com.google.javascript.jscomp

Class StatementFusion

java.lang.Object

com.google.javascript.jscomp.AbstractPeepholeOptimization

com.google.javascript.jscomp.StatementFusion

class StatementFusion
extends AbstractPeepholeOptimization

Tries to fuse all the statements in a block into a one statement by using COMMAs. Because COMMAs has the lowest precedence, we never need to insert extra () around. Once we have only one statement in a block, we can then eliminate a pair of {}'s. Further more, we can also fold a single statement IF into && or create further opportunities for all the other goodies in PeepholeMinimizeConditions.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	favorsCommaOverSemiColon
static boolean	SHOULD_FAVOR_COMMA_OVER_SEMI_COLON

Constructor Summary

Constructors

Constructor and Description
StatementFusion()
StatementFusion(boolean favorsCommaOverSemiColon)

Method Summary

Modifier and Type	Method and Description
private boolean	canFuseIntoOneStatement(Node block)
private static void	fuseExpressionIntoControlFlowStatement(Node before, Node control)
protected static Node	fuseExpressionIntoExpression(Node exp1, Node exp2)
protected static void	fuseExpresssonIntoFirstChild(Node exp, Node stmt)
protected static void	fuseExpresssonIntoSecondChild(Node exp, Node stmt)
private static Node	fuseIntoOneStatement(Node parent, Node first, Node last) Given a block, fuse a list of statements with comma's.
private boolean	isFusableControlStatement(Node n)
(package private) Node	optimizeSubtree(Node n) Given a node to optimize and a traversal, optimize the node.
(package private) Node	tryFuseStatements(Node n)
(package private) Node	tryFuseStatementsAggressively(Node n)

Methods inherited from class com.google.javascript.jscomp.AbstractPeepholeOptimization

areDeclaredGlobalExternsOnWindow, areNodesEqualForInlining, beginTraversal, endTraversal, getCodingConvention, isASTNormalized, isEcmaScript5OrGreater, mayEffectMutableState, mayHaveSideEffects, nodeTypeMayHaveSideEffects, report, reportCodeChange

Methods inherited from class java.lang.Object

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

Field Detail

SHOULD_FAVOR_COMMA_OVER_SEMI_COLON

public static final boolean SHOULD_FAVOR_COMMA_OVER_SEMI_COLON

See Also:

Constant Field Values

favorsCommaOverSemiColon

private final boolean favorsCommaOverSemiColon

Constructor Detail

StatementFusion

public StatementFusion()

StatementFusion

public StatementFusion(boolean favorsCommaOverSemiColon)

Method Detail

optimizeSubtree

Node optimizeSubtree(Node n)

Description copied from class: AbstractPeepholeOptimization

Given a node to optimize and a traversal, optimize the node. Subclasses should override to provide their own peephole optimization.

Specified by:

optimizeSubtree in class AbstractPeepholeOptimization

Parameters:

n - The subtree that will be optimized.

Returns:

The new version of the subtree (or null if the subtree or one of its parents was removed from the AST). If the subtree has not changed, this method must return subtree.

tryFuseStatements

Node tryFuseStatements(Node n)

tryFuseStatementsAggressively

Node tryFuseStatementsAggressively(Node n)

canFuseIntoOneStatement

private boolean canFuseIntoOneStatement(Node block)

isFusableControlStatement

private boolean isFusableControlStatement(Node n)

fuseIntoOneStatement

private static Node fuseIntoOneStatement(Node parent,
                                         Node first,
                                         Node last)

Given a block, fuse a list of statements with comma's.

Parameters:

parent - The parent that contains the statements.

first - The first statement to fuse (inclusive)

last - The last statement to fuse (exclusive)

Returns:

A single statement that contains all the fused statement as one.

fuseExpressionIntoControlFlowStatement

private static void fuseExpressionIntoControlFlowStatement(Node before,
                                                           Node control)

fuseExpressionIntoExpression

protected static Node fuseExpressionIntoExpression(Node exp1,
                                                   Node exp2)

fuseExpresssonIntoFirstChild

protected static void fuseExpresssonIntoFirstChild(Node exp,
                                                   Node stmt)

fuseExpresssonIntoSecondChild

protected static void fuseExpresssonIntoSecondChild(Node exp,
                                                    Node stmt)