/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.commons.jexl3;
  
  import java.util.function.Consumer;
  
  /**
   * The JEXL operators.
   *
   * These are the operators that are executed by JexlArithmetic methods.
   *
   * <p>Each of them  associates a symbol to a method signature.
   * For instance, '+' is associated to 'T add(L x, R y)'.</p>
   *
   * <p>The default JexlArithmetic implements generic versions of these methods using Object as arguments.
   * You can use your own derived JexlArithmetic that override and/or overload those operator methods.
   * Note that these are overloads by convention, not actual Java overloads.
   * The following rules apply to all operator methods:</p>
   * <ul>
   * <li>Operator methods should be public</li>
   * <li>Operators return type should be respected when primitive (int, boolean,...)</li>
   * <li>Operators may be overloaded multiple times with different signatures</li>
   * <li>Operators may return JexlEngine.TRY_AGAIN to fallback on default JEXL implementation</li>
   * </ul>
   *
   * For side effect operators, operators that modify the left-hand size value (+=, -=, etc.), the user implemented
   * overload methods may return:
   * <ul>
   *     <li>JexlEngine.TRY_FAIL to let the default fallback behavior be executed.</li>
   *     <li>Any other value will be used as the new value to be assigned to the left-hand-side.</li>
   * </ul>
   * Note that side effect operators always return the left-hand side value (with an exception for postfix ++ and --).
   *
   * @since 3.0
   */
  public enum JexlOperator {
      /**
       * Add operator.
       * <br><strong>Syntax:</strong> {@code x + y}
       * <br><strong>Method:</strong> {@code T add(L x, R y);}.
       * @see JexlArithmetic#add(Object, Object)
       */
      ADD("+", "add", 2),
  
      /**
       * Subtract operator.
       * <br><strong>Syntax:</strong> {@code x - y}
       * <br><strong>Method:</strong> {@code T subtract(L x, R y);}.
       * @see JexlArithmetic#subtract(Object, Object)
       */
      SUBTRACT("-", "subtract", 2),
  
      /**
       * Multiply operator.
       * <br><strong>Syntax:</strong> {@code x * y}
       * <br><strong>Method:</strong> {@code T multiply(L x, R y);}.
       * @see JexlArithmetic#multiply(Object, Object)
       */
      MULTIPLY("*", "multiply", 2),
  
      /**
       * Divide operator.
       * <br><strong>Syntax:</strong> {@code x / y}
       * <br><strong>Method:</strong> {@code T divide(L x, R y);}.
       * @see JexlArithmetic#divide(Object, Object)
       */
      DIVIDE("/", "divide", 2),
  
      /**
       * Modulo operator.
       * <br><strong>Syntax:</strong> {@code x % y}
       * <br><strong>Method:</strong> {@code T mod(L x, R y);}.
       * @see JexlArithmetic#mod(Object, Object)
       */
      MOD("%", "mod", 2),
  
      /**
       * Bitwise-and operator.
       * <br><strong>Syntax:</strong> {@code x & y}
       * <br><strong>Method:</strong> {@code T and(L x, R y);}.
       * @see JexlArithmetic#and(Object, Object)
       */
      AND("&", "and", 2),
  
     /**
      * Bitwise-or operator.
      * <br><strong>Syntax:</strong> {@code x | y}
      * <br><strong>Method:</strong> {@code T or(L x, R y);}.
      * @see JexlArithmetic#or(Object, Object)
      */
     OR("|", "or", 2),
 
     /**
      * Bitwise-xor operator.
      * <br><strong>Syntax:</strong> {@code x ^ y}
      * <br><strong>Method:</strong> {@code T xor(L x, R y);}.
      * @see JexlArithmetic#xor(Object, Object)
      */
     XOR("^", "xor", 2),
 
