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Intersperse comments nicely when printing an AST.

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gofmt formatted source code looks pretty good already;
with a bit more fine-tuning it should be great.

printer.go:
- Implemented comment intersperse algorithm.
  The approach is a result of many trial-and-error
  experiments but at this point reasonably simple
  and open to arbitrary fine-tuning.

parser.go:
- Simplified handling of lead and line comments
  (formerly called leading and trailing comments).
- Use a comments list instead of an array (I may
  change this back - this is not obviously better
  and uses more space).

doc.go:
- Remove comments from AST nodes that have been
  'consumed' in the documentation to avoid duplicate
  printing of them. Allows for better control of
  what is printed w/o use of printing control flags
  (which are hard to use and not fine-grained enough).

Corresponding adjustments to various clients of these
files.

R=rsc
DELTA=478  (275 added, 108 deleted, 95 changed)
OCL=32185
CL=32380
This commit is contained in:
Robert Griesemer 2009-07-28 16:38:59 -07:00
parent f62585118c
commit 2210a643b7
12 changed files with 362 additions and 193 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/cmd/godoc/godoc.go
View File

@ -207,11 +207,7 @@ func parse(path string, mode uint) (*ast.File, *parseErrors) {
func nodeText(node interface{}) []byte {
var buf bytes.Buffer;
tw := makeTabwriter(&buf);
mode := uint(0);
if _, isProgram := node.(*ast.File); isProgram {
mode = printer.DocComments;
}
printer.Fprint(tw, node, mode);
printer.Fprint(tw, node, 0);
tw.Flush();
return buf.Data();
}

8
src/cmd/gofmt/gofmt.go
View File

@ -28,6 +28,7 @@ var (
// operation modes
allgo = flag.Bool("a", false, "include all .go files for package");
comments = flag.Bool("c", false, "omit comments");
silent = flag.Bool("s", false, "silent mode: parsing only");
verbose = flag.Bool("v", false, "verbose mode: trace parsing");
exports = flag.Bool("x", false, "show exports only");
@ -48,7 +49,10 @@ func usage() {
func parserMode() uint {
mode := parser.ParseComments;
mode := uint(0);
if !*comments {
mode |= parser.ParseComments;
}
if *verbose {
mode |= parser.Trace;
}
@ -99,7 +103,7 @@ func getPackage(path string) (*ast.Package, os.Error) {
func printerMode() uint {
mode := printer.DocComments;
mode := uint(0);
if *optcommas {
mode |= printer.OptCommas;
}

8
src/cmd/gofmt/test.sh
View File

@ -30,11 +30,15 @@ apply1() {
#echo $1 $2
case `basename $F` in
# files with errors (skip them)
# the following have semantic errors: bug039.go | bug040.go
# the following have semantic errors:
# bug039.go | bug040.go
# the following are not idempotent at the moment because of comment formatting:
comment.go | net.go | powser1.go | powser2.go | bug052.go | simpbool.go | "shift.go" | range.go | \
\
test_errors.go | calc.go | method1.go | selftest1.go | func3.go | const2.go | \
bug014.go | bug025.go | bug029.go | bug032.go | bug039.go | bug040.go | bug050.go | bug068.go | \
bug088.go | bug083.go | bug106.go | bug121.go | bug125.go | bug126.go | bug132.go | bug133.go | \
bug134.go | bug160.go | bug163.go | bug166.go ) ;;
bug134.go | bug160.go | bug163.go | bug166.go | bug169.go ) ;;
* ) $1 $2; count $F;;
esac
}

14
src/pkg/go/ast/ast.go
View File

@ -89,12 +89,12 @@ type Comment struct {
}
// A CommentGroup represents a sequence of single comments
// A CommentGroup represents a sequence of comments
// with no other tokens and no empty lines between.
//
type CommentGroup struct {
List []*Comment;
EndLine int; // line where the last comment in the group ends
Next *CommentGroup; // next comment group in source order
}
@ -116,7 +116,7 @@ type (
Names []*Ident; // field/method/parameter names; nil if anonymous field
Type Expr; // field/method/parameter type
Tag []*StringLit; // field tag; or nil
Comment *CommentGroup; // trailing comments on same line; or nil
Comment *CommentGroup; // line comments; or nil
};
)
@ -675,7 +675,7 @@ type (
Doc *CommentGroup; // associated documentation; or nil
Name *Ident; // local package name (including "."); or nil
Path []*StringLit; // package path
Comment *CommentGroup; // trailing comments on same line; or nil
Comment *CommentGroup; // line comments; or nil
};
// A ValueSpec node represents a constant or variable declaration
@ -685,7 +685,7 @@ type (
Names []*Ident; // value names
Type Expr; // value type; or nil
Values []Expr; // initial values; or nil
Comment *CommentGroup; // trailing comments on same line; or nil
Comment *CommentGroup; // line comments; or nil
};
// A TypeSpec node represents a type declaration (TypeSpec production).
@ -693,7 +693,7 @@ type (
Doc *CommentGroup; // associated documentation; or nil
Name *Ident; // type name
Type Expr;
Comment *CommentGroup; // trailing comments on same line; or nil
Comment *CommentGroup; // line comments; or nil
};
)
@ -773,7 +773,7 @@ type File struct {
token.Position; // position of "package" keyword
Name *Ident; // package name
Decls []Decl; // top-level declarations
Comments []*CommentGroup; // list of unassociated comments
Comments *CommentGroup; // list of all comments in the source file
}

