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Copy pathversions.go
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265 lines (248 loc) · 7.44 KB
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// 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 godoc
import (
"bufio"
"go/build"
"log"
"os"
"path/filepath"
"sort"
"strconv"
"strings"
"unicode"
)
// apiVersions 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 apiVersions map[string]pkgAPIVersions // keyed by Go package ("net/http")
// pkgAPIVersions 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 pkgAPIVersions struct {
typeSince map[string]string // "Server" -> "1.7"
methodSince map[string]map[string]string // "*Server" ->"Shutdown"->1.8
funcSince map[string]string // "NewServer" -> "1.7"
fieldSince map[string]map[string]string // "ClientTrace" -> "Got1xxResponse" -> "1.11"
}
// sinceVersionFunc 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 apiVersions) sinceVersionFunc(kind, receiver, name, pkg string) string {
pv := v[pkg]
switch kind {
case "func":
return pv.funcSince[name]
case "type":
return pv.typeSince[name]
case "method":
return pv.methodSince[receiver][name]
}
return ""
}
// versionedRow represents an API feature, a parsed line of a
// $GOROOT/api/go.*txt file.
type versionedRow 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
}
// versionParser parses $GOROOT/api/go*.txt files and stores them in in its rows field.
type versionParser struct {
res apiVersions // 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 *versionParser) parseFile(name string) error {
f, err := os.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(apiVersions)
}
pkgi, ok := vp.res[row.pkg]
if !ok {
pkgi = pkgAPIVersions{
typeSince: make(map[string]string),
methodSince: make(map[string]map[string]string),
funcSince: make(map[string]string),
fieldSince: make(map[string]map[string]string),
}
vp.res[row.pkg] = pkgi
}
switch row.kind {
case "func":
if ver == "1" {
delete(pkgi.funcSince, row.name)
break
}
pkgi.funcSince[row.name] = ver
case "type":
if ver == "1" {
delete(pkgi.typeSince, row.name)
break
}
pkgi.typeSince[row.name] = ver
case "method":
if ver == "1" {
delete(pkgi.methodSince[row.recv], row.name)
break
}
if _, ok := pkgi.methodSince[row.recv]; !ok {
pkgi.methodSince[row.recv] = make(map[string]string)
}
pkgi.methodSince[row.recv][row.name] = ver
case "field":
if ver == "1" {
delete(pkgi.fieldSince[row.structName], row.name)
break
}
if _, ok := pkgi.fieldSince[row.structName]; !ok {
pkgi.fieldSince[row.structName] = make(map[string]string)
}
pkgi.fieldSince[row.structName][row.name] = ver
}
}
return sc.Err()
}
func parseRow(s string) (vr versionedRow, 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
}
// InitVersionInfo parses the $GOROOT/api/go*.txt API definition files to discover
// which API features were added in which Go releases.
func (c *Corpus) InitVersionInfo() {
var err error
c.pkgAPIInfo, err = parsePackageAPIInfo()
if err != nil {
// TODO: consider making this fatal, after the Go 1.11 cycle.
log.Printf("godoc: error parsing API version files: %v", err)
}
}
func parsePackageAPIInfo() (apiVersions, error) {
var apiGlob string
if os.Getenv("GOROOT") == "" {
apiGlob = filepath.Join(build.Default.GOROOT, "api", "go*.txt")
} else {
apiGlob = filepath.Join(os.Getenv("GOROOT"), "api", "go*.txt")
}
files, err := filepath.Glob(apiGlob)
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 := filepath.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(versionParser)
for _, f := range files {
if err := vp.parseFile(f); err != nil {
return nil, err
}
}
return vp.res, nil
}