Rework wrap-width calculation in psql's print_aligned_vertical() function.

This area was rather heavily whacked around in 6513633 and follow-on
commits, and it was showing it, because the logic to calculate the
allowable data width in wrapped expanded mode had only the vaguest
relationship to the logic that was actually printing the data.  It was
not very close to being right about the conditions requiring overhead
columns to be added.  Aside from being wrong, it was pretty unreadable
and under-commented.  Rewrite it so it corresponds to what the printing
code actually does.

In passing, remove a couple of dead tests in the printing logic, too.

Per a complaint from Jeff Janes, though this doesn't look much like his
patch because it fixes a number of other corner-case bogosities too.
One such fix that's visible in the regression test results is that
although the code was attempting to enforce a minimum data width of
3 columns, it sometimes left less space than that available.

Author: tglsfdc

src/bin/psql/print.c

@@ -1346,88 +1346,115 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 #endif
 	}
 
+	/*
+	 * Calculate available width for data in wrapped mode
+	 */
 	if (cont->opt->format == PRINT_WRAPPED)
 	{
-		/*
-		 * Separators width
-		 */
-		unsigned int width,
-					min_width,
-					swidth,
-					iwidth = 0;
+		unsigned int swidth,
+					rwidth = 0,
+					newdwidth;
 
 		if (opt_border == 0)
 		{
 			/*
-			 * For border = 0, one space in the middle.
+			 * For border = 0, one space in the middle.  (If we discover we
+			 * need to wrap, the spacer column will be replaced by a wrap
+			 * marker, and we'll make room below for another wrap marker at
+			 * the end of the line.  But for now, assume no wrap is needed.)
 			 */
 			swidth = 1;
+
+			/* We might need a column for header newline markers, too */
+			if (hmultiline)
+				swidth++;
 		}
 		else if (opt_border == 1)
 		{
 			/*
-			 * For border = 1, one for the pipe (|) in the middle between the
-			 * two spaces.
+			 * For border = 1, two spaces and a vrule in the middle.  (As
+			 * above, we might need one more column for a wrap marker.)
 			 */
 			swidth = 3;
+
+			/* We might need a column for left header newline markers, too */
+			if (hmultiline && (format == &pg_asciiformat_old))
+				swidth++;
 		}
 		else
-
+		{
 			/*
-			 * For border = 2, two more for the pipes (|) at the beginning and
-			 * at the end of the lines.
+			 * For border = 2, two more for the vrules at the beginning and
+			 * end of the lines, plus spacer columns adjacent to these.  (We
+			 * won't need extra columns for wrap/newline markers, we'll just
+			 * repurpose the spacers.)
 			 */
 			swidth = 7;
+		}
 
-		if ((opt_border < 2) &&
-			((hmultiline &&
-			  (format == &pg_asciiformat_old)) ||
-			 (dmultiline &&
-			  (format != &pg_asciiformat_old))))
-			iwidth++;			/* for newline indicators */
-
-		min_width = hwidth + iwidth + swidth + 3;
+		/* Reserve a column for data newline indicators, too, if needed */
+		if (dmultiline &&
+			opt_border < 2 && format != &pg_asciiformat_old)
+			swidth++;
 
-		/*
-		 * Record header width
-		 */
+		/* Determine width required for record header lines */
 		if (!opt_tuples_only)
 		{
-			/*
-			 * Record number
-			 */
-			unsigned int rwidth = 1 + log10(cont->nrows);
-
+			rwidth = 1 + log10(cont->nrows);
 			if (opt_border == 0)
 				rwidth += 9;	/* "* RECORD " */
 			else if (opt_border == 1)
 				rwidth += 12;	/* "-[ RECORD  ]" */
 			else
 				rwidth += 15;	/* "+-[ RECORD  ]-+" */
+		}
+
+		/* We might need to do the rest of the calculation twice */
+		for (;;)
+		{
+			unsigned int width,
+						min_width;
+
+			/* Total width required to not wrap data */
+			width = hwidth + swidth + dwidth;
 
+			/* Minimum acceptable width: room for just 3 columns of data */
+			min_width = hwidth + swidth + 3;
+			/* ... but not less than what the record header lines need */
 			if (rwidth > min_width)
 				min_width = rwidth;
-		}
 
-		/* Wrap to minimum width */
-		width = hwidth + iwidth + swidth + dwidth;
-		if ((width < min_width) || (output_columns < min_width))
-			width = min_width - hwidth - iwidth - swidth;
-		else if (output_columns > 0)
+			if (width < min_width || output_columns < min_width)
+			{
+				/* Set data width to match min_width */
+				newdwidth = min_width - hwidth - swidth;
+			}
+			else if (output_columns > 0)
+			{
+				/* Set data width to match output_columns */
+				newdwidth = output_columns - hwidth - swidth;
+			}
+			else
+			{
+				/* Use native data width */
+				newdwidth = dwidth;
+			}
 
 			/*
-			 * Wrap to maximum width
+			 * If we will need to wrap data and didn't already allocate a data
+			 * newline/wrap marker column, do so and recompute.
 			 */
-			width = output_columns - hwidth - iwidth - swidth;
-
-		if ((width < dwidth) || (dheight > 1))
-		{
-			dmultiline = true;
-			if ((opt_border == 0) &&
-				(format != &pg_asciiformat_old))
-				width--;		/* for wrap indicators */
+			if (newdwidth < dwidth && !dmultiline &&
+				opt_border < 2 && format != &pg_asciiformat_old)
+			{
+				dmultiline = true;
+				swidth++;
+			}
+			else
+				break;
 		}
-		dwidth = width;
+
+		dwidth = newdwidth;
 	}
 
 	/* print records */
@@ -1558,12 +1585,10 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 			{
 				if (offset)
 					fputs(format->midvrule_wrap, fout);
-				else if (!dline)
+				else if (dline == 0)
 					fputs(dformat->midvrule, fout);
-				else if (dline)
-					fputs(format->midvrule_nl, fout);
 				else
-					fputs(format->midvrule_blank, fout);
+					fputs(format->midvrule_nl, fout);
 			}
 
 			/* Data */
@@ -1574,9 +1599,9 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 							swidth = dwidth;
 
 				/*
-				 * Left spacer on wrap indicator
+				 * Left spacer or wrap indicator
 				 */
-				fputs(!dcomplete && !offset ? " " : format->wrap_left, fout);
+				fputs(offset == 0 ? " " : format->wrap_left, fout);
 
 				/*
 				 * Data text