Package org.apache.calcite.linq4j.tree

Class BlockBuilder

java.lang.Object

org.apache.calcite.linq4j.tree.BlockBuilder

public class BlockBuilder
extends Object

Builder for BlockStatement.

Has methods that help ensure that variable names are unique.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	BlockBuilder.InlineVariableVisitor	Inline Variable Visitor.
private static class	BlockBuilder.Slot	Holds the number of times a declaration was used.
private static class	BlockBuilder.SubstituteVariableVisitor	Substitute Variable Visitor.
private static class	BlockBuilder.UseCounter	Use counter.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) Map<Expression,DeclarationStatement>	expressionForReuse	Contains final-fine-to-reuse-declarations.
private static Shuttle	OPTIMIZE_SHUTTLE
private boolean	optimizing
private BlockBuilder	parent
(package private) List<Statement>	statements
(package private) Set<String>	variables

Constructor Summary

Constructors

Constructor	Description
BlockBuilder()	Creates a non-optimizing BlockBuilder.
BlockBuilder(boolean optimizing)	Creates a BlockBuilder.
BlockBuilder(boolean optimizing, BlockBuilder parent)	Creates a BlockBuilder.

Method Summary

Modifier and Type	Method	Description
void	add(Expression expression)
void	add(Statement statement)
protected void	addExpressionForReuse(DeclarationStatement decl)
Expression	append(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.
Expression	append(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.
Expression	append(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.
Expression	append(String name, Expression expression, boolean optimize)	Appends an expression to a list of statements, optionally optimizing if the expression is used more than once.
BlockBuilder	append(Expression expression)
private Expression	append_(String name, Expression expression, boolean optimize)
Expression	appendIfNotNull(String name, Expression expression)	Appends an expression to a list of statements, if it is not null.
void	clear()	Clears this BlockBuilder.
protected Shuttle	createFinishingOptimizeShuttle()	Creates a final optimization shuttle.
protected Shuttle	createOptimizeShuttle()	Creates a shuttle that will be used during block optimization.
DeclarationStatement	getComputedExpression(Expression expr)	Returns the reference to ParameterExpression if given expression was already computed and stored to local variable
boolean	hasVariable(String name)
private boolean	isCostly(DeclarationStatement decl)
protected boolean	isSafeForReuse(DeclarationStatement decl)
protected boolean	isSimpleExpression(Expression expr)	Checks if expression is simple enough to always inline at zero cost.
String	newName(String suggestion)	Creates a name for a new variable, unique within this block.
private String	newName(String suggestion, boolean optimize)	Creates a name for a new variable, unique within this block, controlling whether the variable can be inlined later.
private Expression	normalizeDeclaration(DeclarationStatement decl)	Prepares declaration for inlining: adds cast
private boolean	optimize(Shuttle optimizer, boolean performInline)	Optimizes the list of statements.
BlockStatement	toBlock()	Returns a block consisting of the current list of statements.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

statements

final List<Statement> statements

variables

final Set<String> variables

expressionForReuse

final 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

parent

private final BlockBuilder parent

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(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(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(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(String name,
                                  Expression expression)

Appends an expression to a list of statements, if it is not null.

append

public Expression append(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_(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

isSafeForReuse

protected boolean isSafeForReuse(DeclarationStatement decl)

addExpressionForReuse

protected void addExpressionForReuse(DeclarationStatement decl)

isCostly

private boolean isCostly(DeclarationStatement decl)

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 String newName(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 String newName(String suggestion)

Creates a name for a new variable, unique within this block.

hasVariable

public boolean hasVariable(String name)

append

public BlockBuilder append(Expression expression)