internal/api/api.go - website - Git at Google

 // Copyright 2018 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.

 // This file caches information about which standard library types, methods,
 // and functions appeared in what version of Go

 package api

 import (
 	"bufio"
 	"io/fs"
 	"path"
 	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
 	"unicode"
 )

 // DB is a map of packages to information about those packages'
 // symbols and when they were added to Go.
 //
 // Only things added after Go1 are tracked. Version strings are of the
 // form "1.1", "1.2", etc.
 type DB map[string]PkgDB // keyed by Go package ("net/http")

 // PkgDB contains information about which version of Go added
 // certain package symbols.
 //
 // Only things added after Go1 are tracked. Version strings are of the
 // form "1.1", "1.2", etc.
 type PkgDB struct {
 	Type   map[string]string            // "Server" -> "1.7"
 	Method map[string]map[string]string // "*Server" ->"Shutdown"->1.8
 	Func   map[string]string            // "NewServer" -> "1.7"
 	Field  map[string]map[string]string // "ClientTrace" -> "Got1xxResponse" -> "1.11"
 }

 // Func returns a string (such as "1.7") specifying which Go
 // version introduced a symbol, unless it was introduced in Go1, in
 // which case it returns the empty string.
 //
 // The kind is one of "type", "method", or "func".
 //
 // The receiver is only used for "methods" and specifies the receiver type,
 // such as "*Server".
 //
 // The name is the symbol name ("Server") and the pkg is the package
 // ("net/http").
 func (v DB) Func(pkg, kind, receiver, name string) string {
 	pv := v[pkg]
 	switch kind {
 	case "func":
 		return pv.Func[name]
 	case "type":
 		return pv.Type[name]
 	case "method":
 		return pv.Method[receiver][name]
 	}
 	return ""
 }

 // Load loads a database from fsys's api/go*.txt files.
 // Typically, fsys should be the root of a Go repository (a $GOROOT).
 func Load(fsys fs.FS) (DB, error) {
 	files, err := fs.Glob(fsys, "api/go*.txt")
 	if err != nil {
 		return nil, err
 	}

 	// Process files in go1.n, go1.n-1, ..., go1.2, go1.1, go1 order.
 	//
 	// It's rare, but the signature of an identifier may change
 	// (for example, a function that accepts a type replaced with
 	// an alias), and so an existing symbol may show up again in
 	// a later api/go1.N.txt file. Parsing in reverse version
 	// order means we end up with the earliest version of Go
 	// when the symbol was added. See golang.org/issue/44081.
 	//
 	ver := func(name string) int {
 		base := path.Base(name)
 		ver := strings.TrimPrefix(strings.TrimSuffix(base, ".txt"), "go1.")
 		if ver == "go1" {
 			return 0
 		}
 		v, _ := strconv.Atoi(ver)
 		return v
 	}
 	sort.Slice(files, func(i, j int) bool { return ver(files[i]) > ver(files[j]) })
 	vp := new(parser)
 	for _, f := range files {
 		if err := vp.parseFile(fsys, f); err != nil {
 			return nil, err
 		}
 	}
 	return vp.res, nil
 }

 // parser parses $GOROOT/api/go*.txt files and stores them in its rows field.
 type parser struct {
 	res DB // initialized lazily
 }

 // parseFile parses the named $GOROOT/api/goVERSION.txt file.
 //
 // For each row, it updates the corresponding entry in
 // vp.res to VERSION, overwriting any previous value.
 // As a special case, if goVERSION is "go1", it deletes
 // from the map instead.
 func (vp *parser) parseFile(fsys fs.FS, name string) error {
 	f, err := fsys.Open(name)
 	if err != nil {
 		return err
 	}
 	defer f.Close()

 	base := filepath.Base(name)
 	ver := strings.TrimPrefix(strings.TrimSuffix(base, ".txt"), "go")

