polyglot.visit
Class CFGBuilder

java.lang.Object
  polyglot.visit.CFGBuilder

All Implemented Interfaces:

java.lang.Cloneable, Copy

public class CFGBuilder
extends java.lang.Object
implements Copy

Class used to construct a CFG.

Nested Class Summary

protected static class

CFGBuilder.EdgeKeyTermPair

Field Summary

protected DataFlow	df The data flow analysis for which we are constructing the graph.
protected boolean	errorEdgesToExitNode True if we should add edges for uncaught Errors to the exit node of the graph.
protected FlowGraph	graph The flowgraph under construction.
protected Stmt	innermostTarget The innermost loop or try-block in lexical scope.
protected CFGBuilder	outer The outer CFGBuilder.
protected java.util.List	path_to_finally List of terms on the path to the innermost finally block.
protected boolean	skipInnermostCatches True if we should skip the catch blocks for the innermost try when building edges for an exception throw.
protected TypeSystem	ts The type system.

Constructor Summary

CFGBuilder(TypeSystem ts, FlowGraph graph, DataFlow df)

Method Summary

java.lang.Object	copy() Copy the CFGBuilder.
void	edge(CFGBuilder p_visitor, Term p, Term q, FlowGraph.EdgeKey edgeKey)
void	edge(Term p, Term q) Add an edge to the CFG from p to q.
void	edge(Term p, Term q, FlowGraph.EdgeKey edgeKey) Add an edge to the CFG from p to q.
protected CFGBuilder	enterFinally(Term from) Enter a finally block.
CFGBuilder	push(Stmt n) Construct a new CFGBuilder with the a new innermost loop or try-block n.
CFGBuilder	push(Stmt n, boolean skipInnermostCatches) Construct a new CFGBuilder with the a new innermost loop or try-block n, optionally skipping innermost catch blocks.
protected static CFGBuilder	tryFinally(CFGBuilder v, Term last, CFGBuilder last_visitor, Block finallyBlock) Create edges for the finally block of a try-finally construct.
TypeSystem	typeSystem() Get the type system.
void	visitBranchTarget(Branch b) Visit edges from a branch.
void	visitCFG(Term a, FlowGraph.EdgeKey edgeKey, java.util.List succ) Create edges from node a to all successors succ with the EdgeKey edgeKey for all edges created.
void	visitCFG(Term a, FlowGraph.EdgeKey edgeKey, Term succ) Create an edge for a node a with a single successor succ, and EdgeKey edgeKey
void	visitCFG(Term a, FlowGraph.EdgeKey edgeKey1, Term succ1, FlowGraph.EdgeKey edgeKey2, Term succ2) Create edges from node a to successors succ1 and succ2 with EdgeKeys edgeKey1 and edgeKey2 respecitvely.
protected void	visitCFG(Term a, java.util.List succs) Create edges for a node a with successors succs.
void	visitCFG(Term a, Term succ) Create an edge for a node a with a single successor succ.
void	visitCFGList(java.util.List elements, Term after) Utility function to visit all edges in a list.
void	visitGraph() Visit the AST, constructing the CFG.
void	visitReturn(Return r) Visit edges for a return statement.
void	visitThrow(Term a)
void	visitThrow(Term t, Type type) Create edges for an exception thrown from term t.

Methods inherited from class java.lang.Object

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

Field Detail

graph

protected FlowGraph graph

The flowgraph under construction.

ts

protected TypeSystem ts

The type system.

outer

protected CFGBuilder outer

The outer CFGBuilder. We create a new inner CFGBuilder when entering a loop or try-block and when entering a finally block.

innermostTarget

protected Stmt innermostTarget

The innermost loop or try-block in lexical scope. We maintain a stack of loops and try-blocks in order to add edges for break and continue statements and for exception throws. When such a jump is encountered we traverse the stack, searching for the target of the jump.

path_to_finally

protected java.util.List path_to_finally

List of terms on the path to the innermost finally block. If we are constructing a CFG for a finally block, this is the sequence of terms that caused entry into this and lexically enclosing finally blocks. We construct a unique subgraph for each such path. The list is empty if this CFGBuilder is not constructing the CFG for a finally block.

df

protected DataFlow df

The data flow analysis for which we are constructing the graph.

skipInnermostCatches

protected boolean skipInnermostCatches

True if we should skip the catch blocks for the innermost try when building edges for an exception throw.

errorEdgesToExitNode

protected boolean errorEdgesToExitNode

True if we should add edges for uncaught Errors to the exit node of the graph. By default, we do not, but subclasses can change this behavior if needed.

