Package org.apache.calcite.linq4j.tree

Class BlockBuilder

  • public class BlockBuilder
extends java.lang.Object
    Builder for BlockStatement.

    Has methods that help ensure that variable names are unique.

    • Field Detail

      • statements

        final java.util.List<Statement> statements

      • variables

        final java.util.Set<java.lang.String> variables

      • expressionForReuse

        final java.util.Map<Expression,​DeclarationStatement> expressionForReuse
        Contains final-fine-to-reuse-declarations. An entry to this map is added when adding final declaration of a statement with optimize=true parameter.

      • optimizing

        private final boolean optimizing

      • OPTIMIZE_SHUTTLE

        private static final Shuttle OPTIMIZE_SHUTTLE

    • Constructor Detail

      • BlockBuilder

        public BlockBuilder()
        Creates a non-optimizing BlockBuilder.

      • BlockBuilder

        public BlockBuilder​(boolean optimizing)
        Creates a BlockBuilder.
        Parameters:
        optimizing - Whether to eliminate common sub-expressions

      • BlockBuilder

        public BlockBuilder​(boolean optimizing,
                    BlockBuilder parent)
        Creates a BlockBuilder.
        Parameters:
        optimizing - Whether to eliminate common sub-expressions

    • Method Detail

      • clear

        public void clear()
        Clears this BlockBuilder.

      • append

        public Expression append​(java.lang.String name,
                         BlockStatement block)
        Appends a block to a list of statements and returns an expression (possibly a variable) that represents the result of the newly added block.

      • append

        public Expression append​(java.lang.String name,
                         BlockStatement block,
                         boolean optimize)
        Appends an expression to a list of statements, optionally optimizing it to a variable if it is used more than once.
        Parameters:
        name - Suggested variable name
        block - Expression
        optimize - Whether to try to optimize by assigning the expression to a variable. Do not do this if the expression has side-effects or a time-dependent value.

      • append

        public Expression append​(java.lang.String name,
                         Expression expression)
        Appends an expression to a list of statements, and returns an expression (possibly a variable) that represents the result of the newly added block.

      • appendIfNotNull

        public Expression appendIfNotNull​(java.lang.String name,
                                  Expression expression)
        Appends an expression to a list of statements, if it is not null.

      • append

        public Expression append​(java.lang.String name,
                         Expression expression,
                         boolean optimize)
        Appends an expression to a list of statements, optionally optimizing if the expression is used more than once.

      • append_

        private Expression append_​(java.lang.String name,
                           Expression expression,
                           boolean optimize)

      • isSimpleExpression

        protected boolean isSimpleExpression​(Expression expr)
        Checks if expression is simple enough to always inline at zero cost.
        Parameters:
        expr - expression to test
        Returns:
        true when given expression is safe to always inline

      • normalizeDeclaration

        private Expression normalizeDeclaration​(DeclarationStatement decl)
        Prepares declaration for inlining: adds cast
        Parameters:
        decl - inlining candidate
        Returns:
        normalized expression

      • getComputedExpression

        public DeclarationStatement getComputedExpression​(Expression expr)
        Returns the reference to ParameterExpression if given expression was already computed and stored to local variable
        Parameters:
        expr - expression to test
        Returns:
        existing ParameterExpression or null

      • add

        public void add​(Statement statement)

      • add

        public void add​(Expression expression)

      • toBlock

        public BlockStatement toBlock()
        Returns a block consisting of the current list of statements.

      • optimize

        private boolean optimize​(Shuttle optimizer,
                         boolean performInline)
        Optimizes the list of statements. If an expression is used only once, it is inlined.
        Returns:
        whether any optimizations were made

      • createOptimizeShuttle

        protected Shuttle createOptimizeShuttle()
        Creates a shuttle that will be used during block optimization. Sub-classes might provide more specific optimizations (e.g. partial evaluation).
        Returns:
        shuttle used to optimize the statements when converting to block

      • createFinishingOptimizeShuttle

        protected Shuttle createFinishingOptimizeShuttle()
        Creates a final optimization shuttle. Typically, the visitor will factor out constant expressions.
        Returns:
        shuttle that is used to finalize the optimization

      • newName

        private java.lang.String newName​(java.lang.String suggestion,
                                 boolean optimize)
        Creates a name for a new variable, unique within this block, controlling whether the variable can be inlined later.

      • newName

        public java.lang.String newName​(java.lang.String suggestion)
        Creates a name for a new variable, unique within this block.

      • hasVariable

        public boolean hasVariable​(java.lang.String name)