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/*
* Copyright (C) 2015 Archie L. Cobbs. All rights reserved.
*/
package org.jsimpledb.parse.expr;
import org.jsimpledb.parse.ParseSession;
/**
* Holds a value for use during expression evaluation.
*/
public interface Value {
/** Flag mask value for use with {@link #compare compare()}. */
int LT = 0x01;
/** Flag mask value for use with {@link #compare compare()}. */
int GT = 0x02;
/** Flag mask value for use with {@link #compare compare()}. */
int EQ = 0x04;
/**
* Special value that can be used to indicate "no value" in certain situations, such as return value
* from a method returning void. Actually evaluates to null.
*/
Value NO_VALUE = new ConstValue(null);
/**
* Evaluate this value within the given context.
*
*
* Normally this method should only be invoked once, and the result cached, because evaluation could have side effects.
*
* @param session parse session
* @return the evaluated result
*/
Object get(ParseSession session);
/**
* Get the type of this value without evaluating it.
*
*
* This should perform a best-effort attempt to determine the type, but should not invoke {@link #get get()}.
* If the type is unknown, {@code Object.class} should be returned.
*
* @param session parse session
* @return the expected type of the evaluated result
*/
Class getType(ParseSession session);
/**
* Evaluate this value, verify that it is not null, and return it.
*
* @param session current session
* @param operation description of operation for error messages
* @return the evaluated result
* @throws EvalException if this value is null
*/
Object checkNotNull(ParseSession session, String operation);
/**
* Evaluate this value, verify that it has boolean type, and return it.
*
* @param session current session
* @param operation description of operation for error messages
* @return the evaluated boolean value
* @throws EvalException if this value is not boolean
*/
boolean checkBoolean(ParseSession session, String operation);
/**
* Evaluate this value, verify that it has numeric type (i.e., {@link Number}), and return it.
*
* @param session current session
* @param operation description of operation for error messages
* @return the evaluated numeric value
* @throws EvalException if this value is not numeric
*/
Number checkNumeric(ParseSession session, String operation);
/**
* Evaluate this value, verify that it has integral type (i.e., byte, char, short, or int), and return it.
* Return its integer value.
*
* @param session current session
* @param operation description of operation for error messages
* @return the evaluated integer value
* @throws EvalException if this value is not integral
*/
int checkIntegral(ParseSession session, String operation);
/**
* Evaluate this value, verify that it has the expected type (or any sub-type), and return it.
* Return its value cast to that type.
*
* @param session current session
* @param operation description of operation for error messages
* @param type expected type
* @param expected type
* @return the evaluated value cast to {@code type}
* @throws EvalException if this value does not have the expected type
*/
T checkType(ParseSession session, String operation, Class type);
/**
* Increment/decrement this value. Also supports {@link java.math.BigInteger} and {@link java.math.BigDecimal}.
* This value must be an {@link LValue}.
*
* @param session current session
* @param operation description of operation for error messages
* @param increment true to increment, false to decrement
* @return the adjusted value (which will not be an {@link LValue})
* @throws EvalException if this value is not an {@link LValue}
* @throws EvalException if this value is not numeric, {@link java.math.BigInteger} or {@link java.math.BigDecimal}
*/
Value xxcrement(ParseSession session, String operation, boolean increment);
/**
* Negate this value.
*
* @param session current session
* @return negated result
* @throws EvalException if this value is not numeric
*/
Value negate(ParseSession session);
/**
* Bitwise invert this value.
*
* @param session current session
* @return inverted result
* @throws EvalException if this value is not numeric
*/
Value invert(ParseSession session);
/**
* Multiply this value.
*
* @param session current session
* @param that multiplicand
* @return multiplied result
* @throws EvalException if value(s) are not numeric
*/
Value multiply(ParseSession session, Value that);
/**
* Divide this value.
*
* @param session current session
* @param that divisor
* @return divided result
* @throws EvalException if value(s) are not numeric
*/
Value divide(ParseSession session, Value that);
/**
* Modulo this value.
*
* @param session current session
* @param that divisor
* @return remaindered result
* @throws EvalException if value(s) are not numeric
*/
Value mod(ParseSession session, Value that);
/**
* Add or concatenate this value.
*
* @param session current session
* @param that addend
* @return added result
* @throws EvalException if value(s) are not numeric or {@link String}
*/
Value add(ParseSession session, Value that);
/**
* Subtract this value. Also supports {@link java.util.Set} and {@link java.util.NavigableSet} difference.
*
* @param session current session
* @param that subtrahend
* @return subtracted result
* @throws EvalException if value(s) are not numeric or {@link java.util.Set}
*/
Value subtract(ParseSession session, Value that);
/**
* Left shift this value.
*
* @param session current session
* @param arg shift amount
* @return shifted result
* @throws EvalException if value(s) are not numeric
*/
Value lshift(ParseSession session, Value arg);
/**
* Right shift this value.
*
* @param session current session
* @param arg shift amount
* @return shifted result
* @throws EvalException if value(s) are not numeric
*/
Value rshift(ParseSession session, Value arg);
/**
* Unsigned right shift this value.
*
* @param session current session
* @param arg shift amount
* @return shifted result
* @throws EvalException if value(s) are not numeric
*/
Value urshift(ParseSession session, Value arg);
/**
* And this value. Also supports {@link java.util.Set} and {@link java.util.NavigableSet} intersection.
*
* @param session current session
* @param that and value
* @return and'ed result
* @throws EvalException if value(s) are not numeric, boolean, or {@link java.util.Set}
*/
Value and(ParseSession session, Value that);
/**
* Or this value. Also supports {@link java.util.Set} and {@link java.util.NavigableSet} union.
*
* @param session current session
* @param that or value
* @return or'ed result
* @throws EvalException if value(s) are not numeric, boolean, or {@link java.util.Set}
*/
Value or(ParseSession session, Value that);
/**
* Xor this value. Also supports {@link java.util.Set} and {@link java.util.NavigableSet} symmetric difference.
*
* @param session current session
* @param that xor value
* @return exclusive or'ed result
* @throws EvalException if value(s) are not numeric or boolean
*/
Value xor(ParseSession session, Value that);
/**
* Ordered comparison to another value. Supports numeric and {@link Comparable} comparison.
*
* @param session current session
* @param that value to compare to
* @param mask bit mask with bits {@link #LT}, {@link #GT}, and/or {@link #EQ}
* @return boolean value which will be true if the comparison is true
* @throws EvalException if value(s) are not numeric or mutually {@link Comparable}
*/
Value compare(ParseSession session, Value that, int mask);
/**
* Verify that this instance is actually an {@link LValue}.
*
* @param operation description of operation for error messages
* @return this instance cast to {@link LValue}
* @throws EvalException if this instance is not an {@link LValue}
*/
LValue asLValue(String operation);
}