TypeConverterTools.java

/*
 * Copyright 2009-2016 Tilmann Zaeschke. All rights reserved.
 * 
 * This file is part of ZooDB.
 * 
 * ZooDB is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * ZooDB is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with ZooDB.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * See the README and COPYING files for further information. 
 */
package org.zoodb.internal.query;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Date;

import org.zoodb.api.impl.ZooPC;
import org.zoodb.internal.util.DBLogger;

public class TypeConverterTools {

	
	public static enum COMPARISON_TYPE {
		BIG_DECIMAL(true),
		BIG_INT(true),
		DOUBLE(true),
		FLOAT(true),
		LONG(true),
		INT(true),
		SHORT(true),
		BYTE(true),
		CHAR(true),
		BOOLEAN(false),
		STRING(false),
		DATE(false),
		PC(false),
		SCO(true),  //can be number, e.g. Long.class
		NULL(true),
		UNKNOWN(true);
		private boolean canBeNumber;
		private COMPARISON_TYPE(boolean canBeNumber) {
			this.canBeNumber = canBeNumber;
		}
		public boolean canBeNumber() {
			return canBeNumber;
		}
		public static COMPARISON_TYPE fromObject(Object v) {
			if (v == null || v == QueryTerm.NULL) {
				return NULL;
			}
			return fromClass(v.getClass());
		}
		
		public static COMPARISON_TYPE fromClass(Class<?> type) {
			//TODO we can use perfect hashing here for fast lookup!
			if (type == null) {  //can happen for implicit parameters
				return UNKNOWN;
			} else if (type == Long.class || type ==  Long.TYPE) {
				return LONG;
			} else if (type ==  Integer.class || type == Integer.TYPE) {
				return INT;
			} else if (type ==  Short.class || type == Short.TYPE) {
				return SHORT;
			} else if (type ==  Byte.class || type == Byte.TYPE) {
				return BYTE;
			} else if (type ==  Double.class || type == Double.TYPE) {
				return DOUBLE;
			} else if (type ==  Float.class || type == Float.TYPE) {
				return FLOAT;
			} else if (type ==  Character.class || type == Character.TYPE) {
				return CHAR;
			} else if (type ==  String.class) {
				return STRING;
			} else if (type ==  Boolean.class || type == Boolean.TYPE) {
				return BOOLEAN;
			} else if (ZooPC.class.isAssignableFrom(type)) {
				return PC;
			} else if (type ==  Date.class) {
				return DATE;
			} else if (type ==  BigInteger.class) {
				return BIG_INT;
			} else if (type ==  BigDecimal.class) {
				return BIG_DECIMAL;
			}
			return SCO;
		}
		
		
		public static COMPARISON_TYPE fromOperands(COMPARISON_TYPE lhsCt,
				COMPARISON_TYPE rhsCt) {
			//swap them (according to ordinal()) to eliminate some 'if'. (?)
			if (rhsCt.ordinal() < lhsCt.ordinal()) {
				COMPARISON_TYPE x = lhsCt;
				lhsCt = rhsCt;
				rhsCt = x;
			}
			
			if (lhsCt == SCO && rhsCt == SCO) {
				return SCO;
			}
			
			switch (lhsCt) {
			case BIG_DECIMAL :
			case BIG_INT: 
			case DOUBLE:
			case FLOAT:
			case LONG:
			case INT:
			case SHORT:
			case BYTE:
			case CHAR:
				if (rhsCt.canBeNumber()) {
					return lhsCt;
				} 
				failComp(lhsCt, rhsCt);
			case BOOLEAN:
				if (rhsCt == BOOLEAN) {
					return BOOLEAN;
				}
				if (rhsCt == SCO) {
					return SCO;
				}
				failComp(lhsCt, rhsCt);
			case PC:
				if (rhsCt == PC || rhsCt == NULL) {
					return PC;
				}
				if (rhsCt == SCO) {
					return SCO;
				}
				failComp(lhsCt, rhsCt);
			case STRING:
				if (rhsCt == STRING) {
					return STRING;
				}
				return UNKNOWN;
			default: return UNKNOWN;
			}
		}

		private static void failComp(COMPARISON_TYPE lhsCt,
				COMPARISON_TYPE rhsCt) {
			throw DBLogger.newUser("Cannot compare " + lhsCt + " with " + rhsCt);
		}
	}

	public static COMPARISON_TYPE fromTypes(Class<?> lhs, Class<?> rhs) {
		COMPARISON_TYPE lhsCt = COMPARISON_TYPE.fromClass(lhs);
		COMPARISON_TYPE rhsCt = COMPARISON_TYPE.fromClass(rhs);
		return COMPARISON_TYPE.fromOperands(lhsCt, rhsCt);
	}
	
	/**
	 * This assumes that comparability implies assignability or convertability...
	 * @param o object
	 * @param type type
	 */
	public static void checkAssignability(Object o, Class<?> type) {
		COMPARISON_TYPE ctO = COMPARISON_TYPE.fromObject(o);
		COMPARISON_TYPE ctT = COMPARISON_TYPE.fromClass(type);
		try {
			COMPARISON_TYPE.fromOperands(ctO, ctT);
		} catch (Exception e) {
			throw DBLogger.newUser("Cannot assign " + o.getClass() + " to " + type, e);
		}
	}
	
	/**
	 * This assumes that comparability implies assignability or convertability...
	 * @param c1 type #1
	 * @param c2 type #2
	 */
	public static void checkAssignability(Class<?> c1, Class<?> c2) {
		COMPARISON_TYPE ct1 = COMPARISON_TYPE.fromClass(c1);
		COMPARISON_TYPE ct2 = COMPARISON_TYPE.fromClass(c2);
		try {
			COMPARISON_TYPE.fromOperands(ct1, ct2);
		} catch (Exception e) {
			throw DBLogger.newUser("Cannot assign " + c2 + " to " + c1, e);
		}
	}
	
	public static double toDouble(Object o) { 
		if (o instanceof Double) {
			return (double)o; 
		} else if (o instanceof Float) {
			return (float)o; 
		} 
		return toLong(o);
	}
	
	public static long toLong(Object o) { 
		if (o instanceof Long) {
			return (long)o; 
		}
		return toInt(o);
	}

	public static int toInt(Object o) {
		//TODO use perfect hashing on types to create hashmap?
		if (o instanceof Integer) {
			return (int)(Integer)o;
		} else if (o instanceof Short) {
			return (Short)o;
		} else if (o instanceof Byte) {
			return (Byte)o;
		} else if (o instanceof Character) {
			return (Character)o;
		}
		throw DBLogger.newUser("Cannot cast type to number: " + o.getClass().getName());
	}
	
	
}