Add psql expanded auto mode

This adds the "auto" option to the \x command, which switches to the
expanded mode when the normal output would be wider than the screen.

reviewed by Noah Misch

doc/src/sgml/ref/psql-ref.sgml

@@ -1860,7 +1860,8 @@ lo_import 152801
           <para>
           Sets the target width for the <literal>wrapped</> format, and also
           the width limit for determining whether output is wide enough to
-          require the pager.
+          require the pager or switch to the vertical display in expanded auto
+          mode.
           Zero (the default) causes the target width to be controlled by the
           environment variable <envar>COLUMNS</>, or the detected screen width
           if <envar>COLUMNS</> is not set.
@@ -1876,15 +1877,19 @@ lo_import 152801
           <term><literal>expanded</literal> (or <literal>x</literal>)</term>
           <listitem>
           <para>
-          If <replaceable class="parameter">value</replaceable> is specified
-          it must be either <literal>on</literal> or <literal>off</literal>
-          which will enable or disable expanded mode.  If <replaceable
-          class="parameter">value</replaceable> is omitted the command toggles
-          between regular and expanded mode.
-          When expanded mode is enabled, query results
-          are displayed in two columns, with the column name on the left and
-          the data on the right. This mode is useful if the data wouldn't fit
-          on the screen in the normal <quote>horizontal</quote> mode.
+          If <replaceable class="parameter">value</replaceable> is specified it
+          must be either <literal>on</literal> or <literal>off</literal>, which
+          will enable or disable expanded mode, or <literal>auto</literal>.
+          If <replaceable class="parameter">value</replaceable> is omitted the
+          command toggles between the on and off settings.  When expanded mode
+          is enabled, query results are displayed in two columns, with the
+          column name on the left and the data on the right. This mode is
+          useful if the data wouldn't fit on the screen in the
+          normal <quote>horizontal</quote> mode.  In the auto setting, the
+          expanded mode is used whenever the query output is wider than the
+          screen, otherwise the regular mode is used.  The auto setting is only
+          effective in the aligned and wrapped formats.  In other formats, it
+          always behaves as if the expanded mode is off.
           </para>
           </listitem>
           </varlistentry>
@@ -2326,10 +2331,10 @@ lo_import 152801
 
 
       <varlistentry>
-        <term><literal>\x</literal></term>
+        <term><literal>\x [ <replaceable class="parameter">on</replaceable> | <replaceable class="parameter">off</replaceable> | <replaceable class="parameter">auto</replaceable> ]</literal></term>
         <listitem>
         <para>
-        Toggles expanded table formatting mode. As such it is equivalent to
+        Sets or toggles expanded table formatting mode. As such it is equivalent to
         <literal>\pset expanded</literal>.
        </para>
        </listitem>
@@ -3197,7 +3202,8 @@ $endif
      <para>
       If <literal>\pset columns</> is zero, controls the
       width for the <literal>wrapped</> format and width for determining
-      if wide output requires the pager.
+      if wide output requires the pager or should be switched to the
+      vertical format in expanded auto mode.
      </para>
     </listitem>
    </varlistentry>

src/bin/psql/command.c

@@ -1355,7 +1355,7 @@ exec_command(const char *cmd,
 		free(fname);
 	}
 
-	/* \x -- toggle expanded table representation */
+	/* \x -- set or toggle expanded table representation */
 	else if (strcmp(cmd, "x") == 0)
 	{
 		char	   *opt = psql_scan_slash_option(scan_state,
@@ -2189,14 +2189,21 @@ do_pset(const char *param, const char *value, printQueryOpt *popt, bool quiet)
 	/* set expanded/vertical mode */
 	else if (strcmp(param, "x") == 0 || strcmp(param, "expanded") == 0 || strcmp(param, "vertical") == 0)
 	{
-		if (value)
+		if (value && pg_strcasecmp(value, "auto") == 0)
+			popt->topt.expanded = 2;
+		else if (value)
 			popt->topt.expanded = ParseVariableBool(value);
 		else
 			popt->topt.expanded = !popt->topt.expanded;
 		if (!quiet)
-			printf(popt->topt.expanded
-				   ? _("Expanded display is on.\n")
-				   : _("Expanded display is off.\n"));
+		{
+			if (popt->topt.expanded == 1)
+				printf(_("Expanded display is on.\n"));
+			else if (popt->topt.expanded == 2)
+				printf(_("Expanded display is used automatically.\n"));
+			else
+				printf(_("Expanded display is off.\n"));
+		}
 	}
 
