diff options
Diffstat (limited to 'src/pkg/go/ast/print.go')
| -rw-r--r-- | src/pkg/go/ast/print.go | 94 |
1 files changed, 55 insertions, 39 deletions
diff --git a/src/pkg/go/ast/print.go b/src/pkg/go/ast/print.go index d71490d4a..e6d4e838d 100644 --- a/src/pkg/go/ast/print.go +++ b/src/pkg/go/ast/print.go @@ -21,24 +21,29 @@ type FieldFilter func(name string, value reflect.Value) bool // NotNilFilter returns true for field values that are not nil; // it returns false otherwise. -func NotNilFilter(_ string, value reflect.Value) bool { - v, ok := value.(interface { - IsNil() bool - }) - return !ok || !v.IsNil() +func NotNilFilter(_ string, v reflect.Value) bool { + switch v.Kind() { + case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice: + return !v.IsNil() + } + return true } // Fprint prints the (sub-)tree starting at AST node x to w. +// If fset != nil, position information is interpreted relative +// to that file set. Otherwise positions are printed as integer +// values (file set specific offsets). // // A non-nil FieldFilter f may be provided to control the output: // struct fields for which f(fieldname, fieldvalue) is true are // are printed; all others are filtered from the output. // -func Fprint(w io.Writer, x interface{}, f FieldFilter) (n int, err os.Error) { +func Fprint(w io.Writer, fset *token.FileSet, x interface{}, f FieldFilter) (n int, err os.Error) { // setup printer p := printer{ output: w, + fset: fset, filter: f, ptrmap: make(map[interface{}]int), last: '\n', // force printing of line number on first line @@ -65,16 +70,17 @@ func Fprint(w io.Writer, x interface{}, f FieldFilter) (n int, err os.Error) { // Print prints x to standard output, skipping nil fields. -// Print(x) is the same as Fprint(os.Stdout, x, NotNilFilter). -func Print(x interface{}) (int, os.Error) { - return Fprint(os.Stdout, x, NotNilFilter) +// Print(fset, x) is the same as Fprint(os.Stdout, fset, x, NotNilFilter). +func Print(fset *token.FileSet, x interface{}) (int, os.Error) { + return Fprint(os.Stdout, fset, x, NotNilFilter) } type printer struct { output io.Writer + fset *token.FileSet filter FieldFilter - ptrmap map[interface{}]int // *reflect.PtrValue -> line number + ptrmap map[interface{}]int // *T -> line number written int // number of bytes written to output indent int // current indentation level last byte // the last byte processed by Write @@ -135,73 +141,69 @@ func (p *printer) printf(format string, args ...interface{}) { // Implementation note: Print is written for AST nodes but could be // used to print arbitrary data structures; such a version should // probably be in a different package. +// +// Note: This code detects (some) cycles created via pointers but +// not cycles that are created via slices or maps containing the +// same slice or map. Code for general data structures probably +// should catch those as well. func (p *printer) print(x reflect.Value) { - // Note: This test is only needed because AST nodes - // embed a token.Position, and thus all of them - // understand the String() method (but it only - // applies to the Position field). - // TODO: Should reconsider this AST design decision. - if pos, ok := x.Interface().(token.Position); ok { - p.printf("%s", pos) - return - } - if !NotNilFilter("", x) { p.printf("nil") return } - switch v := x.(type) { - case *reflect.InterfaceValue: - p.print(v.Elem()) + switch x.Kind() { + case reflect.Interface: + p.print(x.Elem()) - case *reflect.MapValue: - p.printf("%s (len = %d) {\n", x.Type().String(), v.Len()) + case reflect.Map: + p.printf("%s (len = %d) {\n", x.Type().String(), x.Len()) p.indent++ - for _, key := range v.Keys() { + for _, key := range x.MapKeys() { p.print(key) p.printf(": ") - p.print(v.Elem(key)) + p.print(x.MapIndex(key)) + p.printf("\n") } p.indent-- p.printf("}") - case *reflect.PtrValue: + case reflect.Ptr: p.printf("*") // type-checked ASTs may contain cycles - use ptrmap // to keep track of objects that have been printed // already and print the respective line number instead - ptr := v.Interface() + ptr := x.Interface() if line, exists := p.ptrmap[ptr]; exists { p.printf("(obj @ %d)", line) } else { p.ptrmap[ptr] = p.line - p.print(v.Elem()) + p.print(x.Elem()) } - case *reflect.SliceValue: - if s, ok := v.Interface().([]byte); ok { + case reflect.Slice: + if s, ok := x.Interface().([]byte); ok { p.printf("%#q", s) return } - p.printf("%s (len = %d) {\n", x.Type().String(), v.Len()) + p.printf("%s (len = %d) {\n", x.Type().String(), x.Len()) p.indent++ - for i, n := 0, v.Len(); i < n; i++ { + for i, n := 0, x.Len(); i < n; i++ { p.printf("%d: ", i) - p.print(v.Elem(i)) + p.print(x.Index(i)) p.printf("\n") } p.indent-- p.printf("}") - case *reflect.StructValue: + case reflect.Struct: p.printf("%s {\n", x.Type().String()) p.indent++ - t := v.Type().(*reflect.StructType) + t := x.Type() for i, n := 0, t.NumField(); i < n; i++ { name := t.Field(i).Name - value := v.Field(i) + value := x.Field(i) if p.filter == nil || p.filter(name, value) { p.printf("%s: ", name) p.print(value) @@ -212,6 +214,20 @@ func (p *printer) print(x reflect.Value) { p.printf("}") default: - p.printf("%v", x.Interface()) + v := x.Interface() + switch v := v.(type) { + case string: + // print strings in quotes + p.printf("%q", v) + return + case token.Pos: + // position values can be printed nicely if we have a file set + if p.fset != nil { + p.printf("%s", p.fset.Position(v)) + return + } + } + // default + p.printf("%v", v) } } |