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Java > Open Source Codes > org > quilt > cl > ControlFlowGraph


1 /* ControlFlowGraph.java */
2 package org.quilt.cl;
3
4 import java.util.HashMap JavaDoc;
5 import java.util.Map JavaDoc;
6 import org.apache.bcel.generic.InstructionList;
7 import org.quilt.graph.*;
8
9 /**
10  * Directed graph extended for use in analyzing method instruction
11  * lists.
12  *
13  * @author <a HREF="jddixon@users.sourceforge.net">Jim Dixon</a>
14  */
15 public class ControlFlowGraph extends Directed {
16
17     /** Key code vertex, value handle on first instruction. */
18     protected Map JavaDoc startHandles = null;
19     /** Key code vertex, value handle on last instruction. */
20     protected Map JavaDoc endHandles = null;
21     /** Key source vertex, value target vertex where connecting
22      * instruction is GotoInstruction. */
23     protected Map JavaDoc gotoFixMeUps = null;
24     /** Instruction list built in walking the graph. */
25     protected InstructionList ilist = null;
26    
27     /** Get a reference to the map of handles on first instructions. */
28     public Map JavaDoc getStartHandles() {
29         return startHandles;
30     }
31     /** Get a reference to the map of handles on last instructions. */
32     public Map JavaDoc getEndHandles() {
33         return endHandles;
34     }
35     /** Get a reference to the source/target vertex map where the
36      * connecting instruction is a GotoInstruction. */
37     public Map JavaDoc getGotoFixMeUps() {
38         return gotoFixMeUps;
39     }
40     /** Get a reference to the instruction list built while walking the
41      * graph. */
42     public InstructionList getInstructionList() {
43         return ilist;
44     }
45
46     /** Create a new top level control flow graph. */
47     public ControlFlowGraph () {
48         super();
49         startHandles = new HashMap JavaDoc();
50         endHandles = new HashMap JavaDoc();
51         gotoFixMeUps = new HashMap JavaDoc();
52         ilist = new InstructionList();
53     }
54     /**
55      * Create a control flow graph without connecting it to this
56      * parent graph but sharing protected data structures.
57      * @param parent The cfg one level up.
58      */
59     protected ControlFlowGraph( ControlFlowGraph parent) {
60         super(parent);
61         startHandles = parent.startHandles;
62         endHandles = parent.endHandles;
63         gotoFixMeUps = parent.gotoFixMeUps;
64         ilist = parent.ilist;
65     }
66     /**
67      * Create a control flow graph, connecting it to this graph as
68      * its parent by inserting it along the directed edge e (the
69      * Entry first, followed by the subgraph Exit.
70      *
71      * @param e Edge along which the subgraph is to be inserted.
72      * @param n Number of extra edges on the ComplexConnector in
73      * the subgraph's Entry vertex (must be at least 1).
74      */
75     public Directed subgraph (final Edge e, final int n) {
76         return super.connectSubgraph( new ControlFlowGraph(this), e, n);
77     }
78
79     /**
80      * Insert a code vertex along an edge, retargeting the edge to
81      * the vertex inserted. The vertex is created by this method.
82      *
83      * @param e Edge along which the vertex is inserted.
84      * @return The CodeVertex created.
85      */
86     public CodeVertex insertCodeVertex (Edge e) {
87         return (CodeVertex) super.insertVertex ( new CodeVertex(this), e);
88     }
89
90     /**
91      * Insert a pre-existing CodeVertex along an edge. The edge
92      * and the vertex must be in the same graph.
93      *
94      * @param v CodeVertex being inserted.
95      * @param e Edge in which it is to be inserted.
96      */
97     public CodeVertex insertCodeVertex (CodeVertex v, Edge e) {
98         return (CodeVertex) super.insertVertex (v, e);
99     }
100 }
101
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