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https://github.com/golang/go
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go/printer: cleanup more string/byte conversions
Slight slow-down for printer benchmark (-0.7%) before applying CL 5416049 (which will wash it out). Code is cleaner and simpler. R=rsc CC=golang-dev https://golang.org/cl/5417053
This commit is contained in:
Robert Griesemer
parent
0b396a1731
commit
8218251498
@ -19,7 +19,7 @@ import (
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)
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const debug = false // enable for debugging
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const infinity = 1 << 30
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type whiteSpace int
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@ -33,18 +33,6 @@ const (
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unindent = whiteSpace('<')
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)
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var (
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esc = []byte{tabwriter.Escape}
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htab = []byte{'\t'}
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htabs = []byte("\t\t\t\t\t\t\t\t")
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newlines = []byte("\n\n\n\n\n\n\n\n") // more than the max determined by nlines
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formfeeds = []byte("\f\f\f\f\f\f\f\f") // more than the max determined by nlines
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)
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// Special positions
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var noPos token.Position // use noPos when a position is needed but not known
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var infinity = 1 << 30
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// Use ignoreMultiLine if the multiLine information is not important.
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var ignoreMultiLine = new(bool)
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@ -58,7 +46,7 @@ const (
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// local error wrapper so we can distinguish errors we want to return
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// as errors from genuine panics (which we don't want to return as errors)
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type osError struct {
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type printerError struct {
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err error
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}
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@ -143,12 +131,15 @@ func (p *printer) nlines(n, min int) int {
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// write0 writes raw (uninterpreted) data to p.output and handles errors.
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// write0 does not indent after newlines, and does not HTML-escape or update p.pos.
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//
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func (p *printer) write0(data []byte) {
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func (p *printer) write0(data string) {
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if len(data) > 0 {
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n, err := p.output.Write(data)
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// TODO(gri) Replace bottleneck []byte conversion
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// with writing into a bytes.Buffer.
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// Will also simplify post-processing.
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n, err := p.output.Write([]byte(data))
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p.written += n
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if err != nil {
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panic(osError{err})
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panic(printerError{err})
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}
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}
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}
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@ -157,12 +148,12 @@ func (p *printer) write0(data []byte) {
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// after a line break unless in a tabwriter escape sequence.
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// It updates p.pos as a side-effect.
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//
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func (p *printer) write(data []byte) {
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func (p *printer) write(data string) {
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i0 := 0
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for i, b := range data {
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switch b {
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for i := 0; i < len(data); i++ {
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switch data[i] {
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case '\n', '\f':
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// write segment ending in b
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// write segment ending in data[i]
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p.write0(data[i0 : i+1])
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// update p.pos
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@ -172,6 +163,7 @@ func (p *printer) write(data []byte) {
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if p.mode&inLiteral == 0 {
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// write indentation
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const htabs = "\t\t\t\t\t\t\t\t"
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// use "hard" htabs - indentation columns
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// must not be discarded by the tabwriter
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j := p.indent
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@ -211,9 +203,9 @@ func (p *printer) writeNewlines(n int, useFF bool) {
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if n > 0 {
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n = p.nlines(n, 0)
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if useFF {
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p.write(formfeeds[0:n])
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p.write("\f\f\f\f"[0:n])
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} else {
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p.write(newlines[0:n])
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p.write("\n\n\n\n"[0:n])
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}
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}
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}
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@ -240,9 +232,9 @@ func (p *printer) writeItem(pos token.Position, data string) {
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if debug {
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// do not update p.pos - use write0
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_, filename := filepath.Split(pos.Filename)
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p.write0([]byte(fmt.Sprintf("[%s:%d:%d]", filename, pos.Line, pos.Column)))
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p.write0(fmt.Sprintf("[%s:%d:%d]", filename, pos.Line, pos.Column))
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}
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p.write([]byte(data))
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p.write(data)
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p.last = p.pos
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}
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@ -301,9 +293,9 @@ func (p *printer) writeCommentPrefix(pos, next token.Position, prev, comment *as
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// next item is on the same line as the comment
