src/pkg/tabwriter/tabwriter.go - go - Git at Google

 // 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.

 // The tabwriter package implements a write filter (tabwriter.Writer)
 // that translates tabbed columns in input into properly aligned text,
 // using the Elastic Tabstops algorithm described at
 // http://nickgravgaard.com/elastictabstops/index.html.
 //
 package tabwriter

 import (
 	"bytes";
 	"container/vector";
 	"io";
 	"os";
 	"utf8";
 )


 // ----------------------------------------------------------------------------
 // Filter implementation

 // A cell represents a segment of text delineated by tabs, form-feed,
 // or newline chars. The text itself is stored in a separate buffer;
 // cell only describes the segment's size in bytes and width in runes.
 //
 type cell struct {
 	size int;  // cell size in bytes
 	width int;  // cell width in runes
 }


 // A Writer is a filter that inserts padding around
 // tab-delimited columns in its input to align them
 // in the output.
 //
 // The Writer treats incoming bytes as UTF-8 encoded text
 // consisting of tab-terminated cells. Cells in adjacent lines
 // constitute a column. The Writer inserts padding as needed
 // to make all cells in a column have the same width, effectively
 // aligning the columns. Note that cells are tab-terminated,
 // not tab-separated: trailing non-tab text at the end of a line
 // is not part of any cell.
 //
 // The Writer assumes that all characters have the same width;
 // this may not be true in some fonts, especially with certain
 // UTF-8 characters.
 //
 // If a Writer is configured to filter HTML, HTML tags and entities
 // are simply passed through. The widths of tags and entities are
 // assumed to be zero (tags) and one (entities) for formatting purposes.
 //
 // The form feed character ('\f') acts like a newline but it also
 // terminates all columns in the current line (effectively calling
 // Flush). Cells in the next line start new columns. Unless found
 // inside an HTML tag, form feed characters appear as newlines in
 // the output.
 //
 // The Writer must buffer input internally, because proper spacing
 // of one line may depend on the cells in future lines. Clients must
 // call Flush when done calling Write.
 //
 type Writer struct {
 	// configuration
 	output io.Writer;
 	cellwidth int;
 	padding int;
 	padbytes [8]byte;
 	flags uint;

 	// current state
 	buf bytes.Buffer;  // collected text w/o tabs, newlines, or form feed chars
 	pos int;  // buffer position up to which width of incomplete cell has been computed
 	cell cell;  // current incomplete cell; cell.width is up to buf[pos] w/o ignored sections
 	html_char byte;  // terminating char of html tag/entity, or 0 ('>', ';', or 0)
 	lines vector.Vector;  // list if lines; each line is a list of cells
 	widths vector.IntVector;  // list of column widths in runes - re-used during formatting
 }


 func (b *Writer) addLine() {
 	b.lines.Push(vector.New(0));
 }


 func (b *Writer) line(i int) *vector.Vector {
 	return b.lines.At(i).(*vector.Vector);
 }


 // Reset the current state.
 func (b *Writer) reset() {
 	b.buf.Reset();
 	b.pos = 0;
 	b.cell = cell{};
 	b.html_char = 0;
 	b.lines.Init(0);
 	b.widths.Init(0);
 	b.addLine();
 }


 // Internal representation (current state):
 //
 // - all text written is appended to buf; form feed chars, tabs and newlines are stripped away
 // - at any given time there is a (possibly empty) incomplete cell at the end
 //   (the cell starts after a tab, form feed, or newline)
 // - size is the number of bytes belonging to the cell so far
 // - width is text width in runes of that cell from the start of the cell to
 //   position pos; html tags and entities are excluded from this width if html
 //   filtering is enabled
 // - the sizes and widths of processed text are kept in the lines_size and
 //   lines_width arrays, which contain an array of sizes or widths for each line
 // - the widths array is a temporary array with current widths used during
 //   formatting; it is kept in Writer because it's re-used
 //
 //                    |<---------- size ---------->|
 //                    |                            |
 //                    |<- width ->|<- ignored ->|  |
 //                    |           |             |  |
 // [---processed---tab------------<tag>...</tag>...]
 // ^                  ^                         ^
 // |                  |                         |
 // buf                start of incomplete cell  pos


