java.lang.Object
org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
org.eclipse.persistence.jpa.jpql.parser.WhenClause
All Implemented Interfaces:
Expression

public final class WhenClause extends AbstractExpression
A WHEN predicate is used to calculate a condition and when it's true, its THEN will be executed.
BNF: when_clause ::= WHEN conditional_expression THEN scalar_expression
or
BNF: simple_when_clause ::= WHEN scalar_expression THEN scalar_expression
Since:
2.3
Version:
2.5
  • Constructor Details

    • WhenClause

      public WhenClause(AbstractExpression parent)
      Creates a new WhenClause.
      Parameters:
      parent - The parent of this expression
  • Method Details

    • accept

      public void accept(ExpressionVisitor visitor)
      Description copied from interface: Expression
      Visits this Expression by the given visitor.
      Parameters:
      visitor - The ExpressionVisitor to visit this object
    • acceptChildren

      public void acceptChildren(ExpressionVisitor visitor)
      Description copied from interface: Expression
      Visits the children of this Expression. This method can be used to optimize traversing the children since a new list is not created every time Expression.children() is called.

      This does not traverse the Expression sub-hierarchy, use a subclass of AbstractTraverseChildrenVisitor in order to traverse the entire sub-hierarchy.

      Parameters:
      visitor - The visitor to visit the children of this object.
    • addChildrenTo

      protected void addChildrenTo(Collection<Expression> children)
      Description copied from class: AbstractExpression
      Adds the children of this AbstractExpression to the given collection.
      Overrides:
      addChildrenTo in class AbstractExpression
      Parameters:
      children - The collection used to store the children
    • addOrderedChildrenTo

      protected void addOrderedChildrenTo(List<Expression> children)
      Description copied from class: AbstractExpression
      Adds the children of this AbstractExpression to the given list.
      Overrides:
      addOrderedChildrenTo in class AbstractExpression
      Parameters:
      children - The list used to store the string representation of this AbstractExpression
    • buildWhenCollectionExpression

      public CollectionExpression buildWhenCollectionExpression()
      Creates a new CollectionExpression that will wrap the single WHEN expression.
      Returns:
      The single WHEN expression represented by a temporary collection
    • findQueryBNF

      public JPQLQueryBNF findQueryBNF(Expression expression)
      Description copied from interface: Expression
      Retrieves the JPQLQueryBNF that represents the fragment of this Expression that was used when parsing the given Expression.
      Specified by:
      findQueryBNF in interface Expression
      Overrides:
      findQueryBNF in class AbstractExpression
      Parameters:
      expression - The Expression that is a descendant of this one
      Returns:
      The JPQLQueryBNF that was used to parse the given expression
    • getActualThenIdentifier

      public String getActualThenIdentifier()
      Returns the actual THEN found in the string representation of the JPQL query, which has the actual case that was used.
      Returns:
      The THEN identifier that was actually parsed, or an empty string if it was not parsed
    • getActualWhenIdentifier

      public String getActualWhenIdentifier()
      Returns the actual WHEN found in the string representation of the JPQL query, which has the actual case that was used.
      Returns:
      The WHEN identifier that was actually parsed
    • getQueryBNF

      public JPQLQueryBNF getQueryBNF()
      Description copied from interface: Expression
      Returns the BNF of this Expression.
      Returns:
      The JPQLQueryBNF, which represents the grammar of this Expression
    • getThenExpression

      public AbstractExpression getThenExpression()
      Returns the Expression representing the expression following the identifier THEN.
      Returns:
      The expression representing the expression executed if the predicate is true
    • getWhenExpression

      public AbstractExpression getWhenExpression()
      Returns the Expression representing the conditional predicate of the clause.
      Returns:
      The expression following the WHEN identifier
    • hasSpaceAfterThen

      public boolean hasSpaceAfterThen()
      Determines whether a whitespace was parsed after THEN.
      Returns:
      true if there was a whitespace after THEN; false otherwise
    • hasSpaceAfterWhen

      public boolean hasSpaceAfterWhen()
      Determines whether a whitespace was parsed after WHEN.
      Returns:
      true if there was a whitespace after WHEN; false otherwise
    • hasSpaceAfterWhenExpression

      public boolean hasSpaceAfterWhenExpression()
      Determines whether a whitespace was parsed after the conditional expression.
      Returns:
      true if there was a whitespace after the conditional expression; false otherwise
    • hasThen

      public boolean hasThen()
      Determines whether the identifier THEN was part of the query.
      Returns:
      true if the identifier THEN was parsed; false otherwise
    • hasThenExpression

      public boolean hasThenExpression()
      Determines whether the THEN expression of the query was parsed.
      Returns:
      true the THEN expression was parsed; false if nothing was parsed
    • hasWhenExpression

      public boolean hasWhenExpression()
      Determines whether the conditional expression of the query was parsed.
      Returns:
      true the conditional expression was parsed; false if nothing was parsed
    • isParsingComplete

      protected boolean isParsingComplete(WordParser wordParser, String word, Expression expression)
      Description copied from class: AbstractExpression
      Determines whether the parsing is complete based on what is left in the given text. The text is never empty.
      Overrides:
      isParsingComplete in class AbstractExpression
      Parameters:
      wordParser - The text to parse based on the current position of the cursor
      word - The word that was retrieved from the given text, which is the first word in the text
      expression - The Expression that has already been parsed
      Returns:
      true if the text no longer can't be parsed by the current expression; false if more can be parsed
    • parse

      protected void parse(WordParser wordParser, boolean tolerant)
      Description copied from class: AbstractExpression
      Parses the query by starting at the current position, which is part of the given WordParser.
      Specified by:
      parse in class AbstractExpression
      Parameters:
      wordParser - The text to parse based on the current position of the cursor
      tolerant - Determines whether the parsing system should be tolerant, meaning if it should try to parse invalid or incomplete queries
    • toParsedText

      protected void toParsedText(StringBuilder writer, boolean actual)
      Description copied from class: AbstractExpression
      Generates a string representation of this Expression, including its children, if it has any.
      Specified by:
      toParsedText in class AbstractExpression
      Parameters:
      writer - The buffer used to append this Expression's string representation
      actual - Determines whether the string representation should represent what was parsed, i.e. include any "virtual" whitespace (such as ending whitespace) and the actual case of the JPQL identifiers