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// (which must be a /*-style comment): separate
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// with a blank instead of a tab
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p.write([]byte{' '})
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p.write(" ")
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} else {
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p.write(htab)
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p.write("\t")
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}
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}
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@ -573,11 +565,10 @@ func (p *printer) writeComment(comment *ast.Comment) {
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// write comment lines, separated by formfeed,
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// without a line break after the last line
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linebreak := formfeeds[0:1]
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pos := p.fset.Position(comment.Pos())
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for i, line := range lines {
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if i > 0 {
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p.write(linebreak)
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p.write("\f")
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pos = p.pos
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}
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if len(line) > 0 {
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@ -617,7 +608,7 @@ func (p *printer) writeCommentSuffix(needsLinebreak bool) (droppedFF bool) {
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// make sure we have a line break
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if needsLinebreak {
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p.write([]byte{'\n'})
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p.write("\n")
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}
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return
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@ -643,7 +634,7 @@ func (p *printer) intersperseComments(next token.Position, tok token.Token) (dro
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if last.Text[1] == '*' && p.fset.Position(last.Pos()).Line == next.Line {
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// the last comment is a /*-style comment and the next item
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// follows on the same line: separate with an extra blank
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p.write([]byte{' '})
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p.write(" ")
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}
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// ensure that there is a line break after a //-style comment,
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// before a closing '}' unless explicitly disabled, or at eof
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@ -663,7 +654,6 @@ func (p *printer) intersperseComments(next token.Position, tok token.Token) (dro
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// whiteWhitespace writes the first n whitespace entries.
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func (p *printer) writeWhitespace(n int) {
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// write entries
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var data [1]byte
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for i := 0; i < n; i++ {
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switch ch := p.wsbuf[i]; ch {
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case ignore:
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@ -695,8 +685,7 @@ func (p *printer) writeWhitespace(n int) {
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}
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fallthrough
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default:
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data[0] = byte(ch)
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p.write(data[0:])
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p.write(string(ch))
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}
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}
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@ -871,6 +860,8 @@ const (
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// However, this would mess up any formatting done by
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// the tabwriter.
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var aNewline = []byte("\n")
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func (p *trimmer) Write(data []byte) (n int, err error) {
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// invariants:
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// p.state == inSpace:
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@ -890,7 +881,7 @@ func (p *trimmer) Write(data []byte) (n int, err error) {
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p.space.WriteByte(b) // WriteByte returns no errors
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case '\n', '\f':
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p.space.Reset() // discard trailing space
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_, err = p.output.Write(newlines[0:1]) // write newline
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_, err = p.output.Write(aNewline)
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case tabwriter.Escape:
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_, err = p.output.Write(p.space.Bytes())
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p.state = inEscape
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@ -917,7 +908,7 @@ func (p *trimmer) Write(data []byte) (n int, err error) {
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_, err = p.output.Write(data[m:n])
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p.state = inSpace
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p.space.Reset()
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_, err = p.output.Write(newlines[0:1]) // write newline
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_, err = p.output.Write(aNewline)
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case tabwriter.Escape:
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_, err = p.output.Write(data[m:n])
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p.state = inEscape
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@ -992,7 +983,7 @@ func (cfg *Config) fprint(output io.Writer, fset *token.FileSet, node interface{
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defer func() {
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written = p.written
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if e := recover(); e != nil {
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err = e.(osError).err // re-panics if it's not a local osError
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err = e.(printerError).err // re-panics if it's not a printerError
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}
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}()
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@ -1020,7 +1011,7 @@ func (cfg *Config) fprint(output io.Writer, fset *token.FileSet, node interface{
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p.useNodeComments = n.Comments == nil
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p.file(n)
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default:
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panic(osError{fmt.Errorf("printer.Fprint: unsupported node type %T", n)})
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panic(printerError{fmt.Errorf("printer.Fprint: unsupported node type %T", n)})
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}
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p.flush(token.Position{Offset: infinity, Line: infinity}, token.EOF)
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