2
src/pkg/go/ast/filter.go
View File

@ -169,7 +169,7 @@ func filterDecl(decl Decl) bool {
// FilterExports trims an AST in place such that only exported nodes remain:
// all top-level identififiers which are not exported and their associated
// all top-level identifiers which are not exported and their associated
// information (such as type, initial value, or function body) are removed.
// Non-exported fields and methods of exported types are stripped, and the
// function bodies of exported functions are set to nil.

21
src/pkg/go/doc/doc.go
View File

@ -27,6 +27,11 @@ type typeDoc struct {
// DocReader accumulates documentation for a single package.
// It modifies the AST: Comments (declaration documentation)
// that have been collected by the DocReader are set to nil
// in the respective AST nodes so that they are not printed
// twice (once when printing the documentation and once when
// printing the corresponding AST node).
//
type DocReader struct {
name string; // package name
@ -151,8 +156,8 @@ func (doc *DocReader) addDecl(decl ast.Decl) {
// makeTypeDocs below). Simpler data structures, but
// would lose GenDecl documentation if the TypeSpec
// has documentation as well.
s := spec.(*ast.TypeSpec);
doc.addType(&ast.GenDecl{d.Doc, d.Pos(), token.TYPE, noPos, []ast.Spec{s}, noPos});
doc.addType(&ast.GenDecl{d.Doc, d.Pos(), token.TYPE, noPos, []ast.Spec{spec}, noPos});
// A new GenDecl node is created, no need to nil out d.Doc.
}
case token.VAR:
// variables are always handled as a group
@ -197,7 +202,8 @@ func (doc *DocReader) AddFile(src *ast.File) {
// add package documentation
// TODO(gri) what to do if there are multiple files?
if src.Doc != nil {
doc.doc = src.Doc
doc.doc = src.Doc;
src.Doc = nil; // doc consumed - remove from ast.File node
}
// add all declarations
@ -206,7 +212,7 @@ func (doc *DocReader) AddFile(src *ast.File) {
}
// collect BUG(...) comments
for _, c := range src.Comments {
for c := src.Comments; c != nil; c = c.Next {
text := c.List[0].Text;
cstr := string(text);
if m := bug_markers.Execute(cstr); len(m) > 0 {
@ -215,10 +221,11 @@ func (doc *DocReader) AddFile(src *ast.File) {
// non-empty BUG comment; collect comment without BUG prefix
list := copyCommentList(c.List);
list[0].Text = text[m[1] : len(text)];
doc.bugs.Push(&ast.CommentGroup{list, c.EndLine});
doc.bugs.Push(&ast.CommentGroup{list, nil});
}
}
}
src.Comments = nil; // consumed unassociated comments - remove from ast.File node
}
// ----------------------------------------------------------------------------
@ -282,6 +289,7 @@ func makeValueDocs(v *vector.Vector) []*ValueDoc {
for i := range d {
decl := v.At(i).(*ast.GenDecl);
d[i] = &ValueDoc{astComment(decl.Doc), decl, i};
decl.Doc = nil; // doc consumed - removed from AST
}
sort.Sort(sortValueDoc(d));
return d;
@ -310,6 +318,7 @@ func makeFuncDocs(m map[string] *ast.FuncDecl) []*FuncDoc {
for _, f := range m {
doc := new(FuncDoc);
doc.Doc = astComment(f.Doc);
f.Doc = nil; // doc consumed - remove from ast.FuncDecl node
if f.Recv != nil {
doc.Recv = f.Recv.Type;
}
@ -359,10 +368,12 @@ func makeTypeDocs(m map[string] *typeDoc) []*TypeDoc {
typespec := old.decl.Specs[0].(*ast.TypeSpec);
t := new(TypeDoc);
doc := typespec.Doc;
typespec.Doc = nil; // doc consumed - remove from ast.TypeSpec node
if doc == nil {
// no doc associated with the spec, use the declaration doc, if any
doc = old.decl.Doc;
}
old.decl.Doc = nil; // doc consumed - remove from ast.Decl node
t.Doc = astComment(doc);
t.Type = typespec;
t.Factories = makeFuncDocs(old.factories);

