Construct JSON path only on exceptional cases.

src/main/java/io/github/jamsesso/jsonlogic/JsonLogic.java

@@ -54,39 +54,6 @@ public JsonLogic() {
     addOperation(MissingExpression.SOME);
   }
 
-  public JsonLogic addOperation(String name, Function<Object[], Object> function) {
-    return addOperation(new PreEvaluatedArgumentsExpression() {
-      @Override
-      public Object evaluate(List arguments, Object data, String jsonPath) {
-        return function.apply(arguments.toArray());
-      }
-
-      @Override
-      public String key() {
-        return name;
-      }
-    });
-  }
-
-  public JsonLogic addOperation(JsonLogicExpression expression) {
-    expressions.put(expression.key(), expression);
-    evaluator = null;
-
-    return this;
-  }
-
-  public Object apply(String json, Object data) throws JsonLogicException {
-    if (!parseCache.containsKey(json)) {
-      parseCache.put(json, JsonLogicParser.parse(json));
-    }
-
-    if (evaluator == null) {
-      evaluator = new JsonLogicEvaluator(expressions);
-    }
-
-    return evaluator.evaluate(parseCache.get(json), data, "$");
-  }
-
   public static boolean truthy(Object value) {
     if (value == null) {
       return false;
@@ -102,8 +69,7 @@ public static boolean truthy(Object value) {
 
         if (d.isNaN()) {
           return false;
-        }
-        else if (d.isInfinite()) {
+        } else if (d.isInfinite()) {
           return true;
         }
       }
@@ -113,8 +79,7 @@ else if (d.isInfinite()) {
 
         if (f.isNaN()) {
           return false;
-        }
-        else if (f.isInfinite()) {
+        } else if (f.isInfinite()) {
           return true;
         }
       }
@@ -136,4 +101,42 @@ else if (f.isInfinite()) {
 
     return true;
   }
+
+  public JsonLogic addOperation(String name, Function<Object[], Object> function) {
+    return addOperation(new PreEvaluatedArgumentsExpression() {
+      @Override
+      public Object evaluate(List arguments, Object data, String jsonPath) {
+        return function.apply(arguments.toArray());
+      }
+
+      @Override
+      public String key() {
+        return name;
+      }
+    });
+  }
+
+  public JsonLogic addOperation(JsonLogicExpression expression) {
+    expressions.put(expression.key(), expression);
+    evaluator = null;
+
+    return this;
+  }
+
+  public Object apply(String json, Object data) throws JsonLogicException {
+    if (!parseCache.containsKey(json)) {
+      parseCache.put(json, JsonLogicParser.parse(json));
+    }
+
+    if (evaluator == null) {
+      evaluator = new JsonLogicEvaluator(expressions);
+    }
+
+    try {
+      return evaluator.evaluate(parseCache.get(json), data, "");
+    } catch (JsonLogicException e) {
+      e.prependPartialJsonPath("$");
+      throw e;
+    }
+  }
 }

src/main/java/io/github/jamsesso/jsonlogic/JsonLogicException.java

@@ -2,28 +2,47 @@
 
 public class JsonLogicException extends Exception {
 
-  private String jsonPath;
+  private final StringBuilder jsonPath = new StringBuilder();
 
   private JsonLogicException() {
     // The default constructor should not be called for exceptions. A reason must be provided.
   }
 
+  public JsonLogicException(String msg) {
+    super(msg);
+  }
+
   public JsonLogicException(String msg, String jsonPath) {
     super(msg);
-    this.jsonPath = jsonPath;
+    prependPartialJsonPath(jsonPath);
+  }
+
+  public JsonLogicException(Throwable cause) {
+    super(cause);
   }
 
   public JsonLogicException(Throwable cause, String jsonPath) {
     super(cause);
-    this.jsonPath = jsonPath;
+    prependPartialJsonPath(jsonPath);
+  }
+
+  public JsonLogicException(String msg, Throwable cause) {
+    super(msg, cause);
   }
 
   public JsonLogicException(String msg, Throwable cause, String jsonPath) {
     super(msg, cause);
-    this.jsonPath = jsonPath;
+    prependPartialJsonPath(jsonPath);
   }
 
   public String getJsonPath() {
-    return jsonPath;
+    return jsonPath.toString();
+  }
+
+  public void prependPartialJsonPath(String partialPath) {
+    if (partialPath == null) {
+      return;
+    }
+    jsonPath.insert(0, partialPath);
   }
 }

