golang filter 代码
文件路径：/src/go/ast/filter.go
/ Copyright 2009 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.
package ast
import (
"go/token"
"sort"
)
/ ----------------------------------------------------------------------------
/ Export filtering
/ exportFilter is a special filter function to extract exported nodes.
func exportFilter(name string) bool {
return IsExported(name)
}
/ FileExports trims the AST for a Go source file in place such that
/ only exported nodes remain: all top-level identifiers which are not exported
/ and their associated information (such as type, initial value, or function
/ body) are removed. Non-exported fields and methods of exported types are
/ stripped. The File.Comments list is not changed.
/
/ FileExports reports whether there are exported declarations.
func FileExports(src *File) bool {
return filterFile(src, exportFilter, true)
}
/ PackageExports trims the AST for a Go package in place such that
/ only exported nodes remain. The pkg.Files list is not changed, so that
/ file names and top-level package comments don't get lost.
/
/ PackageExports reports whether there are exported declarations;
/ it returns false otherwise.
func PackageExports(pkg *Package) bool {
return filterPackage(pkg, exportFilter, true)
}
/ ----------------------------------------------------------------------------
/ General filtering
type Filter func(string) bool
func filterIdentList(list []*Ident, f Filter) []*Ident {
j := 0
for _, x := range list {
if f(x.Name) {
list[j] = x
j++
}
}
return list[0:j]
}
/ fieldName assumes that x is the type of an anonymous field and
/ returns the corresponding field name. If x is not an acceptable
/ anonymous field, the result is nil.
func fieldName(x Expr) *Ident {
switch t := x.(type) {
case *Ident:
return t
case *SelectorExpr:
if _, ok := t.X.(*Ident); ok {
return t.Sel
}
case *StarExpr:
return fieldName(t.X)
}
return nil
}
func filterFieldList(fields *FieldList, filter Filter, export bool) (removedFields bool) {
if fields == nil {
return false
}
list := fields.List
j := 0
for _, f := range list {
keepField := false
if len(f.Names) == 0 {
/ anonymous field
name := fieldName(f.Type)
keepField = name != nil && filter(name.Name)
} else {
n := len(f.Names)
f.Names = filterIdentList(f.Names, filter)
if len(f.Names) < n {
removedFields = true
}
keepField = len(f.Names) > 0
}
if keepField {
if export {
filterType(f.Type, filter, export)
}
list[j] = f
j++
}
}
if j < len(list) {
removedFields = true
}
fields.List = list[0:j]
return
}
func filterCompositeLit(lit *CompositeLit, filter Filter, export bool) {
n := len(lit.Elts)
lit.Elts = filterExprList(lit.Elts, filter, export)
if len(lit.Elts) < n {
lit.Incomplete = true
}
}
func filterExprList(list []Expr, filter Filter, export bool) []Expr {
j := 0
for _, exp := range list {
switch x := exp.(type) {
case *CompositeLit:
filterCompositeLit(x, filter, export)
case *KeyValueExpr:
if x, ok := x.Key.(*Ident); ok && !filter(x.Name) {
continue
}
if x, ok := x.Value.(*CompositeLit); ok {
filterCompositeLit(x, filter, export)
}
}
list[j] = exp
j++
}
return list[0:j]
}
func filterParamList(fields *FieldList, filter Filter, export bool) bool {
if fields == nil {
return false
}
var b bool
for _, f := range fields.List {
if filterType(f.Type, filter, export) {
b = true
}
}
return b
}
func filterType(typ Expr, f Filter, export bool) bool {
switch t := typ.(type) {
case *Ident:
return f(t.Name)
case *ParenExpr:
return filterType(t.X, f, export)
case *ArrayType:
return filterType(t.Elt, f, export)
case *StructType:
if filterFieldList(t.Fields, f, export) {
t.Incomplete = true
}
return len(t.Fields.List) > 0
case *FuncType:
b1 := filterParamList(t.Params, f, export)
b2 := filterParamList(t.Results, f, export)
return b1 || b2
case *InterfaceType:
if filterFieldList(t.Methods, f, export) {
t.Incomplete = true
}
return len(t.Methods.List) > 0
case *MapType:
b1 := filterType(t.Key, f, export)
b2 := filterType(t.Value, f, export)
return b1 || b2
case *ChanType:
return filterType(t.Value, f, export)
}
return false
}
func filterSpec(spec Spec, f Filter, export bool) bool {
switch s := spec.(type) {
case *ValueSpec:
s.Names = filterIdentList(s.Names, f)
s.Values = filterExprList(s.Values, f, export)
if len(s.Names) > 0 {
if export {
filterType(s.Type, f, export)
}
return true
}
case *TypeSpec:
if f(s.Name.Name) {
if export {
filterType(s.Type, f, export)
}
return true
}
if !export {
/ For general filtering (not just exports),
/ filter type even if name is not filtered
/ out.