117
src/pkg/go/parser/parser.go
View File

@ -22,17 +22,6 @@ import (
)
// Names to index the parser's commentIndex array.
const (
leading = iota; // index of the leading comments entry
trailing; // index of the trailing comments entry
)
// Initial value for parser.commentsIndex.
var noIndex = [2]int{-1, -1};
// noPos is used when there is no corresponding source position for a token.
var noPos token.Position;
@ -60,8 +49,10 @@ type parser struct {
indent uint; // indentation used for tracing output
// Comments
comments vector.Vector; // list of collected, unassociated comment groups
commentsIndex [2]int; // comments indexes of last leading/trailing comment group; or -1
comments *ast.CommentGroup; // list of collected comments
lastComment *ast.CommentGroup; // last comment in the comments list
leadComment *ast.CommentGroup; // the last lead comment
lineComment *ast.CommentGroup; // the last line comment
// Next token
pos token.Position; // token position
@ -90,8 +81,6 @@ func (p *parser) init(filename string, src []byte, mode uint) {
p.scanner.Init(filename, src, p, scannerMode(mode));
p.mode = mode;
p.trace = mode & Trace != 0; // for convenience (p.trace is used frequently)
p.comments.Init(0);
p.commentsIndex = noIndex;
p.next();
}
@ -190,42 +179,49 @@ func (p *parser) consumeCommentGroup() int {
group[i] = list.At(i).(*ast.Comment);
}
p.comments.Push(&ast.CommentGroup{group, endline});
// add comment group to the comments list
g := &ast.CommentGroup{group, nil};
if p.lastComment != nil {
p.lastComment.Next = g;
} else {
p.comments = g;
}
p.lastComment = g;
return endline;
}
// Advance to the next non-comment token. In the process, collect
// any comment groups encountered, and remember the last leading
// and trailing comments.
// any comment groups encountered, and remember the last lead and
// and line comments.
//
// A leading comment is a comment group that starts and ends in a
// A lead comment is a comment group that starts and ends in a
// line without any other tokens and that is followed by a non-comment
// token on the line immediately after the comment group.
//
// A trailing comment is a comment group that follows a non-comment
// A line comment is a comment group that follows a non-comment
// token on the same line, and that has no tokens after it on the line
// where it ends.
//
// Leading and trailing comments may be considered documentation
// that is stored in the AST. In that case they are removed from
// the parser's list of unassociated comments (via getComment).
// Lead and line comments may be considered documentation that is
// stored in the AST.
//
func (p *parser) next() {
p.commentsIndex = noIndex;
p.leadComment = nil;
p.lineComment = nil;
line := p.pos.Line; // current line
p.next0();
if p.tok == token.COMMENT {
if p.pos.Line == line {
// The comment is on same line as previous token; it
// cannot be a leading comment but may be a trailing
// comment.
// cannot be a lead comment but may be a line comment.
endline := p.consumeCommentGroup();
if p.pos.Line != endline {
// The next token is on a different line, thus
// the last comment group is a trailing comment.
p.commentsIndex[trailing] = p.comments.Len() - 1;
// the last comment group is a line comment.
p.lineComment = p.lastComment;
}
}
@ -237,27 +233,13 @@ func (p *parser) next() {
if endline >= 0 && endline+1 == p.pos.Line {
// The next token is following on the line immediately after the
// comment group, thus the last comment group is a leading comment.
p.commentsIndex[leading] = p.comments.Len() - 1;
// comment group, thus the last comment group is a lead comment.
p.leadComment = p.lastComment;
}
}
}
// Get leading/trailing comment group, if any.
func (p *parser) getComment(kind int) *ast.CommentGroup {
i := p.commentsIndex[kind];
if i >= 0 {
