From 7cbba19b6ced3ad49f9c718e900970b78814ac6e Mon Sep 17 00:00:00 2001
From: Guillaume Nodet <gnodet@gmail.com>
Date: Tue, 24 Oct 2023 16:52:19 +0200
Subject: [PATCH] Support providing default values for line reader variables
 using system properties (#821)

---
 .../src/main/java/org/jline/reader/LineReader.java   |  7 ++++++-
 .../java/org/jline/reader/impl/LineReaderImpl.java   | 12 ++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/reader/src/main/java/org/jline/reader/LineReader.java b/reader/src/main/java/org/jline/reader/LineReader.java
index fa7451e3..8e03aaa3 100644
--- a/reader/src/main/java/org/jline/reader/LineReader.java
+++ b/reader/src/main/java/org/jline/reader/LineReader.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002-2021, the original author(s).
+ * Copyright (c) 2002-2023, the original author(s).
  *
  * This software is distributable under the BSD license. See the terms of the
  * BSD license in the documentation provided with this software.
@@ -411,6 +411,11 @@ public interface LineReader {
      */
     String INPUT_RC_FILE_NAME = "input-rc-file-name";
 
+    /**
+     * Prefix to automatically delegate variables to system properties
+     */
+    String SYSTEM_PROPERTY_PREFIX = "system-property-prefix";
+
     Map<String, KeyMap<Binding>> defaultKeyMaps();
 
     enum Option {
diff --git a/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java b/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java
index eb7da9d2..e2d971f4 100644
--- a/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java
+++ b/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java
@@ -107,6 +107,7 @@ public class LineReaderImpl implements LineReader, Flushable {
     public static final int DEFAULT_INDENTATION = 0;
     public static final int DEFAULT_FEATURES_MAX_BUFFER_SIZE = 1000;
     public static final int DEFAULT_SUGGESTIONS_MIN_BUFFER_SIZE = 1;
+    public static final String DEFAULT_SYSTEM_PROPERTY_PREFIX = "org.jline.reader.props.";
 
     private static final int MIN_ROWS = 3;
 
@@ -314,6 +315,17 @@ public LineReaderImpl(Terminal terminal, String appName, Map<String, Object> var
         } else {
             this.variables = new HashMap<>();
         }
+        String prefix = getString(SYSTEM_PROPERTY_PREFIX, DEFAULT_SYSTEM_PROPERTY_PREFIX);
+        if (prefix != null) {
+            Properties sysProps = System.getProperties();
+            for (String s : sysProps.stringPropertyNames()) {
+                if (s.startsWith(prefix)) {
+                    String key = s.substring(prefix.length());
+                    InputRC.setVar(this, key, sysProps.getProperty(s));
+                }
+            }
+        }
+
         this.keyMaps = defaultKeyMaps();
         if (!Boolean.getBoolean(PROP_DISABLE_ALTERNATE_CHARSET)) {
             this.alternateIn = Curses.tputs(terminal.getStringCapability(Capability.enter_alt_charset_mode));