com.google.javascript.jscomp

Class MaybeReachingVariableUse

java.lang.Object

com.google.javascript.jscomp.DataFlowAnalysis<Node,MaybeReachingVariableUse.ReachingUses>

com.google.javascript.jscomp.MaybeReachingVariableUse

class MaybeReachingVariableUse
extends DataFlowAnalysis<Node,MaybeReachingVariableUse.ReachingUses>

Computes "may be" reaching use for all definitions of each variables. A use of A in alert(A) is a "may be" reaching use of the definition of A at A = foo() if at least one path from the use node reaches that definition and it is the last definition before the use on that path.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	MaybeReachingVariableUse.ReachingUses May use definition lattice representation.
private static class	MaybeReachingVariableUse.ReachingUsesJoinOp The join is a simple union because of the "may be" nature of the analysis.

Nested classes/interfaces inherited from class com.google.javascript.jscomp.DataFlowAnalysis

DataFlowAnalysis.BranchedFlowState<L extends LatticeElement>, DataFlowAnalysis.BranchedForwardDataFlowAnalysis<N,L extends LatticeElement>, DataFlowAnalysis.FlowState<L extends LatticeElement>, DataFlowAnalysis.MaxIterationsExceededException

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.Set<Var>	escaped
private Scope	jsScope

Fields inherited from class com.google.javascript.jscomp.DataFlowAnalysis

joinOp, MAX_STEPS, orderedWorkSet

Constructor Summary

Constructors

Constructor and Description
MaybeReachingVariableUse(ControlFlowGraph<Node> cfg, Scope jsScope, AbstractCompiler compiler)

Method Summary

Modifier and Type	Method and Description
private void	addToUseIfLocal(java.lang.String name, Node node, MaybeReachingVariableUse.ReachingUses use) Sets the variable for the given name to the node value in the upward exposed lattice.
private void	computeMayUse(Node n, Node cfgNode, MaybeReachingVariableUse.ReachingUses output, boolean conditional)
(package private) MaybeReachingVariableUse.ReachingUses	createEntryLattice() Gets the incoming state of the entry node.
(package private) MaybeReachingVariableUse.ReachingUses	createInitialEstimateLattice() Gets the state of the initial estimation at each node.
(package private) MaybeReachingVariableUse.ReachingUses	flowThrough(Node n, MaybeReachingVariableUse.ReachingUses input) Computes the output state for a given node and input state.
(package private) java.util.Collection<Node>	getUses(java.lang.String name, Node defNode) Gets a list of nodes that may be using the value assigned to name in defNode.
private boolean	hasExceptionHandler(Node cfgNode)
(package private) boolean	isForward() Checks whether the analysis is a forward flow analysis or backward flow analysis.
private void	removeFromUseIfLocal(java.lang.String name, MaybeReachingVariableUse.ReachingUses use) Removes the variable for the given name from the node value in the upward exposed lattice.

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

analyze, analyze, computeEscaped, flow, getCfg, getExitLatticeElement, initialize, join, joinInputs

Methods inherited from class java.lang.Object

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

Field Detail

jsScope

private final Scope jsScope

escaped

private final java.util.Set<Var> escaped

Constructor Detail

MaybeReachingVariableUse

MaybeReachingVariableUse(ControlFlowGraph<Node> cfg,
                         Scope jsScope,
                         AbstractCompiler compiler)

Method Detail

isForward

boolean isForward()

Description copied from class: DataFlowAnalysis

Checks whether the analysis is a forward flow analysis or backward flow analysis.

Specified by:

isForward in class DataFlowAnalysis<Node,MaybeReachingVariableUse.ReachingUses>

Returns:

true if it is a forward analysis.

createEntryLattice

MaybeReachingVariableUse.ReachingUses createEntryLattice()

Description copied from class: DataFlowAnalysis

Gets the incoming state of the entry node.

Specified by:

createEntryLattice in class DataFlowAnalysis<Node,MaybeReachingVariableUse.ReachingUses>

Returns:

Entry state.

createInitialEstimateLattice

MaybeReachingVariableUse.ReachingUses createInitialEstimateLattice()

Description copied from class: DataFlowAnalysis

Gets the state of the initial estimation at each node.

Specified by:

createInitialEstimateLattice in class DataFlowAnalysis<Node,MaybeReachingVariableUse.ReachingUses>

Returns:

Initial state.

flowThrough

MaybeReachingVariableUse.ReachingUses flowThrough(Node n,
                                                  MaybeReachingVariableUse.ReachingUses input)

Description copied from class: DataFlowAnalysis

Computes the output state for a given node and input state.

Specified by:

flowThrough in class DataFlowAnalysis<Node,MaybeReachingVariableUse.ReachingUses>

Parameters:

n - The node.

input - Input lattice that should be read-only.

Returns:

Output lattice.

hasExceptionHandler

private boolean hasExceptionHandler(Node cfgNode)

computeMayUse

private void computeMayUse(Node n,
                           Node cfgNode,
                           MaybeReachingVariableUse.ReachingUses output,
                           boolean conditional)

addToUseIfLocal

private void addToUseIfLocal(java.lang.String name,
                             Node node,
                             MaybeReachingVariableUse.ReachingUses use)

Sets the variable for the given name to the node value in the upward exposed lattice. Do nothing if the variable name is one of the escaped variable.

removeFromUseIfLocal

private void removeFromUseIfLocal(java.lang.String name,
                                  MaybeReachingVariableUse.ReachingUses use)

Removes the variable for the given name from the node value in the upward exposed lattice. Do nothing if the variable name is one of the escaped variable.

getUses

java.util.Collection<Node> getUses(java.lang.String name,
                                   Node defNode)

Gets a list of nodes that may be using the value assigned to name in defNode. defNode must be one of the control flow graph nodes.

Parameters:

name - name of the variable. It can only be names of local variable that are not function parameters, escaped variables or variables declared in catch.

defNode - The list of upward exposed use for the variable.