net.hydromatic.linq4j.expressions

Class BlockBuilder

java.lang.Object

net.hydromatic.linq4j.expressions.BlockBuilder

public class BlockBuilder
extends Object

Builder for BlockStatement.

Has methods that help ensure that variable names are unique.

Constructor Summary

Constructors

Constructor and 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 and Description
void	add(Expression expression)
void	add(Statement statement)
protected void	addExpresisonForReuse(DeclarationStatement decl)
BlockBuilder	append(Expression expression)
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.
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 Visitor	createFinishingOptimizeVisitor() Creates a final optimization visitor.
protected Visitor	createOptimizeVisitor() Creates a visitor 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)
protected boolean	isSafeForReuse(DeclarationStatement decl)
protected boolean	isSimpleExpression(Expression expr) Checks if experssion is simple enough for always inline
String	newName(String suggestion) Creates a name for a new variable, unique within this block.
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

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.

isSimpleExpression

protected boolean isSimpleExpression(Expression expr)

Checks if experssion is simple enough for always inline

Parameters:

expr - expression to test

Returns:

true when given expression is safe to always inline

isSafeForReuse

protected boolean isSafeForReuse(DeclarationStatement decl)

addExpresisonForReuse

protected void addExpresisonForReuse(DeclarationStatement decl)

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.

createOptimizeVisitor

protected Visitor createOptimizeVisitor()

Creates a visitor that will be used during block optimization. Subclasses might provide more specific optimizations (e.g. partial evaluation).

Returns:

visitor used to optimize the statements when converting to block

createFinishingOptimizeVisitor

protected Visitor createFinishingOptimizeVisitor()

Creates a final optimization visitor. Typically, the visitor will factor out constant expressions.

Returns:

visitor that is used to finalize the optimization

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)