func ExampleFprint() {
// Parse source file and extract the AST without comments for
// this function, with position information referring to the
// file set fset.
funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
// Print the function body into buffer buf.
// The file set is provided to the printer so that it knows
// about the original source formatting and can add additional
// line breaks where they were present in the source.
var buf bytes.Buffer
printer.Fprint(&buf, fset, funcAST.Body)
// Remove braces {} enclosing the function body, unindent,
// and trim leading and trailing white space.
s := buf.String()
s = s[1 : len(s)-1]
s = strings.TrimSpace(strings.Replace(s, "\n\t", "\n", -1))
// Print the cleaned-up body text to stdout.
fmt.Println(s)
// output:
// funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
//
// var buf bytes.Buffer
// printer.Fprint(&buf, fset, funcAST.Body)
//
// s := buf.String()
// s = s[1 : len(s)-1]
// s = strings.TrimSpace(strings.Replace(s, "\n\t", "\n", -1))
//
// fmt.Println(s)
}
func ExampleConvertAST() {
fset := token.NewFileSet()
a, _ := parser.ParseFile(fset, "example.sgo", `
package example
type LinkedList struct {
Head int
// For SGo: ?*LinkedList
Tail *LinkedList
}
`, parser.ParseComments)
info := &types.Info{
Defs: map[*ast.Ident]types.Object{},
Uses: map[*ast.Ident]types.Object{},
}
cfg := &types.Config{}
cfg.Check("", fset, []*ast.File{a}, info)
importer.ConvertAST(a, info, nil)
printer.Fprint(os.Stdout, fset, a)
// Output:
// package example
//
// type LinkedList struct {
// Head int
// // For SGo: ?*LinkedList
// Tail ?*LinkedList
// }
}
func (c *converter) convertReturnStmt(v *ast.ReturnStmt) {
if v == nil {
return
}
if v.Results.EntangledPos == 1 {
// return \ err
resultsLen := c.lastFunc.Results().Len()
results := make([][]byte, 0, resultsLen)
for i := 0; i < resultsLen; i++ {
typ := c.lastFunc.Results().At(i).Type()
switch underlying := typ.Underlying().(type) {
case *types.Pointer, *types.Map, *types.Slice, *types.Signature, *types.Interface, *types.Optional:
results = append(results, []byte("nil"))
case *types.Struct:
typ := c.lastFuncAST.Results.List[i].Type
buf := &bytes.Buffer{}
printer.Fprint(buf, c.fset, typ)
results = append(results, append(buf.Bytes(), '{', '}'))
case *types.Basic:
info := underlying.Info()
switch {
case info&types.IsBoolean != 0:
results = append(results, []byte("false"))
case info&types.IsInteger != 0:
results = append(results, []byte("0"))
case info&types.IsFloat != 0, info&types.IsComplex != 0:
results = append(results, []byte("0.0"))
case info&types.IsString != 0:
results = append(results, []byte(`""`))
default:
results = append(results, []byte("nil"))
}
default:
panic(fmt.Sprintf("unhandled Type %v", typ))
}
}
text := append(bytes.Join(results, []byte(", ")), []byte(", ")...)
c.putChunks(int(v.Results.Pos())-1, c.src[c.lastChunkEnd:int(v.Pos())-c.base-1+len("return ")], text)
}
for _, v := range v.Results.List {
c.convertExpr(v)
}
if v.Results.EntangledPos > 1 {
// return x, y, z \
chunk := ", nil"
if c.lastFunc.Results().Entangled().Type() == types.Typ[types.Bool] {
chunk = ", true"
}
c.putChunks(int(v.Results.End())+1, c.src[c.lastChunkEnd:int(v.Results.End())-c.base-1], []byte(chunk))
}
}
func nodeFmt(node interface{}, fset *token.FileSet) string {
var buf bytes.Buffer
printer.Fprint(&buf, fset, node)
return strings.Replace(strings.TrimSpace(buf.String()), "\n", "\n\t", -1)
}
func fileWithAnnotationComments(file *ast.File, fset, oldFset *token.FileSet, src []byte) ([]byte, *ast.File, error) {
// TODO: So this is an extremely hacky way of doing this. We're going to
// add the comments directly to the source comments, as text, and then
// we're going to re-parse it. This is because I tried manipulating the
// AST, adding the commments there an shifting the nodes' positions, but
// doing that right is very very convoluted; you need to be tracking all
// the time where you are, where you _were_, figure out where's a line
// break, etc. So, well, this will do for now.
var err error
var dstChunks [][]byte
var lastChunkEnd int
skipNextSpec := false
addDoc := func(node ast.Node, name *ast.Ident, typ ast.Expr) {
if typ == nil {
return
}
if name != nil && len(name.Name) > 0 {
c := name.Name[0]
if !(c >= 'A' && c <= 'Z') {
return
}
}
buf := &bytes.Buffer{}
err = printer.Fprint(buf, token.NewFileSet(), typ)
if err != nil {
return
}
pos := int(node.Pos()) - oldFset.File(file.Pos()).Base()
var space []byte
for i := pos - 1; i >= 0 && (src[i] == ' ' || src[i] == '\t'); i-- {
space = append([]byte{src[i]}, space...)
}
text := append([]byte("// For SGo: "+buf.String()+"\n"), space...)
dstChunks = append(dstChunks, src[lastChunkEnd:pos], text)
lastChunkEnd = pos
}
var visitor visitorFunc
visitor = visitorFunc(func(node ast.Node) (w ast.Visitor) {
var typ ast.Expr
var name *ast.Ident
switch node := node.(type) {
case *ast.FuncDecl:
typ = node.Type
name = node.Name
case *ast.GenDecl:
if node.Lparen != 0 || node.Tok == token.IMPORT || node.Tok == token.CONST {
return visitor
}
switch spec := node.Specs[0].(type) {
case *ast.TypeSpec:
skipNextSpec = true
typ = spec.Type
name = spec.Name
case *ast.ValueSpec:
skipNextSpec = true
typ = spec.Type
if len(spec.Names.List) > 0 {
name = spec.Names.List[0]
}
}
switch typ.(type) {
case *ast.InterfaceType, *ast.StructType:
return visitor
}
case *ast.InterfaceType:
for i := 0; i < len(node.Methods.List); i++ {
item := node.Methods.List[i]
if len(item.Names) > 0 {
name = item.Names[0]
}
addDoc(item, name, item.Type)
}
return visitor
case *ast.StructType:
for i := 0; i < len(node.Fields.List); i++ {
item := node.Fields.List[i]
if len(item.Names) > 0 {
name = item.Names[0]
}
addDoc(item, name, item.Type)
}
return visitor
case *ast.TypeSpec:
if skipNextSpec {
skipNextSpec = false
return visitor
}
typ = node.Type
name = node.Name
case *ast.ValueSpec:
if skipNextSpec {
skipNextSpec = false
return visitor
}
typ = node.Type
if len(node.Names.List) > 0 {
name = node.Names.List[0]
}
default:
return visitor
}
addDoc(node, name, typ)
return visitor
})
ast.Walk(visitor, file)
if err != nil {
return nil, nil, err
}
dst := append(
[]byte("// Autogenerated by SGo revision: "+SGoRevision+"\n// DO NOT EDIT!\n\n"),
bytes.Join(append(dstChunks, src[lastChunkEnd:]), nil)...)
dstFile, err := parser.ParseFile(fset, file.Name.Name, dst, parser.ParseComments)
return dst, dstFile, err
}