// get comment and remove if from the list of unassociated comment groups
c := p.comments.At(i).(*ast.CommentGroup);
p.comments.Set(i, nil); // clear entry
p.commentsIndex[kind] = -1; // comment was consumed
return c;
}
return nil;
}
func (p *parser) errorExpected(pos token.Position, msg string) {
msg = "expected " + msg;
if pos.Offset == p.pos.Offset {
@ -435,7 +417,7 @@ func (p *parser) parseFieldDecl() *ast.Field {
defer un(trace(p, "FieldDecl"));
}
doc := p.getComment(leading);
doc := p.leadComment;
// a list of identifiers looks like a list of type names
list := vector.New(0);
@ -496,9 +478,9 @@ func (p *parser) parseStructType() *ast.StructType {
list.Push(f);
if p.tok == token.SEMICOLON {
p.next();
f.Comment = p.getComment(trailing);
f.Comment = p.lineComment;
} else {
f.Comment = p.getComment(trailing);
f.Comment = p.lineComment;
break;
}
}
@ -680,7 +662,7 @@ func (p *parser) parseMethodSpec() *ast.Field {
defer un(trace(p, "MethodSpec"));
}
doc := p.getComment(leading);
doc := p.leadComment;
var idents []*ast.Ident;
var typ ast.Expr;
x := p.parseQualifiedIdent();
@ -1680,7 +1662,7 @@ func (p *parser) parseStmt() ast.Stmt {
type parseSpecFunction func(p *parser, doc *ast.CommentGroup, getSemi bool) (spec ast.Spec, gotSemi bool)
// Consume semicolon if there is one and getSemi is set, and get any trailing comment.
// Consume semicolon if there is one and getSemi is set, and get any line comment.
// Return the comment if any and indicate if a semicolon was consumed.
//
func (p *parser) parseComment(getSemi bool) (comment *ast.CommentGroup, gotSemi bool) {
@ -1688,7 +1670,7 @@ func (p *parser) parseComment(getSemi bool) (comment *ast.CommentGroup, gotSemi
p.next();
gotSemi = true;
}
return p.getComment(trailing), gotSemi;
return p.lineComment, gotSemi;
}
@ -1772,7 +1754,7 @@ func (p *parser) parseGenDecl(keyword token.Token, f parseSpecFunction, getSemi
defer un(trace(p, keyword.String() + "Decl"));
}
doc := p.getComment(leading);
doc := p.leadComment;
pos := p.expect(keyword);
var lparen, rparen token.Position;
list := vector.New(0);
@ -1780,7 +1762,7 @@ func (p *parser) parseGenDecl(keyword token.Token, f parseSpecFunction, getSemi
lparen = p.pos;
p.next();
for p.tok != token.RPAREN && p.tok != token.EOF {
doc := p.getComment(leading);
doc := p.leadComment;
spec, semi := f(p, doc, true); // consume semicolon if any
list.Push(spec);
if !semi {
@ -1845,7 +1827,7 @@ func (p *parser) parseFunctionDecl() *ast.FuncDecl {
defer un(trace(p, "FunctionDecl"));
}
doc := p.getComment(leading);
doc := p.leadComment;
pos := p.expect(token.FUNC);
var recv *ast.Field;
@ -1883,13 +1865,7 @@ func (p *parser) parseDecl(getSemi bool) (decl ast.Decl, gotSemi bool) {
case token.FUNC:
decl = p.parseFunctionDecl();
// Do not use parseComment here to consume a semicolon
// because we don't want to remove a trailing comment
// from the list of unassociated comments.
if getSemi && p.tok == token.SEMICOLON {
p.next();
gotSemi = true;
}
_, gotSemi := p.parseComment(getSemi);
return decl, gotSemi;
default:
@ -1915,7 +1891,7 @@ func (p *parser) parseFile() *ast.File {
}
// package clause
comment := p.getComment(leading);
doc := p.leadComment;
pos := p.expect(token.PACKAGE);
ident := p.parseIdent();
var decls []ast.Decl;
@ -1946,22 +1922,5 @@ func (p *parser) parseFile() *ast.File {
}
}
// convert comments list
// 1) determine number of remaining comments
n := 0;
for i := 0; i < p.comments.Len(); i++ {
if p.comments.At(i) != nil {
n++;
}
}
// 2) convert the remaining comments
comments := make([]*ast.CommentGroup, n);
for i, j := 0, 0; i < p.comments.Len(); i++ {
if p.comments.At(i) != nil {
comments[j] = p.comments.At(i).(*ast.CommentGroup);
j++;
}
}
return &ast.File{comment, pos, ident, decls, comments};
return &ast.File{doc, pos, ident, decls, p.comments};
}

