Package org.apache.openjpa.kernel.exps

Class AbstractExpressionBuilder

  • Direct Known Subclasses:
    JPQLExpressionBuilder
    public abstract class AbstractExpressionBuilder
extends Object
    Abstract base class to help build expressions. Provides generic language-independent support for variable resolution, path traversal, and error messages.
    Author:
    Marc Prud'hommeaux

    • Constructor Detail

      • AbstractExpressionBuilder

        public AbstractExpressionBuilder​(ExpressionFactory factory,
                                 Resolver resolver)
        Constructor.
        Parameters:
        factory - the expression factory to use
        resolver - used to resolve variables, parameters, and class names used in the query

    • Method Detail

      • getClassLoader

        protected abstract ClassLoader getClassLoader()
        Returns the class loader that should be used for resolving class names (in addition to the resolver in the query).

      • addAccessPath

        protected ClassMetaData addAccessPath​(ClassMetaData meta)
        Register the specified metadata as being in the query's access path.

      • getAccessPath

        protected ClassMetaData[] getAccessPath()
        Return the recorded query access path.

      • isBound

        protected boolean isBound​(Value var)
        Return true if the given variable has been bound.

      • bind

        protected void bind​(Value var)
        Record that the given variable is bound.

      • getVariable

        protected Value getVariable​(String id,
                            boolean bind)
        Returns a value for the given id.

      • createVariable

        protected Value createVariable​(String id,
                               boolean bind)

      • assertUnboundVariablesValid

        protected void assertUnboundVariablesValid()
        Validate that all unbound variables are of a PC type. If not, assume that the user actually made a typo that we took for an implicit unbound variable.

      • isDeclaredVariable

        protected abstract boolean isDeclaredVariable​(String id)
        Returns whether the specified variable name has been explicitly declared. Note all query languages necessarily support declaring variables.
        Parameters:
        id - the variable to check
        Returns:
        true if the variabe has been explicitely declared

      • isSeenVariable

        protected boolean isSeenVariable​(String id)
        Return whether the given id has been used as a variable.

      • getMetaData

        protected ClassMetaData getMetaData​(Class<?> c,
                                    boolean required)
        Convenience method to get metadata for the given type.

      • getMetaData

        protected ClassMetaData getMetaData​(Class<?> c,
                                    boolean required,
                                    ClassLoader loader)
        Convenience method to get metadata for the given type.

      • traversePath

        protected Value traversePath​(Path path,
                             String field)
        Traverse the given field in the given path.

      • traverseXPath

        protected Value traverseXPath​(Path path,
                              String field)

      • traversePath

        protected Value traversePath​(Path path,
                             String field,
                             boolean pcOnly,
                             boolean allowNull)
        Traverse the given field in the given path.

      • traverseStaticField

        protected Object traverseStaticField​(Class<?> cls,
                                     String field)
        Return a constant containing the value of the given static field.

      • getDeclaredVariableType

        protected abstract Class<?> getDeclaredVariableType​(String name)
        Returns the type of the named variable if it has been declared.

      • setImplicitTypes

        protected void setImplicitTypes​(Value val1,
                                Value val2,
                                Class<?> expected)
        Set the implicit types of the given values based on the fact that they're used together, and based on the operator type.

      • setImplicitTypes

        protected static void setImplicitTypes​(Value val1,
                                       Value val2,
                                       Class<?> expected,
                                       Resolver resolver)

      • convertTypes

        public static void convertTypes​(Value val1,
                                Value val2)
        Perform conversions to make values compatible.

      • convertTypesQuotedNumbers

        public static void convertTypesQuotedNumbers​(Value val1,
                                             Value val2)
        Perform conversions to make values compatible.

      • isNumeric

        public static boolean isNumeric​(Class<?> type)
        Return true if given class can be used as a number.

      • setImplicitContainsTypes

        protected void setImplicitContainsTypes​(Value val1,
                                        Value val2,
                                        int op)
        Set the implicit types of the given values based on the fact that the first is supposed to contain the second.

      • setImplicitType

        protected static void setImplicitType​(Value val,
                                      Class<?> expected)
        Set the implicit type of the given value to the given class.

      • getLocalizer

        protected abstract Localizer getLocalizer()
        Used for obtaining the Localizer to use for translating error messages.

      • currentQuery

        protected abstract String currentQuery()
        Returns the current string being parsed; used for error messages.

      • addSchemaToContext

        protected abstract void addSchemaToContext​(String alias,
                                           ClassMetaData meta)
        Register the schema alias to the current JPQL query context.

      • addVariableToContext

        protected abstract void addVariableToContext​(String id,
                                             Value var)
        Register the variable associated with the schema alias (id) to the current JPQL query context.

      • getVariable

        protected abstract Value getVariable​(String id)
        Returns the variable associated with the schema alias (id).