 // Formatting can be controlled with these flags.
 const (
 	// Ignore html tags and treat entities (starting with '&'
 	// and ending in ';') as single characters (width = 1).
 	FilterHTML = 1 << iota;

 	// Force right-alignment of cell content.
 	// Default is left-alignment.
 	AlignRight;
 )


 // A Writer must be initialized with a call to Init. The first parameter (output)
 // specifies the filter output. The remaining parameters control the formatting:
 //
 //	cellwidth	minimal cell width
 //	padding		additional cell padding
 //	padchar		ASCII char used for padding
 //				if padchar == '\t', the Writer will assume that the
 //				width of a '\t' in the formatted output is cellwidth,
 //				and cells are left-aligned independent of align_left
 //				(for correct-looking results, cellwidth must correspond
 //				to the tab width in the viewer displaying the result)
 //	flags		formatting control
 //
 func (b *Writer) Init(output io.Writer, cellwidth, padding int, padchar byte, flags uint) *Writer {
 	if cellwidth < 0 {
 		panic("negative cellwidth");
 	}
 	if padding < 0 {
 		panic("negative padding");
 	}
 	b.output = output;
 	b.cellwidth = cellwidth;
 	b.padding = padding;
 	for i := len(b.padbytes) - 1; i >= 0; i-- {
 		b.padbytes[i] = padchar;
 	}
 	if padchar == '\t' {
 		// tab enforces left-alignment
 		flags &^= AlignRight;
 	}
 	b.flags = flags;

 	b.reset();

 	return b;
 }


 // debugging support (keep code around)
 /*
 func (b *Writer) dump() {
 	pos := 0;
 	for i := 0; i < b.lines_size.Len(); i++ {
 		line_size, line_width := b.line(i);
 		print("(", i, ") ");
 		for j := 0; j < line_size.Len(); j++ {
 			s := line_size.At(j);
 			print("[", string(b.buf.slice(pos, pos + s)), "]");
 			pos += s;
 		}
 		print("\n");
 	}
 	print("\n");
 }
 */


 func (b *Writer) write0(buf []byte) os.Error {
 	n, err := b.output.Write(buf);
 	if n != len(buf) && err == nil {
 		err = os.EIO;
 	}
 	return err;
 }


 var newline = []byte{'\n'}

 func (b *Writer) writePadding(textw, cellw int) os.Error {
 	if b.padbytes[0] == '\t' {
 		// make cell width a multiple of cellwidth
 		cellw = ((cellw + b.cellwidth - 1) / b.cellwidth) * b.cellwidth;
 	}

 	n := cellw - textw;
 	if n < 0 {
 		panic("internal error");
 	}

 	if b.padbytes[0] == '\t' {
 		n = (n + b.cellwidth - 1) / b.cellwidth;
 	}

 	for n > len(b.padbytes) {
 		if err := b.write0(&b.padbytes); err != nil {
 			return err;
 		}
 		n -= len(b.padbytes);
 	}

 	return b.write0(b.padbytes[0 : n]);
 }


 func (b *Writer) writeLines(pos0 int, line0, line1 int) (int, os.Error) {
 	pos := pos0;
 	for i := line0; i < line1; i++ {
 		line := b.line(i);
 		for j := 0; j < line.Len(); j++ {
 			c := line.At(j).(cell);

 			switch {
 			default: // align left

 				if err := b.write0(b.buf.Bytes()[pos : pos + c.size]); err != nil {
 					return pos, err;
 				}
 				pos += c.size;
 				if j < b.widths.Len() {
 					if err := b.writePadding(c.width, b.widths.At(j)); err != nil {
 						return pos, err;
 					}
 				}

