Add support for wrapping to psql's "extended" mode. This makes it very

feasible to display tables that have both many columns and some large
data in some columns (such as pg_stats).

Emre Hasegeli with review and rewriting from Sergey Muraviov and
reviewed by Greg Stark

Author: gsstark

src/bin/psql/print.c

@@ -1161,6 +1161,7 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 	struct lineptr *hlineptr,
 			   *dlineptr;
 	bool		is_pager = false;
+	int			output_columns = 0;		/* Width of interactive console */
 
 	if (cancel_pressed)
 		return;
@@ -1234,24 +1235,86 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 			fprintf(fout, "%s\n", cont->title);
 	}
 
+	/*
+	 * Choose target output width: \pset columns, or $COLUMNS, or ioctl
+	 */
+	if (cont->opt->columns > 0)
+		output_columns = cont->opt->columns;
+	else if ((fout == stdout && isatty(fileno(stdout))) || is_pager)
+	{
+		if (cont->opt->env_columns > 0)
+			output_columns = cont->opt->env_columns;
+#ifdef TIOCGWINSZ
+		else
+		{
+			struct winsize screen_size;
+
+			if (ioctl(fileno(stdout), TIOCGWINSZ, &screen_size) != -1)
+				output_columns = screen_size.ws_col;
+		}
+#endif
+	}
+
+	if (cont->opt->format == PRINT_WRAPPED)
+	{
+		/* Calculate the available width to wrap the columns to after
+		 * subtracting the maximum header width and separators. At a minimum
+		 * enough to print "[ RECORD N ]" */
+		unsigned int width, swidth;
+
+		if (opt_border == 0)
+			swidth = 1; /* "header data" */
+		else if (opt_border == 1)
+			swidth = 3; /* "header | data" */
+		else if (opt_border > 1)
+			swidth = 7; /* "| header | data |" */
+
+		/* Wrap to maximum width */
+		width = dwidth + swidth + hwidth;
+		if ((output_columns > 0) && (width > output_columns))
+		{
+			dwidth = output_columns - hwidth - swidth;
+			width = output_columns;
+		}
+
+		/* Wrap to minimum width */
+		if (!opt_tuples_only)
+		{
+			int delta = 1 + log10(cont->nrows) - width;
+			if (opt_border == 0)
+				delta += 6; /* "* RECORD " */
+			else if (opt_border == 1)
+				delta += 10; /* "-[ RECORD  ]" */
+			else if (opt_border == 2)
+				delta += 15; /* "+-[ RECORD  ]-+" */
+
+			if (delta > 0)
+				dwidth += delta;
+		}
+		else if (dwidth < 3)
+			dwidth = 3;
+	}
+
 	/* print records */
 	for (i = 0, ptr = cont->cells; *ptr; i++, ptr++)
 	{
 		printTextRule pos;
-		int			line_count,
+		int			dline,
+					hline,
 					dcomplete,
-					hcomplete;
+					hcomplete,
+					offset,
+					chars_to_output;
 
 		if (cancel_pressed)
 			break;
 
 		if (i == 0)
 			pos = PRINT_RULE_TOP;
-		else if (!(*(ptr + 1)))
-			pos = PRINT_RULE_BOTTOM;
 		else
 			pos = PRINT_RULE_MIDDLE;
 
+		/* Print record header (e.g. "[ RECORD N ]") above each record */
 		if (i % cont->ncolumns == 0)
 		{
 			if (!opt_tuples_only)
@@ -1270,48 +1333,120 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 		pg_wcsformat((const unsigned char *) *ptr, strlen(*ptr), encoding,
 					 dlineptr, dheight);
 