 	sc := bufio.NewScanner(f)
 	for sc.Scan() {
 		row, ok := parseRow(sc.Text())
 		if !ok {
 			continue
 		}
 		if vp.res == nil {
 			vp.res = make(DB)
 		}
 		pkgi, ok := vp.res[row.pkg]
 		if !ok {
 			pkgi = PkgDB{
 				Type:   make(map[string]string),
 				Method: make(map[string]map[string]string),
 				Func:   make(map[string]string),
 				Field:  make(map[string]map[string]string),
 			}
 			vp.res[row.pkg] = pkgi
 		}
 		switch row.kind {
 		case "func":
 			if ver == "1" {
 				delete(pkgi.Func, row.name)
 				break
 			}
 			pkgi.Func[row.name] = ver
 		case "type":
 			if ver == "1" {
 				delete(pkgi.Type, row.name)
 				break
 			}
 			pkgi.Type[row.name] = ver
 		case "method":
 			if ver == "1" {
 				delete(pkgi.Method[row.recv], row.name)
 				break
 			}
 			if _, ok := pkgi.Method[row.recv]; !ok {
 				pkgi.Method[row.recv] = make(map[string]string)
 			}
 			pkgi.Method[row.recv][row.name] = ver
 		case "field":
 			if ver == "1" {
 				delete(pkgi.Field[row.structName], row.name)
 				break
 			}
 			if _, ok := pkgi.Field[row.structName]; !ok {
 				pkgi.Field[row.structName] = make(map[string]string)
 			}
 			pkgi.Field[row.structName][row.name] = ver
 		}
 	}
 	return sc.Err()
 }

 // row represents an API feature, a parsed line of a
 // $GOROOT/api/go.*txt file.
 type row struct {
 	pkg        string // "net/http"
 	kind       string // "type", "func", "method", "field" TODO: "const", "var"
 	recv       string // for methods, the receiver type ("Server", "*Server")
 	name       string // name of type, (struct) field, func, method
 	structName string // for struct fields, the outer struct name
 }

 func parseRow(s string) (vr row, ok bool) {
 	if !strings.HasPrefix(s, "pkg ") {
 		// Skip comments, blank lines, etc.
 		return
 	}
 	rest := s[len("pkg "):]
 	endPkg := strings.IndexFunc(rest, func(r rune) bool { return !(unicode.IsLetter(r) || r == '/' || unicode.IsDigit(r)) })
 	if endPkg == -1 {
 		return
 	}
 	vr.pkg, rest = rest[:endPkg], rest[endPkg:]
 	if !strings.HasPrefix(rest, ", ") {
 		// If the part after the pkg name isn't ", ", then it's a OS/ARCH-dependent line of the form:
 		//   pkg syscall (darwin-amd64), const ImplementsGetwd = false
 		// We skip those for now.
 		return
 	}
 	rest = rest[len(", "):]

 	switch {
 	case strings.HasPrefix(rest, "type "):
 		rest = rest[len("type "):]
 		sp := strings.IndexByte(rest, ' ')
 		if sp == -1 {
 			return
 		}
 		vr.name, rest = rest[:sp], rest[sp+1:]
 		if !strings.HasPrefix(rest, "struct, ") {
 			vr.kind = "type"
 			return vr, true
 		}
 		rest = rest[len("struct, "):]
 		if i := strings.IndexByte(rest, ' '); i != -1 {
 			vr.kind = "field"
 			vr.structName = vr.name
 			vr.name = rest[:i]
 			return vr, true
 		}
 	case strings.HasPrefix(rest, "func "):
 		vr.kind = "func"
 		rest = rest[len("func "):]
 		if i := strings.IndexByte(rest, '('); i != -1 {
 			vr.name = rest[:i]
 			return vr, true
 		}
 	case strings.HasPrefix(rest, "method "): // "method (*File) SetModTime(time.Time)"
 		vr.kind = "method"
 		rest = rest[len("method "):] // "(*File) SetModTime(time.Time)"
 		sp := strings.IndexByte(rest, ' ')
 		if sp == -1 {
 			return
 		}
 		vr.recv = strings.Trim(rest[:sp], "()") // "*File"
 		rest = rest[sp+1:]                      // SetMode(os.FileMode)
 		paren := strings.IndexByte(rest, '(')
 		if paren == -1 {
 			return
 		}
 		vr.name = rest[:paren]
 		return vr, true
 	}
 	return // TODO: handle more cases
 }
	// Copyright 2018 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.

