--- /dev/null
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Stringer is a tool to automate the creation of methods that satisfy the fmt.Stringer
+// interface. Given the name of a (signed or unsigned) integer type T that has constants
+// defined, stringer will create a new self-contained Go source file implementing
+// func (t T) String() string
+// The file is created in the same package and directory as the package that defines T.
+// It has helpful defaults designed for use with go generate.
+//
+// Stringer works best with constants that are consecutive values such as created using iota,
+// but creates good code regardless. In the future it might also provide custom support for
+// constant sets that are bit patterns.
+//
+// For example, given this snippet,
+//
+// package painkiller
+//
+// type Pill int
+//
+// const (
+// Placebo Pill = iota
+// Aspirin
+// Ibuprofen
+// Paracetamol
+// Acetaminophen = Paracetamol
+// )
+//
+// running this command
+//
+// stringer -type=Pill
+//
+// in the same directory will create the file pill_string.go, in package painkiller,
+// containing a definition of
+//
+// func (Pill) String() string
+//
+// That method will translate the value of a Pill constant to the string representation
+// of the respective constant name, so that the call fmt.Print(painkiller.Aspirin) will
+// print the string "Aspirin".
+//
+// Typically this process would be run using go generate, like this:
+//
+// //go:generate stringer -type=Pill
+//
+// If multiple constants have the same value, the lexically first matching name will
+// be used (in the example, Acetaminophen will print as "Paracetamol").
+//
+// With no arguments, it processes the package in the current directory.
+// Otherwise, the arguments must name a single directory holding a Go package
+// or a set of Go source files that represent a single Go package.
+//
+// The -type flag accepts a comma-separated list of types so a single run can
+// generate methods for multiple types. The default output file is t_string.go,
+// where t is the lower-cased name of the first type listed. It can be overridden
+// with the -output flag.
+//
+// The -linecomment flag tells stringer to generate the text of any line comment, trimmed
+// of leading spaces, instead of the constant name. For instance, if the constants above had a
+// Pill prefix, one could write
+//
+// PillAspirin // Aspirin
+//
+// to suppress it in the output.
+package main // import "golang.org/x/tools/cmd/stringer"
+
+import (
+ "bytes"
+ "flag"
+ "fmt"
+ "go/ast"
+ "go/constant"
+ "go/format"
+ "go/token"
+ "go/types"
+ "io/ioutil"
+ "log"
+ "os"
+ "path/filepath"
+ "sort"
+ "strings"
+
+ "golang.org/x/tools/go/packages"
+)
+
+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")
+ linecomment = flag.Bool("linecomment", false, "use line comment text as printed text when present")
+ buildTags = flag.String("tags", "", "comma-separated list of build tags to apply")
+)
+
+// Usage is a replacement usage function for the flags package.
+func Usage() {
+ fmt.Fprintf(os.Stderr, "Usage of stringer:\n")
+ fmt.Fprintf(os.Stderr, "\tstringer [flags] -type T [directory]\n")
+ fmt.Fprintf(os.Stderr, "\tstringer [flags] -type T files... # Must be a single package\n")
+ fmt.Fprintf(os.Stderr, "For more information, see:\n")
+ fmt.Fprintf(os.Stderr, "\thttp://godoc.org/golang.org/x/tools/cmd/stringer\n")
+ fmt.Fprintf(os.Stderr, "Flags:\n")
+ flag.PrintDefaults()
+}
+
+func main() {
+ log.SetFlags(0)
+ log.SetPrefix("stringer: ")
+ 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,
+ lineComment: *linecomment,
+ }
+ // 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)
+
+ // Print the header and package clause.
+ g.Printf("// Code generated by \"stringer %s\"; DO NOT EDIT.\n", strings.Join(os.Args[1:], " "))
+ g.Printf("\n")
+ g.Printf("package %s", g.pkg.name)
+ g.Printf("\n")
+ g.Printf("import \"strconv\"\n") // Used by all methods.
+
+ // Run generate for each type.
+ for _, typeName := range types {
+ g.generate(typeName)
+ }
+
+ // Format the output.
+ src := g.format()
+
+ // Write to file.
+ outputName := *output
+ if outputName == "" {
+ baseName := fmt.Sprintf("%s_string.go", types[0])
+ outputName = filepath.Join(dir, strings.ToLower(baseName))
+ }
+ err := ioutil.WriteFile(outputName, src, 0644)
+ 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
+ lineComment bool
+}
+
+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
+ lineComment bool
+}
+
+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{
+ 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,
+ lineComment: g.lineComment,
+ }
+ }
+}
+
+// generate produces the String method 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 _() {\n")
+ g.Printf("\t// An \"invalid array index\" compiler error signifies that the constant values have changed.\n")
+ g.Printf("\t// Re-run the stringer command to generate them again.\n")
+ g.Printf("\tvar x [1]struct{}\n")
+ for _, v := range values {
+ g.Printf("\t_ = x[%s - %s]\n", v.originalName, v.str)
+ }
+ g.Printf("}\n")
+ runs := splitIntoRuns(values)
+ // The decision of which pattern to use depends on the number of
+ // runs in the numbers. If there's only one, it's easy. For more than
+ // one, there's a tradeoff between complexity and size of the data
+ // and code vs. the simplicity of a map. A map takes more space,
+ // but so does the code. The decision here (crossover at 10) is
+ // arbitrary, but considers that for large numbers of runs the cost
+ // of the linear scan in the switch might become important, and
+ // rather than use yet another algorithm such as binary search,
+ // we punt and use a map. In any case, the likelihood of a map
+ // being necessary for any realistic example other than bitmasks
+ // is very low. And bitmasks probably deserve their own analysis,
+ // to be done some other day.
