Golang ast.GenDecl类代码示例

// 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)
	}
}

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
}

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")
	}
}

// readType processes a type declaration.
//
func (r *reader) readType(decl *ast.GenDecl, spec *ast.TypeSpec) {
	typ := r.lookupType(spec.Name.Name)
	if typ == nil {
		return // no name or blank name - ignore the type
	}

	// A type should be added at most once, so typ.decl
	// should be nil - if it is not, simply overwrite it.
	typ.decl = decl

	// compute documentation
	doc := spec.Doc
	spec.Doc = nil // doc consumed - remove from AST
	if doc == nil {
		// no doc associated with the spec, use the declaration doc, if any
		doc = decl.Doc
	}
	decl.Doc = nil // doc consumed - remove from AST
	typ.doc = doc.Text()

	// record anonymous fields (they may contribute methods)
	// (some fields may have been recorded already when filtering
	// exports, but that's ok)
	var list []*ast.Field
	list, typ.isStruct = fields(spec.Type)
	for _, field := range list {
		if len(field.Names) == 0 {
			r.recordAnonymousField(typ, field.Type)
		}
	}
}

func ast_decl_split(d ast.Decl) []ast.Decl {
	var decls []ast.Decl
	if t, ok := d.(*ast.GenDecl); ok {
		decls = make([]ast.Decl, len(t.Specs))
		for i, s := range t.Specs {
			decl := new(ast.GenDecl)
			*decl = *t
			decl.Specs = make([]ast.Spec, 1)
			decl.Specs[0] = s
			decls[i] = decl
		}
	} else {
		decls = make([]ast.Decl, 1)
		decls[0] = d
	}
	return decls
}

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)
	}
}

func newValue(decl *ast.GenDecl) *Value {
	v := new(Value)
	v.Doc = doc.CommentText(decl.Doc)
	decl.Doc = nil

	// count names and figure out type
	n := 0
	for _, spec := range decl.Specs {
		vspec := spec.(*ast.ValueSpec)
		for _, name := range vspec.Names {
			if ast.IsExported(name.Name) {
				n++
			}
		}

		if v.Type == "" {
			t := typeAsString(vspec.Type)
			if t != "" && ast.IsExported(t) {
				v.Type = t
			}
		}
	}

	if n == 0 {
		return nil
	}

	// collect names
	v.Names = make([]string, n)

	i := 0
	for _, spec := range decl.Specs {
		vspec := spec.(*ast.ValueSpec)
		for _, name := range vspec.Names {
			if !ast.IsExported(name.Name) {
				continue
			}
			v.Names[i] = name.Name
			i++
		}
	}

	v.Decl = decl
	return v
}