From 63e971fc4cfc4d7a5638da032326eaf016c62719 Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Sat, 10 Jun 2017 05:11:29 -0400
Subject: [PATCH] Enable input editing with the linenoise library.

---
 NEWS        |  1 +
 advent.adoc | 10 +++++++++-
 advent.h    |  2 +-
 main.c      |  3 +++
 misc.c      | 21 ++++++++++++++++-----
 5 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/NEWS b/NEWS
index 46acfa3..0614e59 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@
 
 Repository head::
   Include tests directory in generated tarball.
+  Support command-line editing with arrow keys and Emacs keystrokes.
 
 1.0: 2016-06-05::
   Forward port of Crowther & Woods's 430-point Adventure 2.5.
diff --git a/advent.adoc b/advent.adoc
index a53ccd3..1005809 100644
--- a/advent.adoc
+++ b/advent.adoc
@@ -25,11 +25,19 @@ PDP-10 on which it originally ran limited filenames to 6 characters.
 This version is released as open source with the permission and
 encouragement of the original authors.
 
+Unlike the original, this version supports use of your arrow keys to edit
+your command line in place.  Basic Emacs keystrokes are supported, and
+your up/down arrows access a command history.
+
+To exit the game, type Ctrl-D (EOF).
+
+There have been no gameplay changes.
+
 == OPTIONS ==
 
 -l:: Log commands to specified file.
 
--o:: Old-style.  Restores original interface, no prompt.
+-o:: Old-style.  Restores original interface, no prompt or command history.
 
 == BUGS ==
 
diff --git a/advent.h b/advent.h
index 51e7317..9e50d9c 100644
--- a/advent.h
+++ b/advent.h
@@ -118,7 +118,7 @@ extern long SETBIT(long);
 extern bool TSTBIT(long,int);
 extern long RNDVOC(long,long);
 extern void BUG(long) __attribute__((noreturn));
-extern void MAPLIN(FILE *);
+extern bool MAPLIN(FILE *);
 extern void TYPE(void);
 
 extern void fSAVEIO(long,long,long*);
diff --git a/main.c b/main.c
index 4a5d3c5..31eaf46 100644
--- a/main.c
+++ b/main.c
@@ -11,6 +11,7 @@
 #include <time.h>
 #include "advent.h"
 #include "database.h"
+#include "linenoise/linenoise.h"
 
 struct game_t game;
 
@@ -82,6 +83,8 @@ case 'l':
 	}
     }
 
+    linenoiseHistorySetMaxLen(350);
+
     /* Logical variables:
      *
      *  game.closed says whether we're all the way closed
diff --git a/misc.c b/misc.c
index b991117..0eae162 100644
--- a/misc.c
+++ b/misc.c
@@ -703,6 +703,7 @@ void BUG(long num)
 bool MAPLIN(FILE *fp)
 {
     long i, val;
+    bool eof;
 
     /*  Read a line of input, from the specified input source,
      *  translate the chars to integers in the range 0-126 and store
@@ -729,13 +730,23 @@ bool MAPLIN(FILE *fp)
      *  and is not changed thereafter unless the routines on this page choose
      *  to do so. */
 
-    if (!oldstyle && fp == stdin)
-	fputs("> ", stdout);
     do {
-	IGNORE(fgets(rawbuf,sizeof(rawbuf)-1,fp));
+	if (oldstyle) {
+	    IGNORE(fgets(rawbuf,sizeof(rawbuf)-1,fp));
+	    eof = (feof(fp));
+	} else {
+	    char *cp = linenoise("> ");
+	    eof = (cp == NULL);
+	    if (!eof) {
+		strncpy(rawbuf, cp, sizeof(rawbuf)-1);
+		linenoiseHistoryAdd(rawbuf);
+		strncat(rawbuf, "\n", sizeof(rawbuf)-1);
+		linenoiseFree(cp);
+	    }
+	}
     } while
-	    (!feof(fp) && rawbuf[0] == '#');
-    if (feof(fp)) {
+	    (!eof && rawbuf[0] == '#');
+    if (eof) {
 	if (logfp && fp == stdin)
 	    fclose(logfp);
 	return false;
-- 
2.31.1