Package org.apache.calcite.rex

Provides a language for representing row-expressions.

See: Description

Interface Summary

Interface	Description
RexAction	A RexAction is called when a RexPattern finds a match.
RexBiVisitor<R,P>	Visitor pattern for traversing a tree of RexNode objects and passing a payload to each.
RexExecutor	Can reduce expressions, writing a literal for each into a list.
RexPattern	A RexPattern represents an expression with holes in it.
RexSimplify.Predicate	Marker interface for predicates (expressions that evaluate to BOOLEAN).
RexSqlConvertlet	Converts a RexNode expression into a SqlNode expression.
RexSqlConvertletTable	Collection of RexSqlConvertlets.
RexToSqlNodeConverter	Converts expressions from RexNode to SqlNode.
RexVisitor<R>	Visitor pattern for traversing a tree of RexNode objects.

Class Summary

Class	Description
LogicVisitor	Visitor pattern for traversing a tree of RexNode objects.
RexAnalyzer	Analyzes an expression, figures out what are the unbound variables, assigns a variety of values to each unbound variable, and evaluates the expression.
RexAnalyzer.VariableCollector	Collects the variables (or other bindable sites) in an expression, and counts features (such as CAST) that RexInterpreter cannot handle.
RexBuilder	Factory for row expressions.
RexCall	An expression formed by a call to an operator with zero or more expressions as operands.
RexCallBinding	RexCallBinding implements SqlOperatorBinding by referring to an underlying collection of RexNode operands.
RexCallBinding.RexCastCallBinding	To be compatible with SqlCall, CAST needs to pretend that it has two arguments, the second of which is the target type.
RexChecker	Visitor which checks the validity of a RexNode expression.
RexCopier	Shuttle which creates a deep copy of a Rex expression.
RexCorrelVariable	Reference to the current row of a correlating relational expression.
RexDynamicParam	Dynamic parameter reference in a row-expression.
RexExecutable	Result of compiling code generated from a RexNode expression.
RexExecutorImpl	Evaluates a RexNode expression.
RexExecutorImpl.DataContextInputGetter	Implementation of RexToLixTranslator.InputGetter that reads the values of input fields by calling DataContext.get(java.lang.String)("inputRecord").
RexFieldAccess	Access to a field of a row-expression.
RexFieldCollation	Expression combined with sort flags (DESCENDING, NULLS LAST).
RexFieldCollation.Initializer	Helper, used during initialization, that builds a canonizing map from sets of SqlKind to immutable sets of SqlKind.
RexInputRef	Variable which references a field of an input relational expression.
RexInterpreter	Evaluates RexNode expressions.
RexLiteral	Constant value in a row-expression.
RexLocalRef	Local variable.
RexMultisetUtil	Utility class for various methods related to multisets.
RexMultisetUtil.RexCallMultisetOperatorCounter	A RexShuttle that traverse all RexNode and counts total number of RexCalls traversed and number of multiset calls traversed.
RexNode	Row expression.
RexOver	Call to an aggregate function over a window.
RexOver.Finder	Visitor which detects a RexOver inside a RexNode expression.
RexPatternFieldRef	Variable which references a field of an input relational expression
RexPermutationShuttle	Visitor which replaces RexLocalRef objects after the expressions in a RexProgram have been reordered.
RexPermuteInputsShuttle	Shuttle which applies a permutation to its input fields.
RexProgram	A collection of expressions which read inputs, compute output expressions, and optionally use a condition to filter rows.
RexProgram.Checker	Visitor which walks over a program and checks validity.
RexProgram.ExpansionShuttle	A RexShuttle used in the implementation of RexProgram.expandLocalRef(org.apache.calcite.rex.RexLocalRef).
RexProgramBuilder	Workspace for constructing a RexProgram.
RexRangeRef	Reference to a range of columns.
RexShuttle	Passes over a row-expression, calling a handler method for each node, appropriate to the type of the node.
RexSimplify	Context required to simplify a row-expression.
RexSimplify.CaseBranch	Object to describe a Case branch
RexSimplify.Comparison	Represents a simple Comparison.
RexSimplify.IsPredicate	Represents an IS Predicate.
RexSlot	Abstract base class for RexInputRef and RexLocalRef.
RexSlot.SelfPopulatingList	Thread-safe list that populates itself if you make a reference beyond the end of the list.
RexSqlReflectiveConvertletTable	Implementation of RexSqlConvertletTable.
RexSqlStandardConvertletTable	Standard implementation of RexSqlConvertletTable.
RexSubQuery	Scalar expression that represents an IN, EXISTS or scalar sub-query.
RexTableInputRef	Variable which references a column of a table occurrence in a relational plan.
RexTableInputRef.RelTableRef	Identifies uniquely a table by its qualified name and its entity number (occurrence)
RexToSqlNodeConverterImpl	Standard implementation of RexToSqlNodeConverter.
RexTransformer	Takes a tree of RexNode objects and transforms it into another in one sense equivalent tree.
RexUtil	Utility methods concerning row-expressions.
RexUtil.CnfHelper	Helps RexUtil.toCnf(org.apache.calcite.rex.RexBuilder, org.apache.calcite.rex.RexNode).
RexUtil.ConstantFinder	Walks over an expression and determines whether it is constant.
RexUtil.CorrelationFinder	Visitor that throws Util.FoundOne if applied to an expression that contains a RexCorrelVariable.
RexUtil.DnfHelper	Helps RexUtil.toDnf(org.apache.calcite.rex.RexBuilder, org.apache.calcite.rex.RexNode).
RexUtil.ExpressionNormalizer	Walks over expressions and builds a bank of common sub-expressions.
RexUtil.ExprSimplifier	Deprecated
RexUtil.FieldAccessFinder	Visitor which builds a bitmap of the inputs used by an expression.
RexUtil.FixNullabilityShuttle	Shuttle that fixes up an expression to match changes in nullability of input fields.
RexUtil.ForwardRefFinder	Walks over an expression and throws an exception if it finds an RexInputRef with an ordinal beyond the number of fields in the input row type, or a RexLocalRef with ordinal greater than that set using RexUtil.ForwardRefFinder.setLimit(int).
RexUtil.RexShiftShuttle	Shuttle that adds offset to each RexInputRef in an expression.
RexUtil.SubQueryFinder	Visitor that throws Util.FoundOne if applied to an expression that contains a RexSubQuery.
RexVariable	A row-expression which references a field.
RexVisitorImpl<R>	Default implementation of RexVisitor, which visits each node but does nothing while it's there.
RexWindow	Specification of the window of rows over which a RexOver windowed aggregate is evaluated.
RexWindowBound	Abstracts "XX PRECEDING/FOLLOWING" and "CURRENT ROW" bounds for windowed aggregates.
RexWindowBound.RexWindowBoundBounded	Implements XX PRECEDING/FOLLOWING bound where XX is not UNBOUNDED.
RexWindowBound.RexWindowBoundCurrentRow	Implements CURRENT ROW bound.
RexWindowBound.RexWindowBoundUnbounded	Implements UNBOUNDED PRECEDING/FOLLOWING bound.

