Add psql PROMPT variable showing which line of a statement is being edited.

The new %l substitution shows the line number inside a (potentially
multi-line) statement starting from one.

Author: Sawada Masahiko, heavily editorialized by me.
Reviewed-By: Jeevan Chalke, Alvaro Herrera

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

@@ -3315,6 +3315,15 @@ testdb=&gt; <userinput>INSERT INTO my_table VALUES (:'content');</userinput>
         </listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><literal>%l</literal></term>
+        <listitem>
+         <para>
+          The line number inside the current statement, starting from <literal>1</>.
+         </para>
+        </listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><literal>%</literal><replaceable class="parameter">digits</replaceable></term>
         <listitem>

src/bin/psql/copy.c

@@ -517,8 +517,8 @@ bool
 handleCopyIn(PGconn *conn, FILE *copystream, bool isbinary, PGresult **res)
 {
 	bool		OK;
-	const char *prompt;
 	char		buf[COPYBUFSIZ];
+	bool		showprompt = false;
 
 	/*
 	 * Establish longjmp destination for exiting from wait-for-input. (This is
@@ -540,21 +540,20 @@ handleCopyIn(PGconn *conn, FILE *copystream, bool isbinary, PGresult **res)
 	/* Prompt if interactive input */
 	if (isatty(fileno(copystream)))
 	{
+		showprompt = true;
 		if (!pset.quiet)
 			puts(_("Enter data to be copied followed by a newline.\n"
 				   "End with a backslash and a period on a line by itself."));
-		prompt = get_prompt(PROMPT_COPY);
 	}
-	else
-		prompt = NULL;
 
 	OK = true;
 
 	if (isbinary)
 	{
 		/* interactive input probably silly, but give one prompt anyway */
-		if (prompt)
+		if (showprompt)
 		{
+			const char *prompt = get_prompt(PROMPT_COPY);
 			fputs(prompt, stdout);
 			fflush(stdout);
 		}
@@ -589,8 +588,9 @@ handleCopyIn(PGconn *conn, FILE *copystream, bool isbinary, PGresult **res)
 			bool		firstload;
 			bool		linedone;
 
-			if (prompt)
+			if (showprompt)
 			{
+				const char *prompt = get_prompt(PROMPT_COPY);
 				fputs(prompt, stdout);
 				fflush(stdout);
 			}
@@ -650,7 +650,10 @@ handleCopyIn(PGconn *conn, FILE *copystream, bool isbinary, PGresult **res)
 			}
 
 			if (copystream == pset.cur_cmd_source)
+			{
 				pset.lineno++;
+				pset.stmt_lineno++;
+			}
 		}
 	}
 

src/bin/psql/mainloop.c

@@ -58,6 +58,7 @@ MainLoop(FILE *source)
 	pset.cur_cmd_source = source;
 	pset.cur_cmd_interactive = ((source == stdin) && !pset.notty);
 	pset.lineno = 0;
+	pset.stmt_lineno = 1;
 
 	/* Create working state */
 	scan_state = psql_scan_create();
@@ -110,6 +111,7 @@ MainLoop(FILE *source)
 			count_eof = 0;
 			slashCmdStatus = PSQL_CMD_UNKNOWN;
 			prompt_status = PROMPT_READY;
+			pset.stmt_lineno = 1;
 			cancel_pressed = false;
 
 			if (pset.cur_cmd_interactive)
@@ -225,7 +227,10 @@ MainLoop(FILE *source)
 		{
 			PsqlScanResult scan_result;
 			promptStatus_t prompt_tmp = prompt_status;
+			size_t		pos_in_query;
+			char	   *tmp_line;
 
+			pos_in_query = query_buf->len;
 			scan_result = psql_scan(scan_state, query_buf, &prompt_tmp);
 			prompt_status = prompt_tmp;
 
@@ -235,6 +240,22 @@ MainLoop(FILE *source)
 				exit(EXIT_FAILURE);
 			}
 
+			/*
+			 * Increase statement line number counter for each linebreak added
+			 * to the query buffer by the last psql_scan() call. There only
+			 * will be ones to add when navigating to a statement in
+			 * readline's history containing newlines.
+			 */
+			tmp_line = query_buf->data + pos_in_query;
+			while (*tmp_line != '\0')
+			{
+				if (*(tmp_line++) == '\n')
+					pset.stmt_lineno++;
+			}
+
+			if (scan_result == PSCAN_EOL)
+				pset.stmt_lineno++;
+
 			/*
 			 * Send command if semicolon found, or if end of line and we're in
 			 * single-line mode.
@@ -256,6 +277,7 @@ MainLoop(FILE *source)
 				/* execute query */
 				success = SendQuery(query_buf->data);
 				slashCmdStatus = success ? PSQL_CMD_SEND : PSQL_CMD_ERROR;
+				pset.stmt_lineno = 1;
 
 				/* transfer query to previous_buf by pointer-swapping */
 				{
@@ -303,6 +325,7 @@ MainLoop(FILE *source)
 												 query_buf : previous_buf);
 
 				success = slashCmdStatus != PSQL_CMD_ERROR;
+				pset.stmt_lineno = 1;
 
 				if ((slashCmdStatus == PSQL_CMD_SEND || slashCmdStatus == PSQL_CMD_NEWEDIT) &&
 					query_buf->len == 0)

src/bin/psql/prompt.c

@@ -44,6 +44,7 @@
  *		in prompt2 -, *, ', or ";
  *		in prompt3 nothing
  * %x - transaction status: empty, *, !, ? (unknown or no connection)
+ * %l - The line number inside the current statement, starting from 1.
  * %? - the error code of the last query (not yet implemented)
  * %% - a percent sign
  *
@@ -229,6 +230,10 @@ get_prompt(promptStatus_t status)
 						}
 					break;
 
+				case 'l':
+					snprintf(buf, sizeof(buf), UINT64_FORMAT, pset.stmt_lineno);
+					break;
+
 				case '?':
 					/* not here yet */
 					break;

src/bin/psql/settings.h

@@ -88,6 +88,7 @@ typedef struct _psqlSettings
 	const char *progname;		/* in case you renamed psql */
 	char	   *inputfile;		/* file being currently processed, if any */
 	uint64		lineno;			/* also for error reporting */
+	uint64		stmt_lineno;	/* line number inside the current statement */
 
 	bool		timing;			/* enable timing of all queries */