This is a patch to support readline prompts which contain non-printing

characters, as for fancy colorized prompts.  This was nearly a direct
lift from bash-2.05b's lib/readline/display.c, per guidance from Chet Ramey.

Reece Hart

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

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/psql-ref.sgml,v 1.102 2003/12/23 23:13:14 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/psql-ref.sgml,v 1.103 2004/01/20 19:49:34 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -2315,6 +2315,28 @@ testdb=> <userinput>\set content '\'' `sed -e "s/'/\\\\\\'/g" < my_file.txt` '\'
 	</listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><literal>%[</literal> ... <literal>%]</literal></term>
+	<listitem>
+         <para>
+         Prompts may contain terminal control characters which, for
+         example, change the color, background, or style of the prompt
+         text, or change the title of the terminal window. In order for
+         the line editing features of readline to work properly, these
+         non-printing control characters must be designated as invisible
+         by surrounding them with <literal>%[</literal> and
+         <literal>%]</literal>. Multiple pairs of these may occur within
+         the prompt.  For example,
+<programlisting>
+testdb=> \set PROMPT1 '%[%033[1;33;40m%]%n@%/%R%[%033[0m%#%] '
+</programlisting>
+         results in a boldfaced (<literal>1;</literal>) yellow-on-black
+         (<literal>33;40</literal>) prompt on VT100-compatible, color-capable
+	 terminals.
+    	</para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
 
     To insert a percent sign into your prompt, write

src/bin/psql/prompt.c

@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2000-2003, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/bin/psql/prompt.c,v 1.31 2003/11/29 19:52:07 pgsql Exp $
+ * $PostgreSQL: pgsql/src/bin/psql/prompt.c,v 1.32 2004/01/20 19:49:34 tgl Exp $
  */
 #include "postgres_fe.h"
 #include "prompt.h"
@@ -12,6 +12,7 @@
 
 #include "settings.h"
 #include "common.h"
+#include "input.h"
 #include "variables.h"
 
 #ifdef WIN32
@@ -57,7 +58,9 @@
  * %:name:		   - The value of the psql variable 'name'
  * (those will not be rescanned for more escape sequences!)
  *
- * If the application-wide prompts became NULL somehow, the returned string
+ * %[ ... %]	   - tell readline that the contained text is invisible
+ *
+ * If the application-wide prompts become NULL somehow, the returned string
  * will be empty (not NULL!).
  *--------------------------
  */
@@ -282,10 +285,23 @@ get_prompt(promptStatus_t status)
 						break;
 					}
 
+			    case '[':
+			    case ']':
+#if defined(USE_READLINE) && defined(RL_PROMPT_START_IGNORE)
+				  /*
+				   * readline >=4.0 undocumented feature: non-printing
+				   * characters in prompt strings must be marked as such,
+				   * in order to properly display the line during editing.
+				   */
+				  buf[0] = '\001';
+				  buf[1] = (*p == '[') ? RL_PROMPT_START_IGNORE : RL_PROMPT_END_IGNORE;
+#endif /* USE_READLINE */
+				  break;
 
 				default:
 					buf[0] = *p;
 					buf[1] = '\0';
+					break;
 
 			}
 			esc = false;