Package org.zkoss.zel.impl.lang

Class ELSupport

  • Direct Known Subclasses:
    SimpleNode
    public class ELSupport
extends java.lang.Object
    A helper class that implements the EL Specification
    Author:
    Jacob Hookom [jacob@hookom.net]

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected static boolean COERCE_NULL_TO_NULL
      EL 2.2 by spec. should coerce "null" value to 0 number, 0 character, "" String, false boolean.
      protected static boolean COERCE_TO_ZERO  

    • Constructor Summary

      Constructors 
      Constructor Description
      ELSupport()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static java.lang.Boolean coerceToBoolean​(java.lang.Object obj, boolean primitive)
      Convert an object to Boolean.
      static java.util.Date coerceToDateTime​(java.lang.Object obj, java.lang.Class type)
      Coerce an object to an instance of java.util.Date
      static java.lang.Enum<?> coerceToEnum​(java.lang.Object obj, java.lang.Class type)  
      protected static java.lang.Number coerceToNumber​(java.lang.Number number, java.lang.Class<?> type)  
      static java.lang.Number coerceToNumber​(java.lang.Object obj, java.lang.Class<?> type)  
      protected static java.lang.Number coerceToNumber​(java.lang.String val, java.lang.Class<?> type)  
      static java.lang.String coerceToString​(java.lang.Object obj)
      Coerce an object to a string.
      static java.lang.Object coerceToType​(java.lang.Object obj, java.lang.Class<?> type)  
      protected static java.lang.Object coerceToTypeForSetValue​(java.lang.Object obj, java.lang.Class<?> type)  
      static int compare​(java.lang.Object obj0, java.lang.Object obj1)
      Compare two objects, after coercing to the same type if appropriate.
      static boolean equals​(java.lang.Object obj0, java.lang.Object obj1)
      Compare two objects for equality, after coercing to the same type if appropriate.
      static boolean isBigDecimalOp​(java.lang.Object obj0, java.lang.Object obj1)  
      static boolean isBigIntegerOp​(java.lang.Object obj0, java.lang.Object obj1)  
      static boolean isDateTimeType​(java.lang.Class<?> type)  
      static boolean isDoubleOp​(java.lang.Object obj0, java.lang.Object obj1)  
      static boolean isLongOp​(java.lang.Object obj0, java.lang.Object obj1)  
      static boolean isStringFloat​(java.lang.String str)  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • COERCE_NULL_TO_NULL

        protected static final boolean COERCE_NULL_TO_NULL
        EL 2.2 by spec. should coerce "null" value to 0 number, 0 character, "" String, false boolean. This spec. makes it impossible to store null state into java lang object when doing setValue() and can set unexpected coerced value into java lang object. So we provide a system property "org.zkoss.zel.impl.parser.COERCE_NULL_TO_NULL" to switch this behavior when doing setValue(). By default we will set org.zkoss.zel.impl.parser.COERCE_NULL_TO_NULL to true to allow set null value though this is not compliant to the EL 2.2 spec. Shall you need to make ZEL to follow EL 2.2 spec. when doing setValue, please set "org.zkoss.zel.impl.parser.COERCE_NULL_TO_NULL" system property to false. Ref. https://services.brics.dk/java/courseadmin/SWP2011/documents/getDocument/expression_language-2_2-mrel-spec.pdf?d=41976

      • COERCE_TO_ZERO

        protected static final boolean COERCE_TO_ZERO

    • Constructor Detail

      • ELSupport

        public ELSupport()

    • Method Detail

      • compare

        public static final int compare​(java.lang.Object obj0,
                                java.lang.Object obj1)
                         throws ELException
        Compare two objects, after coercing to the same type if appropriate. If the objects are identical, or they are equal according to equals(Object, Object) then return 0. If either object is a BigDecimal, then coerce both to BigDecimal first. Similarly for Double(Float), BigInteger, and Long(Integer, Char, Short, Byte). Otherwise, check that the first object is an instance of Comparable, and compare against the second object. If that is null, return 1, otherwise return the result of comparing against the second object. Similarly, if the second object is Comparable, if the first is null, return -1, else return the result of comparing against the first object. A null object is considered as:
        • ZERO when compared with Numbers
        • the empty string for String compares
        • Otherwise null is considered to be lower than anything else.
        Parameters:
        obj0 - first object
        obj1 - second object
        Returns:
        -1, 0, or 1 if this object is less than, equal to, or greater than val.
        Throws:
        ELException - if neither object is Comparable
        java.lang.ClassCastException - if the objects are not mutually comparable

