Expose maxPaddingWidth in OutputSettings keeping default as 30 (#1655)

Co-authored-by: Jonathan Hedley <jonathan@hedley.net>

CHANGES

@@ -17,6 +17,10 @@ jsoup changelog
     element, e.g. ancestor-or-self::*.
     <https://github.com/jhy/jsoup/issues/1652>
 
+  * Improvement: allow a maxPaddingWidth on the indent level in OutputSettings when pretty printing. This defaults to
+    30 to limit the indent level for very deeply nested elements, and may be disabled by setting to -1.
+    <https://github.com/jhy/jsoup/pull/1655>
+
   * Bugfix: boolean attribute names should be case-insensitive, but were not when the parser was configured to preserve
     case.
     <https://github.com/jhy/jsoup/issues/1656>

src/main/java/org/jsoup/internal/StringUtil.java

@@ -16,11 +16,10 @@
  notice.
  */
 public final class StringUtil {
-    // memoised padding up to 21
+    // memoised padding up to 21 (blocks 0 to 20 spaces)
     static final String[] padding = {"", " ", "  ", "   ", "    ", "     ", "      ", "       ", "        ",
         "         ", "          ", "           ", "            ", "             ", "              ", "               ",
         "                ", "                 ", "                  ", "                   ", "                    "};
-    private static final int maxPaddingWidth = 30; // so very deeply nested nodes don't get insane padding amounts
 
     /**
      * Join a collection of strings by a separator
@@ -115,17 +114,28 @@ public String complete() {
     }
 
     /**
-     * Returns space padding (up to a max of 30).
+     * Returns space padding (up to the default max of 30). Use {@link #padding(int, int)} to specify a different limit.
      * @param width amount of padding desired
      * @return string of spaces * width
-     */
+     * @see #padding(int, int) 
+      */
     public static String padding(int width) {
-        if (width < 0)
-            throw new IllegalArgumentException("width must be > 0");
+        return padding(width, 30);
+    }
 
+    /**
+     * Returns space padding, up to a max of maxPaddingWidth.
+     * @param width amount of padding desired
+     * @param maxPaddingWidth maximum padding to apply. Set to {@code -1} for unlimited.
+     * @return string of spaces * width
+     */
+    public static String padding(int width, int maxPaddingWidth) {
+        Validate.isTrue(width >= 0, "width must be >= 0");
+        Validate.isTrue(maxPaddingWidth >= -1);
+        if (maxPaddingWidth != -1)
+            width = Math.min(width, maxPaddingWidth);
         if (width < padding.length)
-            return padding[width];
-        width = Math.min(width, maxPaddingWidth);
+            return padding[width];        
         char[] out = new char[width];
         for (int i = 0; i < width; i++)
             out[i] = ' ';

src/main/java/org/jsoup/nodes/Document.java

@@ -412,6 +412,7 @@ public enum Syntax {html, xml}
         private boolean prettyPrint = true;
         private boolean outline = false;
         private int indentAmount = 1;
+        private int maxPaddingWidth = 30;
         private Syntax syntax = Syntax.html;
 
         public OutputSettings() {}
@@ -560,6 +561,27 @@ public OutputSettings indentAmount(int indentAmount) {
             return this;
         }
 
+        /**
+         * Get the current max padding amount, used when pretty printing
+         * so very deeply nested nodes don't get insane padding amounts.
+         * @return the current indent amount
+         */
+        public int maxPaddingWidth() {
+            return maxPaddingWidth;
+        }
+
+        /**
+         * Set the max padding amount for pretty printing so very deeply nested nodes don't get insane padding amounts.
+         * @param maxPaddingWidth number of spaces to use for indenting each level of nested nodes. Must be {@literal >=} -1.
+         *        Default is 30 and -1 means unlimited.
+         * @return this, for chaining
+         */
+        public OutputSettings maxPaddingWidth(int maxPaddingWidth) {
+            Validate.isTrue(maxPaddingWidth >= -1);
+            this.maxPaddingWidth = maxPaddingWidth;
+            return this;
+        }
+
         @Override
         public OutputSettings clone() {
             OutputSettings clone;
@@ -570,7 +592,7 @@ public OutputSettings clone() {
             }
             clone.charset(charset.name()); // new charset and charset encoder
             clone.escapeMode = Entities.EscapeMode.valueOf(escapeMode.name());
-            // indentAmount, prettyPrint are primitives so object.clone() will handle
+            // indentAmount, maxPaddingWidth, and prettyPrint are primitives so object.clone() will handle
             return clone;
         }
     }

src/main/java/org/jsoup/nodes/Node.java

@@ -683,7 +683,7 @@ public String toString() {
     }
 
     protected void indent(Appendable accum, int depth, Document.OutputSettings out) throws IOException {
-        accum.append('\n').append(StringUtil.padding(depth * out.indentAmount()));
+        accum.append('\n').append(StringUtil.padding(depth * out.indentAmount(), out.maxPaddingWidth()));
     }
 
