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path: root/src/pkg/go/printer/printer.go
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Diffstat (limited to 'src/pkg/go/printer/printer.go')
-rw-r--r--src/pkg/go/printer/printer.go241
1 files changed, 155 insertions, 86 deletions
diff --git a/src/pkg/go/printer/printer.go b/src/pkg/go/printer/printer.go
index 53632c83d..a4ddad50e 100644
--- a/src/pkg/go/printer/printer.go
+++ b/src/pkg/go/printer/printer.go
@@ -18,10 +18,7 @@ import (
)
-const (
- debug = false // enable for debugging
- maxNewlines = 3 // maximum vertical white space
-)
+const debug = false // enable for debugging
type whiteSpace int
@@ -41,8 +38,8 @@ var (
esc = []byte{tabwriter.Escape}
htab = []byte{'\t'}
htabs = []byte("\t\t\t\t\t\t\t\t")
- newlines = []byte("\n\n\n\n\n\n\n\n") // more than maxNewlines
- formfeeds = []byte("\f\f\f\f\f\f\f\f") // more than maxNewlines
+ newlines = []byte("\n\n\n\n\n\n\n\n") // more than the max determined by nlines
+ formfeeds = []byte("\f\f\f\f\f\f\f\f") // more than the max determined by nlines
esc_quot = []byte(""") // shorter than """
esc_apos = []byte("'") // shorter than "'"
@@ -65,12 +62,15 @@ type printer struct {
// Configuration (does not change after initialization)
output io.Writer
Config
+ fset *token.FileSet
errors chan os.Error
// Current state
- written int // number of bytes written
- indent int // current indentation
- escape bool // true if in escape sequence
+ nesting int // nesting level (0: top-level (package scope), >0: functions/decls.)
+ written int // number of bytes written
+ indent int // current indentation
+ escape bool // true if in escape sequence
+ lastTok token.Token // the last token printed (token.ILLEGAL if it's whitespace)
// Buffered whitespace
buffer []whiteSpace
@@ -95,9 +95,10 @@ type printer struct {
}
-func (p *printer) init(output io.Writer, cfg *Config) {
+func (p *printer) init(output io.Writer, cfg *Config, fset *token.FileSet) {
p.output = output
p.Config = *cfg
+ p.fset = fset
p.errors = make(chan os.Error)
p.buffer = make([]whiteSpace, 0, 16) // whitespace sequences are short
}
@@ -106,12 +107,31 @@ func (p *printer) init(output io.Writer, cfg *Config) {
func (p *printer) internalError(msg ...interface{}) {
if debug {
fmt.Print(p.pos.String() + ": ")
- fmt.Println(msg)
+ fmt.Println(msg...)
panic("go/printer")
}
}
+// nlines returns the adjusted number of linebreaks given the desired number
+// of breaks n such that min <= result <= max where max depends on the current
+// nesting level.
+//
+func (p *printer) nlines(n, min int) int {
+ if n < min {
+ return min
+ }
+ max := 3 // max. number of newlines at the top level (p.nesting == 0)
+ if p.nesting > 0 {
+ max = 2 // max. number of newlines everywhere else
+ }
+ if n > max {
+ return max
+ }
+ return n
+}
+
+
// write0 writes raw (uninterpreted) data to p.output and handles errors.
// write0 does not indent after newlines, and does not HTML-escape or update p.pos.
