- debugging support

R=rsc
DELTA=110  (98 added, 0 deleted, 12 changed)
OCL=35487
CL=35490

2 files changed, 110 insertions, 12 deletions

diff --git a/src/pkg/tabwriter/tabwriter.go b/src/pkg/tabwriter/tabwriter.go
index 15ffc79cc..372ebff8b 100644
--- a/src/pkg/tabwriter/tabwriter.go
+++ b/src/pkg/tabwriter/tabwriter.go
@@ -21,7 +21,7 @@ import (
 // ----------------------------------------------------------------------------
 // Filter implementation
 
-// A cell represents a segment of text delineated by tabs, form-feed,
+// A cell represents a segment of text delineated by tabs, formfeed,
 // or newline chars. The text itself is stored in a separate buffer;
 // cell only describes the segment's size in bytes, its width in runes,
 // and whether it's an htab ('\t') or vtab ('\v') terminated call.
@@ -59,10 +59,10 @@ type cell struct {
 // 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
+// The formfeed 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
+// inside an HTML tag, formfeed characters appear as newlines in
 // the output.
 //
 // The Writer must buffer input internally, because proper spacing
@@ -78,7 +78,7 @@ type Writer struct {
 	flags uint;
 
 	// current state
-	buf bytes.Buffer;  // collected text w/o tabs, newlines, or form feed chars
+	buf bytes.Buffer;  // collected text w/o tabs, newlines, or formfeed 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)
@@ -111,9 +111,9 @@ func (b *Writer) reset() {
 
 // Internal representation (current state):
 //
-// - all text written is appended to buf; form feed chars, tabs and newlines are stripped away
+// - all text written is appended to buf; formfeed 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)
+//   (the cell starts after a tab, formfeed, or newline)
 // - cell.size is the number of bytes belonging to the cell so far
 // - cell.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
@@ -146,6 +146,10 @@ const (
 	// Handle empty columns as if they were not present in
 	// the input in the first place.
 	DiscardEmptyColumns;
+
+	// Print a vertical bar ('|') between columns (after formatting).
+	// Discarded colums appear as zero-width columns ("||").
+	Debug;
 )
 
 
@@ -153,15 +157,21 @@ const (
 // specifies the filter output. The remaining parameters control the formatting:
 //
 //	cellwidth	minimal cell width
-//	padding		additional cell padding
+//	padding		cell padding added to cell before computing its width
 //	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)
+//			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
 //
+// To format in tab-separated columns with a tab stop of 8:
+//	b.Init(w, 8, 1, '\t', 0);
+//
+// To format in space-separated columns with at least 4 spaces between columns:
+//	b.Init(w, 1, 4, ' ', 0);
+//
 func (b *Writer) Init(output io.Writer, cellwidth, padding int, padchar byte, flags uint) *Writer {
 	if cellwidth < 0 {
 		panic("negative cellwidth");
@@ -243,6 +253,8 @@ func (b *Writer) writePadding(textw, cellw int) os.Error {
 }
 
 
+var vbar = []byte{'|'};
+
 func (b *Writer) writeLines(pos0 int, line0, line1 int) (pos int, err os.Error) {
 	pos = pos0;
 	for i := line0; i < line1; i++ {
@@ -250,6 +262,11 @@ func (b *Writer) writeLines(pos0 int, line0, line1 int) (pos int, err os.Error)
 		for j := 0; j < line.Len(); j++ {
 			c := line.At(j).(cell);
 
+			if j > 0 && b.flags&Debug != 0 {
+				if err = b.write0(vbar); err != nil {
+					return;
+				}
+			}
 			switch {
 			default: // align left
 
diff --git a/src/pkg/tabwriter/tabwriter_test.go b/src/pkg/tabwriter/tabwriter_test.go
index b43a26980..927ed5e21 100644
--- a/src/pkg/tabwriter/tabwriter_test.go
+++ b/src/pkg/tabwriter/tabwriter_test.go
@@ -120,6 +120,13 @@ var tests = []entry {
 	},
 