313
src/pkg/go/printer/printer.go
View File

@ -16,54 +16,49 @@ import (
)
const (
debug = false; // enable for debugging
maxNewlines = 3; // maximum vertical white space
)
// Printing is controlled with these flags supplied
// to Fprint via the mode parameter.
//
const (
DocComments uint = 1 << iota; // print documentation comments
OptCommas; // print optional commas
OptCommas = 1 << iota; // print optional commas
OptSemis; // print optional semicolons
)
type whiteSpace int
const (
blank = whiteSpace(' ');
tab = whiteSpace('\t');
newline = whiteSpace('\n');
formfeed = whiteSpace('\f');
)
type printer struct {
// configuration (does not change after initialization)
output io.Writer;
mode uint;
errors chan os.Error;
comments []*ast.CommentGroup; // list of unassociated comments; or nil
// current state (changes during printing)
written int; // number of bytes written
level int; // function nesting level; 0 = package scope, 1 = top-level function scope, etc.
indent int; // indent level
pos token.Position; // output position (possibly estimated) in "AST space"
indent int; // current indentation
prev, pos token.Position;
// buffered whitespace
buffer [8]whiteSpace; // whitespace sequences are short (1 or 2); 8 entries is plenty
buflen int;
// comments
cindex int; // the current comment group index
cpos token.Position; // the position of the next comment group
}
func (p *printer) hasComment(pos token.Position) bool {
return p.cpos.Offset < pos.Offset;
}
func (p *printer) nextComment() {
p.cindex++;
if p.comments != nil && p.cindex < len(p.comments) && p.comments[p.cindex] != nil {
p.cpos = p.comments[p.cindex].List[0].Pos();
} else {
p.cpos = token.Position{"", 1<<30, 1<<30, 1}; // infinite
}
}
func (p *printer) setComments(comments []*ast.CommentGroup) {
p.comments = comments;
p.cindex = -1;
p.nextComment();
comment *ast.CommentGroup; // list of comments; or nil
}
@ -71,20 +66,12 @@ func (p *printer) init(output io.Writer, mode uint) {
p.output = output;
p.mode = mode;
p.errors = make(chan os.Error);
p.setComments(nil);
}
var (
blank = []byte{' '};
tab = []byte{'\t'};
newline = []byte{'\n'};
formfeed = []byte{'\f'};
)
// Writing to p.output is done with write0 which also handles errors.
// It should only be called by write.
// It should only be called by write and debug routines which are not
// supposed to update the p.pos estimation.
//
func (p *printer) write0(data []byte) {
n, err := p.output.Write(data);
@ -100,11 +87,13 @@ func (p *printer) write(data []byte) {
for i, b := range data {
if b == '\n' || b == '\f' {
// write segment ending in a newline/formfeed followed by indentation
// TODO should convert '\f' into '\n' if the output is not going through
// tabwriter
// TODO(gri) should convert '\f' into '\n' if the output is not going
// through tabwriter
p.write0(data[i0 : i+1]);
// TODO(gri) should not write indentation is there is nothing else
// on the line
for j := p.indent; j > 0; j-- {
p.write0(tab);
p.write0([]byte{'\t'}); // TODO(gri) don't do allocation in every iteration
}
i0 = i+1;
@ -125,7 +114,39 @@ func (p *printer) write(data []byte) {
}
// TODO(gri) Enable this code to intersperse comments
// TODO(gri) Don't go through write and make this more efficient.
func (p *printer) writeByte(b byte) {
p.write([]byte{b});
}
func (p *printer) writeNewlines(n int) {
if n > maxNewlines {
n = maxNewlines;
}
for ; n > 0; n-- {
p.writeByte('\n');
}
}
func (p *printer) writePos(pos token.Position) {
// use write0 so not to disturb the p.pos update by write
p.write0(strings.Bytes(fmt.Sprintf("[%d:%d]", pos.Line, pos.Column)));
}
func (p *printer) writeItem(pos token.Position, data []byte) {
p.pos = pos;
if debug {
p.writePos(pos);
}
p.write(data);
p.prev = p.pos;
}
// TODO(gri) decide if this is needed - keep around for now
/*
// Reduce contiguous sequences of '\t' in a []byte to a single '\t'.
func untabify(src []byte) []byte {
@ -139,26 +160,110 @@ func untabify(src []byte) []byte {
}
return dst[0 : j];
}
func (p *printer) adjustSpacingAndMergeComments() {
for ; p.hasComment(p.pos); p.nextComment() {
// we have a comment that comes before the current position
comment := p.comments[p.cindex];
p.write(untabify(comment.Text));
// TODO
// - classify comment and provide better formatting
// - add extra newlines if so indicated by source positions
}
}
*/
func (p *printer) writeComment(comment *ast.Comment) {
// separation from previous item
if p.prev.IsValid() {
// there was a preceding item (otherwise, the comment is the
// first item to be printed - in that case do not apply extra
// spacing)
n := comment.Pos().Line - p.prev.Line;
if n == 0 {
// comment on the same line as previous item; separate with tab
p.writeByte('\t');
} else {
// comment on a different line; separate with newlines
p.writeNewlines(n);
}
}
// write comment
p.writeItem(comment.Pos(), comment.Text);