//
@@ -192,6 +212,11 @@ func (p *printer) write(data []byte) {
case tabwriter.Escape:
p.escape = !p.escape
+
+ // ignore escape chars introduced by printer - they are
+ // invisible and must not affect p.pos (was issue #1089)
+ p.pos.Offset--
+ p.pos.Column--
}
}
@@ -207,9 +232,7 @@ func (p *printer) write(data []byte) {
func (p *printer) writeNewlines(n int, useFF bool) {
if n > 0 {
- if n > maxNewlines {
- n = maxNewlines
- }
+ n = p.nlines(n, 0)
if useFF {
p.write(formfeeds[0:n])
} else {
@@ -292,8 +315,8 @@ func (p *printer) writeCommentPrefix(pos, next token.Position, isFirst, isKeywor
}
if pos.IsValid() && pos.Filename != p.last.Filename {
- // comment in a different file - separate with newlines
- p.writeNewlines(maxNewlines, true)
+ // comment in a different file - separate with newlines (writeNewlines will limit the number)
+ p.writeNewlines(10, true)
return
}
@@ -380,7 +403,6 @@ func (p *printer) writeCommentPrefix(pos, next token.Position, isFirst, isKeywor
func (p *printer) writeCommentLine(comment *ast.Comment, pos token.Position, line []byte) {
// line must pass through unchanged, bracket it with tabwriter.Escape
- esc := []byte{tabwriter.Escape}
line = bytes.Join([][]byte{esc, line, esc}, nil)
// apply styler, if any
@@ -576,7 +598,7 @@ func (p *printer) writeComment(comment *ast.Comment) {
// shortcut common case of //-style comments
if text[1] == '/' {
- p.writeCommentLine(comment, comment.Pos(), text)
+ p.writeCommentLine(comment, p.fset.Position(comment.Pos()), text)
return
}
@@ -588,7 +610,7 @@ func (p *printer) writeComment(comment *ast.Comment) {
// write comment lines, separated by formfeed,
// without a line break after the last line
linebreak := formfeeds[0:1]
- pos := comment.Pos()
+ pos := p.fset.Position(comment.Pos())
for i, line := range lines {
if i > 0 {
p.write(linebreak)
@@ -649,14 +671,14 @@ func (p *printer) intersperseComments(next token.Position, tok token.Token) (dro
var last *ast.Comment
for ; p.commentBefore(next); p.cindex++ {
for _, c := range p.comments[p.cindex].List {
- p.writeCommentPrefix(c.Pos(), next, last == nil, tok.IsKeyword())
+ p.writeCommentPrefix(p.fset.Position(c.Pos()), next, last == nil, tok.IsKeyword())
p.writeComment(c)
last = c
}
}
if last != nil {
- if last.Text[1] == '*' && last.Pos().Line == next.Line {
+ if last.Text[1] == '*' && p.fset.Position(last.Pos()).Line == next.Line {
// the last comment is a /*-style comment and the next item
// follows on the same line: separate with an extra blank
p.write([]byte{' '})
@@ -726,6 +748,26 @@ func (p *printer) writeWhitespace(n int) {
// ----------------------------------------------------------------------------
// Printing interface
+
+func mayCombine(prev token.Token, next byte) (b bool) {
+ switch prev {
+ case token.INT:
+ b = next == '.' // 1.
+ case token.ADD:
+ b = next == '+' // ++
+ case token.SUB:
+ b = next == '-' // --
+ case token.QUO:
+ b = next == '*' // /*
+ case token.LSS:
+ b = next == '-' || next == '<' // <- or <<
+ case token.AND:
+ b = next == '&' || next == '^' // && or &^
+ }
+ return
+}
+
+
// 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
@@ -743,6 +785,7 @@ func (p *printer) print(args ...interface{}) {
var data []byte
var tag HTMLTag
var tok token.Token
+
switch x := f.(type) {
case whiteSpace:
if x == ignore {
@@ -765,7 +808,7 @@ func (p *printer) print(args ...interface{}) {
if p.Styler != nil {
data, tag = p.Styler.Ident(x)
} else {
- data = []byte(x.Name())
+ data = []byte(x.Name)
}
tok = token.IDENT
case *ast.BasicLit:
@@ -779,22 +822,38 @@ func (p *printer) print(args ...interface{}) {
// bytes since they do not appear in legal UTF-8 sequences)
// TODO(gri): do this more efficiently.