-		line_count = 0;
+		/* Loop through header and data in parallel dealing with newlines and
+		 * wrapped lines until they're both exhausted */
+		dline = hline = 0;
 		dcomplete = hcomplete = 0;
+		offset = 0;
+		chars_to_output = dlineptr[dline].width;
 		while (!dcomplete || !hcomplete)
 		{
+			/* Left border */
 			if (opt_border == 2)
-				fprintf(fout, "%s ", dformat->leftvrule);
+				fprintf(fout, "%s", dformat->leftvrule);
+
+			/* Header (never wrapped so just need to deal with newlines) */
 			if (!hcomplete)
 			{
-				fprintf(fout, "%-s%*s", hlineptr[line_count].ptr,
-						hwidth - hlineptr[line_count].width, "");
+				int swidth, twidth = hwidth + 1;
+				fputs(hline? format->header_nl_left: " ", fout);
+				strlen_max_width((char *) hlineptr[hline].ptr, &twidth,
+								 encoding);
+				fprintf(fout, "%-s", hlineptr[hline].ptr);
+
+				swidth = hwidth - twidth;
+				if (swidth > 0) /* spacer */
+					fprintf(fout, "%*s", swidth, " ");
 
-				if (!hlineptr[line_count + 1].ptr)
+				if (hlineptr[hline + 1].ptr)
+				{
+					/* More lines after this one due to a newline */
+					fputs(format->header_nl_right, fout);
+					hline++;
+				} 
+				else 
+				{
+					/* This was the last line of the header */
+					fputs(" ", fout);
 					hcomplete = 1;
+				}
 			}
 			else
-				fprintf(fout, "%*s", hwidth, "");
+			{
+				/* Header exhausted but more data for column */
+				fprintf(fout, "%*s", hwidth + 2, "");
+			}
 
+			/* Separator */
 			if (opt_border > 0)
-				fprintf(fout, " %s ", dformat->midvrule);
-			else
-				fputc(' ', fout);
+			{
+				if (offset)
+					fputs(format->midvrule_wrap, fout);
+				else if (!dline)
+					fputs(dformat->midvrule, fout);
+				else if (dline)
+					fputs(format->midvrule_nl, fout);
+				else
+					fputs(format->midvrule_blank, fout);
+			}
 
+			/* Data */
 			if (!dcomplete)
 			{
-				if (opt_border < 2)
-					fprintf(fout, "%s\n", dlineptr[line_count].ptr);
-				else
-					fprintf(fout, "%-s%*s %s\n", dlineptr[line_count].ptr,
-							dwidth - dlineptr[line_count].width, "",
-							dformat->rightvrule);
+				int target_width,
+					bytes_to_output,
+					swidth;
+
+				fputs(!dcomplete && !offset? " ": format->wrap_left, fout);
 
-				if (!dlineptr[line_count + 1].ptr)
+				target_width = dwidth;
+				bytes_to_output = strlen_max_width(dlineptr[dline].ptr + offset,
+												   &target_width, encoding);
+				fputnbytes(fout, (char *)(dlineptr[dline].ptr + offset),
+						   bytes_to_output);
+
+				chars_to_output -= target_width;
+				offset += bytes_to_output;
+
+				/* spacer */
+				swidth = dwidth - target_width;
+				if (swidth > 0)
+					fprintf(fout, "%*s", swidth, "");
+
+				if (chars_to_output)
+				{
+					/* continuing a wrapped column */
+					fputs(format->wrap_right, fout);
+				}
+				else if (dlineptr[dline + 1].ptr)
+				{
+					/* reached a newline in the column */
+					fputs(format->nl_right, fout);
+					dline++;
+					offset = 0;
+					chars_to_output = dlineptr[dline].width;
+				}
+				else
+				{
+					/* reached the end of the cell */
+					fputs(" ", fout);
 					dcomplete = 1;
+				}
+
+				if (opt_border == 2)
+					fputs(dformat->rightvrule, fout);
+
+				fputs("\n", fout);
 			}
 			else
 			{
+				/* data exhausted (this can occur if header is longer than the
+				 * data due to newlines in the header) */
 				if (opt_border < 2)
-					fputc('\n', fout);
+					fputs("\n", fout);
 				else
-					fprintf(fout, "%*s %s\n", dwidth, "", dformat->rightvrule);
+					fprintf(fout, "%*s  %s\n", dwidth, "", dformat->rightvrule);
 			}
-			line_count++;
 		}
 	}