 	/* locale-aware numeric output */
@@ -2356,7 +2363,7 @@ do_pset(const char *param, const char *value, printQueryOpt *popt, bool quiet)
 			popt->topt.columns = atoi(value);
 
 		if (!quiet)
-			printf(_("Target width for \"wrapped\" format is %d.\n"), popt->topt.columns);
+			printf(_("Target width is %d.\n"), popt->topt.columns);
 	}
 
 	else

src/bin/psql/help.c

@@ -242,8 +242,8 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\t [on|off]            show only rows (currently %s)\n"),
 			ON(pset.popt.topt.tuples_only));
 	fprintf(output, _("  \\T [STRING]            set HTML <table> tag attributes, or unset if none\n"));
-	fprintf(output, _("  \\x [on|off]            toggle expanded output (currently %s)\n"),
-			ON(pset.popt.topt.expanded));
+	fprintf(output, _("  \\x [on|off|auto]       toggle expanded output (currently %s)\n"),
+			pset.popt.topt.expanded == 2 ? "auto" : ON(pset.popt.topt.expanded));
 	fprintf(output, "\n");
 
 	fprintf(output, _("Connection\n"));

src/bin/psql/print.c

@@ -122,9 +122,11 @@ const printTextFormat pg_utf8format =
 
 /* Local functions */
 static int	strlen_max_width(unsigned char *str, int *target_width, int encoding);
-static void IsPagerNeeded(const printTableContent *cont, const int extra_lines,
+static void IsPagerNeeded(const printTableContent *cont, const int extra_lines, bool expanded,
 			  FILE **fout, bool *is_pager);
 
+static void print_aligned_vertical(const printTableContent *cont, FILE *fout);
+
 
 static void *
 pg_local_malloc(size_t size)
@@ -713,6 +715,17 @@ print_aligned_text(const printTableContent *cont, FILE *fout)
 		}
 	}
 
+	/*
+	 * If in expanded auto mode, we have now calculated the expected width, so
+	 * we can now escape to vertical mode if necessary.
+	 */
+	if (cont->opt->expanded == 2 && output_columns > 0 &&
+		(output_columns < total_header_width || output_columns < width_total))
+	{
+		print_aligned_vertical(cont, fout);
+		return;
+	}
+
 	/* If we wrapped beyond the display width, use the pager */
 	if (!is_pager && fout == stdout && output_columns > 0 &&
 		(output_columns < total_header_width || output_columns < width_total))
@@ -756,7 +769,7 @@ print_aligned_text(const printTableContent *cont, FILE *fout)
 				extra_row_output_lines = 0;
 			}
 		}
-		IsPagerNeeded(cont, extra_output_lines, &fout, &is_pager);
+		IsPagerNeeded(cont, extra_output_lines, false, &fout, &is_pager);
 	}
 
 	/* time to output */
@@ -1125,6 +1138,7 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 				dformatsize = 0;
 	struct lineptr *hlineptr,
 			   *dlineptr;
+	bool		is_pager = false;
 
 	if (cancel_pressed)
 		return;
@@ -1139,6 +1153,13 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 		return;
 	}
 
