Golang GenDecl.Lparen方法代码示例

func constDecl(kind token.Token, args ...string) *ast.GenDecl {
	decl := ast.GenDecl{Tok: token.CONST}

	if len(args)%3 != 0 {
		panic("Number of values passed to ConstString must be a multiple of 3")
	}
	for i := 0; i < len(args); i += 3 {
		name, typ, val := args[i], args[i+1], args[i+2]
		lit := &ast.BasicLit{Kind: kind}
		if kind == token.STRING {
			lit.Value = strconv.Quote(val)
		} else {
			lit.Value = val
		}
		a := &ast.ValueSpec{
			Names:  []*ast.Ident{ast.NewIdent(name)},
			Values: []ast.Expr{lit},
		}
		if typ != "" {
			a.Type = ast.NewIdent(typ)
		}
		decl.Specs = append(decl.Specs, a)
	}

	if len(decl.Specs) > 1 {
		decl.Lparen = 1
	}

	return &decl
}

// addImport adds the import path to the file f, if absent.
func addImport(f *ast.File, path string) {
	if imports(f, path) {
		return
	}

	newImport := &ast.ImportSpec{
		Path: &ast.BasicLit{
			Kind:  token.STRING,
			Value: strconv.Quote(path),
		},
	}

	var impdecl *ast.GenDecl

	// Find an import decl to add to.
	for _, decl := range f.Decls {
		gen, ok := decl.(*ast.GenDecl)

		if ok && gen.Tok == token.IMPORT {
			impdecl = gen
			break
		}
	}

	// No import decl found.  Add one.
	if impdecl == nil {
		impdecl = &ast.GenDecl{
			Tok: token.IMPORT,
		}
		f.Decls = append(f.Decls, nil)
		copy(f.Decls[1:], f.Decls)
		f.Decls[0] = impdecl
	}

	// Ensure the import decl has parentheses, if needed.
	if len(impdecl.Specs) > 0 && !impdecl.Lparen.IsValid() {
		impdecl.Lparen = impdecl.Pos()
	}

	// Assume the import paths are alphabetically ordered.
	// If they are not, the result is ugly, but legal.
	insertAt := len(impdecl.Specs) // default to end of specs
	for i, spec := range impdecl.Specs {
		impspec := spec.(*ast.ImportSpec)
		if importPath(impspec) > path {
			insertAt = i
			break
		}
	}

	impdecl.Specs = append(impdecl.Specs, nil)
	copy(impdecl.Specs[insertAt+1:], impdecl.Specs[insertAt:])
	impdecl.Specs[insertAt] = newImport

	f.Imports = append(f.Imports, newImport)
}

// importsToDecl turns Lisp import into Go AST
func importsToDecl(specs []ast.Spec) ast.Decl {
	s := ast.GenDecl{
		Doc:   genComment(),
		Tok:   token.IMPORT,
		Specs: specs,
	}
	// https://godoc.org/go/ast#GenDecl
	// A valid Lparen position (Lparen.Line > 0) indicates a parenthesized declaration.
	s.Lparen = 1
	return &s
}

//.........这里部分代码省略.........
			}
		}
	}

	// If no import decl found, add one after the last import.
	if impDecl == nil {
		impDecl = &ast.GenDecl{
			Tok: token.IMPORT,
		}
		if lastImport >= 0 {
			impDecl.TokPos = f.Decls[lastImport].End()
		} else {
			// There are no existing imports.
			// Our new import goes after the package declaration and after
			// the comment, if any, that starts on the same line as the
			// package declaration.
			impDecl.TokPos = f.Package

			file := fset.File(f.Package)
			pkgLine := file.Line(f.Package)
			for _, c := range f.Comments {
				if file.Line(c.Pos()) > pkgLine {
					break
				}
				impDecl.TokPos = c.End()
			}
		}
		f.Decls = append(f.Decls, nil)
		copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
		f.Decls[lastImport+1] = impDecl
	}

	// Insert new import at insertAt.
	insertAt := 0
	if impIndex >= 0 {
		// insert after the found import
		insertAt = impIndex + 1
	}
	impDecl.Specs = append(impDecl.Specs, nil)
	copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
	impDecl.Specs[insertAt] = newImport
	pos := impDecl.Pos()
	if insertAt > 0 {
		// If there is a comment after an existing import, preserve the comment
		// position by adding the new import after the comment.
		if spec, ok := impDecl.Specs[insertAt-1].(*ast.ImportSpec); ok && spec.Comment != nil {
			pos = spec.Comment.End()
		} else {
			// Assign same position as the previous import,
			// so that the sorter sees it as being in the same block.
			pos = impDecl.Specs[insertAt-1].Pos()
		}
	}
	if newImport.Name != nil {
		newImport.Name.NamePos = pos
	}
	newImport.Path.ValuePos = pos
	newImport.EndPos = pos