}
func (p *printer) intersperseComments(next token.Position) {
firstLine := 0;
needsNewline := false;
for ; p.comment != nil && p.comment.List[0].Pos().Offset < next.Offset; p.comment = p.comment.Next {
for _, c := range p.comment.List {
if firstLine == 0 {
firstLine = c.Pos().Line;
}
p.writeComment(c);
needsNewline = c.Text[1] == '/';
}
}
// Eliminate non-newline whitespace from whitespace buffer.
j := 0;
for i := 0; i < p.buflen; i++ {
ch := p.buffer[i];
if ch == '\n' || ch == '\f' {
p.buffer[j] = ch;
j++;
}
}
p.buflen = j;
// Eliminate extra newlines from whitespace buffer if they
// are not present in the original source. This makes sure
// that comments that need to be adjacent to a declaration
// remain adjacent.
if p.prev.IsValid() {
n := next.Line - p.prev.Line;
if n < p.buflen {
p.buflen = n;
}
}
// If the whitespace buffer is not empty, it contains only
// newline or formfeed chars. Force a formfeed char if the
// comments span more than one line - in this case the
// structure of the next line is likely to change. Otherwise
// use the existing char, if any.
if needsNewline {
ch := p.buffer[0]; // existing char takes precedence
if p.buflen == 0 {
p.buflen = 1;
ch = newline; // original ch was a lie
}
if p.prev.Line > firstLine {
ch = formfeed; // comments span at least 2 lines
}
p.buffer[0] = ch;
}
}
func (p *printer) writeWhitespace() {
for i := 0; i < p.buflen; i++ {
p.writeByte(byte(p.buffer[i]));
}
p.buflen = 0;
}
// print prints a list of "items" (roughly corresponding to syntactic
// tokens, but also including whitespace and formatting information).
// It is the only print function that should be called directly from
// any of the AST printing functions below.
//
// Whitespace is accumulated until a non-whitespace token appears. Any
// comments that need to appear before that token are printed first,
// taking into account the amount and structure of any pending white-
// space for best commemnt placement. Then, any leftover whitespace is
// printed, followed by the actual token.
//
func (p *printer) print(args ...) {
v := reflect.NewValue(args).(*reflect.StructValue);
for i := 0; i < v.NumField(); i++ {
//p.adjustSpacingAndMergeComments(); // TODO(gri) enable to intersperse comments
f := v.Field(i);
next := p.pos; // estimated position of next item
var data []byte;
switch x := f.Interface().(type) {
case int:
// indentation delta
@ -166,22 +271,52 @@ func (p *printer) print(args ...) {
if p.indent < 0 {
panic("print: negative indentation");
}
case whiteSpace:
if p.buflen >= len(p.buffer) {
// Whitespace sequences are very short so this should
// never happen. Handle gracefully (but possibly with
// bad comment placement) if it does happen.
p.writeWhitespace();
}
p.buffer[p.buflen] = x;
p.buflen++;
case []byte:
p.write(x);
data = x;
case string:
p.write(strings.Bytes(x));
data = strings.Bytes(x);
case token.Token:
p.write(strings.Bytes(x.String()));
data = strings.Bytes(x.String());
case token.Position:
// set current position
p.pos = x;
next = x; // accurate position of next item
default:
panicln("print: unsupported argument type", f.Type().String());
}
p.pos = next;
if data != nil {
// if there are comments before the next item, intersperse them
if p.comment != nil && p.comment.List[0].Pos().Offset < next.Offset {
p.intersperseComments(next);
}
p.writeWhitespace();
// intersperse extra newlines if present in the source
p.writeNewlines(next.Line - p.pos.Line);
p.writeItem(next, data);
}
}
}
// Flush prints any pending whitespace.
func (p *printer) flush() {
// TODO(gri) any special handling of pending comments needed?
p.writeWhitespace();
}
// ----------------------------------------------------------------------------
// Printing of common AST nodes.
@ -190,6 +325,10 @@ func (p *printer) optSemis() bool {
}
// TODO(gri) The code for printing lead and line comments
// should be eliminated in favor of reusing the
// comment intersperse mechanism above somehow.
// Print a list of individual comments.
func (p *printer) commentList(list []*ast.Comment) {
for i, c := range list {
@ -203,20 +342,22 @@ func (p *printer) commentList(list []*ast.Comment) {
}
// Print a leading comment followed by a newline.
func (p *printer) leadingComment(d *ast.CommentGroup) {
if p.mode & DocComments != 0 && d != nil {
// Print a lead comment followed by a newline.
func (p *printer) leadComment(d *ast.CommentGroup) {
// Ignore the comment if we have comments interspersed (p.comment != nil).
if p.comment == nil && d != nil {
p.commentList(d.List);
p.print(newline);
}
}
// Print a tab followed by a trailing comment.
// Print a tab followed by a line comment.
// A newline must be printed afterwards since
// the comment may be a //-style comment.
func (p *printer) trailingComment(d *ast.CommentGroup) {
if d != nil {
func (p *printer) lineComment(d *ast.CommentGroup) {