     /**

src/test/java/org/jsoup/internal/StringUtilTest.java

@@ -24,7 +24,34 @@ public void join() {
         assertEquals(" ", StringUtil.padding(1));
         assertEquals("  ", StringUtil.padding(2));
         assertEquals("               ", StringUtil.padding(15));
-        assertEquals("                              ", StringUtil.padding(45)); // we tap out at 30
+        assertEquals("                              ", StringUtil.padding(45)); // we default to tap out at 30
+
+        // memoization is up to 21 blocks (0 to 20 spaces) and exits early before min checks making maxPaddingWidth unused
+        assertEquals("", StringUtil.padding(0, -1));
+        assertEquals("                    ", StringUtil.padding(20, -1));
+
+        // this test escapes memoization and continues through
+        assertEquals("                     ", StringUtil.padding(21, -1));
+
+        // this test escapes memoization and using unlimited length (-1) will allow requested spaces
+        assertEquals("                              ", StringUtil.padding(30, -1));
+        assertEquals("                                             ", StringUtil.padding(45, -1));
+
+        // we tap out at 0 for this test
+        assertEquals("", StringUtil.padding(0, 0));
+
+        // as memoization is escaped, setting zero for max padding will not allow any requested width
+        assertEquals("", StringUtil.padding(21, 0));
+
+        // we tap out at 30 for these tests making > 30 use 30
+        assertEquals("", StringUtil.padding(0, 30));
+        assertEquals(" ", StringUtil.padding(1, 30));
+        assertEquals("  ", StringUtil.padding(2, 30));
+        assertEquals("               ", StringUtil.padding(15, 30));
+        assertEquals("                              ", StringUtil.padding(45, 30));
+
+        // max applies regardless of memoized
+        assertEquals(5, StringUtil.padding(20, 5).length());
     }
 
     @Test public void paddingInACan() {

src/test/java/org/jsoup/nodes/ElementTest.java

@@ -2,6 +2,7 @@
 
 import org.jsoup.Jsoup;
 import org.jsoup.TextUtil;
+import org.jsoup.internal.StringUtil;
 import org.jsoup.parser.ParseSettings;
 import org.jsoup.parser.Parser;
 import org.jsoup.parser.Tag;
@@ -430,6 +431,38 @@ public void testSetIndent() {
         assertEquals("<html>\n<head></head>\n<body>\n<div>\n<p>Hello there</p>\n</div>\n</body>\n</html>", doc.html());
     }
 
+    @Test void testIndentLevel() {
+        // deep to test default and extended max
+        StringBuilder divs = new StringBuilder();
+        for (int i = 0; i < 40; i++) {
+            divs.append("<div>");
+        }
+        divs.append("Foo");
+        Document doc = Jsoup.parse(divs.toString());
+        Document.OutputSettings settings = doc.outputSettings();
+
+        int defaultMax = 30;
+        assertEquals(defaultMax, settings.maxPaddingWidth());
+        String html = doc.html();
+        assertTrue(html.contains("                              <div>\n" +
+            "                              Foo\n" +
+            "                              </div>"));
+
+        settings.maxPaddingWidth(32);
+        assertEquals(32, settings.maxPaddingWidth());
+        html = doc.html();
+        assertTrue(html.contains("                                <div>\n" +
+            "                                Foo\n" +
+            "                                </div>"));
+
+        settings.maxPaddingWidth(-1);
+        assertEquals(-1, settings.maxPaddingWidth());
+        html = doc.html();
+        assertTrue(html.contains("                                         <div>\n" +
+            "                                          Foo\n" +
+            "                                         </div>"));
+    }
+
     @Test
     public void testNotPretty() {
         Document doc = Jsoup.parse("<div>   \n<p>Hello\n there\n</p></div>");