+ switch {
+ case len(runs) == 1:
+ g.buildOneRun(runs, typeName)
+ case len(runs) <= 10:
+ g.buildMultipleRuns(runs, typeName)
+ default:
+ g.buildMap(runs, typeName)
+ }
+}
+
+// splitIntoRuns breaks the values into runs of contiguous sequences.
+// For example, given 1,2,3,5,6,7 it returns {1,2,3},{5,6,7}.
+// The input slice is known to be non-empty.
+func splitIntoRuns(values []Value) [][]Value {
+ // We use stable sort so the lexically first name is chosen for equal elements.
+ sort.Stable(byValue(values))
+ // Remove duplicates. Stable sort has put the one we want to print first,
+ // so use that one. The String method won't care about which named constant
+ // was the argument, so the first name for the given value is the only one to keep.
+ // We need to do this because identical values would cause the switch or map
+ // to fail to compile.
+ j := 1
+ for i := 1; i < len(values); i++ {
+ if values[i].value != values[i-1].value {
+ values[j] = values[i]
+ j++
+ }
+ }
+ values = values[:j]
+ runs := make([][]Value, 0, 10)
+ for len(values) > 0 {
+ // One contiguous sequence per outer loop.
+ i := 1
+ for i < len(values) && values[i].value == values[i-1].value+1 {
+ i++
+ }
+ runs = append(runs, values[:i])
+ values = values[i:]
+ }
+ return runs
+}
+
+// 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 {
+ 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
+}
+
+// byValue lets us sort the constants into increasing order.
+// We take care in the Less method to sort in signed or unsigned order,
+// as appropriate.
+type byValue []Value
+
+func (b byValue) Len() int { return len(b) }
+func (b byValue) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
+func (b byValue) Less(i, j int) bool {
+ if b[i].signed {
+ return int64(b[i].value) < int64(b[j].value)
+ }
+ return b[i].value < b[j].value
+}
+
+// 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 c := vspec.Comment; f.lineComment && c != nil && len(c.List) == 1 {
+ v.name = strings.TrimSpace(c.Text())
+ } else {
+ v.name = strings.TrimPrefix(v.originalName, f.trimPrefix)
+ }
+ f.values = append(f.values, v)
+ }
+ }
+ return false
+}
+
+// Helpers
+
+// usize returns the number of bits of the smallest unsigned integer
+// type that will hold n. Used to create the smallest possible slice of
+// integers to use as indexes into the concatenated strings.
+func usize(n int) int {
+ switch {
+ case n < 1<<8:
+ return 8
+ case n < 1<<16:
+ return 16
+ default:
+ // 2^32 is enough constants for anyone.
+ return 32
+ }
+}
+
+// declareIndexAndNameVars declares the index slices and concatenated names
+// strings representing the runs of values.
+func (g *Generator) declareIndexAndNameVars(runs [][]Value, typeName string) {
+ var indexes, names []string
+ for i, run := range runs {
+ index, name := g.createIndexAndNameDecl(run, typeName, fmt.Sprintf("_%d", i))
+ if len(run) != 1 {
+ indexes = append(indexes, index)
+ }
+ names = append(names, name)
+ }
+ g.Printf("const (\n")
+ for _, name := range names {
+ g.Printf("\t%s\n", name)
+ }
+ g.Printf(")\n\n")
+
+ if len(indexes) > 0 {
+ g.Printf("var (")
+ for _, index := range indexes {
+ g.Printf("\t%s\n", index)
+ }
+ g.Printf(")\n\n")
+ }
+}
+
+// declareIndexAndNameVar is the single-run version of declareIndexAndNameVars
+func (g *Generator) declareIndexAndNameVar(run []Value, typeName string) {
+ index, name := g.createIndexAndNameDecl(run, typeName, "")
+ g.Printf("const %s\n", name)
+ g.Printf("var %s\n", index)
+}
+
+// createIndexAndNameDecl returns the pair of declarations for the run. The caller will add "const" and "var".
+func (g *Generator) createIndexAndNameDecl(run []Value, typeName string, suffix string) (string, string) {
+ b := new(bytes.Buffer)
+ indexes := make([]int, len(run))
+ for i := range run {
+ b.WriteString(run[i].name)
+ indexes[i] = b.Len()
+ }
+ nameConst := fmt.Sprintf("_%s_name%s = %q", typeName, suffix, b.String())
+ nameLen := b.Len()
+ b.Reset()
+ fmt.Fprintf(b, "_%s_index%s = [...]uint%d{0, ", typeName, suffix, usize(nameLen))
+ for i, v := range indexes {
+ if i > 0 {
+ fmt.Fprintf(b, ", ")
+ }
+ fmt.Fprintf(b, "%d", v)
+ }
+ fmt.Fprintf(b, "}")
+ return b.String(), nameConst
+}
+
+// declareNameVars declares the concatenated names string representing all the values in the runs.