	// This file caches information about which standard library types, methods,
	// and functions appeared in what version of Go

	package api

	import (
	"bufio"
	"io/fs"
	"path"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"unicode"
	)

	// DB is a map of packages to information about those packages'
	// symbols and when they were added to Go.
	//
	// Only things added after Go1 are tracked. Version strings are of the
	// form "1.1", "1.2", etc.
	type DB map[string]PkgDB // keyed by Go package ("net/http")

	// PkgDB contains information about which version of Go added
	// certain package symbols.
	//
	// Only things added after Go1 are tracked. Version strings are of the
	// form "1.1", "1.2", etc.
	type PkgDB struct {
	Type map[string]string // "Server" -> "1.7"
	Method map[string]map[string]string // "*Server" ->"Shutdown"->1.8
	Func map[string]string // "NewServer" -> "1.7"
	Field map[string]map[string]string // "ClientTrace" -> "Got1xxResponse" -> "1.11"
	}

	// Func returns a string (such as "1.7") specifying which Go
	// version introduced a symbol, unless it was introduced in Go1, in
	// which case it returns the empty string.
	//
	// The kind is one of "type", "method", or "func".
	//
	// The receiver is only used for "methods" and specifies the receiver type,
	// such as "*Server".
	//
	// The name is the symbol name ("Server") and the pkg is the package
	// ("net/http").
	func (v DB) Func(pkg, kind, receiver, name string) string {
	pv := v[pkg]
	switch kind {
	case "func":
	return pv.Func[name]
	case "type":
	return pv.Type[name]
	case "method":
	return pv.Method[receiver][name]
	}
	return ""
	}

	// Load loads a database from fsys's api/go*.txt files.
	// Typically, fsys should be the root of a Go repository (a $GOROOT).
	func Load(fsys fs.FS) (DB, error) {
	files, err := fs.Glob(fsys, "api/go*.txt")
	if err != nil {
	return nil, err
	}

	// Process files in go1.n, go1.n-1, ..., go1.2, go1.1, go1 order.
	//
	// It's rare, but the signature of an identifier may change
	// (for example, a function that accepts a type replaced with
	// an alias), and so an existing symbol may show up again in
	// a later api/go1.N.txt file. Parsing in reverse version
	// order means we end up with the earliest version of Go
	// when the symbol was added. See golang.org/issue/44081.
	//
	ver := func(name string) int {
	base := path.Base(name)
	ver := strings.TrimPrefix(strings.TrimSuffix(base, ".txt"), "go1.")
	if ver == "go1" {
	return 0
	}
	v, _ := strconv.Atoi(ver)
	return v
	}
	sort.Slice(files, func(i, j int) bool { return ver(files[i]) > ver(files[j]) })
	vp := new(parser)
	for _, f := range files {
	if err := vp.parseFile(fsys, f); err != nil {
	return nil, err
	}
	}
	return vp.res, nil
	}

	// parser parses $GOROOT/api/go*.txt files and stores them in its rows field.
	type parser struct {
	res DB // initialized lazily
	}

	// parseFile parses the named $GOROOT/api/goVERSION.txt file.
	//
	// For each row, it updates the corresponding entry in
	// vp.res to VERSION, overwriting any previous value.
	// As a special case, if goVERSION is "go1", it deletes
	// from the map instead.
	func (vp *parser) parseFile(fsys fs.FS, name string) error {
	f, err := fsys.Open(name)
	if err != nil {
	return err
	}
	defer f.Close()

	base := filepath.Base(name)
	ver := strings.TrimPrefix(strings.TrimSuffix(base, ".txt"), "go")