Enum Summary

Enum	Description
RexDigestIncludeType	Defines if type information should be printed for RexLiteral.
RexInterpreter.Truthy	An enum that wraps boolean and unknown values and makes them comparable.
RexSimplify.SafeRexVisitor	Decides whether it is safe to flatten the given case part into AND/ORs
RexUnknownAs	Policy for whether a simplified expression may instead return another value.

Exception Summary

Exception	Description
RexOver.OverFound	Exception thrown when an OVER is found.
RexUtil.CnfHelper.OverflowError	Exception to catch when we pass the limit.
RexUtil.ExpressionNormalizer.SubExprExistsException	Thrown if there is a sub-expression.
RexUtil.ForwardRefFinder.IllegalForwardRefException	Thrown to abort a visit when we find an illegal forward reference.

Package org.apache.calcite.rex Description

Provides a language for representing row-expressions.

Life-cycle

A SqlToRelConverter converts a SQL parse tree consisting of SqlNode objects into a relational expression (RelNode). Several kinds of nodes in this tree have row expressions (RexNode).

After the relational expression has been optimized, a JavaRelImplementor converts it into to a plan. If the plan is a Java parse tree, row-expressions are translated into equivalent Java expressions.

Expressions

Every row-expression has a type. (Compare with SqlNode, which is created before validation, and therefore types may not be available.)

Every node in the parse tree is a RexNode. Sub-types are:

• RexLiteral represents a boolean, numeric, string, or date constant, or the value NULL.
• RexVariable represents a leaf of the tree. It has sub-types:
  • RexCorrelVariable is a correlating variable for nested-loop joins
  • RexInputRef refers to a field of an input relational expression
  • RexCall is a call to an operator or function. By means of special operators, we can use this construct to represent virtually every non-leaf node in the tree.
  • RexRangeRef refers to a collection of contiguous fields from an input relational expression. It usually exists only during translation.

Expressions are generally created using a RexBuilder factory.

Related packages

• org.apache.calcite.sql SQL object model
• org.apache.calcite.plan Core classes, including RelDataType and RelDataTypeFactory.