1 files changed, 47 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/text/ParenthesisExpressionPrettyPrinter.java b/vespajlib/src/main/java/com/yahoo/text/ParenthesisExpressionPrettyPrinter.java
new file mode 100644
index 00000000000..ad235d78679
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/text/ParenthesisExpressionPrettyPrinter.java
@@ -0,0 +1,47 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.text;
+
+/**
+ * Pretty prints any parenthesis expression
+ *
+ * @author bratseth
+ */
+public class ParenthesisExpressionPrettyPrinter {
+
+    private static final int indentUnit = 2;
+
+    public static String prettyPrint(String parenthesisExpression) {
+        StringBuilder b = new StringBuilder();
+        prettyPrint(parenthesisExpression, 0, b);
+        return b.toString();
+    }
+
+    private static void prettyPrint(String expression, int indent, StringBuilder b) {
+        int nextStartParenthesis = expression.indexOf("(");
+        int nextEndParenthesis = expression.indexOf(")");
+        if (nextStartParenthesis < 0)
+            nextStartParenthesis = Integer.MAX_VALUE;
+        if (nextEndParenthesis < 0)
+            nextEndParenthesis = Integer.MAX_VALUE;
+
+        boolean start = nextStartParenthesis < nextEndParenthesis;
+        int nextParenthesis = Math.min(nextStartParenthesis, nextEndParenthesis);
+
+        int effectiveIndent = start || nextParenthesis > 0 ? indent : indent - 2;
+        b.append(" ".repeat(Math.max(0, effectiveIndent)));
+        if (nextParenthesis == Integer.MAX_VALUE) {
+            b.append(expression);
+        }
+        else {
+            if (! start && nextParenthesis > 0) {
+                b.append(expression, 0, nextParenthesis).append("\n");
+                b.append(" ".repeat(Math.max(0, indent - 2))).append(")\n");
+            }
+            else {
+                b.append(expression, 0, nextParenthesis + 1).append("\n");
+            }
+            prettyPrint(expression.substring(nextParenthesis + 1), indent + (start ? indentUnit : -indentUnit), b);
+        }
+    }
+
+}