/ If the type contains filtered elements,
/ keep the declaration.
return filterType(s.Type, f, export)
}
}
return false
}
func filterSpecList(list []Spec, f Filter, export bool) []Spec {
j := 0
for _, s := range list {
if filterSpec(s, f, export) {
list[j] = s
j++
}
}
return list[0:j]
}
/ FilterDecl trims the AST for a Go declaration in place by removing
/ all names (including struct field and interface method names, but
/ not from parameter lists) that don't pass through the filter f.
/
/ FilterDecl reports whether there are any declared names left after
/ filtering.
func FilterDecl(decl Decl, f Filter) bool {
return filterDecl(decl, f, false)
}
func filterDecl(decl Decl, f Filter, export bool) bool {
switch d := decl.(type) {
case *GenDecl:
d.Specs = filterSpecList(d.Specs, f, export)
return len(d.Specs) > 0
case *FuncDecl:
return f(d.Name.Name)
}
return false
}
/ FilterFile trims the AST for a Go file in place by removing all
/ names from top-level declarations (including struct field and
/ interface method names, but not from parameter lists) that don't
/ pass through the filter f. If the declaration is empty afterwards,
/ the declaration is removed from the AST. Import declarations are
/ always removed. The File.Comments list is not changed.
/
/ FilterFile reports whether there are any top-level declarations
/ left after filtering.
func FilterFile(src *File, f Filter) bool {
return filterFile(src, f, false)
}
func filterFile(src *File, f Filter, export bool) bool {
j := 0
for _, d := range src.Decls {
if filterDecl(d, f, export) {
src.Decls[j] = d
j++
}
}
src.Decls = src.Decls[0:j]
return j > 0
}
/ FilterPackage trims the AST for a Go package in place by removing
/ all names from top-level declarations (including struct field and
/ interface method names, but not from parameter lists) that don't
/ pass through the filter f. If the declaration is empty afterwards,
/ the declaration is removed from the AST. The pkg.Files list is not
/ changed, so that file names and top-level package comments don't get
/ lost.
/
/ FilterPackage reports whether there are any top-level declarations
/ left after filtering.
func FilterPackage(pkg *Package, f Filter) bool {
return filterPackage(pkg, f, false)
}
func filterPackage(pkg *Package, f Filter, export bool) bool {
hasDecls := false
for _, src := range pkg.Files {
if filterFile(src, f, export) {
hasDecls = true
}
}
return hasDecls
}
/ ----------------------------------------------------------------------------
/ Merging of package files
/ The MergeMode flags control the behavior of MergePackageFiles.
type MergeMode uint
const (
/ If set, duplicate function declarations are excluded.
FilterFuncDuplicates MergeMode = 1 << iota
/ If set, comments that are not associated with a specific
/ AST node (as Doc or Comment) are excluded.
FilterUnassociatedComments
/ If set, duplicate import declarations are excluded.
FilterImportDuplicates
)
/ nameOf returns the function (foo) or method name (foo.bar) for
/ the given function declaration. If the AST is incorrect for the
/ receiver, it assumes a function instead.
func nameOf(f *FuncDecl) string {
if r := f.Recv; r != nil && len(r.List) == 1 {
/ looks like a correct receiver declaration
t := r.List[0].Type
/ dereference pointer receiver types
if p, _ := t.(*StarExpr); p != nil {
t = p.X
}
/ the receiver type must be a type name
if p, _ := t.(*Ident); p != nil {
return p.Name + "." + f.Name.Name
}
/ otherwise assume a function instead
}
return f.Name.Name
}
/ separator is an empty /-style comment that is interspersed between
/ different comment groups when they are concatenated into a single group
var separator = &Comment{token.NoPos, "/"}
/ MergePackageFiles creates a file AST by merging the ASTs of the
/ files belonging to a package. The mode flags control merging behavior.