     /**
      * Bit-pattern right-shift operator.
      * <br><strong>Syntax:</strong> {@code x >> y}
      * <br><strong>Method:</strong> {@code T rightShift(L x, R y);}.
      * @see JexlArithmetic#shiftRight(Object, Object)
      */
     SHIFTRIGHT(">>", "shiftRight", 2),
 
     /**
      * Bit-pattern right-shift unsigned operator.
      * <br><strong>Syntax:</strong> {@code x >>> y}
      * <br><strong>Method:</strong> {@code T rightShiftUnsigned(L x, R y);}.
      * @see JexlArithmetic#shiftRightUnsigned(Object, Object)
      */
     SHIFTRIGHTU(">>>", "shiftRightUnsigned", 2),
 
     /**
      * Bit-pattern left-shift operator.
      * <br><strong>Syntax:</strong> {@code x << y}
      * <br><strong>Method:</strong> {@code T leftShift(L x, R y);}.
      * @see JexlArithmetic#shiftLeft(Object, Object)
      */
     SHIFTLEFT("<<", "shiftLeft", 2),
 
     /**
      * Equals operator.
      * <br><strong>Syntax:</strong> {@code x == y}
      * <br><strong>Method:</strong> {@code boolean equals(L x, R y);}.
      * @see JexlArithmetic#equals(Object, Object)
      */
     EQ("==", "equals", 2),
 
     /**
      * Equal-strict operator.
      * <br><strong>Syntax:</strong> {@code x === y}
      * <br><strong>Method:</strong> {@code boolean strictEquals(L x, R y);}.
      * @see JexlArithmetic#strictEquals(Object, Object)
      */
     EQSTRICT("===", "strictEquals", 2),
 
     /**
      * Less-than operator.
      * <br><strong>Syntax:</strong> {@code x < y}
      * <br><strong>Method:</strong> {@code boolean lessThan(L x, R y);}.
      * @see JexlArithmetic#lessThan(Object, Object)
      */
     LT("<", "lessThan", 2),
 
     /**
      * Less-than-or-equal operator.
      * <br><strong>Syntax:</strong> {@code x <= y}
      * <br><strong>Method:</strong> {@code boolean lessThanOrEqual(L x, R y);}.
      * @see JexlArithmetic#lessThanOrEqual(Object, Object)
      */
     LTE("<=", "lessThanOrEqual", 2),
 
     /**
      * Greater-than operator.
      * <br><strong>Syntax:</strong> {@code x > y}
      * <br><strong>Method:</strong> {@code boolean greaterThan(L x, R y);}.
      * @see JexlArithmetic#greaterThan(Object, Object)
      */
     GT(">", "greaterThan", 2),
 
     /**
      * Greater-than-or-equal operator.
      * <br><strong>Syntax:</strong> {@code x >= y}
      * <br><strong>Method:</strong> {@code boolean greaterThanOrEqual(L x, R y);}.
      * @see JexlArithmetic#greaterThanOrEqual(Object, Object)
      */
     GTE(">=", "greaterThanOrEqual", 2),
 
     /**
      * Contains operator.
      * <br><strong>Syntax:</strong> {@code x =~ y}
      * <br><strong>Method:</strong> {@code boolean contains(L x, R y);}.
      * @see JexlArithmetic#contains(Object, Object)
      */
     CONTAINS("=~", "contains", 2),
 
     /**
      * Starts-with operator.
      * <br><strong>Syntax:</strong> {@code x =^ y}
      * <br><strong>Method:</strong> {@code boolean startsWith(L x, R y);}.
      * @see JexlArithmetic#startsWith(Object, Object)
      */
     STARTSWITH("=^", "startsWith", 2),
 
     /**
      * Ends-with operator.
      * <br><strong>Syntax:</strong> {@code x =$ y}
      * <br><strong>Method:</strong> {@code boolean endsWith(L x, R y);}.
      * @see JexlArithmetic#endsWith(Object, Object)
      */
     ENDSWITH("=$", "endsWith", 2),
 