// Ignore the comment if we have comments interspersed (p.comment != nil).
if p.comment == nil && d != nil {
p.print(tab);
p.commentList(d.List);
}
@ -306,7 +447,7 @@ func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace tok
isAnon := len(f.Names) == 0;
if i > 0 {
p.print(token.SEMICOLON);
p.trailingComment(lastComment);
p.lineComment(lastComment);
if lastWasAnon == isAnon {
// previous and current line have same structure;
// continue with existing columns
@ -315,13 +456,13 @@ func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace tok
// previous and current line have different structure;
// flush tabwriter and start new columns (the "type
// column" on a line with named fields may line up
// with the "trailing comment column" on a line with
// with the "line comment column" on a line with
// an anonymous field, leading to bad alignment)
p.print(formfeed);
}
}
p.leadingComment(f.Doc);
p.leadComment(f.Doc);
if !isAnon {
p.identList(f.Names);
p.print(tab);
@ -350,7 +491,7 @@ func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace tok
if p.optSemis() {
p.print(token.SEMICOLON);
}
p.trailingComment(lastComment);
p.lineComment(lastComment);
p.print(-1, newline, rbrace, token.RBRACE);
@ -624,11 +765,11 @@ func (p *printer) stmt(stmt ast.Stmt) (optSemi bool) {
var comment *ast.CommentGroup;
comment, optSemi = p.decl(s.Decl);
if comment != nil {
// Trailing comments of declarations in statement lists
// Line comments of declarations in statement lists
// are not associated with the declaration in the parser;
// this case should never happen. Print anyway to continue
// gracefully.
p.trailingComment(comment);
p.lineComment(comment);
p.print(newline);
}
@ -780,12 +921,12 @@ func (p *printer) stmt(stmt ast.Stmt) (optSemi bool) {
// ----------------------------------------------------------------------------
// Declarations
// Returns trailing comment, if any, and whether a separating semicolon is optional.
// Returns line comment, if any, and whether a separating semicolon is optional.
//
func (p *printer) spec(spec ast.Spec) (comment *ast.CommentGroup, optSemi bool) {
switch s := spec.(type) {
case *ast.ImportSpec:
p.leadingComment(s.Doc);
p.leadComment(s.Doc);
if s.Name != nil {
p.expr(s.Name);
}
@ -794,7 +935,7 @@ func (p *printer) spec(spec ast.Spec) (comment *ast.CommentGroup, optSemi bool)
comment = s.Comment;
case *ast.ValueSpec:
p.leadingComment(s.Doc);
p.leadComment(s.Doc);
p.identList(s.Names);
if s.Type != nil {
p.print(blank); // TODO switch to tab? (indent problem with structs)
@ -808,7 +949,7 @@ func (p *printer) spec(spec ast.Spec) (comment *ast.CommentGroup, optSemi bool)
comment = s.Comment;
case *ast.TypeSpec:
p.leadingComment(s.Doc);
p.leadComment(s.Doc);
p.expr(s.Name);
p.print(blank); // TODO switch to tab? (but indent problem with structs)
optSemi = p.expr(s.Type);
@ -829,7 +970,7 @@ func (p *printer) decl(decl ast.Decl) (comment *ast.CommentGroup, optSemi bool)
p.print(d.Pos(), "BadDecl");
case *ast.GenDecl:
p.leadingComment(d.Doc);
p.leadComment(d.Doc);
p.print(d.Pos(), d.Tok, blank);
if d.Lparen.IsValid() {
@ -840,7 +981,7 @@ func (p *printer) decl(decl ast.Decl) (comment *ast.CommentGroup, optSemi bool)
for i, s := range d.Specs {
if i > 0 {
p.print(token.SEMICOLON);
p.trailingComment(comment);
p.lineComment(comment);
p.print(newline);
}
comment, optSemi = p.spec(s);
@ -848,7 +989,7 @@ func (p *printer) decl(decl ast.Decl) (comment *ast.CommentGroup, optSemi bool)
if p.optSemis() {
p.print(token.SEMICOLON);
}
p.trailingComment(comment);
p.lineComment(comment);
p.print(-1, newline);
}
p.print(d.Rparen, token.RPAREN);
@ -861,7 +1002,7 @@ func (p *printer) decl(decl ast.Decl) (comment *ast.CommentGroup, optSemi bool)
}
case *ast.FuncDecl:
p.leadingComment(d.Doc);
p.leadComment(d.Doc);
p.print(d.Pos(), token.FUNC, blank);
if recv := d.Recv; recv != nil {
// method: print receiver
@ -894,9 +1035,7 @@ func (p *printer) decl(decl ast.Decl) (comment *ast.CommentGroup, optSemi bool)
// Files
func (p *printer) file(src *ast.File) {
p.setComments(src.Comments); // unassociated comments
p.leadingComment(src.Doc);
p.leadComment(src.Doc);
p.print(src.Pos(), token.PACKAGE, blank);
p.expr(src.Name);
@ -906,7 +1045,7 @@ func (p *printer) file(src *ast.File) {
if p.optSemis() {
p.print(token.SEMICOLON);
}
p.trailingComment(comment);
p.lineComment(comment);
}
p.print(newline);
@ -934,12 +1073,14 @@ func Fprint(output io.Writer, node interface{}, mode uint) (int, os.Error) {
p.stmt(n);
case ast.Decl:
comment, _ := p.decl(n);
p.trailingComment(comment); // no newline at end
p.lineComment(comment); // no newline at end
case *ast.File:
p.comment = n.Comments;
p.file(n);
default:
p.errors <- os.NewError("unsupported node type");
}
p.flush();
p.errors <- nil; // no errors
}();
err := <-p.errors; // wait for completion of goroutine