 			case b.flags & AlignRight != 0:  // align right

 				if j < b.widths.Len() {
 					if err := b.writePadding(c.width, b.widths.At(j)); err != nil {
 						return pos, err;
 					}
 				}
 				if err := b.write0(b.buf.Bytes()[pos : pos + c.size]); err != nil {
 					return pos, err;
 				}
 				pos += c.size;
 			}
 		}

 		if i+1 == b.lines.Len() {
 			// last buffered line - we don't have a newline, so just write
 			// any outstanding buffered data
 			if err := b.write0(b.buf.Bytes()[pos : pos + b.cell.size]); err != nil {
 				return pos, err;
 			}
 			pos += b.cell.size;
 		} else {
 			// not the last line - write newline
 			if err := b.write0(newline); err != nil {
 				return pos, err;
 			}
 		}
 	}
 	return pos, nil;
 }


 func (b *Writer) format(pos0 int, line0, line1 int) (pos int, err os.Error) {
 	pos = pos0;
 	column := b.widths.Len();
 	last := line0;
 	for this := line0; this < line1; this++ {
 		line := b.line(this);

 		if column < line.Len() - 1 {
 			// cell exists in this column
 			// (note that the last cell per line is ignored)

 			// print unprinted lines until beginning of block
 			pos, err = b.writeLines(pos, last, this);
 			if err != nil {
 				return pos, err;
 			}
 			last = this;

 			// column block begin
 			width := b.cellwidth;  // minimal width
 			for ; this < line1; this++ {
 				line = b.line(this);
 				if column < line.Len() - 1 {
 					// cell exists in this column => update width
 					w := line.At(column).(cell).width + b.padding;
 					if w > width {
 						width = w;
 					}
 				} else {
 					break
 				}
 			}
 			// column block end

 			// format and print all columns to the right of this column
 			// (we know the widths of this column and all columns to the left)
 			b.widths.Push(width);
 			pos, err = b.format(pos, last, this);
 			b.widths.Pop();
 			last = this;
 		}
 	}

 	// print unprinted lines until end
 	return b.writeLines(pos, last, line1);
 }


 // Append text to current cell. Only update the cell width if updateWidth
 // is set (the cell width can only be updated if we know that we cannot be
 // in the middle of a UTF-8 encoded Unicode character).
 //
 func (b *Writer) append(text []byte, updateWidth bool) {
 	b.buf.Write(text);
 	b.cell.size += len(text);
 	if updateWidth {
 		b.cell.width += utf8.RuneCount(b.buf.Bytes()[b.pos : b.buf.Len()]);
 		b.pos = b.buf.Len();
 	}
 }


 // Start HTML-escape mode.
 func (b *Writer) startHTML(ch byte) {
 	if ch == '<' {
 		b.html_char = '>';
 	} else {
 		b.html_char = ';';
 	}
 }


 // Terminate HTML-escape mode. If the HTML text was an entity, its width
 // is assumed to be one for formatting purposes; otherwise it assumed to
 // be zero.
 //
 func (b *Writer) terminateHTML() {
 	if b.html_char == ';' {
 		// was entity, count as one rune
 		b.cell.width++;
 	}
 	b.pos = b.buf.Len();
 	b.html_char = 0;
 }


 // Terminate the current cell by adding it to the list of cells of the
 // current line. Returns the number of cells in that line.
 //
 func (b *Writer) terminateCell() int {
 	line := b.line(b.lines.Len() - 1);
 	line.Push(b.cell);
 	b.cell = cell{};
 	return line.Len();
 }


 // Flush should be called after the last call to Write to ensure
 // that any data buffered in the Writer is written to output. Any
 // incomplete HTML tag or entity at the end is simply considered
 // complete for formatting purposes.
 //
 func (b *Writer) Flush() os.Error {
 	// add current cell if not empty
 	if b.cell.size > 0 {
 		if b.html_char != 0 {
 			// inside html tag/entity - terminate it even if incomplete
 			b.terminateHTML();
 		}
 		b.terminateCell();
 	}