     /**
      * Not operator.
      * <br><strong>Syntax:</strong> {@code !x}
      * <br><strong>Method:</strong> {@code T not(L x);}.
      * @see JexlArithmetic#not(Object)
      */
     NOT("!", "not", 1),
 
     /**
      * Complement operator.
      * <br><strong>Syntax:</strong> {@code ~x}
      * <br><strong>Method:</strong> {@code T complement(L x);}.
      * @see JexlArithmetic#complement(Object)
      */
     COMPLEMENT("~", "complement", 1),
 
     /**
      * Negate operator.
      * <br><strong>Syntax:</strong> {@code -x}
      * <br><strong>Method:</strong> {@code T negate(L x);}.
      * @see JexlArithmetic#negate(Object)
      */
     NEGATE("-", "negate", 1),
 
     /**
      * Positivize operator.
      * <br><strong>Syntax:</strong> {@code +x}
      * <br><strong>Method:</strong> {@code T positivize(L x);}.
      * @see JexlArithmetic#positivize(Object)
      */
     POSITIVIZE("+", "positivize", 1),
 
     /**
      * Empty operator.
      * <br><strong>Syntax:</strong> {@code empty x} or {@code empty(x)}
      * <br><strong>Method:</strong> {@code boolean empty(L x);}.
      * @see JexlArithmetic#empty(Object)
      */
     EMPTY("empty", "empty", 1),
 
     /**
      * Size operator.
      * <br><strong>Syntax:</strong> {@code size x} or {@code size(x)}
      * <br><strong>Method:</strong> {@code int size(L x);}.
      * @see JexlArithmetic#size(Object)
      */
     SIZE("size", "size", 1),
 
     /**
      * Self-add operator.
      * <br><strong>Syntax:</strong> {@code x += y}
      * <br><strong>Method:</strong> {@code T selfAdd(L x, R y);}.
      */
     SELF_ADD("+=", "selfAdd", ADD),
 
     /**
      * Self-subtract operator.
      * <br><strong>Syntax:</strong> {@code x -= y}
      * <br><strong>Method:</strong> {@code T selfSubtract(L x, R y);}.
      */
     SELF_SUBTRACT("-=", "selfSubtract", SUBTRACT),
 
     /**
      * Self-multiply operator.
      * <br><strong>Syntax:</strong> {@code x *= y}
      * <br><strong>Method:</strong> {@code T selfMultiply(L x, R y);}.
      */
     SELF_MULTIPLY("*=", "selfMultiply", MULTIPLY),
 
     /**
      * Self-divide operator.
      * <br><strong>Syntax:</strong> {@code x /= y}
      * <br><strong>Method:</strong> {@code T selfDivide(L x, R y);}.
      */
     SELF_DIVIDE("/=", "selfDivide", DIVIDE),
 
     /**
      * Self-modulo operator.
      * <br><strong>Syntax:</strong> {@code x %= y}
      * <br><strong>Method:</strong> {@code T selfMod(L x, R y);}.
      */
     SELF_MOD("%=", "selfMod", MOD),
 
     /**
      * Self-and operator.
      * <br><strong>Syntax:</strong> {@code x &amp;= y}
      * <br><strong>Method:</strong> {@code T selfAnd(L x, R y);}.
      */
     SELF_AND("&=", "selfAnd", AND),
 
     /**
      * Self-or operator.
      * <br><strong>Syntax:</strong> {@code x |= y}
      * <br><strong>Method:</strong> {@code T selfOr(L x, R y);}.
      */
     SELF_OR("|=", "selfOr", OR),
 
     /**
      * Self-xor operator.
      * <br><strong>Syntax:</strong> {@code x ^= y}
      * <br><strong>Method:</strong> {@code T selfXor(L x, R y);}.
      */
     SELF_XOR("^=", "selfXor", XOR),
 
