func stripParens(x ast.Expr) ast.Expr {
if px, strip := x.(*ast.ParenExpr); strip {
// parentheses must not be stripped if there are any
// unparenthesized composite literals starting with
// a type name
ast.Inspect(px.X, func(node ast.Node) bool {
switch x := node.(type) {
case *ast.ParenExpr:
// parentheses protect enclosed composite literals
return false
case *ast.CompositeLit:
if isTypeName(x.Type) {
strip = false // do not strip parentheses
}
return false
}
// in all other cases, keep inspecting
return true
})
if strip {
return stripParens(px.X)
}
}
return x
}
// TestIncompleteSelection ensures that an incomplete selector
// expression is parsed as a (blank) *ast.SelectorExpr, not a
// *ast.BadExpr.
func TestIncompleteSelection(t *testing.T) {
for _, src := range []string{
"package p; var _ = fmt.", // at EOF
"package p; var _ = fmt.\ntype X int", // not at EOF
} {
fset := token.NewFileSet()
f, err := ParseFile(fset, "", src, 0)
if err == nil {
t.Errorf("ParseFile(%s) succeeded unexpectedly", src)
continue
}
const wantErr = "expected selector or type assertion"
if !strings.Contains(err.Error(), wantErr) {
t.Errorf("ParseFile returned wrong error %q, want %q", err, wantErr)
}
var sel *ast.SelectorExpr
ast.Inspect(f, func(n ast.Node) bool {
if n, ok := n.(*ast.SelectorExpr); ok {
sel = n
}
return true
})
if sel == nil {
t.Error("found no *ast.SelectorExpr")
continue
}
const wantSel = "&{fmt _}"
if fmt.Sprint(sel) != wantSel {
t.Errorf("found selector %s, want %s", sel, wantSel)
continue
}
}
}
func TestObjects(t *testing.T) {
const src = `
package p
import fmt "fmt"
const pi = 3.14
type T struct{}
var x int
func f() { L: }
`
f, err := ParseFile(token.NewFileSet(), "", src, 0)
if err != nil {
t.Fatal(err)
}
objects := map[string]ast.ObjKind{
"p": ast.Bad, // not in a scope
"fmt": ast.Bad, // not resolved yet
"pi": ast.Con,
"T": ast.Typ,
"x": ast.Var,
"int": ast.Bad, // not resolved yet
"f": ast.Fun,
"L": ast.Lbl,
}
ast.Inspect(f, func(n ast.Node) bool {
if ident, ok := n.(*ast.Ident); ok {
obj := ident.Obj
if obj == nil {
if objects[ident.Name] != ast.Bad {
t.Errorf("no object for %s", ident.Name)
}
return true
}
if obj.Name != ident.Name {
t.Errorf("names don't match: obj.Name = %s, ident.Name = %s", obj.Name, ident.Name)
}
kind := objects[ident.Name]
if obj.Kind != kind {
t.Errorf("%s: obj.Kind = %s; want %s", ident.Name, obj.Kind, kind)
}
}
return true
})
}
// TestIssue9979 verifies that empty statements are contained within their enclosing blocks.
func TestIssue9979(t *testing.T) {
for _, src := range []string{
"package p; func f() {;}",
"package p; func f() {L:}",
"package p; func f() {L:;}",
"package p; func f() {L:\n}",
"package p; func f() {L:\n;}",
"package p; func f() { ; }",
"package p; func f() { L: }",
"package p; func f() { L: ; }",
"package p; func f() { L: \n}",
"package p; func f() { L: \n; }",
} {
fset := token.NewFileSet()
f, err := ParseFile(fset, "", src, 0)
if err != nil {
t.Fatal(err)
}
var pos, end token.Pos
ast.Inspect(f, func(x ast.Node) bool {
switch s := x.(type) {
case *ast.BlockStmt:
pos, end = s.Pos()+1, s.End()-1 // exclude "{", "}"
case *ast.LabeledStmt:
pos, end = s.Pos()+2, s.End() // exclude "L:"
case *ast.EmptyStmt:
// check containment
if s.Pos() < pos || s.End() > end {
t.Errorf("%s: %T[%d, %d] not inside [%d, %d]", src, s, s.Pos(), s.End(), pos, end)
}
// check semicolon
offs := fset.Position(s.Pos()).Offset
if ch := src[offs]; ch != ';' != s.Implicit {
want := "want ';'"
if s.Implicit {
want = "but ';' is implicit"
}
t.Errorf("%s: found %q at offset %d; %s", src, ch, offs, want)
}
}
return true
})
}
}
// playExample synthesizes a new *ast.File based on the provided
// file with the provided function body as the body of main.