 	// format contents of buffer
 	_, err := b.format(0, 0, b.lines.Len());

 	// reset, even in the presence of errors
 	b.reset();

 	return err;
 }


 // Write writes buf to the writer b.
 // The only errors returned are ones encountered
 // while writing to the underlying output stream.
 //
 func (b *Writer) Write(buf []byte) (written int, err os.Error) {
 	// split text into cells
 	i0 := 0;
 	for i, ch := range buf {
 		if b.html_char == 0 {
 			// outside html tag/entity
 			switch ch {
 			case '\t', '\n', '\f':
 				// end of cell
 				b.append(buf[i0 : i], true);
 				i0 = i+1;  // exclude ch from (next) cell
 				ncells := b.terminateCell();
 				if ch != '\t' {
 					// terminate line
 					b.addLine();
 					if ch == '\f' || ncells == 1 {
 						// A '\f' always forces a flush. Otherwise, if the previous
 						// line has only one cell which does not have an impact on
 						// the formatting of the following lines (the last cell per
 						// line is ignored by format()), thus we can flush the
 						// Writer contents.
 						if err = b.Flush(); err != nil {
 							return i0, err;
 						}
 					}
 				}

 			case '<', '&':
 				// possibly an html tag/entity
 				if b.flags & FilterHTML != 0 {
 					// begin of tag/entity
 					b.append(buf[i0 : i], true);
 					i0 = i;
 					b.startHTML(ch);
 				}
 			}

 		} else {
 			// inside html tag/entity
 			if ch == b.html_char {
 				// end of tag/entity
 				b.append(buf[i0 : i+1], false);
 				i0 = i+1;  // exclude ch from (next) cell
 				b.terminateHTML();
 			}
 		}
 	}

 	// append leftover text
 	b.append(buf[i0 : len(buf)], false);
 	return len(buf), nil;
 }


 // NewWriter allocates and initializes a new tabwriter.Writer.
 // The parameters are the same as for the the Init function.
 //
 func NewWriter(output io.Writer, cellwidth, padding int, padchar byte, flags uint) *Writer {
 	return new(Writer).Init(output, cellwidth, padding, padchar, flags)
 }
	// 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.

	// The tabwriter package implements a write filter (tabwriter.Writer)
	// that translates tabbed columns in input into properly aligned text,
	// using the Elastic Tabstops algorithm described at
	// http://nickgravgaard.com/elastictabstops/index.html.
	//
	package tabwriter

	import (
	"bytes";
	"container/vector";
	"io";
	"os";
	"utf8";
	)


	// ----------------------------------------------------------------------------
	// Filter implementation

	// A cell represents a segment of text delineated by tabs, form-feed,
	// or newline chars. The text itself is stored in a separate buffer;
	// cell only describes the segment's size in bytes and width in runes.
	//
	type cell struct {
	size int; // cell size in bytes
	width int; // cell width in runes
	}


	// A Writer is a filter that inserts padding around
	// tab-delimited columns in its input to align them
	// in the output.
	//
	// The Writer treats incoming bytes as UTF-8 encoded text
	// consisting of tab-terminated cells. Cells in adjacent lines
	// constitute a column. The Writer inserts padding as needed
	// to make all cells in a column have the same width, effectively
	// aligning the columns. Note that cells are tab-terminated,
	// not tab-separated: trailing non-tab text at the end of a line
	// is not part of any cell.
	//
	// The Writer assumes that all characters have the same width;
	// this may not be true in some fonts, especially with certain
	// UTF-8 characters.
	//
	// If a Writer is configured to filter HTML, HTML tags and entities
	// are simply passed through. The widths of tags and entities are
	// assumed to be zero (tags) and one (entities) for formatting purposes.
	//
	// The form feed character ('\f') acts like a newline but it also
	// terminates all columns in the current line (effectively calling
	// Flush). Cells in the next line start new columns. Unless found
	// inside an HTML tag, form feed characters appear as newlines in
	// the output.
	//
	// The Writer must buffer input internally, because proper spacing
	// of one line may depend on the cells in future lines. Clients must
	// call Flush when done calling Write.
	//
	type Writer struct {
	// configuration
	output io.Writer;
	cellwidth int;
	padding int;
	padbytes [8]byte;
	flags uint;

