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org.apache.commons.el
Class Coercions
java.lang.Objectorg.apache.commons.el.Coercions
- public class Coercions
- extends java.lang.Object
This class contains the logic for coercing data types before operators are applied to them.
The following is the list of rules applied for various type conversions.
Applying arithmetic operator
Binary operator - A {+,-,*} B
if A and B are null
return 0
if A or B is BigDecimal, coerce both to BigDecimal and then:
if operator is +, return A.add(B)
if operator is -, return A.subtract(B)
if operator is *, return A.multiply(B)
if A or B is Float, Double, or String containing ".", "e", or "E"
if A or B is BigInteger, coerce both A and B to BigDecimal and apply operator
coerce both A and B to Double and apply operator
if A or B is BigInteger, coerce both to BigInteger and then:
if operator is +, return A.add(B)
if operator is -, return A.subtract(B)
if operator is *, return A.multiply(B)
otherwise
coerce both A and B to Long
apply operator
if operator results in exception (such as divide by 0), error
Binary operator - A {/,div} B
if A and B are null
return 0
if A or B is a BigDecimal or BigInteger, coerce both to BigDecimal and
return A.divide(B, BigDecimal.ROUND_HALF_UP)
otherwise
coerce both A and B to Double
apply operator
if operator results in exception (such as divide by 0), error
Binary operator - A {%,mod} B
if A and B are null
return 0
if A or B is BigDecimal, Float, Double, or String containing ".", "e" or "E"
coerce both to Double
apply operator
if A or B is BigInteger, coerce both to BigInteger and return
A.remainder(B)
otherwise
coerce both A and B to Long
apply operator
if operator results in exception (such as divide by 0), error
Unary minus operator - -A
if A is null
return 0
if A is BigInteger or BigDecimal, return A.negate()
if A is String
if A contains ".", "e", or "E"
coerce to Double, apply operator
otherwise
coerce to a Long and apply operator
if A is Byte,Short,Integer,Long,Float,Double
retain type, apply operator
if operator results in exception, error
otherwise
error
Applying "empty" operator - empty A
if A is null
return true
if A is zero-length String
return true
if A is zero-length array
return true
if A is List and ((List) A).isEmpty()
return true
if A is Map and ((Map) A).isEmpty()
return true
if A is Collection an ((Collection) A).isEmpty()
return true
otherwise
return false
Applying logical operators
Binary operator - A {and,or} B
coerce both A and B to Boolean, apply operator
NOTE - operator stops as soon as expression can be determined, i.e.,
A and B and C and D - if B is false, then only A and B is evaluated
Unary not operator - not A
coerce A to Boolean, apply operator
Applying relational operator
A {<,>,<=,>=,lt,gt,lte,gte} B
if A==B
if operator is >= or <=
return true
otherwise
return false
if A or B is null
return false
if A or B is BigDecimal, coerce both A and B to BigDecimal and use the
return value of A.compareTo(B)
if A or B is Float or Double
coerce both A and B to Double
apply operator
if A or B is BigInteger, coerce both A and B to BigInteger and use the
return value of A.compareTo(B)
if A or B is Byte,Short,Character,Integer,Long
coerce both A and B to Long
apply operator
if A or B is String
coerce both A and B to String, compare lexically
if A is Comparable
if A.compareTo (B) throws exception
error
otherwise
use result of A.compareTo(B)
if B is Comparable
if B.compareTo (A) throws exception
error
otherwise
use result of B.compareTo(A)
otherwise
error
Applying equality operator
A {==,!=} B
if A==B
apply operator
if A or B is null
return false for ==, true for !=
if A or B is BigDecimal, coerce both A and B to BigDecimal and then:
if operator is == or eq, return A.equals(B)
if operator is != or ne, return !A.equals(B)
if A or B is Float or Double
coerce both A and B to Double
apply operator
if A or B is BigInteger, coerce both A and B to BigInteger and then:
if operator is == or eq, return A.equals(B)
if operator is != or ne, return !A.equals(B)
if A or B is Byte,Short,Character,Integer,Long
coerce both A and B to Long
apply operator
if A or B is Boolean
coerce both A and B to Boolean
apply operator
if A or B is String
coerce both A and B to String, compare lexically
otherwise
if an error occurs while calling A.equals(B)
error
apply operator to result of A.equals(B)
coercions
coerce A to String
A is String
return A
A is null
return ""
A.toString throws exception
error
otherwise
return A.toString
coerce A to Number type N
A is null or ""
return 0
A is Character
convert to short, apply following rules
A is Boolean
error
A is Number type N
return A
A is Number, coerce quietly to type N using the following algorithm
If N is BigInteger
If A is BigDecimal, return A.toBigInteger()
Otherwise, return BigInteger.valueOf(A.longValue())
if N is BigDecimal
If A is a BigInteger, return new BigDecimal(A)
Otherwise, return new BigDecimal(A.doubleValue())
If N is Byte, return new Byte(A.byteValue())
If N is Short, return new Short(A.shortValue())
If N is Integer, return new Integer(A.integerValue())
If N is Long, return new Long(A.longValue())
If N is Float, return new Float(A.floatValue())