data = []byte("\xff" + string(data) + "\xff")
- tok = token.INT // representing all literal tokens
+ tok = x.Kind
case token.Token:
+ s := x.String()
+ if mayCombine(p.lastTok, s[0]) {
+ // the previous and the current token must be
+ // separated by a blank otherwise they combine
+ // into a different incorrect token sequence
+ // (except for token.INT followed by a '.' this
+ // should never happen because it is taken care
+ // of via binary expression formatting)
+ if len(p.buffer) != 0 {
+ p.internalError("whitespace buffer not empty")
+ }
+ p.buffer = p.buffer[0:1]
+ p.buffer[0] = ' '
+ }
if p.Styler != nil {
data, tag = p.Styler.Token(x)
} else {
- data = []byte(x.String())
+ data = []byte(s)
}
tok = x
- case token.Position:
+ case token.Pos:
if x.IsValid() {
- next = x // accurate position of next item
+ next = p.fset.Position(x) // accurate position of next item
}
+ tok = p.lastTok
default:
fmt.Fprintf(os.Stderr, "print: unsupported argument type %T\n", f)
panic("go/printer type")
}
+ p.lastTok = tok
p.pos = next
if data != nil {
@@ -816,11 +875,11 @@ func (p *printer) print(args ...interface{}) {
// before the next position in the source code.
//
func (p *printer) commentBefore(next token.Position) bool {
- return p.cindex < len(p.comments) && p.comments[p.cindex].List[0].Pos().Offset < next.Offset
+ return p.cindex < len(p.comments) && p.fset.Position(p.comments[p.cindex].List[0].Pos()).Offset < next.Offset
}
-// Flush prints any pending comments and whitespace occuring
+// Flush prints any pending comments and whitespace occurring
// textually before the position of the next token tok. Flush
// returns true if a pending formfeed character was dropped
// from the whitespace buffer as a result of interspersing
@@ -844,81 +903,85 @@ func (p *printer) flush(next token.Position, tok token.Token) (droppedFF bool) {
// A trimmer is an io.Writer filter for stripping tabwriter.Escape
// characters, trailing blanks and tabs, and for converting formfeed
// and vtab characters into newlines and htabs (in case no tabwriter
-// is used).
+// is used). Text bracketed by tabwriter.Escape characters is passed
+// through unchanged.
//
type trimmer struct {
output io.Writer
- buf bytes.Buffer
+ space bytes.Buffer
+ state int
}
-// Design note: It is tempting to eliminate extra blanks occuring in
+// trimmer is implemented as a state machine.
+// It can be in one of the following states:
+const (
+ inSpace = iota
+ inEscape
+ inText
+)
+
+
+// Design note: It is tempting to eliminate extra blanks occurring in
// whitespace in this function as it could simplify some
// of the blanks logic in the node printing functions.
// However, this would mess up any formatting done by
// the tabwriter.
func (p *trimmer) Write(data []byte) (n int, err os.Error) {
- // m < 0: no unwritten data except for whitespace
- // m >= 0: data[m:n] unwritten and no whitespace
- m := 0
- if p.buf.Len() > 0 {
- m = -1
- }
-
+ m := 0 // if p.state != inSpace, data[m:n] is unwritten
var b byte
for n, b = range data {
- switch b {
- default:
- // write any pending whitespace
- if m < 0 {
- if _, err = p.output.Write(p.buf.Bytes()); err != nil {
- return
- }
- p.buf.Reset()
- m = n
- }
-
- case '\v':
+ if b == '\v' {
b = '\t' // convert to htab
- fallthrough
-
- case '\t', ' ', tabwriter.Escape:
- // write any pending (non-whitespace) data
- if m >= 0 {
- if _, err = p.output.Write(data[m:n]); err != nil {
- return
- }
- m = -1
+ }
+ switch p.state {
+ case inSpace:
+ switch b {
+ case '\t', ' ':
+ p.space.WriteByte(b) // WriteByte returns no errors
+ case '\f', '\n':
+ p.space.Reset() // discard trailing space
+ _, err = p.output.Write(newlines[0:1]) // write newline
+ case tabwriter.Escape:
+ _, err = p.output.Write(p.space.Bytes())
+ p.space.Reset()
+ p.state = inEscape
+ m = n + 1 // drop tabwriter.Escape
+ default:
+ _, err = p.output.Write(p.space.Bytes())
+ p.space.Reset()
+ p.state = inText
+ m = n
}
- // collect whitespace but discard tabwriter.Escapes.
