Golang GenDecl.Pos方法代码示例

// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) genDecl(d *ast.GenDecl, multiLine *bool) {
	p.setComment(d.Doc)
	p.print(d.Pos(), d.Tok, blank)

	if d.Lparen.IsValid() {
		// group of parenthesized declarations
		p.print(d.Lparen, token.LPAREN)
		if len(d.Specs) > 0 {
			p.print(indent, formfeed)
			var ml bool
			for i, s := range d.Specs {
				if i > 0 {
					p.linebreak(s.Pos().Line, 1, ignore, ml)
				}
				ml = false
				p.spec(s, len(d.Specs), false, &ml)
			}
			p.print(unindent, formfeed)
			*multiLine = true
		}
		p.print(d.Rparen, token.RPAREN)

	} else {
		// single declaration
		p.spec(d.Specs[0], 1, true, multiLine)
	}
}

// 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)
}

func genSnippet(fset *token.FileSet, d *ast.GenDecl, id *ast.Ident) *Snippet {
	s := findSpec(d.Specs, id)
	if s == nil {
		return nil //  declaration doesn't contain id - exit gracefully
	}

	// only use the spec containing the id for the snippet
	dd := &ast.GenDecl{d.Doc, d.Pos(), d.Tok, d.Lparen, []ast.Spec{s}, d.Rparen}

	return newSnippet(fset, dd, id)
}

func isEmpty(f *ast.File, g *ast.GenDecl) bool {
	if g.Doc != nil || g.Specs != nil {
		return false
	}

	for _, c := range f.Comments {
		// if there is a comment in the declaration, it is not considered empty
		if g.Pos() <= c.Pos() && c.End() <= g.End() {
			return false
		}
	}

	return true
}

func (p *printer) genDecl(d *ast.GenDecl) {
	p.setComment(d.Doc)
	p.print(d.Pos(), d.Tok, blank)

	if d.Lparen.IsValid() {
		// group of parenthesized declarations
		p.print(d.Lparen, token.LPAREN)
		if n := len(d.Specs); n > 0 {
			p.print(indent, formfeed)
			if n > 1 && (d.Tok == token.CONST || d.Tok == token.VAR) {
				// two or more grouped const/var declarations:
				// determine if the type column must be kept
				keepType := keepTypeColumn(d.Specs)
				var line int
				for i, s := range d.Specs {
					if i > 0 {
						p.linebreak(p.lineFor(s.Pos()), 1, ignore, p.linesFrom(line) > 0)
					}
					p.recordLine(&line)
					switch t := s.(type) {
					case *ast.AliasSpec:
						p.aliasSpec(t, keepType[i])

					case *ast.ValueSpec:
						p.valueSpec(t, keepType[i])

					default:
						p.internalError("unknown ast.Spec type: %T", t)
					}
				}
			} else {
				var line int
				for i, s := range d.Specs {
					if i > 0 {
						p.linebreak(p.lineFor(s.Pos()), 1, ignore, p.linesFrom(line) > 0)
					}
					p.recordLine(&line)
					p.spec(s, n, false)
				}
			}
			p.print(unindent, formfeed)
		}
		p.print(d.Rparen, token.RPAREN)

	} else {
		// single declaration
		p.spec(d.Specs[0], 1, true)
	}
}

// assocInitvals associates "inherited" initialization expressions
// with the corresponding *ast.ValueSpec in the check.initexprs map
// for constant declarations without explicit initialization expressions.
//
func (check *checker) assocInitvals(decl *ast.GenDecl) {
	var values []ast.Expr
	for _, s := range decl.Specs {
		if s, ok := s.(*ast.ValueSpec); ok {
			if len(s.Values) > 0 {
				values = s.Values
			} else {
				check.initexprs[s] = values
			}
		}
	}
	if len(values) == 0 {
		check.invalidAST(decl.Pos(), "no initialization values provided")
	}
}

