psql: Add \gx command

It can often be useful to use expanded mode output (\x) for just a
single query.  Introduce a \gx which acts exactly like \g except that it
will force expanded output mode for that one \gx call.  This is simpler
than having to use \x as a toggle and also means that the user doesn't
have to worry about the current state of the expanded variable, or
resetting it later, to ensure a given query is always returned in
expanded mode.

Primairly Christoph's patch, though I did tweak the documentation and help
text a bit, and re-indented the tab completion section.

Author: Christoph Berg
Reviewed By: Daniel Verite
Discussion: https://postgr.es/m/20170127132737.6skslelaf4txs6iw%40msg.credativ.de

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

@@ -1890,6 +1890,18 @@ Tue Oct 26 21:40:57 CEST 1999
       </varlistentry>
 
 
+      <varlistentry>
+        <term><literal>\gx [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
+        <term><literal>\gx [ |<replaceable class="parameter">command</replaceable> ]</literal></term>
+        <listitem>
+        <para>
+        <literal>\gx</literal> is equivalent to <literal>\g</literal>, but
+        forces expanded output mode for this query.  See <literal>\x</literal>.
+        </para>
+        </listitem>
+      </varlistentry>
+
+
       <varlistentry>
         <term><literal>\gexec</literal></term>
 

src/bin/psql/command.c

@@ -906,8 +906,11 @@ exec_command(const char *cmd,
 		free(fname);
 	}
 
-	/* \g [filename] -- send query, optionally with output to file/pipe */
-	else if (strcmp(cmd, "g") == 0)
+	/*
+	 * \g [filename] -- send query, optionally with output to file/pipe
+	 * \gx [filename] -- same as \g, with expanded mode forced
+	 */
+	else if (strcmp(cmd, "g") == 0 || strcmp(cmd, "gx") == 0)
 	{
 		char	   *fname = psql_scan_slash_option(scan_state,
 												   OT_FILEPIPE, NULL, false);
@@ -920,6 +923,8 @@ exec_command(const char *cmd,
 			pset.gfname = pg_strdup(fname);
 		}
 		free(fname);
+		if (strcmp(cmd, "gx") == 0)
+			pset.g_expanded = true;
 		status = PSQL_CMD_SEND;
 	}
 

src/bin/psql/common.c

@@ -770,6 +770,10 @@ PrintQueryTuples(const PGresult *results)
 {
 	printQueryOpt my_popt = pset.popt;
 
+	/* one-shot expanded output requested via \gx */
+	if (pset.g_expanded)
+		my_popt.topt.expanded = 1;
+
 	/* write output to \g argument, if any */
 	if (pset.gfname)
 	{
@@ -1410,6 +1414,9 @@ sendquery_cleanup:
 		pset.gfname = NULL;
 	}
 
+	/* reset \gx's expanded-mode flag */
+	pset.g_expanded = false;
+
 	/* reset \gset trigger */
 	if (pset.gset_prefix)
 	{

src/bin/psql/help.c

@@ -173,6 +173,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\copyright             show PostgreSQL usage and distribution terms\n"));
 	fprintf(output, _("  \\errverbose            show most recent error message at maximum verbosity\n"));
 	fprintf(output, _("  \\g [FILE] or ;         execute query (and send results to file or |pipe)\n"));
+	fprintf(output, _("  \\gx [FILE]             as \\g, but forces expanded output mode\n"));
 	fprintf(output, _("  \\gexec                 execute query, then execute each value in its result\n"));
 	fprintf(output, _("  \\gset [PREFIX]         execute query and store results in psql variables\n"));
 	fprintf(output, _("  \\q                     quit psql\n"));

src/bin/psql/settings.h

@@ -91,6 +91,7 @@ typedef struct _psqlSettings
 	printQueryOpt popt;
 
 	char	   *gfname;			/* one-shot file output argument for \g */
+	bool		g_expanded;		/* one-shot expanded output requested via \gx */
 	char	   *gset_prefix;	/* one-shot prefix argument for \gset */
 	bool		gexec_flag;		/* one-shot flag to execute query's results */
 	bool		crosstab_flag;	/* one-shot request to crosstab results */

src/bin/psql/tab-complete.c

@@ -1375,11 +1375,12 @@ psql_completion(const char *text, int start, int end)
 		"\\dm", "\\dn", "\\do", "\\dO", "\\dp", "\\drds", "\\ds", "\\dS",
 		"\\dt", "\\dT", "\\dv", "\\du", "\\dx", "\\dy",
 		"\\e", "\\echo", "\\ef", "\\encoding", "\\errverbose", "\\ev",
-		"\\f", "\\g", "\\gexec", "\\gset", "\\h", "\\help", "\\H", "\\i", "\\ir", "\\l",
-		"\\lo_import", "\\lo_export", "\\lo_list", "\\lo_unlink",
-		"\\o", "\\p", "\\password", "\\prompt", "\\pset", "\\q", "\\qecho", "\\r",
-		"\\s", "\\set", "\\setenv", "\\sf", "\\sv", "\\t", "\\T",
-		"\\timing", "\\unset", "\\x", "\\w", "\\watch", "\\z", "\\!", NULL
+		"\\f", "\\g", "\\gexec", "\\gset", "\\gx", "\\h", "\\help", "\\H",
+		"\\i", "\\ir", "\\l", "\\lo_import", "\\lo_export", "\\lo_list",
+		"\\lo_unlink", "\\o", "\\p", "\\password", "\\prompt", "\\pset", "\\q",
+		"\\qecho", "\\r", "\\s", "\\set", "\\setenv", "\\sf", "\\sv", "\\t",
+		"\\T", "\\timing", "\\unset", "\\x", "\\w", "\\watch", "\\z", "\\!",
+		NULL
 	};
 
 	(void) end;					/* "end" is not used */

src/test/regress/expected/psql.out

@@ -28,6 +28,29 @@ on
 \unset ON_ERROR_ROLLBACK
 \echo :ON_ERROR_ROLLBACK
 off
+-- \g and \gx
+SELECT 1 as one, 2 as two \g
+ one | two 
+-----+-----
+   1 |   2
+(1 row)
+
+\gx
+-[ RECORD 1 ]
+one | 1
+two | 2
+
+SELECT 3 as three, 4 as four \gx
+-[ RECORD 1 ]
+three | 3
+four  | 4
+
+\g
+ three | four 
+-------+------
+     3 |    4
+(1 row)
+
 -- \gset
 select 10 as test01, 20 as test02, 'Hello' as test03 \gset pref01_
 \echo :pref01_test01 :pref01_test02 :pref01_test03

src/test/regress/sql/psql.sql

@@ -21,6 +21,13 @@
 \unset ON_ERROR_ROLLBACK
 \echo :ON_ERROR_ROLLBACK
 
+-- \g and \gx
+
+SELECT 1 as one, 2 as two \g
+\gx
+SELECT 3 as three, 4 as four \gx
+\g
+
 -- \gset
 
 select 10 as test01, 20 as test02, 'Hello' as test03 \gset pref01_