {
g.pkg.files[i] = &File{
file: file,
pkg: g.pkg,
trimPrefix: g.trimPrefix,
}
}
}
// generate produces the register calls for the named type.
func (g *Generator) generate(typeName string) {
values := make([]Value, 0, 100)
for _, file := range g.pkg.files {
// Set the state for this run of the walker.
file.typeName = typeName
file.values = nil
if file.file != nil {
ast.Inspect(file.file, file.genDecl)
values = append(values, file.values...)
}
}
if len(values) == 0 {
log.Fatalf("no values defined for type %s", typeName)
}
// Generate code that will fail if the constants change value.
g.Printf("func init() {\n")
for _, v := range values {
code, description := v.ParseComment()
g.Printf("\tregister(%s, %s, \"%s\")\n", v.originalName, code, description)
}
g.Printf("}\n")
}
// generateDocs produces error code markdown document for the named type.
func (g *Generator) generateDocs(typeName string) {
values := make([]Value, 0, 100)
for _, file := range g.pkg.files {
// Set the state for this run of the walker.
file.typeName = typeName
file.values = nil
if file.file != nil {
ast.Inspect(file.file, file.genDecl)
values = append(values, file.values...)
}
}
if len(values) == 0 {
log.Fatalf("no values defined for type %s", typeName)
}
tmpl, _ := template.New("doc").Parse(errCodeDocPrefix)
var buf bytes.Buffer
_ = tmpl.Execute(&buf, "`")
// Generate code that will fail if the constants change value.
g.Printf(buf.String())
for _, v := range values {
code, description := v.ParseComment()
// g.Printf("\tregister(%s, %s, \"%s\")\n", v.originalName, code, description)
g.Printf("| %s | %d | %s | %s |\n", v.originalName, v.value, code, description)
}
g.Printf("\n")
}
// format returns the gofmt-ed contents of the Generator's buffer.
func (g *Generator) format() []byte {
src, err := format.Source(g.buf.Bytes())
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 g.buf.Bytes()
}
return src
}
// Value represents a declared constant.
type Value struct {
comment string
originalName string // The name of the constant.
name string // The name with trimmed prefix.
// The value is stored as a bit pattern alone. The boolean tells us
// whether to interpret it as an int64 or a uint64; the only place
// this matters is when sorting.
// Much of the time the str field is all we need; it is printed
// by Value.String.
value uint64 // Will be converted to int64 when needed.
signed bool // Whether the constant is a signed type.
str string // The string representation given by the "go/constant" package.
}
func (v *Value) String() string {
return v.str
}
// ParseComment parse comment to http code and error code description.
func (v *Value) ParseComment() (string, string) {
reg := regexp.MustCompile(`\w\s*-\s*(\d{3})\s*:\s*([A-Z].*)\s*\.\n*`)
if !reg.MatchString(v.comment) {
log.Printf("constant '%s' have wrong comment format, register with 500 as default", v.originalName)
return "500", "Internal server error"
}
groups := reg.FindStringSubmatch(v.comment)
if len(groups) != 3 {
return "500", "Internal server error"
}
return groups[1], groups[2]
}
// nolint: gocognit
// genDecl processes one declaration clause.
func (f *File) genDecl(node ast.Node) bool {
decl, ok := node.(*ast.GenDecl)
if !ok || decl.Tok != token.CONST {
// We only care about const declarations.
return true
}
// The name of the type of the constants we are declaring.
// Can change if this is a multi-element declaration.
typ := ""
// Loop over the elements of the declaration. Each element is a ValueSpec:
// a list of names possibly followed by a type, possibly followed by values.
// If the type and value are both missing, we carry down the type (and value,
// but the "go/types" package takes care of that).
for _, spec := range decl.Specs {
vspec, _ := spec.(*ast.ValueSpec) // Guaranteed to succeed as this is CONST.
if vspec.Type == nil && len(vspec.Values) > 0 {
// "X = 1". With no type but a value. If the constant is untyped,
// skip this vspec and reset the remembered type.
typ = ""
// If this is a simple type conversion, remember the type.
// We don't mind if this is actually a call; a qualified call won't
// be matched (that will be SelectorExpr, not Ident), and only unusual
// situations will result in a function call that appears to be
// a type conversion.
ce, ok := vspec.Values[0].(*ast.CallExpr)
if !ok {
continue
}
id, ok := ce.Fun.(*ast.Ident)
if !ok {
continue
}
typ = id.Name
}
if vspec.Type != nil {
// "X T". We have a type. Remember it.
ident, ok := vspec.Type.(*ast.Ident)
if !ok {
continue
}
typ = ident.Name
}
if typ != f.typeName {
// This is not the type we're looking for.
continue
}
// We now have a list of names (from one line of source code) all being
// declared with the desired type.
// Grab their names and actual values and store them in f.values.
for _, name := range vspec.Names {
if name.Name == "_" {
continue
}
// This dance lets the type checker find the values for us. It's a
// bit tricky: look up the object declared by the name, find its
// types.Const, and extract its value.
obj, ok := f.pkg.defs[name]
if !ok {
log.Fatalf("no value for constant %s", name)
}
info := obj.Type().Underlying().(*types.Basic).Info()
if info&types.IsInteger == 0 {
log.Fatalf("can't handle non-integer constant type %s", typ)
}
value := obj.(*types.Const).Val() // Guaranteed to succeed as this is CONST.
if value.Kind() != constant.Int {
log.Fatalf("can't happen: constant is not an integer %s", name)
}
i64, isInt := constant.Int64Val(value)
u64, isUint := constant.Uint64Val(value)
if !isInt && !isUint {
log.Fatalf("internal error: value of %s is not an integer: %s", name, value.String())
}
if !isInt {
u64 = uint64(i64)
}
v := Value{
originalName: name.Name,
value: u64,
signed: info&types.IsUnsigned == 0,
str: value.String(),
}
if vspec.Doc != nil && vspec.Doc.Text() != "" {
v.comment = vspec.Doc.Text()
} else if c := vspec.Comment; c != nil && len(c.List) == 1 {
v.comment = c.Text()
}
v.name = strings.TrimPrefix(v.originalName, f.trimPrefix)
f.values = append(f.values, v)
}
}
return false
}