	// current state
	buf bytes.Buffer; // collected text w/o tabs, newlines, or form feed chars
	pos int; // buffer position up to which width of incomplete cell has been computed
	cell cell; // current incomplete cell; cell.width is up to buf[pos] w/o ignored sections
	html_char byte; // terminating char of html tag/entity, or 0 ('>', ';', or 0)
	lines vector.Vector; // list if lines; each line is a list of cells
	widths vector.IntVector; // list of column widths in runes - re-used during formatting
	}


	func (b *Writer) addLine() {
	b.lines.Push(vector.New(0));
	}


	func (b Writer) line(i int) vector.Vector {
	return b.lines.At(i).(*vector.Vector);
	}


	// Reset the current state.
	func (b *Writer) reset() {
	b.buf.Reset();
	b.pos = 0;
	b.cell = cell{};
	b.html_char = 0;
	b.lines.Init(0);
	b.widths.Init(0);
	b.addLine();
	}


	// Internal representation (current state):
	//
	// - all text written is appended to buf; form feed chars, tabs and newlines are stripped away
	// - at any given time there is a (possibly empty) incomplete cell at the end
	// (the cell starts after a tab, form feed, or newline)
	// - size is the number of bytes belonging to the cell so far
	// - width is text width in runes of that cell from the start of the cell to
	// position pos; html tags and entities are excluded from this width if html
	// filtering is enabled
	// - the sizes and widths of processed text are kept in the lines_size and
	// lines_width arrays, which contain an array of sizes or widths for each line
	// - the widths array is a temporary array with current widths used during
	// formatting; it is kept in Writer because it's re-used
	//
	// \|<---------- size ---------->\|
	// \| \|
	// \|<- width ->\|<- ignored ->\| \|
	// \| \| \| \|
	// [---processed---tab------------<tag>...</tag>...]
	// ^ ^ ^
	// \| \| \|
	// buf start of incomplete cell pos


	// Formatting can be controlled with these flags.
	const (
	// Ignore html tags and treat entities (starting with '&'
	// and ending in ';') as single characters (width = 1).
	FilterHTML = 1 << iota;

	// Force right-alignment of cell content.
	// Default is left-alignment.
	AlignRight;
	)


	// A Writer must be initialized with a call to Init. The first parameter (output)
	// specifies the filter output. The remaining parameters control the formatting:
	//
	// cellwidth minimal cell width
	// padding additional cell padding
	// padchar ASCII char used for padding
	// if padchar == '\t', the Writer will assume that the
	// width of a '\t' in the formatted output is cellwidth,
	// and cells are left-aligned independent of align_left
	// (for correct-looking results, cellwidth must correspond
	// to the tab width in the viewer displaying the result)
	// flags formatting control
	//
	func (b Writer) Init(output io.Writer, cellwidth, padding int, padchar byte, flags uint) Writer {
	if cellwidth < 0 {
	panic("negative cellwidth");
	}
	if padding < 0 {
	panic("negative padding");
	}
	b.output = output;
	b.cellwidth = cellwidth;
	b.padding = padding;
	for i := len(b.padbytes) - 1; i >= 0; i-- {
	b.padbytes[i] = padchar;
	}
	if padchar == '\t' {
	// tab enforces left-alignment
	flags &^= AlignRight;
	}
	b.flags = flags;

	b.reset();

