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org.apache.taglibs.standard.lang.jstl
Class Coercions
java.lang.Objectorg.apache.taglibs.standard.lang.jstl.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 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
- Version:
- $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: pierred $
| 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 |
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 |
isPrimitiveNumberClass(java.lang.Class pClass)
Returns true if the given class is Byte, Short, Integer, Long, Float, Double |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| 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 ELException
- Coerces the given value to the specified class.
isPrimitiveNumberClass
static boolean isPrimitiveNumberClass(java.lang.Class pClass)
- Returns true if the given class is Byte, Short, Integer, Long,
Float, Double
coerceToString
public static java.lang.String coerceToString(java.lang.Object pValue, Logger pLogger) throws 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 ELException
- Coerces a value to the given primitive number class
coerceToInteger
public static java.lang.Integer coerceToInteger(java.lang.Object pValue, Logger pLogger) throws 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 ELException
- Coerces a long to the given primitive number class
coerceToPrimitiveNumber
static java.lang.Number coerceToPrimitiveNumber(double pValue, java.lang.Class pClass) throws 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 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 ELException
- Coerces a String to the given primitive number class
coerceToCharacter
public static java.lang.Character coerceToCharacter(java.lang.Object pValue, Logger pLogger) throws ELException
- Coerces a value to a Character
coerceToBoolean
public static java.lang.Boolean coerceToBoolean(java.lang.Object pValue, Logger pLogger) throws 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 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 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 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 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
|
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| Home >> All >> org >> apache >> taglibs >> standard >> lang >> [ jstl overview ] | PREV CLASS NEXT CLASS | ||||||||
|
SUMMARY: JAVADOC | SOURCE | DOWNLOAD | NESTED | FIELD | CONSTR | METHOD |
DETAIL: FIELD | CONSTR | METHOD | ||||||||