func MergePackageFiles(pkg *Package, mode MergeMode) *File {
/ Count the number of package docs, comments and declarations across
/ all package files. Also, compute sorted list of filenames, so that
/ subsequent iterations can always iterate in the same order.
ndocs := 0
ncomments := 0
ndecls := 0
filenames := make([]string, len(pkg.Files))
i := 0
for filename, f := range pkg.Files {
filenames[i] = filename
i++
if f.Doc != nil {
ndocs += len(f.Doc.List) + 1 / +1 for separator
}
ncomments += len(f.Comments)
ndecls += len(f.Decls)
}
sort.Strings(filenames)
/ Collect package comments from all package files into a single
/ CommentGroup - the collected package documentation. In general
/ there should be only one file with a package comment; but it's
/ better to collect extra comments than drop them on the floor.
var doc *CommentGroup
var pos token.Pos
if ndocs > 0 {
list := make([]*Comment, ndocs-1) / -1: no separator before first group
i := 0
for _, filename := range filenames {
f := pkg.Files[filename]
if f.Doc != nil {
if i > 0 {
/ not the first group - add separator
list[i] = separator
i++
}
for _, c := range f.Doc.List {
list[i] = c
i++
}
if f.Package > pos {
/ Keep the maximum package clause position as
/ position for the package clause of the merged
/ files.
pos = f.Package
}
}
}
doc = &CommentGroup{list}
}
/ Collect declarations from all package files.
var decls []Decl
if ndecls > 0 {
decls = make([]Decl, ndecls)
funcs := make(map[string]int) / map of func name -> decls index
i := 0 / current index
n := 0 / number of filtered entries
for _, filename := range filenames {
f := pkg.Files[filename]
for _, d := range f.Decls {
if mode&FilterFuncDuplicates != 0 {
/ A language entity may be declared multiple
/ times in different package files; only at
/ build time declarations must be unique.
/ For now, exclude multiple declarations of
/ functions - keep the one with documentation.
/
/ TODO(gri): Expand this filtering to other
/ entities (const, type, vars) if
/ multiple declarations are common.
if f, isFun := d.(*FuncDecl); isFun {
name := nameOf(f)
if j, exists := funcs[name]; exists {
/ function declared already
if decls[j] != nil && decls[j].(*FuncDecl).Doc == nil {
/ existing declaration has no documentation;
/ ignore the existing declaration
decls[j] = nil
} else {
/ ignore the new declaration
d = nil
}
n++ / filtered an entry
} else {
funcs[name] = i
}
}
}
decls[i] = d
i++
}
}
/ Eliminate nil entries from the decls list if entries were
/ filtered. We do this using a 2nd pass in order to not disturb
/ the original declaration order in the source (otherwise, this
/ would also invalidate the monotonically increasing position
/ info within a single file).
if n > 0 {
i = 0
for _, d := range decls {
if d != nil {
decls[i] = d
i++
}
}
decls = decls[0:i]
}
}
/ Collect import specs from all package files.
var imports []*ImportSpec
if mode&FilterImportDuplicates != 0 {
seen := make(map[string]bool)
for _, filename := range filenames {
f := pkg.Files[filename]
for _, imp := range f.Imports {
if path := imp.Path.Value; !seen[path] {
/ TODO: consider handling cases where:
/ - 2 imports exist with the same import path but
/ have different local names (one should probably
/ keep both of them)
/ - 2 imports exist but only one has a comment
/ - 2 imports exist and they both have (possibly
/ different) comments
imports = append(imports, imp)
seen[path] = true
}
}
}
} else {
/ Iterate over filenames for deterministic order.
for _, filename := range filenames {
f := pkg.Files[filename]
imports = append(imports, f.Imports...)
}
}
/ Collect comments from all package files.
var comments []*CommentGroup
if mode&FilterUnassociatedComments == 0 {
comments = make([]*CommentGroup, ncomments)
i := 0
for _, filename := range filenames {
f := pkg.Files[filename]
i += copy(comments[i:], f.Comments)
}
}
/ TODO(gri) need to compute unresolved identifiers!
return &File{doc, pos, NewIdent(pkg.Name), decls, pkg.Scope, imports, nil, comments}
}