3
src/pkg/go/printer/printer_test.go
View File

@ -49,12 +49,13 @@ func check(t *testing.T, source, golden string, exports bool) {
// filter exports if necessary
if exports {
ast.FilterExports(prog); // ignore result
prog.Comments = nil; // don't print comments that are not in AST
}
// format source
var buf bytes.Buffer;
w := tabwriter.NewWriter(&buf, tabwidth, padding, tabchar, 0);
Fprint(w, prog, DocComments);
Fprint(w, prog, 0);
w.Flush();
res := buf.Data();

34
src/pkg/go/printer/testdata/golden1.go vendored
View File

@ -1,26 +1,52 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This is a package for testing purposes.
//
package main
import "fmt" // fmt
const c0 = 0 // zero
const (
c1 = iota; // c1
c2 // c2
)
// The T type.
type T struct {
a, b, c int // 3 fields
}
var x int // x
// This comment group should be separated
// with a newline from the next comment
// group.
// This comment should NOT be associated with the next declaration.
var x int // x
var ()
// This comment SHOULD be associated with the next declaration.
func f0() {
const pi = 3.14;
var s1 struct {}
const pi = 3.14; // pi
var s1 struct {} /* an empty struct */ /* foo */
// a struct constructor
// --------------------
var s2 struct {} = struct {}{};
x := pi
}
//
// NO SPACE HERE
//
func f1() {
f0();
/* 1 */
// 2
/* 3 */
/* 4 */
f0()
}

2
src/pkg/go/printer/testdata/golden1.x vendored
View File

@ -1,3 +1,5 @@
// This is a package for testing purposes.
//
package main
// The T type.

27
src/pkg/go/printer/testdata/source1.go vendored
View File

@ -1,3 +1,9 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This is a package for testing purposes.
//
package main
import "fmt" // fmt
@ -14,14 +20,33 @@ type T struct {
a, b, c int // 3 fields
}
// This comment group should be separated
// with a newline from the next comment
// group.
// This comment should NOT be associated with the next declaration.
var x int; // x
var ()
// This comment SHOULD be associated with the next declaration.
func f0() {
const pi = 3.14; // pi
var s1 struct {}
var s1 struct {} /* an empty struct */ /* foo */
// a struct constructor
// --------------------
var s2 struct {} = struct {}{};
x := pi;
}
//
// NO SPACE HERE
//
func f1() {
f0();
/* 1 */
// 2
/* 3 */
/* 4 */
f0();
}