Class EmptyExpression

  • All Implemented Interfaces:
    java.lang.Iterable<java.lang.String>, Expression

    class EmptyExpression
    extends java.lang.Object
    implements Expression
    The EmptyExpression object is used to represent a path that represents the current context. This is a much more lightweight alternative to parsing "." with the PathParser object as it does not require the allocation of collections or buffers.
    See Also:
    PathParser
    • Field Summary

      Fields 
      Modifier and Type Field Description
      private java.util.List<java.lang.String> list
      This is a list that is used to create an empty iterator.
      private Style style
      This is the style that is used to style any paths created.
    • Constructor Summary

      Constructors 
      Constructor Description
      EmptyExpression​(Format format)
      Constructor for EmptyExpression object.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.String getAttribute​(java.lang.String name)
      This is used to acquire the attribute path using this XPath expression.
      java.lang.String getElement​(java.lang.String name)
      This is used to acquire the element path using this XPath expression.
      java.lang.String getFirst()
      This can be used to acquire the first path segment within the expression.
      int getIndex()
      If the first path segment contains an index it is provided by this method.
      java.lang.String getLast()
      This can be used to acquire the last path segment within the expression.
      java.lang.String getPath()
      This location contains the full path expression with all of the indexes explicitly shown for each path segment.
      Expression getPath​(int from)
      This allows an expression to be extracted from the current context.
      Expression getPath​(int from, int trim)
      This allows an expression to be extracted from the current context.
      java.lang.String getPrefix()
      This is used to extract a namespace prefix from the path expression.
      boolean isAttribute()
      This is used to determine if the expression points to an attribute value.
      boolean isEmpty()
      This method is used to determine if this expression is an empty path.
      boolean isPath()
      This is used to determine if the expression is a path.
      java.util.Iterator<java.lang.String> iterator()
      This is used to iterate over the path segments that have been extracted from the source XPath expression.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
      • Methods inherited from interface java.lang.Iterable

        forEach, spliterator
    • Field Detail

      • list

        private final java.util.List<java.lang.String> list
        This is a list that is used to create an empty iterator.
      • style

        private final Style style
        This is the style that is used to style any paths created.
    • Constructor Detail

      • EmptyExpression

        public EmptyExpression​(Format format)
        Constructor for EmptyExpression object. This is used to create an expression for an empty path. An empty path is basically the root element ".".
        Parameters:
        format - the format used to style the paths created
    • Method Detail

      • iterator

        public java.util.Iterator<java.lang.String> iterator()
        This is used to iterate over the path segments that have been extracted from the source XPath expression. Iteration over the segments is done in the order they were parsed from the source path.
        Specified by:
        iterator in interface java.lang.Iterable<java.lang.String>
        Returns:
        this returns an iterator for the path segments
      • getIndex

        public int getIndex()
        If the first path segment contains an index it is provided by this method. There may be several indexes within a path, however only the index at the first segment is issued by this method. If there is no index this will return 1.
        Specified by:
        getIndex in interface Expression
        Returns:
        this returns the index of this path expression
      • getPrefix

        public java.lang.String getPrefix()
        This is used to extract a namespace prefix from the path expression. A prefix is used to qualify the XML element name and does not form part of the actual path structure. This can be used to add the namespace in addition to the name.
        Specified by:
        getPrefix in interface Expression
        Returns:
        this returns the prefix for the path expression
      • getFirst

        public java.lang.String getFirst()
        This can be used to acquire the first path segment within the expression. The first segment represents the parent XML element of the path. All segments returned do not contain any slashes and so represents the real element name.
        Specified by:
        getFirst in interface Expression
        Returns:
        this returns the parent element for the path
      • getLast

        public java.lang.String getLast()
        This can be used to acquire the last path segment within the expression. The last segment represents the leaf XML element of the path. All segments returned do not contain any slashes and so represents the real element name.
        Specified by:
        getLast in interface Expression
        Returns:
        this returns the leaf element for the path
      • getPath

        public java.lang.String getPath()
        This location contains the full path expression with all of the indexes explicitly shown for each path segment. This is used to create a uniform representation that can be used for comparisons of different path expressions.
        Specified by:
        getPath in interface Expression
        Returns:
        this returns an expanded version of the path
      • getElement

        public java.lang.String getElement​(java.lang.String name)
        This is used to acquire the element path using this XPath expression. The element path is simply the fully qualified path for this expression with the provided name appended. If this is an empty path, the provided name is returned.
        Specified by:
        getElement in interface Expression
        Parameters:
        name - this is the name of the element to be used
        Returns:
        a fully qualified path for the specified name
      • getAttribute

        public java.lang.String getAttribute​(java.lang.String name)
        This is used to acquire the attribute path using this XPath expression. The attribute path is simply the fully qualified path for this expression with the provided name appended. If this is an empty path, the provided name is returned.
        Specified by:
        getAttribute in interface Expression
        Parameters:
        name - this is the name of the attribute to be used
        Returns:
        a fully qualified path for the specified name
      • getPath

        public Expression getPath​(int from)
        This allows an expression to be extracted from the current context. Extracting expressions in this manner makes it more convenient for navigating structures representing the XML document. If an expression can not be extracted with the given criteria an exception will be thrown.
        Specified by:
        getPath in interface Expression
        Parameters:
        from - this is the number of segments to skip to
        Returns:
        this returns an expression from this one
      • getPath

        public Expression getPath​(int from,
                                  int trim)
        This allows an expression to be extracted from the current context. Extracting expressions in this manner makes it more convenient for navigating structures representing the XML document. If an expression can not be extracted with the given criteria an exception will be thrown.
        Specified by:
        getPath in interface Expression
        Parameters:
        from - this is the number of segments to skip to
        trim - the number of segments to trim from the end
        Returns:
        this returns an expression from this one
      • isAttribute

        public boolean isAttribute()
        This is used to determine if the expression points to an attribute value. An attribute value contains an '@' character before the last segment name. Such expressions distinguish element references from attribute references.
        Specified by:
        isAttribute in interface Expression
        Returns:
        this returns true if the path has an attribute
      • isPath

        public boolean isPath()
        This is used to determine if the expression is a path. An expression represents a path if it contains more than one segment. If only one segment exists it is an element name.
        Specified by:
        isPath in interface Expression
        Returns:
        true if this contains more than one segment
      • isEmpty

        public boolean isEmpty()
        This method is used to determine if this expression is an empty path. An empty path can be represented by a single period, '.'. It identifies the current path.
        Specified by:
        isEmpty in interface Expression
        Returns:
        returns true if this represents an empty path