	return b;
	}


	// debugging support (keep code around)
	/*
	func (b *Writer) dump() {
	pos := 0;
	for i := 0; i < b.lines_size.Len(); i++ {
	line_size, line_width := b.line(i);
	print("(", i, ") ");
	for j := 0; j < line_size.Len(); j++ {
	s := line_size.At(j);
	print("[", string(b.buf.slice(pos, pos + s)), "]");
	pos += s;
	}
	print("\n");
	}
	print("\n");
	}
	*/


	func (b *Writer) write0(buf []byte) os.Error {
	n, err := b.output.Write(buf);
	if n != len(buf) && err == nil {
	err = os.EIO;
	}
	return err;
	}


	var newline = []byte{'\n'}

	func (b *Writer) writePadding(textw, cellw int) os.Error {
	if b.padbytes[0] == '\t' {
	// make cell width a multiple of cellwidth
	cellw = ((cellw + b.cellwidth - 1) / b.cellwidth) * b.cellwidth;
	}

	n := cellw - textw;
	if n < 0 {
	panic("internal error");
	}

	if b.padbytes[0] == '\t' {
	n = (n + b.cellwidth - 1) / b.cellwidth;
	}

	for n > len(b.padbytes) {
	if err := b.write0(&b.padbytes); err != nil {
	return err;
	}
	n -= len(b.padbytes);
	}

	return b.write0(b.padbytes[0 : n]);
	}


	func (b *Writer) writeLines(pos0 int, line0, line1 int) (int, os.Error) {
	pos := pos0;
	for i := line0; i < line1; i++ {
	line := b.line(i);
	for j := 0; j < line.Len(); j++ {
	c := line.At(j).(cell);

	switch {
	default: // align left

	if err := b.write0(b.buf.Bytes()[pos : pos + c.size]); err != nil {
	return pos, err;
	}
	pos += c.size;
	if j < b.widths.Len() {
	if err := b.writePadding(c.width, b.widths.At(j)); err != nil {
	return pos, err;
	}
	}

	case b.flags & AlignRight != 0: // align right

	if j < b.widths.Len() {
	if err := b.writePadding(c.width, b.widths.At(j)); err != nil {
	return pos, err;
	}
	}
	if err := b.write0(b.buf.Bytes()[pos : pos + c.size]); err != nil {
	return pos, err;
	}
	pos += c.size;
	}
	}

	if i+1 == b.lines.Len() {
	// last buffered line - we don't have a newline, so just write
	// any outstanding buffered data
	if err := b.write0(b.buf.Bytes()[pos : pos + b.cell.size]); err != nil {
	return pos, err;
	}
	pos += b.cell.size;
	} else {
	// not the last line - write newline
	if err := b.write0(newline); err != nil {
	return pos, err;
	}
	}
	}
	return pos, nil;
	}


	func (b *Writer) format(pos0 int, line0, line1 int) (pos int, err os.Error) {
	pos = pos0;
	column := b.widths.Len();
	last := line0;
	for this := line0; this < line1; this++ {
	line := b.line(this);

	if column < line.Len() - 1 {
	// cell exists in this column
	// (note that the last cell per line is ignored)

	// print unprinted lines until beginning of block
	pos, err = b.writeLines(pos, last, this);
	if err != nil {
	return pos, err;
	}
	last = this;

	// column block begin
	width := b.cellwidth; // minimal width
	for ; this < line1; this++ {
	line = b.line(this);
	if column < line.Len() - 1 {
	// cell exists in this column => update width
	w := line.At(column).(cell).width + b.padding;
	if w > width {
	width = w;
	}
	} else {
	break
	}
	}
	// column block end

	// format and print all columns to the right of this column
	// (we know the widths of this column and all columns to the left)
	b.widths.Push(width);
	pos, err = b.format(pos, last, this);
	b.widths.Pop();
	last = this;
	}
	}