func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
if !strings.HasSuffix(file.Name.Name, "_test") {
// We don't support examples that are part of the
// greater package (yet).
return nil
}
// Find top-level declarations in the file.
topDecls := make(map[*ast.Object]bool)
for _, decl := range file.Decls {
switch d := decl.(type) {
case *ast.FuncDecl:
topDecls[d.Name.Obj] = true
case *ast.GenDecl:
for _, spec := range d.Specs {
switch s := spec.(type) {
case *ast.TypeSpec:
topDecls[s.Name.Obj] = true
case *ast.ValueSpec:
for _, id := range s.Names {
topDecls[id.Obj] = true
}
}
}
}
}
// Find unresolved identifiers and uses of top-level declarations.
unresolved := make(map[string]bool)
usesTopDecl := false
var inspectFunc func(ast.Node) bool
inspectFunc = func(n ast.Node) bool {
// For selector expressions, only inspect the left hand side.
// (For an expression like fmt.Println, only add "fmt" to the
// set of unresolved names, not "Println".)
if e, ok := n.(*ast.SelectorExpr); ok {
ast.Inspect(e.X, inspectFunc)
return false
}
// For key value expressions, only inspect the value
// as the key should be resolved by the type of the
// composite literal.
if e, ok := n.(*ast.KeyValueExpr); ok {
ast.Inspect(e.Value, inspectFunc)
return false
}
if id, ok := n.(*ast.Ident); ok {
if id.Obj == nil {
unresolved[id.Name] = true
} else if topDecls[id.Obj] {
usesTopDecl = true
}
}
return true
}
ast.Inspect(body, inspectFunc)
if usesTopDecl {
// We don't support examples that are not self-contained (yet).
return nil
}
// Remove predeclared identifiers from unresolved list.
for n := range unresolved {
if predeclaredTypes[n] || predeclaredConstants[n] || predeclaredFuncs[n] {
delete(unresolved, n)
}
}
// Use unresolved identifiers to determine the imports used by this
// example. The heuristic assumes package names match base import
// paths for imports w/o renames (should be good enough most of the time).
namedImports := make(map[string]string) // [name]path
var blankImports []ast.Spec // _ imports
for _, s := range file.Imports {
p, err := strconv.Unquote(s.Path.Value)
if err != nil {
continue
}
n := path.Base(p)
if s.Name != nil {
n = s.Name.Name
switch n {
case "_":
blankImports = append(blankImports, s)
continue
case ".":
// We can't resolve dot imports (yet).
return nil
}
}
if unresolved[n] {
namedImports[n] = p
delete(unresolved, n)
}
}
// If there are other unresolved identifiers, give up because this
// synthesized file is not going to build.
if len(unresolved) > 0 {
return nil
}
// Include documentation belonging to blank imports.
var comments []*ast.CommentGroup
for _, s := range blankImports {
if c := s.(*ast.ImportSpec).Doc; c != nil {
comments = append(comments, c)
}
}
// Include comments that are inside the function body.
for _, c := range file.Comments {
if body.Pos() <= c.Pos() && c.End() <= body.End() {
comments = append(comments, c)
}
}
// Strip "Output:" comment and adjust body end position.
body, comments = stripOutputComment(body, comments)
// Synthesize import declaration.
importDecl := &ast.GenDecl{
Tok: token.IMPORT,
Lparen: 1, // Need non-zero Lparen and Rparen so that printer
Rparen: 1, // treats this as a factored import.
}
for n, p := range namedImports {
s := &ast.ImportSpec{Path: &ast.BasicLit{Value: strconv.Quote(p)}}
if path.Base(p) != n {
s.Name = ast.NewIdent(n)
}
importDecl.Specs = append(importDecl.Specs, s)
}
importDecl.Specs = append(importDecl.Specs, blankImports...)
// Synthesize main function.
funcDecl := &ast.FuncDecl{
Name: ast.NewIdent("main"),
Type: &ast.FuncType{Params: &ast.FieldList{}}, // FuncType.Params must be non-nil
Body: body,
}
// Synthesize file.
return &ast.File{
Name: ast.NewIdent("main"),
Decls: []ast.Decl{importDecl, funcDecl},
Comments: comments,
}
}