	// Clean up parens. impDecl contains at least one spec.
	if len(impDecl.Specs) == 1 {
		// Remove unneeded parens.
		impDecl.Lparen = token.NoPos
	} else if !impDecl.Lparen.IsValid() {
		// impDecl needs parens added.
		impDecl.Lparen = impDecl.Specs[0].Pos()
	}

	f.Imports = append(f.Imports, newImport)

	if len(f.Decls) <= 1 {
		return true
	}

	// Merge all the import declarations into the first one.
	var first *ast.GenDecl
	for i := 0; i < len(f.Decls); i++ {
		decl := f.Decls[i]
		gen, ok := decl.(*ast.GenDecl)
		if !ok || gen.Tok != token.IMPORT || declImports(gen, "C") {
			continue
		}
		if first == nil {
			first = gen
			continue // Don't touch the first one.
		}
		// We now know there is more than one package in this import
		// declaration. Ensure that it ends up parenthesized.
		first.Lparen = first.Pos()
		// Move the imports of the other import declaration to the first one.
		for _, spec := range gen.Specs {
			spec.(*ast.ImportSpec).Path.ValuePos = first.Pos()
			first.Specs = append(first.Specs, spec)
		}
		f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
		i--
	}

	return true
}

func imp(fset *token.FileSet, af *ast.File, toggle []ImportDeclArg) *ast.File {
	add := map[ImportDecl]bool{}
	del := map[ImportDecl]bool{}
	for _, sda := range toggle {
		sd := ImportDecl{
			Path: sda.Path,
			Name: sda.Name,
		}
		if sda.Add {
			add[sd] = true
		} else {
			del[sd] = true
		}
	}

	var firstDecl *ast.GenDecl
	imports := map[ImportDecl]bool{}
	for _, decl := range af.Decls {
		if gdecl, ok := decl.(*ast.GenDecl); ok && len(gdecl.Specs) > 0 {
			hasC := false
			sj := 0
			for _, spec := range gdecl.Specs {
				if ispec, ok := spec.(*ast.ImportSpec); ok {
					sd := ImportDecl{
						Path: unquote(ispec.Path.Value),
					}
					if ispec.Name != nil {
						sd.Name = ispec.Name.String()
					}

					if sd.Path == "C" {
						hasC = true
					} else if del[sd] {
						if sj > 0 {
							if lspec, ok := gdecl.Specs[sj-1].(*ast.ImportSpec); ok {
								lspec.EndPos = ispec.Pos()
							}
						}
						continue
					} else {
						imports[sd] = true
					}
				}

				gdecl.Specs[sj] = spec
				sj += 1
			}
			gdecl.Specs = gdecl.Specs[:sj]

			if !hasC && firstDecl == nil {
				firstDecl = gdecl
			}
		}
	}

	if len(add) > 0 {
		if firstDecl == nil {
			firstDecl = &ast.GenDecl{
				Tok:    token.IMPORT,
				Lparen: 1,
			}
			af.Decls = append(af.Decls, firstDecl)
		} else if firstDecl.Lparen == token.NoPos {
			firstDecl.Lparen = 1
		}

		for sd, _ := range add {
			if !imports[sd] {
				ispec := &ast.ImportSpec{
					Path: &ast.BasicLit{
						Value: quote(sd.Path),
						Kind:  token.STRING,
					},
				}
				if sd.Name != "" {
					ispec.Name = &ast.Ident{
						Name: sd.Name,
					}
				}
				firstDecl.Specs = append(firstDecl.Specs, ispec)
				imports[sd] = true
			}
		}
	}

	dj := 0
	for _, decl := range af.Decls {
		if gdecl, ok := decl.(*ast.GenDecl); ok {
			if len(gdecl.Specs) == 0 {
				continue
			}
		}
		af.Decls[dj] = decl
		dj += 1
	}
	af.Decls = af.Decls[:dj]

	ast.SortImports(fset, af)
	return af
}

// 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
	}
//.........这里部分代码省略.........

// addImport adds the import path to the file f, if absent.
func addImport(f *ast.File, ipath string) (added bool) {
	if imports(f, ipath) {
		return false
	}

	// Determine name of import.
	// Assume added imports follow convention of using last element.
	_, name := path.Split(ipath)

	// Rename any conflicting top-level references from name to name_.
	renameTop(f, name, name+"_")

	newImport := &ast.ImportSpec{
		Path: &ast.BasicLit{
			Kind:  token.STRING,
			Value: strconv.Quote(ipath),
		},
	}

	// Find an import decl to add to.
	var (
		bestMatch  = -1
		lastImport = -1
		impDecl    *ast.GenDecl
		impIndex   = -1
	)
	for i, decl := range f.Decls {
		gen, ok := decl.(*ast.GenDecl)
		if ok && gen.Tok == token.IMPORT {
			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 {
		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()
	}

	f.Imports = append(f.Imports, newImport)
	return true
}