+func (g *Generator) declareNameVars(runs [][]Value, typeName string, suffix string) {
+ g.Printf("const _%s_name%s = \"", typeName, suffix)
+ for _, run := range runs {
+ for i := range run {
+ g.Printf("%s", run[i].name)
+ }
+ }
+ g.Printf("\"\n")
+}
+
+// buildOneRun generates the variables and String method for a single run of contiguous values.
+func (g *Generator) buildOneRun(runs [][]Value, typeName string) {
+ values := runs[0]
+ g.Printf("\n")
+ g.declareIndexAndNameVar(values, typeName)
+ // The generated code is simple enough to write as a Printf format.
+ lessThanZero := ""
+ if values[0].signed {
+ lessThanZero = "i < 0 || "
+ }
+ if values[0].value == 0 { // Signed or unsigned, 0 is still 0.
+ g.Printf(stringOneRun, typeName, usize(len(values)), lessThanZero)
+ } else {
+ g.Printf(stringOneRunWithOffset, typeName, values[0].String(), usize(len(values)), lessThanZero)
+ }
+}
+
+// Arguments to format are:
+// [1]: type name
+// [2]: size of index element (8 for uint8 etc.)
+// [3]: less than zero check (for signed types)
+const stringOneRun = `func (i %[1]s) String() string {
+ if %[3]si >= %[1]s(len(_%[1]s_index)-1) {
+ return "%[1]s(" + strconv.FormatInt(int64(i), 10) + ")"
+ }
+ return _%[1]s_name[_%[1]s_index[i]:_%[1]s_index[i+1]]
+}
+`
+
+// Arguments to format are:
+// [1]: type name
+// [2]: lowest defined value for type, as a string
+// [3]: size of index element (8 for uint8 etc.)
+// [4]: less than zero check (for signed types)
+/*
+ */
+const stringOneRunWithOffset = `func (i %[1]s) String() string {
+ i -= %[2]s
+ if %[4]si >= %[1]s(len(_%[1]s_index)-1) {
+ return "%[1]s(" + strconv.FormatInt(int64(i + %[2]s), 10) + ")"
+ }
+ return _%[1]s_name[_%[1]s_index[i] : _%[1]s_index[i+1]]
+}
+`
+
+// buildMultipleRuns generates the variables and String method for multiple runs of contiguous values.
+// For this pattern, a single Printf format won't do.
+func (g *Generator) buildMultipleRuns(runs [][]Value, typeName string) {
+ g.Printf("\n")
+ g.declareIndexAndNameVars(runs, typeName)
+ g.Printf("func (i %s) String() string {\n", typeName)
+ g.Printf("\tswitch {\n")
+ for i, values := range runs {
+ if len(values) == 1 {
+ g.Printf("\tcase i == %s:\n", &values[0])
+ g.Printf("\t\treturn _%s_name_%d\n", typeName, i)
+ continue
+ }
+ if values[0].value == 0 && !values[0].signed {
+ // For an unsigned lower bound of 0, "0 <= i" would be redundant.
+ g.Printf("\tcase i <= %s:\n", &values[len(values)-1])
+ } else {
+ g.Printf("\tcase %s <= i && i <= %s:\n", &values[0], &values[len(values)-1])
+ }
+ if values[0].value != 0 {
+ g.Printf("\t\ti -= %s\n", &values[0])
+ }
+ g.Printf("\t\treturn _%s_name_%d[_%s_index_%d[i]:_%s_index_%d[i+1]]\n",
+ typeName, i, typeName, i, typeName, i)
+ }
+ g.Printf("\tdefault:\n")
+ g.Printf("\t\treturn \"%s(\" + strconv.FormatInt(int64(i), 10) + \")\"\n", typeName)
+ g.Printf("\t}\n")
+ g.Printf("}\n")
+}
+
+// buildMap handles the case where the space is so sparse a map is a reasonable fallback.
+// It's a rare situation but has simple code.
+func (g *Generator) buildMap(runs [][]Value, typeName string) {
+ g.Printf("\n")
+ g.declareNameVars(runs, typeName, "")
+ g.Printf("\nvar _%s_map = map[%s]string{\n", typeName, typeName)
+ n := 0
+ for _, values := range runs {
+ for _, value := range values {
+ g.Printf("\t%s: _%s_name[%d:%d],\n", &value, typeName, n, n+len(value.name))
+ n += len(value.name)
+ }
+ }
+ g.Printf("}\n\n")
+ g.Printf(stringMap, typeName)
+}
+
+// Argument to format is the type name.
+const stringMap = `func (i %[1]s) String() string {
+ if str, ok := _%[1]s_map[i]; ok {
+ return str
+ }
+ return "%[1]s(" + strconv.FormatInt(int64(i), 10) + ")"
+}
+`
projects / dotfiles / .git / blobdiff