	sc := bufio.NewScanner(f)
	for sc.Scan() {
	row, ok := parseRow(sc.Text())
	if !ok {
	continue
	}
	if vp.res == nil {
	vp.res = make(DB)
	}
	pkgi, ok := vp.res[row.pkg]
	if !ok {
	pkgi = PkgDB{
	Type: make(map[string]string),
	Method: make(map[string]map[string]string),
	Func: make(map[string]string),
	Field: make(map[string]map[string]string),
	}
	vp.res[row.pkg] = pkgi
	}
	switch row.kind {
	case "func":
	if ver == "1" {
	delete(pkgi.Func, row.name)
	break
	}
	pkgi.Func[row.name] = ver
	case "type":
	if ver == "1" {
	delete(pkgi.Type, row.name)
	break
	}
	pkgi.Type[row.name] = ver
	case "method":
	if ver == "1" {
	delete(pkgi.Method[row.recv], row.name)
	break
	}
	if _, ok := pkgi.Method[row.recv]; !ok {
	pkgi.Method[row.recv] = make(map[string]string)
	}
	pkgi.Method[row.recv][row.name] = ver
	case "field":
	if ver == "1" {
	delete(pkgi.Field[row.structName], row.name)
	break
	}
	if _, ok := pkgi.Field[row.structName]; !ok {
	pkgi.Field[row.structName] = make(map[string]string)
	}
	pkgi.Field[row.structName][row.name] = ver
	}
	}
	return sc.Err()
	}

	// row represents an API feature, a parsed line of a
	// $GOROOT/api/go.*txt file.
	type row struct {
	pkg string // "net/http"
	kind string // "type", "func", "method", "field" TODO: "const", "var"
	recv string // for methods, the receiver type ("Server", "*Server")
	name string // name of type, (struct) field, func, method
	structName string // for struct fields, the outer struct name
	}

	func parseRow(s string) (vr row, ok bool) {
	if !strings.HasPrefix(s, "pkg ") {
	// Skip comments, blank lines, etc.
	return
	}
	rest := s[len("pkg "):]
	endPkg := strings.IndexFunc(rest, func(r rune) bool { return !(unicode.IsLetter(r) \|\| r == '/' \|\| unicode.IsDigit(r)) })
	if endPkg == -1 {
	return
	}
	vr.pkg, rest = rest[:endPkg], rest[endPkg:]
	if !strings.HasPrefix(rest, ", ") {
	// If the part after the pkg name isn't ", ", then it's a OS/ARCH-dependent line of the form:
	// pkg syscall (darwin-amd64), const ImplementsGetwd = false
	// We skip those for now.
	return
	}
	rest = rest[len(", "):]

	switch {
	case strings.HasPrefix(rest, "type "):
	rest = rest[len("type "):]
	sp := strings.IndexByte(rest, ' ')
	if sp == -1 {
	return
	}
	vr.name, rest = rest[:sp], rest[sp+1:]
	if !strings.HasPrefix(rest, "struct, ") {
	vr.kind = "type"
	return vr, true
	}
	rest = rest[len("struct, "):]
	if i := strings.IndexByte(rest, ' '); i != -1 {
	vr.kind = "field"
	vr.structName = vr.name
	vr.name = rest[:i]
	return vr, true
	}
	case strings.HasPrefix(rest, "func "):
	vr.kind = "func"
	rest = rest[len("func "):]
	if i := strings.IndexByte(rest, '('); i != -1 {
	vr.name = rest[:i]
	return vr, true
	}
	case strings.HasPrefix(rest, "method "): // "method (*File) SetModTime(time.Time)"
	vr.kind = "method"
	rest = rest[len("method "):] // "(*File) SetModTime(time.Time)"
	sp := strings.IndexByte(rest, ' ')
	if sp == -1 {
	return
	}
	vr.recv = strings.Trim(rest[:sp], "()") // "*File"
	rest = rest[sp+1:] // SetMode(os.FileMode)
	paren := strings.IndexByte(rest, '(')
	if paren == -1 {
	return
	}
	vr.name = rest[:paren]
	return vr, true
	}
	return // TODO: handle more cases
	}