	// print unprinted lines until end
	return b.writeLines(pos, last, line1);
	}


	// Append text to current cell. Only update the cell width if updateWidth
	// is set (the cell width can only be updated if we know that we cannot be
	// in the middle of a UTF-8 encoded Unicode character).
	//
	func (b *Writer) append(text []byte, updateWidth bool) {
	b.buf.Write(text);
	b.cell.size += len(text);
	if updateWidth {
	b.cell.width += utf8.RuneCount(b.buf.Bytes()[b.pos : b.buf.Len()]);
	b.pos = b.buf.Len();
	}
	}


	// Start HTML-escape mode.
	func (b *Writer) startHTML(ch byte) {
	if ch == '<' {
	b.html_char = '>';
	} else {
	b.html_char = ';';
	}
	}


	// Terminate HTML-escape mode. If the HTML text was an entity, its width
	// is assumed to be one for formatting purposes; otherwise it assumed to
	// be zero.
	//
	func (b *Writer) terminateHTML() {
	if b.html_char == ';' {
	// was entity, count as one rune
	b.cell.width++;
	}
	b.pos = b.buf.Len();
	b.html_char = 0;
	}


	// Terminate the current cell by adding it to the list of cells of the
	// current line. Returns the number of cells in that line.
	//
	func (b *Writer) terminateCell() int {
	line := b.line(b.lines.Len() - 1);
	line.Push(b.cell);
	b.cell = cell{};
	return line.Len();
	}


	// Flush should be called after the last call to Write to ensure
	// that any data buffered in the Writer is written to output. Any
	// incomplete HTML tag or entity at the end is simply considered
	// complete for formatting purposes.
	//
	func (b *Writer) Flush() os.Error {
	// add current cell if not empty
	if b.cell.size > 0 {
	if b.html_char != 0 {
	// inside html tag/entity - terminate it even if incomplete
	b.terminateHTML();
	}
	b.terminateCell();
	}

	// format contents of buffer
	_, err := b.format(0, 0, b.lines.Len());

	// reset, even in the presence of errors
	b.reset();

	return err;
	}


	// Write writes buf to the writer b.
	// The only errors returned are ones encountered
	// while writing to the underlying output stream.
	//
	func (b *Writer) Write(buf []byte) (written int, err os.Error) {
	// split text into cells
	i0 := 0;
	for i, ch := range buf {
	if b.html_char == 0 {
	// outside html tag/entity
	switch ch {
	case '\t', '\n', '\f':
	// end of cell
	b.append(buf[i0 : i], true);
	i0 = i+1; // exclude ch from (next) cell
	ncells := b.terminateCell();
	if ch != '\t' {
	// terminate line
	b.addLine();
	if ch == '\f' \|\| ncells == 1 {
	// A '\f' always forces a flush. Otherwise, if the previous
	// line has only one cell which does not have an impact on
	// the formatting of the following lines (the last cell per
	// line is ignored by format()), thus we can flush the
	// Writer contents.
	if err = b.Flush(); err != nil {
	return i0, err;
	}
	}
	}

	case '<', '&':
	// possibly an html tag/entity
	if b.flags & FilterHTML != 0 {
	// begin of tag/entity
	b.append(buf[i0 : i], true);
	i0 = i;
	b.startHTML(ch);
	}
	}

	} else {
	// inside html tag/entity
	if ch == b.html_char {
	// end of tag/entity
	b.append(buf[i0 : i+1], false);
	i0 = i+1; // exclude ch from (next) cell
	b.terminateHTML();
	}
	}
	}

	// append leftover text
	b.append(buf[i0 : len(buf)], false);
	return len(buf), nil;
	}


	// NewWriter allocates and initializes a new tabwriter.Writer.
	// The parameters are the same as for the the Init function.
	//
	func NewWriter(output io.Writer, cellwidth, padding int, padchar byte, flags uint) *Writer {
	return new(Writer).Init(output, cellwidth, padding, padchar, flags)
	}