      • equals

        public static final boolean equals​(java.lang.Object obj0,
                                   java.lang.Object obj1)
                            throws ELException
        Compare two objects for equality, after coercing to the same type if appropriate. If the objects are identical (including both null) return true. If either object is null, return false. If either object is Boolean, coerce both to Boolean and check equality. Similarly for Enum, String, BigDecimal, Double(Float), Long(Integer, Short, Byte, Character) Otherwise default to using Object.equals().
        Parameters:
        obj0 - the first object
        obj1 - the second object
        Returns:
        true if the objects are equal
        Throws:
        ELException - if one of the coercion fails

      • coerceToEnum

        public static final java.lang.Enum<?> coerceToEnum​(java.lang.Object obj,
                                                   java.lang.Class type)

      • coerceToBoolean

        public static final java.lang.Boolean coerceToBoolean​(java.lang.Object obj,
                                                      boolean primitive)
                                               throws ELException
        Convert an object to Boolean. Null and empty string are false.
        Parameters:
        obj - the object to convert
        primitive - is the target a primitive in which case coercion to null is not permitted
        Returns:
        the Boolean value of the object
        Throws:
        ELException - if object is not Boolean or String

      • coerceToNumber

        protected static final java.lang.Number coerceToNumber​(java.lang.Number number,
                                                       java.lang.Class<?> type)
                                                throws ELException
        Throws:
        ELException

      • coerceToNumber

        public static final java.lang.Number coerceToNumber​(java.lang.Object obj,
                                                    java.lang.Class<?> type)
                                             throws ELException
        Throws:
        ELException

      • coerceToNumber

        protected static final java.lang.Number coerceToNumber​(java.lang.String val,
                                                       java.lang.Class<?> type)
                                                throws ELException
        Throws:
        ELException

      • coerceToString

        public static final java.lang.String coerceToString​(java.lang.Object obj)
        Coerce an object to a string.
        Parameters:
        obj - the object to convert
        Returns:
        the String value of the object

      • coerceToTypeForSetValue

        protected static final java.lang.Object coerceToTypeForSetValue​(java.lang.Object obj,
                                                                java.lang.Class<?> type)
                                                         throws ELException
        Throws:
        ELException

      • coerceToType

        public static final java.lang.Object coerceToType​(java.lang.Object obj,
                                                  java.lang.Class<?> type)
                                           throws ELException
        Throws:
        ELException

      • isBigDecimalOp

        public static final boolean isBigDecimalOp​(java.lang.Object obj0,
                                           java.lang.Object obj1)

      • isBigIntegerOp

        public static final boolean isBigIntegerOp​(java.lang.Object obj0,
                                           java.lang.Object obj1)

      • isDoubleOp

        public static final boolean isDoubleOp​(java.lang.Object obj0,
                                       java.lang.Object obj1)

      • isLongOp

        public static final boolean isLongOp​(java.lang.Object obj0,
                                     java.lang.Object obj1)

      • isStringFloat

        public static final boolean isStringFloat​(java.lang.String str)

      • isDateTimeType

        public static final boolean isDateTimeType​(java.lang.Class<?> type)

      • coerceToDateTime

        public static final java.util.Date coerceToDateTime​(java.lang.Object obj,
                                                    java.lang.Class type)
                                             throws ELException
        Coerce an object to an instance of java.util.Date
        Parameters:
        obj - the object to be converted; must be an instance of java.util.Date or a number which represents the millisecond since "the epoch" base time, namely January 1, 1970, 00:00:00 GMT.
        type - the class type which shall be a kind of java.util.Date; e.g. java.sql.Date, java.sql.Time, java.sql.Timestamp
        Returns:
        the instance as requested by the specified type
        Throws:
        ELException