     /**
      * Self-right-shift operator.
      * <br><strong>Syntax:</strong> {@code x >>= y}
      * <br><strong>Method:</strong> {@code T selfShiftRight(L x, R y);}.
      */
     SELF_SHIFTRIGHT(">>=", "selfShiftRight", SHIFTRIGHT),
 
     /**
      * Self-right-shift unsigned operator.
      * <br><strong>Syntax:</strong> {@code x >>> y}
      * <br><strong>Method:</strong> {@code T selfShiftRightUnsigned(L x, R y);}.
      */
     SELF_SHIFTRIGHTU(">>>=", "selfShiftRightUnsigned", SHIFTRIGHTU),
 
     /**
      * Self-left-shift operator.
      * <br><strong>Syntax:</strong> {@code x << y}
      * <br><strong>Method:</strong> {@code T selfShiftLeft(L x, R y);}.
      */
     SELF_SHIFTLEFT("<<=", "selfShiftLeft", SHIFTLEFT),
 
     /**
      * Increment pseudo-operator.
      * <br>No syntax, used as helper for the prefix and postfix versions of {@code ++}.
      * @see JexlArithmetic#increment(Object)
      */
     INCREMENT("+1", "increment", 1),
 
     /**
      * Decrement pseudo-operator.
      * <br>No syntax, used as helper for the prefix and postfix versions of {@code --}.
      * @see JexlArithmetic#decrement(Object)
      */
     DECREMENT("-1", "decrement", 1),
 
     /**
      * Prefix ++ operator, increments and returns the value after incrementing.
      * <br><strong>Syntax:</strong> {@code ++x}
      * <br><strong>Method:</strong> {@code T incrementAndGet(L x);}.
      */
     INCREMENT_AND_GET("++.", "incrementAndGet", INCREMENT, 1),
 
     /**
      * Postfix ++, increments and returns the value before incrementing.
      * <br><strong>Syntax:</strong> {@code x++}
      * <br><strong>Method:</strong> {@code T getAndIncrement(L x);}.
      */
     GET_AND_INCREMENT(".++", "getAndIncrement", INCREMENT, 1),
 
     /**
      * Prefix --, decrements and returns the value after decrementing.
      * <br><strong>Syntax:</strong> {@code --x}
      * <br><strong>Method:</strong> {@code T decrementAndGet(L x);}.
      */
     DECREMENT_AND_GET("--.", "decrementAndGet", DECREMENT, 1),
 
     /**
      * Postfix --, decrements and returns the value before decrementing.
      * <br><strong>Syntax:</strong> {@code x--}
      * <br><strong>Method:</strong> {@code T getAndDecrement(L x);}.
      */
     GET_AND_DECREMENT(".--", "getAndDecrement", DECREMENT, 1),
 
     /**
      * Marker for side effect.
      * <br>Returns this from 'self*' overload method to let the engine know the side effect has been performed and
      * there is no need to assign the result.
      * @deprecated 3.5.0
      */
     ASSIGN("=", null, null),
 
     /**
      * Property get operator as in: x.y.
      * <br><strong>Syntax:</strong> {@code x.y}
      * <br><strong>Method:</strong> {@code Object propertyGet(L x, R y);}.
      */
     PROPERTY_GET(".", "propertyGet", 2),
 
     /**
      * Property set operator as in: x.y = z.
      * <br><strong>Syntax:</strong> {@code x.y = z}
      * <br><strong>Method:</strong> {@code void propertySet(L x, R y, V z);}.
      */
     PROPERTY_SET(".=", "propertySet", 3),
 
     /**
      * Array get operator as in: x[y].
      * <br><strong>Syntax:</strong> {@code x.y}
      * <br><strong>Method:</strong> {@code Object arrayGet(L x, R y);}.
      */
     ARRAY_GET("[]", "arrayGet", 2),
 
     /**
      * Array set operator as in: x[y] = z.
      * <br><strong>Syntax:</strong> {@code x[y] = z}
      * <br><strong>Method:</strong> {@code void arraySet(L x, R y, V z);}.
      */
     ARRAY_SET("[]=", "arraySet", 3),
 
