/
imports.go
371 lines (332 loc) · 9.38 KB
/
imports.go
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// Copyright 2013 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 astutil contains common utilities for working with the Go AST.
package astutil // import "golang.org/x/tools/astutil"
import (
"bufio"
"bytes"
"fmt"
"go/ast"
"go/format"
"go/parser"
"go/token"
"log"
"strconv"
"strings"
)
// AddImport adds the import path to the file f, if absent.
func AddImport(fset *token.FileSet, f *ast.File, ipath string) (added bool) {
return AddNamedImport(fset, f, "", ipath)
}
// AddNamedImport adds the import path to the file f, if absent.
// If name is not empty, it is used to rename the import.
//
// For example, calling
// AddNamedImport(fset, f, "pathpkg", "path")
// adds
// import pathpkg "path"
func AddNamedImport(fset *token.FileSet, f *ast.File, name, ipath string) (added bool) {
if imports(f, ipath) {
return false
}
newImport := &ast.ImportSpec{
Path: &ast.BasicLit{
Kind: token.STRING,
Value: strconv.Quote(ipath),
},
}
if name != "" {
newImport.Name = &ast.Ident{Name: name}
}
// Find an import decl to add to.
var (
bestMatch = -1
lastImport = -1
impDecl *ast.GenDecl
impIndex = -1
hasImports = false
)
for i, decl := range f.Decls {
gen, ok := decl.(*ast.GenDecl)
if ok && gen.Tok == token.IMPORT {
hasImports = true
lastImport = i
// Do not add to import "C", to avoid disrupting the
// association with its doc comment, breaking cgo.
if declImports(gen, "C") {
continue
}
// Compute longest shared prefix with imports in this block.
for j, spec := range gen.Specs {
impspec := spec.(*ast.ImportSpec)
n := matchLen(importPath(impspec), ipath)
if n > bestMatch {
bestMatch = n
impDecl = gen
impIndex = j
}
}
}
}
// If no import decl found, add one after the last import.
if impDecl == nil {
// TODO(bradfitz): remove this hack. See comment below on
// addImportViaSourceModification.
if !hasImports {
f2, err := addImportViaSourceModification(fset, f, name, ipath)
if err == nil {
*f = *f2
return true
}
log.Printf("addImportViaSourceModification error: %v", err)
}
// TODO(bradfitz): fix above and resume using this old code:
impDecl = &ast.GenDecl{
Tok: token.IMPORT,
}
f.Decls = append(f.Decls, nil)
copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
f.Decls[lastImport+1] = impDecl
}
// Ensure the import decl has parentheses, if needed.
if len(impDecl.Specs) > 0 && !impDecl.Lparen.IsValid() {
impDecl.Lparen = impDecl.Pos()
}
insertAt := impIndex + 1
if insertAt == 0 {
insertAt = len(impDecl.Specs)
}
impDecl.Specs = append(impDecl.Specs, nil)
copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
impDecl.Specs[insertAt] = newImport
if insertAt > 0 {
// Assign same position as the previous import,
// so that the sorter sees it as being in the same block.
prev := impDecl.Specs[insertAt-1]
newImport.Path.ValuePos = prev.Pos()
newImport.EndPos = prev.Pos()
}
if len(impDecl.Specs) > 1 && impDecl.Lparen == 0 {
// set Lparen to something not zero, so the printer prints
// the full block rather just the first ImportSpec.
impDecl.Lparen = 1
}
f.Imports = append(f.Imports, newImport)
return true
}
// DeleteImport deletes the import path from the file f, if present.
func DeleteImport(fset *token.FileSet, f *ast.File, path string) (deleted bool) {
var delspecs []*ast.ImportSpec
// Find the import nodes that import path, if any.
for i := 0; i < len(f.Decls); i++ {
decl := f.Decls[i]
gen, ok := decl.(*ast.GenDecl)
if !ok || gen.Tok != token.IMPORT {
continue
}
for j := 0; j < len(gen.Specs); j++ {
spec := gen.Specs[j]
impspec := spec.(*ast.ImportSpec)
if importPath(impspec) != path {
continue
}
// We found an import spec that imports path.
// Delete it.
delspecs = append(delspecs, impspec)
deleted = true
copy(gen.Specs[j:], gen.Specs[j+1:])
gen.Specs = gen.Specs[:len(gen.Specs)-1]
// If this was the last import spec in this decl,
// delete the decl, too.
if len(gen.Specs) == 0 {
copy(f.Decls[i:], f.Decls[i+1:])
f.Decls = f.Decls[:len(f.Decls)-1]
i--
break
} else if len(gen.Specs) == 1 {
gen.Lparen = token.NoPos // drop parens
}
if j > 0 {
lastImpspec := gen.Specs[j-1].(*ast.ImportSpec)
lastLine := fset.Position(lastImpspec.Path.ValuePos).Line
line := fset.Position(impspec.Path.ValuePos).Line
// We deleted an entry but now there may be
// a blank line-sized hole where the import was.
if line-lastLine > 1 {
// There was a blank line immediately preceding the deleted import,
// so there's no need to close the hole.
// Do nothing.