// assocInitvals associates "inherited" initialization expressions
// with the corresponding *ast.ValueSpec in the check.initspecs map
// for constant declarations without explicit initialization expressions.
//
func (check *checker) assocInitvals(decl *ast.GenDecl) {
	var last *ast.ValueSpec
	for _, s := range decl.Specs {
		if s, ok := s.(*ast.ValueSpec); ok {
			if len(s.Values) > 0 {
				last = s
			} else {
				check.initspecs[s] = last
			}
		}
	}
	if last == nil {
		check.invalidAST(decl.Pos(), "no initialization values provided")
	}
}

func (p *Presentation) genSnippet(fset *token.FileSet, d *ast.GenDecl, id *ast.Ident) *Snippet {
	s := findSpec(d.Specs, id)
	if s == nil {
		return nil //  declaration doesn't contain id - exit gracefully
	}

	// only use the spec containing the id for the snippet
	dd := &ast.GenDecl{
		Doc:    d.Doc,
		TokPos: d.Pos(),
		Tok:    d.Tok,
		Lparen: d.Lparen,
		Specs:  []ast.Spec{s},
		Rparen: d.Rparen,
	}

	return p.newSnippet(fset, dd, id)
}

// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) genDecl(d *ast.GenDecl, multiLine *bool) {
	p.setComment(d.Doc)
	p.print(d.Pos(), d.Tok, blank)

	if d.Lparen.IsValid() {
		// group of parenthesized declarations
		p.print(d.Lparen, token.LPAREN)
		if n := len(d.Specs); n > 0 {
			p.print(indent, formfeed)
			if n > 1 && (d.Tok == token.CONST || d.Tok == token.VAR) {
				// two or more grouped const/var declarations:
				// determine if the type column must be kept
				keepType := keepTypeColumn(d.Specs)
				var ml bool
				for i, s := range d.Specs {
					if i > 0 {
						p.linebreak(p.fset.Position(s.Pos()).Line, 1, ignore, ml)
					}
					ml = false
					p.valueSpec(s.(*ast.ValueSpec), keepType[i], false, &ml)
				}
			} else {
				var ml bool
				for i, s := range d.Specs {
					if i > 0 {
						p.linebreak(p.fset.Position(s.Pos()).Line, 1, ignore, ml)
					}
					ml = false
					p.spec(s, n, false, &ml)
				}
			}
			p.print(unindent, formfeed)
			*multiLine = true
		}
		p.print(d.Rparen, token.RPAREN)

	} else {
		// single declaration
		p.spec(d.Specs[0], 1, true, multiLine)
	}
}

func (p *printer) genDecl(d *ast.GenDecl) {
	p.setComment(d.Doc)
	p.print(d.Pos(), d.Tok, blank)

	if d.Lparen.IsValid() {
		// group of parenthesized declarations
		p.print(d.Lparen, token.LPAREN)
		if n := len(d.Specs); n > 0 {
			p.print(indent, formfeed)
			if n > 1 && (d.Tok == token.CONST || d.Tok == token.VAR) {
				// two or more grouped const/var declarations:
				// determine if the type column must be kept
				keepType := keepTypeColumn(d.Specs)
				newSection := false
				for i, s := range d.Specs {
					if i > 0 {
						p.linebreak(p.lineFor(s.Pos()), 1, ignore, newSection)
					}
					p.valueSpec(s.(*ast.ValueSpec), keepType[i], false)
					newSection = p.isMultiLine(s)
				}
			} else {
				newSection := false
				for i, s := range d.Specs {
					if i > 0 {
						p.linebreak(p.lineFor(s.Pos()), 1, ignore, newSection)
					}
					p.spec(s, n, false)
					newSection = p.isMultiLine(s)
				}
			}
			p.print(unindent, formfeed)
		}
		p.print(d.Rparen, token.RPAREN)

	} else {
		// single declaration
		p.spec(d.Specs[0], 1, true)
	}
}

// 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.
	// The goal is to find an existing import
	// whose import path has the longest shared
	// prefix with ipath.
	var (
		bestMatch  = -1         // length of longest shared prefix
		lastImport = -1         // index in f.Decls of the file's final import decl
		impDecl    *ast.GenDecl // import decl containing the best match
		impIndex   = -1         // spec index in impDecl containing the best match
	)
	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
			}

			// Match an empty import decl if that's all that is available.
			if len(gen.Specs) == 0 && bestMatch == -1 {
				impDecl = gen
			}

			// Compute longest shared prefix with imports in this group.
			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,
		}
		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
//.........这里部分代码省略.........

// 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
}