| java.lang.Object
 org.apache.taglibs.standard.lang.jstl.Coercions
| Coercions | | public class Coercions (Code) | | 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 Float, Double, or String containing ".", "e", or "E"
coerce both A and B to Double
apply operator
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
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 Float, Double, or String containing ".", "e" or "E"
coerce both to Double
apply operator
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 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
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 Float or Double
coerce both A and B to Double
apply operator
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 Float or Double
coerce both A and B to Double
apply operator
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 primitive 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 with less precision than N
coerce quietly
A is Number with greater precision than N
coerce quietly
A is String
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
author:
Nathan Abramson - Art Technology Group
version:
$Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: tcfujii $ |
| Method Summary | |
| public static Object | applyArithmeticOperator(Object pLeft, Object pRight, ArithmeticOperator pOperator, Logger pLogger)
Performs all of the necessary type conversions, then calls on the
appropriate operator. | | public static Object | applyEqualityOperator(Object pLeft, Object pRight, EqualityOperator pOperator, Logger pLogger)
Performs all of the necessary type conversions, then calls on the
appropriate operator. | | public static Object | applyRelationalOperator(Object pLeft, Object pRight, RelationalOperator pOperator, Logger pLogger)
Performs all of the necessary type conversions, then calls on the
appropriate operator. | | public static Object | coerce(Object pValue, Class pClass, Logger pLogger)
Coerces the given value to the specified class. | | public static Boolean | coerceToBoolean(Object pValue, Logger pLogger)
| | public static Character | coerceToCharacter(Object pValue, Logger pLogger)
| | public static Integer | coerceToInteger(Object pValue, Logger pLogger)
Coerces a value to an Integer, returning null if the coercion
isn't possible. | | public static Object | coerceToObject(Object pValue, Class pClass, Logger pLogger)
| | public static Number | coerceToPrimitiveNumber(Object pValue, Class pClass, Logger pLogger)
| | static Number | coerceToPrimitiveNumber(long pValue, Class pClass)
| | static Number | coerceToPrimitiveNumber(double pValue, Class pClass)
| | static Number | coerceToPrimitiveNumber(Number pValue, Class pClass)
| | static Number | coerceToPrimitiveNumber(String pValue, Class pClass)
| | public static String | coerceToString(Object pValue, Logger pLogger)
| | public static boolean | isFloatingPointString(Object pObject)
| | public static boolean | isFloatingPointType(Object pObject)
| | public static boolean | isFloatingPointType(Class pClass)
| | public static boolean | isIntegerType(Object pObject)
| | public static boolean | isIntegerType(Class pClass)
| | static boolean | isPrimitiveNumberClass(Class pClass)
|
| coerceToInteger | | public static Integer coerceToInteger(Object pValue, Logger pLogger) throws ELException(Code) | | Coerces a value to an Integer, returning null if the coercion
isn't possible.
|
| coerceToObject | | public static Object coerceToObject(Object pValue, Class pClass, Logger pLogger) throws ELException(Code) | | Coerces a value to the specified Class that is not covered by any
of the above cases
|
| coerceToPrimitiveNumber | | static Number coerceToPrimitiveNumber(long pValue, Class pClass) throws ELException(Code) | | Coerces a long to the given primitive number class
|
| coerceToPrimitiveNumber | | static Number coerceToPrimitiveNumber(double pValue, Class pClass) throws ELException(Code) | | Coerces a double to the given primitive number class
|
| isFloatingPointString | | public static boolean isFloatingPointString(Object pObject)(Code) | | Returns true if the given string might contain a floating point
number - i.e., it contains ".", "e", or "E"
|
| isFloatingPointType | | public static boolean isFloatingPointType(Object pObject)(Code) | | Returns true if the given Object is of a floating point type
|
| isFloatingPointType | | public static boolean isFloatingPointType(Class pClass)(Code) | | Returns true if the given class is of a floating point type
|
| isIntegerType | | public static boolean isIntegerType(Object pObject)(Code) | | Returns true if the given Object is of an integer type
|
| isIntegerType | | public static boolean isIntegerType(Class pClass)(Code) | | Returns true if the given class is of an integer type
|
| isPrimitiveNumberClass | | static boolean isPrimitiveNumberClass(Class pClass)(Code) | | Returns true if the given class is Byte, Short, Integer, Long,
Float, Double
|
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