Add a property to customize the tab width (fixes #861) (#880)

Author: gnodet

reader/src/main/java/org/jline/reader/LineReader.java

@@ -401,6 +401,11 @@ public interface LineReader {
      */
     String MAX_REPEAT_COUNT = "max-repeat-count";
 
+    /**
+     * Number of spaces to display a tabulation, the default is 4.
+     */
+    String TAB_WIDTH = "tab-width";
+
     Map<String, KeyMap<Binding>> defaultKeyMaps();
 
     enum Option {

reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java

@@ -70,8 +70,14 @@
 public class LineReaderImpl implements LineReader, Flushable {
     public static final char NULL_MASK = 0;
 
+    /**
+     * @deprecated use {@link #DEFAULT_TAB_WIDTH} and {@link #getTabWidth()}
+     */
+    @Deprecated
     public static final int TAB_WIDTH = 4;
 
+    public static final int DEFAULT_TAB_WIDTH = 4;
+
     public static final String DEFAULT_WORDCHARS = "*?_-.[]~=/&;!#$%^(){}<>";
     public static final String DEFAULT_REMOVE_SUFFIX_CHARS = " \t\n;&|";
     public static final String DEFAULT_COMMENT_BEGIN = "#";
@@ -1111,6 +1117,10 @@ public void editAndAddInBuffer(File file) throws Exception {
         }
     }
 
+    protected int getTabWidth() {
+        return getInt(LineReader.TAB_WIDTH, DEFAULT_TAB_WIDTH);
+    }
+
     //
     // Widget implementation
     //
@@ -3844,7 +3854,7 @@ protected void redisplay(boolean flush) {
             }
 
             if (size.getRows() > 0 && size.getRows() < MIN_ROWS) {
-                AttributedStringBuilder sb = new AttributedStringBuilder().tabs(TAB_WIDTH);
+                AttributedStringBuilder sb = new AttributedStringBuilder().tabs(getTabWidth());
 
                 sb.append(prompt);
                 concat(getHighlightedBuffer(buf.toString()).columnSplitLength(Integer.MAX_VALUE), sb);
@@ -3917,7 +3927,7 @@ protected void redisplay(boolean flush) {
             int cursorNewLinesId = -1;
             int cursorColPos = -1;
             if (size.getColumns() > 0) {
-                AttributedStringBuilder sb = new AttributedStringBuilder().tabs(TAB_WIDTH);
+                AttributedStringBuilder sb = new AttributedStringBuilder().tabs(getTabWidth());
                 sb.append(prompt);
                 String buffer = buf.upToCursor();
                 if (maskingCallback != null) {
@@ -4024,7 +4034,7 @@ public AttributedString getDisplayedBufferWithPrompts(List<AttributedString> sec
         AttributedString attBuf = getHighlightedBuffer(buf.toString());
 
         AttributedString tNewBuf = insertSecondaryPrompts(attBuf, secondaryPrompts);
-        AttributedStringBuilder full = new AttributedStringBuilder().tabs(TAB_WIDTH);
+        AttributedStringBuilder full = new AttributedStringBuilder().tabs(getTabWidth());
         full.append(prompt);
         full.append(tNewBuf);
         if (doAutosuggestion && !isTerminalDumb()) {
@@ -5835,7 +5845,7 @@ public boolean mouse() {
             List<AttributedString> secondaryPrompts = new ArrayList<>();
             getDisplayedBufferWithPrompts(secondaryPrompts);
 
-            AttributedStringBuilder sb = new AttributedStringBuilder().tabs(TAB_WIDTH);
+            AttributedStringBuilder sb = new AttributedStringBuilder().tabs(getTabWidth());
             sb.append(prompt);
             sb.append(insertSecondaryPrompts(new AttributedString(buf.upToCursor()), secondaryPrompts, false));
             List<AttributedString> promptLines =