If N is Double, return new Double(A.doubleValue())
otherwise ERROR
A is String
If N is BigDecimal then:
If new BigDecimal(A) throws an exception then ERROR
Otherwise, return new BigDecimal(A)
If N is BigInteger then:
If new BigInteger(A) throws an exception, then ERROR
Otherwise, return new BigInteger(A)
new N.valueOf(A) throws exception
error
return N.valueOf(A)
otherwise
error
coerce A to Character should be
A is null or ""
return (char) 0
A is Character
return A
A is Boolean
error
A is Number with less precision than short
coerce quietly - return (char) A
A is Number with greater precision than short
coerce quietly - return (char) A
A is String
return A.charAt (0)
otherwise
error
coerce A to Boolean
A is null or ""
return false
A is Boolean
return A
A is String
Boolean.valueOf(A) throws exception
error
return Boolean.valueOf(A)
otherwise
error
coerce A to any other type T
A is null
return null
A is assignable to T
coerce quietly
A is String
T has no PropertyEditor
if A is "", return null
otherwise error
T's PropertyEditor throws exception
if A is "", return null
otherwise error
otherwise
apply T's PropertyEditor
otherwise
error
- Version:
- $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: luehe $
| Field Summary | |
private static java.lang.Number |
ZERO
|
| Constructor Summary | |
Coercions()
|
|
| Method Summary | |
static java.lang.Object |
applyArithmeticOperator(java.lang.Object pLeft,
java.lang.Object pRight,
ArithmeticOperator pOperator,
Logger pLogger)
Performs all of the necessary type conversions, then calls on the appropriate operator. |
static java.lang.Object |
applyEqualityOperator(java.lang.Object pLeft,
java.lang.Object pRight,
EqualityOperator pOperator,
Logger pLogger)
Performs all of the necessary type conversions, then calls on the appropriate operator. |
static java.lang.Object |
applyRelationalOperator(java.lang.Object pLeft,
java.lang.Object pRight,
RelationalOperator pOperator,
Logger pLogger)
Performs all of the necessary type conversions, then calls on the appropriate operator. |
static java.lang.Object |
coerce(java.lang.Object pValue,
java.lang.Class pClass,
Logger pLogger)
Coerces the given value to the specified class. |
static java.lang.Boolean |
coerceToBoolean(java.lang.Object pValue,
Logger pLogger)
Coerces a value to a Boolean |
static java.lang.Character |
coerceToCharacter(java.lang.Object pValue,
Logger pLogger)
Coerces a value to a Character |
static java.lang.Integer |
coerceToInteger(java.lang.Object pValue,
Logger pLogger)
Coerces a value to an Integer, returning null if the coercion isn't possible. |
static java.lang.Object |
coerceToObject(java.lang.Object pValue,
java.lang.Class pClass,
Logger pLogger)
Coerces a value to the specified Class that is not covered by any of the above cases |
(package private) static java.lang.Number |
coerceToPrimitiveNumber(double pValue,
java.lang.Class pClass)
Coerces a double to the given primitive number class |
(package private) static java.lang.Number |
coerceToPrimitiveNumber(long pValue,
java.lang.Class pClass)
Coerces a long to the given primitive number class |
(package private) static java.lang.Number |
coerceToPrimitiveNumber(java.lang.Number pValue,
java.lang.Class pClass)
Coerces a Number to the given primitive number class |
static java.lang.Number |
coerceToPrimitiveNumber(java.lang.Object pValue,
java.lang.Class pClass,
Logger pLogger)
Coerces a value to the given primitive number class |
(package private) static java.lang.Number |
coerceToPrimitiveNumber(java.lang.String pValue,
java.lang.Class pClass)
Coerces a String to the given primitive number class |
static java.lang.String |
coerceToString(java.lang.Object pValue,
Logger pLogger)
Coerces the specified value to a String |
static boolean |
isBigDecimal(java.lang.Object pObject)
Returns true if the given object is BigDecimal. |
static boolean |
isBigInteger(java.lang.Object pObject)
Returns true if the given object is BigInteger. |
static boolean |
isFloatingPointString(java.lang.Object pObject)
Returns true if the given string might contain a floating point number - i.e., it contains ".", "e", or "E" |
static boolean |
isFloatingPointType(java.lang.Class pClass)
Returns true if the given class is of a floating point type |
static boolean |
isFloatingPointType(java.lang.Object pObject)
Returns true if the given Object is of a floating point type |
static boolean |
isIntegerType(java.lang.Class pClass)
Returns true if the given class is of an integer type |
static boolean |
isIntegerType(java.lang.Object pObject)
Returns true if the given Object is of an integer type |
(package private) static boolean |
isNumberClass(java.lang.Class pClass)
Returns true if the given class is Byte, Short, Integer, Long, Float, Double, BigInteger, or BigDecimal |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
ZERO
private static final java.lang.Number ZERO
| Constructor Detail |
Coercions
public Coercions()
| Method Detail |
coerce
public static java.lang.Object coerce(java.lang.Object pValue, java.lang.Class pClass, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Coerces the given value to the specified class.