+	/*
+	 * Deal with the pager here instead of in printTable(), because we could
+	 * get here via print_aligned_text() in expanded auto mode, and so we have
+	 * to recalcuate the pager requirement based on vertical output.
+	 */
+	IsPagerNeeded(cont, 0, true, &fout, &is_pager);
+
 	/* Find the maximum dimensions for the headers */
 	for (i = 0; i < cont->ncolumns; i++)
 	{
@@ -1295,6 +1316,9 @@ print_aligned_vertical(const printTableContent *cont, FILE *fout)
 	free(dlineptr->ptr);
 	free(hlineptr);
 	free(dlineptr);
+
+	if (is_pager)
+		ClosePager(fout);
 }
 
 
@@ -2265,14 +2289,14 @@ printTableCleanup(printTableContent *const content)
  * Setup pager if required
  */
 static void
-IsPagerNeeded(const printTableContent *cont, const int extra_lines, FILE **fout,
+IsPagerNeeded(const printTableContent *cont, const int extra_lines, bool expanded, FILE **fout,
 			  bool *is_pager)
 {
 	if (*fout == stdout)
 	{
 		int			lines;
 
-		if (cont->opt->expanded)
+		if (expanded)
 			lines = (cont->ncolumns + 1) * cont->nrows;
 		else
 			lines = cont->nrows + 1;
@@ -2310,11 +2334,10 @@ printTable(const printTableContent *cont, FILE *fout, FILE *flog)
 	if (cont->opt->format == PRINT_NOTHING)
 		return;
 
-	/* print_aligned_text() handles the pager itself */
-	if ((cont->opt->format != PRINT_ALIGNED &&
-		 cont->opt->format != PRINT_WRAPPED) ||
-		cont->opt->expanded)
-		IsPagerNeeded(cont, 0, &fout, &is_pager);
+	/* print_aligned_*() handles the pager themselves */
+	if (cont->opt->format != PRINT_ALIGNED &&
+		cont->opt->format != PRINT_WRAPPED)
+		IsPagerNeeded(cont, 0, (cont->opt->expanded == 1), &fout, &is_pager);
 
 	/* print the stuff */
 
@@ -2324,32 +2347,32 @@ printTable(const printTableContent *cont, FILE *fout, FILE *flog)
 	switch (cont->opt->format)
 	{
 		case PRINT_UNALIGNED:
-			if (cont->opt->expanded)
+			if (cont->opt->expanded == 1)
 				print_unaligned_vertical(cont, fout);
 			else
 				print_unaligned_text(cont, fout);
 			break;
 		case PRINT_ALIGNED:
 		case PRINT_WRAPPED:
-			if (cont->opt->expanded)
+			if (cont->opt->expanded == 1)
 				print_aligned_vertical(cont, fout);
 			else
 				print_aligned_text(cont, fout);
 			break;
 		case PRINT_HTML:
-			if (cont->opt->expanded)
+			if (cont->opt->expanded == 1)
 				print_html_vertical(cont, fout);
 			else
 				print_html_text(cont, fout);
 			break;
 		case PRINT_LATEX:
-			if (cont->opt->expanded)
+			if (cont->opt->expanded == 1)
 				print_latex_vertical(cont, fout);
 			else
 				print_latex_text(cont, fout);
 			break;
 		case PRINT_TROFF_MS:
-			if (cont->opt->expanded)
+			if (cont->opt->expanded == 1)
 				print_troff_ms_vertical(cont, fout);
 			else
 				print_troff_ms_text(cont, fout);

src/bin/psql/print.h

@@ -70,8 +70,8 @@ typedef struct printTextFormat
 typedef struct printTableOpt
 {
 	enum printFormat format;	/* see enum above */
-	bool		expanded;		/* expanded/vertical output (if supported by
-								 * output format) */
+	unsigned short int expanded;/* expanded/vertical output (if supported by
+								 * output format); 0=no, 1=yes, 2=auto */
 	unsigned short int border;	/* Print a border around the table. 0=none,
 								 * 1=dividing lines, 2=full */
 	unsigned short int pager;	/* use pager for output (if to stdout and