 	entry{
+		"1 debug",
+		8, 1, '.', Debug,
+		"",
+		""
+	},
+
+	entry{
 		"2",
 		8, 1, '.', 0,
 		"\n\n\n",
@@ -169,6 +176,13 @@ var tests = []entry {
 	},
 
 	entry{
+		"5c debug",
+		8, 1, '.', Debug,
+		"*\t*\t",
+		"*.......|*"
+	},
+
+	entry{
 		"5d",
 		8, 1, '.', AlignRight,
 		"*\t*\t",
@@ -232,6 +246,13 @@ var tests = []entry {
 	},
 
 	entry{
+		"7g debug",
+		8, 1, '.', FilterHTML | Debug,
+		"g) f&lt;o\t<b>bar</b>\t non-terminated entity &amp",
+		"g) f&lt;o..|<b>bar</b>.....| non-terminated entity &amp"
+	},
+
+	entry{
 		"8",
 		8, 1, '*', 0,
 		"Hello, world!\n",
@@ -269,6 +290,16 @@ var tests = []entry {
 	},
 
 	entry{
+		"9c debug",
+		0, 0, '.', Debug,
+		"1\t2\t3\t4\f"  // \f causes a newline and flush
+		"11\t222\t3333\t44444\n",
+
+		"1|2|3|4\n"
+		"11|222|3333|44444\n"
+	},
+
+	entry{
 		"10a",
 		5, 0, '.', 0,
 		"1\t2\t3\t4\n",
@@ -409,6 +440,24 @@ var tests = []entry {
 	},
 
 	entry{
+		"14 debug",
+		0, 2, ' ', AlignRight | Debug,
+		".0\t.3\t2.4\t-5.1\t\n"
+		"23.0\t12345678.9\t2.4\t-989.4\t\n"
+		"5.1\t12.0\t2.4\t-7.0\t\n"
+		".0\t0.0\t332.0\t8908.0\t\n"
+		".0\t-.3\t456.4\t22.1\t\n"
+		".0\t1.2\t44.4\t-13.3\t\t",
+
+		"    .0|          .3|    2.4|    -5.1|\n"
+		"  23.0|  12345678.9|    2.4|  -989.4|\n"
+		"   5.1|        12.0|    2.4|    -7.0|\n"
+		"    .0|         0.0|  332.0|  8908.0|\n"
+		"    .0|         -.3|  456.4|    22.1|\n"
+		"    .0|         1.2|   44.4|   -13.3|"
+	},
+
+	entry{
 		"15a",
 		4, 0, '.', 0,
 		"a\t\tb",
@@ -469,6 +518,22 @@ var tests = []entry {
 	},
 
 	entry{
+		"16b debug",
+		100, 0, '\t', DiscardEmptyColumns | Debug,
+		"a\vb\v\vd\n"
+		"a\vb\v\vd\ve\n"
+		"a\n"
+		"a\vb\vc\vd\n"
+		"a\vb\vc\vd\ve\n",
+
+		"a\t|b\t||d\n"
+		"a\t|b\t||d\t|e\n"
+		"a\n"
+		"a\t|b\t|c\t|d\n"
+		"a\t|b\t|c\t|d\t|e\n"
+	},
+
+	entry{
 		"16c",
 		100, 0, '\t', DiscardEmptyColumns,
 		"a\tb\t\td\n"  // hard tabs - do not discard column
@@ -483,6 +548,22 @@ var tests = []entry {
 		"a\tb\tc\td\n"
 		"a\tb\tc\td\te\n"
 	},
+
+	entry{
+		"16c debug",
+		100, 0, '\t', DiscardEmptyColumns | Debug,
+		"a\tb\t\td\n"  // hard tabs - do not discard column
+		"a\tb\t\td\te\n"
+		"a\n"
+		"a\tb\tc\td\n"
+		"a\tb\tc\td\te\n",
+
+		"a\t|b\t|\t|d\n"
+		"a\t|b\t|\t|d\t|e\n"
+		"a\n"
+		"a\t|b\t|c\t|d\n"
+		"a\t|b\t|c\t|d\t|e\n"
+	},
 }