- if b != tabwriter.Escape {
- p.buf.WriteByte(b) // WriteByte returns no errors
+ case inEscape:
+ if b == tabwriter.Escape {
+ _, err = p.output.Write(data[m:n])
+ p.state = inSpace
}
-
- case '\f', '\n':
- // discard whitespace
- p.buf.Reset()
- // write any pending (non-whitespace) data
- if m >= 0 {
- if _, err = p.output.Write(data[m:n]); err != nil {
- return
- }
- m = -1
- }
- // convert formfeed into newline
- if _, err = p.output.Write(newlines[0:1]); err != nil {
- return
+ case inText:
+ switch b {
+ case '\t', ' ':
+ _, err = p.output.Write(data[m:n])
+ p.state = inSpace
+ p.space.WriteByte(b) // WriteByte returns no errors
+ case '\f':
+ data[n] = '\n' // convert to newline
+ case tabwriter.Escape:
+ _, err = p.output.Write(data[m:n])
+ p.state = inEscape
+ m = n + 1 // drop tabwriter.Escape
}
}
+ if err != nil {
+ return
+ }
}
n = len(data)
- // write any pending non-whitespace
- if m >= 0 {
- if _, err = p.output.Write(data[m:n]); err != nil {
- return
- }
+ if p.state != inSpace {
+ _, err = p.output.Write(data[m:n])
+ p.state = inSpace
}
return
@@ -965,10 +1028,11 @@ type Config struct {
// Fprint "pretty-prints" an AST node to output and returns the number
// of bytes written and an error (if any) for a given configuration cfg.
+// Position information is interpreted relative to the file set fset.
// The node type must be *ast.File, or assignment-compatible to ast.Expr,
// ast.Decl, ast.Spec, or ast.Stmt.
//
-func (cfg *Config) Fprint(output io.Writer, node interface{}) (int, os.Error) {
+func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node interface{}) (int, os.Error) {
// redirect output through a trimmer to eliminate trailing whitespace
// (Input to a tabwriter must be untrimmed since trailing tabs provide
// formatting information. The tabwriter could provide trimming
@@ -1000,13 +1064,15 @@ func (cfg *Config) Fprint(output io.Writer, node interface{}) (int, os.Error) {
// setup printer and print node
var p printer
- p.init(output, cfg)
+ p.init(output, cfg, fset)
go func() {
switch n := node.(type) {
case ast.Expr:
+ p.nesting = 1
p.useNodeComments = true
p.expr(n, ignoreMultiLine)
case ast.Stmt:
+ p.nesting = 1
p.useNodeComments = true
// A labeled statement will un-indent to position the
// label. Set indent to 1 so we don't get indent "underflow".
@@ -1015,17 +1081,20 @@ func (cfg *Config) Fprint(output io.Writer, node interface{}) (int, os.Error) {
}
p.stmt(n, false, ignoreMultiLine)
case ast.Decl:
+ p.nesting = 1
p.useNodeComments = true
p.decl(n, ignoreMultiLine)
case ast.Spec:
+ p.nesting = 1
p.useNodeComments = true
p.spec(n, 1, false, ignoreMultiLine)
case *ast.File:
+ p.nesting = 0
p.comments = n.Comments
p.useNodeComments = n.Comments == nil
p.file(n)
default:
- p.errors <- os.NewError(fmt.Sprintf("printer.Fprint: unsupported node type %T", n))
+ p.errors <- fmt.Errorf("printer.Fprint: unsupported node type %T", n)
runtime.Goexit()
}
p.flush(token.Position{Offset: infinity, Line: infinity}, token.EOF)
@@ -1045,7 +1114,7 @@ func (cfg *Config) Fprint(output io.Writer, node interface{}) (int, os.Error) {
// Fprint "pretty-prints" an AST node to output.
// It calls Config.Fprint with default settings.
//
-func Fprint(output io.Writer, node interface{}) os.Error {
- _, err := (&Config{Tabwidth: 8}).Fprint(output, node) // don't care about number of bytes written
+func Fprint(output io.Writer, fset *token.FileSet, node interface{}) os.Error {
+ _, err := (&Config{Tabwidth: 8}).Fprint(output, fset, node) // don't care about number of bytes written
return err
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-01 14:17:41 +0000