} else {
// There was no blank line. Close the hole.
fset.File(gen.Rparen).MergeLine(line)
}
}
j--
}
}
// Delete them from f.Imports.
for i := 0; i < len(f.Imports); i++ {
imp := f.Imports[i]
for j, del := range delspecs {
if imp == del {
copy(f.Imports[i:], f.Imports[i+1:])
f.Imports = f.Imports[:len(f.Imports)-1]
copy(delspecs[j:], delspecs[j+1:])
delspecs = delspecs[:len(delspecs)-1]
i--
break
}
}
}
if len(delspecs) > 0 {
panic(fmt.Sprintf("deleted specs from Decls but not Imports: %v", delspecs))
}
return
}
// RewriteImport rewrites any import of path oldPath to path newPath.
func RewriteImport(fset *token.FileSet, f *ast.File, oldPath, newPath string) (rewrote bool) {
for _, imp := range f.Imports {
if importPath(imp) == oldPath {
rewrote = true
// record old End, because the default is to compute
// it using the length of imp.Path.Value.
imp.EndPos = imp.End()
imp.Path.Value = strconv.Quote(newPath)
}
}
return
}
// UsesImport reports whether a given import is used.
func UsesImport(f *ast.File, path string) (used bool) {
spec := importSpec(f, path)
if spec == nil {
return
}
name := spec.Name.String()
switch name {
case "<nil>":
// If the package name is not explicitly specified,
// make an educated guess. This is not guaranteed to be correct.
lastSlash := strings.LastIndex(path, "/")
if lastSlash == -1 {
name = path
} else {
name = path[lastSlash+1:]
}
case "_", ".":
// Not sure if this import is used - err on the side of caution.
return true
}
ast.Walk(visitFn(func(n ast.Node) {
sel, ok := n.(*ast.SelectorExpr)
if ok && isTopName(sel.X, name) {
used = true
}
}), f)
return
}
type visitFn func(node ast.Node)
func (fn visitFn) Visit(node ast.Node) ast.Visitor {
fn(node)
return fn
}
// imports returns true if f imports path.
func imports(f *ast.File, path string) bool {
return importSpec(f, path) != nil
}
// importSpec returns the import spec if f imports path,
// or nil otherwise.
func importSpec(f *ast.File, path string) *ast.ImportSpec {
for _, s := range f.Imports {
if importPath(s) == path {
return s
}
}
return nil
}
// importPath returns the unquoted import path of s,
// or "" if the path is not properly quoted.
func importPath(s *ast.ImportSpec) string {
t, err := strconv.Unquote(s.Path.Value)
if err == nil {
return t
}
return ""
}
// declImports reports whether gen contains an import of path.
func declImports(gen *ast.GenDecl, path string) bool {
if gen.Tok != token.IMPORT {
return false
}
for _, spec := range gen.Specs {
impspec := spec.(*ast.ImportSpec)
if importPath(impspec) == path {
return true
}
}
return false
}
// matchLen returns the length of the longest prefix shared by x and y.
func matchLen(x, y string) int {
i := 0
for i < len(x) && i < len(y) && x[i] == y[i] {
i++
}
return i
}
// isTopName returns true if n is a top-level unresolved identifier with the given name.
func isTopName(n ast.Expr, name string) bool {
id, ok := n.(*ast.Ident)
return ok && id.Name == name && id.Obj == nil
}
// Imports returns the file imports grouped by paragraph.
func Imports(fset *token.FileSet, f *ast.File) [][]*ast.ImportSpec {
var groups [][]*ast.ImportSpec
for _, decl := range f.Decls {
genDecl, ok := decl.(*ast.GenDecl)
if !ok || genDecl.Tok != token.IMPORT {
break
}
group := []*ast.ImportSpec{}
var lastLine int
for _, spec := range genDecl.Specs {
importSpec := spec.(*ast.ImportSpec)
pos := importSpec.Path.ValuePos
line := fset.Position(pos).Line
if lastLine > 0 && pos > 0 && line-lastLine > 1 {
groups = append(groups, group)
group = []*ast.ImportSpec{}
}
group = append(group, importSpec)
lastLine = line
}
groups = append(groups, group)
}
return groups
}
// NOTE(bradfitz): this is a bit of a hack for golang.org/issue/6884
// because we can't get the comment positions correct. Instead of modifying
// the AST, we print it, modify the text, and re-parse it. Gross.
func addImportViaSourceModification(fset *token.FileSet, f *ast.File, name, ipath string) (*ast.File, error) {
var buf bytes.Buffer
if err := format.Node(&buf, fset, f); err != nil {
return nil, fmt.Errorf("Error formatting ast.File node: %v", err)
}
var out bytes.Buffer
sc := bufio.NewScanner(bytes.NewReader(buf.Bytes()))
didAdd := false
for sc.Scan() {
ln := sc.Text()
out.WriteString(ln)
out.WriteByte('\n')
if !didAdd && strings.HasPrefix(ln, "package ") {
fmt.Fprintf(&out, "\nimport %s %q\n\n", name, ipath)
didAdd = true
}
}
if err := sc.Err(); err != nil {
return nil, err
}
return parser.ParseFile(fset, "", out.Bytes(), parser.ParseComments)
}