     /**
      * Iterator generator as in for(var x : y).
      * If the returned Iterator is AutoCloseable, close will be called after the last execution of the loop block.
      * <br><strong>Syntax:</strong> <code>for(var x : y){...}</code>
      * <br><strong>Method:</strong> {@code Iterator<Object> forEach(R y);}.
      * @since 3.1
      */
     FOR_EACH("for(...)", "forEach", 1),
 
     /**
      * Test condition in if, for, while.
      * <br><strong>Method:</strong> {@code boolean testCondition(R y);}.
      * @since 3.3
      */
     CONDITION("?", "testCondition", 1),
 
     /**
      * Compare overload as in compare(x, y).
      * <br><strong>Method:</strong> {@code boolean compare(L x, R y);}.
      * @since 3.5.0
      */
     COMPARE("<>", "compare", 2),
 
     /**
      * Not-Contains operator.
      * <p>Not overridable, calls !(contain(...))</p>
      */
     NOT_CONTAINS("!~", null, CONTAINS),
 
     /**
      * Not-Starts-With operator.
      * <p>Not overridable, calls !(startsWith(...))</p>
      */
     NOT_STARTSWITH("!^", null, STARTSWITH),
 
     /**
      * Not-Ends-With operator.
      * <p>Not overridable, calls !(endsWith(...))</p>
      */
     NOT_ENDSWITH("!$", null, ENDSWITH),;
 
     /**
      * The operator symbol.
      */
     private final String operator;
 
     /**
      * The associated operator method name.
      */
     private final String methodName;
 
     /**
      * The method arity (ie number of arguments).
      */
     private final int arity;
 
     /**
      * The base operator.
      */
     private final JexlOperator base;
 
     /**
      * Creates a base operator.
      *
      * @param o    the operator name
      * @param m    the method name associated to this operator in a JexlArithmetic
      * @param argc the number of parameters for the method
      */
     JexlOperator(final String o, final String m, final int argc) {
         this(o, m, null, argc);
     }
 
     /**
      * Creates a side effect operator with arity == 2.
      *
      * @param o the operator name
      * @param m the method name associated to this operator in a JexlArithmetic
      * @param b the base operator, ie + for +=
      */
     JexlOperator(final String o, final String m, final JexlOperator b) {
         this(o, m, b, 2);
     }
 
     /**
      * Creates a side effect operator.
      *
      * @param o the operator name
      * @param m the method name associated to this operator in a JexlArithmetic
      * @param b the base operator, ie + for +=
      * @param a the operator arity
      */
     JexlOperator(final String o, final String m, final JexlOperator b, final int a) {
         this.operator = o;
         this.methodName = m;
         this.arity = a;
         this.base = b;
     }
 
     /**
      * Gets this operator number of parameters.
      *
      * @return the method arity
      */
     public int getArity() {
         return arity;
     }
 
     /**
      * Gets the base operator.
      *
      * @return the base operator
      */
     public final JexlOperator getBaseOperator() {
         return base;
     }
 
     /**
      * Gets this operator method name in a JexlArithmetic.
      *
      * @return the method name
      */
     public final String getMethodName() {
         return methodName;
     }
 
     /**
      * Gets this operator symbol.
      *
      * @return the symbol
      */
     public final String getOperatorSymbol() {
         return operator;
     }
 