Constructor Detail

CFGBuilder

public CFGBuilder(TypeSystem ts,
                  FlowGraph graph,
                  DataFlow df)

Method Detail

typeSystem

public TypeSystem typeSystem()

Get the type system.

copy

public java.lang.Object copy()

Copy the CFGBuilder.

Specified by:

copy in interface Copy

push

public CFGBuilder push(Stmt n)

Construct a new CFGBuilder with the a new innermost loop or try-block n.

push

public CFGBuilder push(Stmt n,
                       boolean skipInnermostCatches)

Construct a new CFGBuilder with the a new innermost loop or try-block n, optionally skipping innermost catch blocks.

visitBranchTarget

public void visitBranchTarget(Branch b)

Visit edges from a branch. Simulate breaking/continuing out of the loop, visiting any finally blocks encountered.

visitReturn

public void visitReturn(Return r)

Visit edges for a return statement. Simulate the return, visiting any finally blocks encountered.

visitGraph

public void visitGraph()

Visit the AST, constructing the CFG.

visitCFGList

public void visitCFGList(java.util.List elements,
                         Term after)

Utility function to visit all edges in a list.

visitCFG

public void visitCFG(Term a,
                     Term succ)

Create an edge for a node a with a single successor succ. The EdgeKey used for the edge from a to succ will be FlowGraph.EDGE_KEY_OTHER

visitCFG

public void visitCFG(Term a,
                     FlowGraph.EdgeKey edgeKey,
                     Term succ)

Create an edge for a node a with a single successor succ, and EdgeKey edgeKey

visitCFG

public void visitCFG(Term a,
                     FlowGraph.EdgeKey edgeKey1,
                     Term succ1,
                     FlowGraph.EdgeKey edgeKey2,
                     Term succ2)

Create edges from node a to successors succ1 and succ2 with EdgeKeys edgeKey1 and edgeKey2 respecitvely.

visitCFG

public void visitCFG(Term a,
                     FlowGraph.EdgeKey edgeKey,
                     java.util.List succ)

Create edges from node a to all successors succ with the EdgeKey edgeKey for all edges created.

visitCFG

protected void visitCFG(Term a,
                        java.util.List succs)

Create edges for a node a with successors succs.

Parameters:

a - the source node for the edges.

succs - a list of EdgeKeyTermPairs

visitThrow

public void visitThrow(Term a)

visitThrow

public void visitThrow(Term t,
                       Type type)

Create edges for an exception thrown from term t.

tryFinally

protected static CFGBuilder tryFinally(CFGBuilder v,
                                       Term last,
                                       CFGBuilder last_visitor,
                                       Block finallyBlock)

Create edges for the finally block of a try-finally construct.

Parameters:

v - v.innermostTarget is the Try term that the finallyBlock is assoicated with. @@@XXX

last - the last term visited before the finally block is entered.

last_visitor - @@@XXX

finallyBlock - the finally block associated with a try finally block.

enterFinally

protected CFGBuilder enterFinally(Term from)

Enter a finally block. This method returns a new CFGBuilder with the path_to_finally field pointing to a list that has the Term from appended.

edge

public void edge(Term p,
                 Term q)

Add an edge to the CFG from p to q.

edge

public void edge(Term p,
                 Term q,
                 FlowGraph.EdgeKey edgeKey)

Add an edge to the CFG from p to q.

edge

public void edge(CFGBuilder p_visitor,
                 Term p,
                 Term q,
                 FlowGraph.EdgeKey edgeKey)

Parameters:

p_visitor - The visitor used to create p ("this" is the visitor that created q)

p - The predecessor node in the forward graph

q - The successor node in the forward graph