isNumberClass
static boolean isNumberClass(java.lang.Class pClass)
- Returns true if the given class is Byte, Short, Integer, Long,
Float, Double, BigInteger, or BigDecimal
coerceToString
public static java.lang.String coerceToString(java.lang.Object pValue, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Coerces the specified value to a String
coerceToPrimitiveNumber
public static java.lang.Number coerceToPrimitiveNumber(java.lang.Object pValue, java.lang.Class pClass, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Coerces a value to the given primitive number class
coerceToInteger
public static java.lang.Integer coerceToInteger(java.lang.Object pValue, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Coerces a value to an Integer, returning null if the coercion
isn't possible.
coerceToPrimitiveNumber
static java.lang.Number coerceToPrimitiveNumber(long pValue, java.lang.Class pClass) throws javax.servlet.jsp.el.ELException
- Coerces a long to the given primitive number class
coerceToPrimitiveNumber
static java.lang.Number coerceToPrimitiveNumber(double pValue, java.lang.Class pClass) throws javax.servlet.jsp.el.ELException
- Coerces a double to the given primitive number class
coerceToPrimitiveNumber
static java.lang.Number coerceToPrimitiveNumber(java.lang.Number pValue, java.lang.Class pClass) throws javax.servlet.jsp.el.ELException
- Coerces a Number to the given primitive number class
coerceToPrimitiveNumber
static java.lang.Number coerceToPrimitiveNumber(java.lang.String pValue, java.lang.Class pClass) throws javax.servlet.jsp.el.ELException
- Coerces a String to the given primitive number class
coerceToCharacter
public static java.lang.Character coerceToCharacter(java.lang.Object pValue, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Coerces a value to a Character
coerceToBoolean
public static java.lang.Boolean coerceToBoolean(java.lang.Object pValue, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Coerces a value to a Boolean
coerceToObject
public static java.lang.Object coerceToObject(java.lang.Object pValue, java.lang.Class pClass, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Coerces a value to the specified Class that is not covered by any
of the above cases
applyArithmeticOperator
public static java.lang.Object applyArithmeticOperator(java.lang.Object pLeft, java.lang.Object pRight, ArithmeticOperator pOperator, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Performs all of the necessary type conversions, then calls on the
appropriate operator.
applyRelationalOperator
public static java.lang.Object applyRelationalOperator(java.lang.Object pLeft, java.lang.Object pRight, RelationalOperator pOperator, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Performs all of the necessary type conversions, then calls on the
appropriate operator.
applyEqualityOperator
public static java.lang.Object applyEqualityOperator(java.lang.Object pLeft, java.lang.Object pRight, EqualityOperator pOperator, Logger pLogger) throws javax.servlet.jsp.el.ELException
- Performs all of the necessary type conversions, then calls on the
appropriate operator.
isFloatingPointType
public static boolean isFloatingPointType(java.lang.Object pObject)
- Returns true if the given Object is of a floating point type
isFloatingPointType
public static boolean isFloatingPointType(java.lang.Class pClass)
- Returns true if the given class is of a floating point type
isFloatingPointString
public static boolean isFloatingPointString(java.lang.Object pObject)
- Returns true if the given string might contain a floating point
number - i.e., it contains ".", "e", or "E"
isIntegerType
public static boolean isIntegerType(java.lang.Object pObject)
- Returns true if the given Object is of an integer type
isIntegerType
public static boolean isIntegerType(java.lang.Class pClass)
- Returns true if the given class is of an integer type
isBigInteger
public static boolean isBigInteger(java.lang.Object pObject)
- Returns true if the given object is BigInteger.
isBigDecimal
public static boolean isBigDecimal(java.lang.Object pObject)
- Returns true if the given object is BigDecimal.
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SUMMARY: JAVADOC | SOURCE | DOWNLOAD | NESTED | FIELD | CONSTR | METHOD |
DETAIL: FIELD | CONSTR | METHOD | ||||||||