     /**
      * Uberspect that solves and evaluates JexlOperator overloads.
      * <p>This is used by the interpreter to find and execute operator overloads implemented in a derived
      * JexlArithmetic - or in some cases, as methods of the left argument type (contains, size, ...).</p>
      * <p>This also allows reusing the core logic when extending the applicative type-system; for
      * instance, implementing a Comparator class that calls compare
      * (<code>operator.tryOverload(this, JexlOperator.COMPARE, left, right)</code>, etc.</p>
      * @since 3.5.0
      */
     public interface Uberspect extends JexlArithmetic.Uberspect {
         /**
          * Try to find the most specific method and evaluate an operator.
          * <p>This method does not call {@link #overloads(JexlOperator)} and shall not be called with an
          * assignment operator; use {@link #tryAssignOverload(JexlCache.Reference, JexlOperator, Consumer, Object...)}
          * in that case.</p>
          *
          * @param reference an optional reference caching resolved method or failing signature
          * @param operator the operator
          * @param args      the arguments
          * @return TRY_FAILED if no specific method could be found, the evaluation result otherwise
          */
         Object tryOverload(JexlCache.Reference reference, JexlOperator operator, Object...args);
 
         /**
          * Evaluates an assign operator.
          * <p>
          * This takes care of finding and caching the operator method when appropriate.
          * If an overloads returns a value not-equal to TRY_FAILED, it means the side-effect is complete.
          * Otherwise, {@code a += b <=> a = a + b}
          * </p>
          * @param node     an optional reference caching resolved method or failing signature
          * @param operator the operator
          * @param assign   the actual function that performs the side effect
          * @param args     the arguments, the first one being the target of assignment
          * @return JexlEngine.TRY_FAILED if no operation was performed,
          *         the value to use as the side effect argument otherwise
          */
         Object tryAssignOverload(final JexlCache.Reference node,
                                  final JexlOperator operator,
                                  final Consumer<Object> assign,
                                  final Object... args);
 
         /**
          * Calculate the {@code size} of various types:
          * Collection, Array, Map, String, and anything that has an int size() method.
          * <p>Seeks an overload or use the default arithmetic implementation.</p>
          * <p>Note that the result may not be an integer.
          *
          * @param node   an optional reference caching resolved method or failing signature
          * @param object the object to get the size of
          * @return the evaluation result
          */
         Object size(final JexlCache.Reference node, final Object object);
 
         /**
          * Check for emptiness of various types: Collection, Array, Map, String, and anything that has a boolean isEmpty()
          * method.
          * <p>Seeks an overload or use the default arithmetic implementation.</p>
          * <p>Note that the result may not be a boolean.
          *
          * @param node   the node holding the object
          * @param object the object to check the emptiness of
          * @return the evaluation result
          */
         Object empty(final JexlCache.Reference node, final Object object);
 
         /**
          * The 'match'/'in' operator implementation.
          * <p>Seeks an overload or use the default arithmetic implementation.</p>
          * <p>
          * Note that 'x in y' or 'x matches y' means 'y contains x' ;
          * the JEXL operator arguments order syntax is the reverse of this method call.
          * </p>
          * @param node  an optional reference caching resolved method or failing signature
          * @param operator    the calling operator, =~ or !~
          * @param right the left operand
          * @param left  the right operand
          * @return true if left matches right, false otherwise
          */
         boolean contains(final JexlCache.Reference node,
                          final JexlOperator operator,
                          final Object left,
                          final Object right);
 
         /**
          * The 'startsWith' operator implementation.
          * <p>Seeks an overload or use the default arithmetic implementation.</p>
          * @param node     an optional reference caching resolved method or failing signature
          * @param operator the calling operator, $= or $!
          * @param left     the left operand
          * @param right    the right operand
          * @return true if left starts with right, false otherwise
          */
         boolean startsWith(final JexlCache.Reference node,
                            final JexlOperator operator,
                            final Object left,
                            final Object right);
 
         /**
          * The 'endsWith' operator implementation.
          * <p>Seeks an overload or use the default arithmetic implementation.</p>
          * @param node     an optional reference caching resolved method or failing signature
          * @param operator the calling operator, ^= or ^!
          * @param left     the left operand
          * @param right    the right operand
          * @return true if left ends with right, false otherwise
          */
         boolean endsWith(final JexlCache.Reference node,
                          final JexlOperator operator,
                          final Object left,
                          final Object right);
     }
 }