src/main/java/io/github/jamsesso/jsonlogic/ast/JsonLogicParseException.java

@@ -14,4 +14,8 @@ public JsonLogicParseException(Throwable cause, String jsonPath) {
   public JsonLogicParseException(String msg, Throwable cause, String jsonPath) {
     super(msg, cause, jsonPath);
   }
+
+  public JsonLogicParseException(String msg) {
+    super(msg);
+  }
 }

src/main/java/io/github/jamsesso/jsonlogic/ast/JsonLogicParser.java

@@ -16,16 +16,15 @@ private JsonLogicParser() {
   public static JsonLogicNode parse(String json) throws JsonLogicParseException {
     try {
       return parse(PARSER.parse(json));
-    }
-    catch (JsonSyntaxException e) {
+    } catch (JsonLogicParseException e) {
+      e.prependPartialJsonPath("$");
+      throw e;
+    } catch (JsonSyntaxException e) {
       throw new JsonLogicParseException(e, "$");
     }
   }
 
   private static JsonLogicNode parse(JsonElement root) throws JsonLogicParseException {
-    return parse(root, "$");
-  }
-  private static JsonLogicNode parse(JsonElement root, String jsonPath) throws JsonLogicParseException {
     // Handle null
     if (root.isJsonNull()) {
       return JsonLogicNull.NULL;
@@ -45,8 +44,7 @@ private static JsonLogicNode parse(JsonElement root, String jsonPath) throws Jso
 
       if (primitive.isBoolean() && primitive.getAsBoolean()) {
         return JsonLogicBoolean.TRUE;
-      }
-      else {
+      } else {
         return JsonLogicBoolean.FALSE;
       }
     }
@@ -56,9 +54,16 @@ private static JsonLogicNode parse(JsonElement root, String jsonPath) throws Jso
       JsonArray array = root.getAsJsonArray();
       List<JsonLogicNode> elements = new ArrayList<>(array.size());
 
-      int index = 0;
-      for (JsonElement element : array) {
-        elements.add(parse(element, String.format("%s[%d]", jsonPath, index++)));
+      for (int index = 0; index < array.size(); index++) {
+        JsonElement element = array.get(index);
+        JsonLogicNode arrayNode;
+        try {
+          arrayNode = parse(element);
+        } catch (JsonLogicParseException e) {
+          e.prependPartialJsonPath("[" + (index) + "]");
+          throw e;
+        }
+        elements.add(arrayNode);
       }
 
       return new JsonLogicArray(elements);
@@ -68,18 +73,24 @@ private static JsonLogicNode parse(JsonElement root, String jsonPath) throws Jso
     JsonObject object = root.getAsJsonObject();
 
     if (object.keySet().size() != 1) {
-      throw new JsonLogicParseException("objects must have exactly 1 key defined, found " + object.keySet().size(), jsonPath);
+      throw new JsonLogicParseException("objects must have exactly 1 key defined, found " + object.keySet().size());
     }
 
     String key = object.keySet().stream().findAny().get();
-    JsonLogicNode argumentNode = parse(object.get(key), String.format("%s.%s", jsonPath, key));
+    JsonLogicNode argumentNode;
     JsonLogicArray arguments;
 
+    try {
+      argumentNode = parse(object.get(key));
+    } catch (JsonLogicParseException e) {
+      e.prependPartialJsonPath("." + key);
+      throw e;
+    }
+
     // Always coerce single-argument operations into a JsonLogicArray with a single element.
     if (argumentNode instanceof JsonLogicArray) {
       arguments = (JsonLogicArray) argumentNode;
-    }
-    else {
+    } else {
       arguments = new JsonLogicArray(Collections.singletonList(argumentNode));
     }
 

src/main/java/io/github/jamsesso/jsonlogic/evaluator/JsonLogicEvaluationException.java

@@ -3,14 +3,26 @@
 import io.github.jamsesso.jsonlogic.JsonLogicException;
 
 public class JsonLogicEvaluationException extends JsonLogicException {
+  public JsonLogicEvaluationException(String msg) {
+    super(msg);
+  }
+
   public JsonLogicEvaluationException(String msg, String jsonPath) {
     super(msg, jsonPath);
   }
 
+  public JsonLogicEvaluationException(Throwable cause) {
+    super(cause);
+  }
+
   public JsonLogicEvaluationException(Throwable cause, String jsonPath) {
     super(cause, jsonPath);
   }
 
+  public JsonLogicEvaluationException(String msg, Throwable cause) {
+    super(msg, cause);
+  }
+
   public JsonLogicEvaluationException(String msg, Throwable cause, String jsonPath) {
     super(msg, cause, jsonPath);
   }