Repair/RepairCompiler/MCC/IR/LogicStatement.java

   1 package MCC.IR;
   2
   3 import java.util.*;
   4
   5 public class LogicStatement {
   6
   7     public static final Operation AND = new Operation("AND");
   8     public static final Operation OR = new Operation("OR");
   9     public static final Operation NOT = new Operation("NOT");
  10
  11     public static class Operation {
  12         private final String name;
  13         private Operation(String opname) { name = opname; }
  14         public String toString() { return name; }
  15     }
  16
  17     Operation op;
  18     LogicStatement left;
  19     LogicStatement right;
  20
  21     public LogicStatement(Operation op, LogicStatement left, LogicStatement right) {
  22         if (op == NOT) {
  23             throw new IllegalArgumentException("Must be a AND or OR expression.");
  24         }
  25
  26         this.op = op;
  27         this.left = left;
  28         this.right = right;
  29     }
  30
  31     public LogicStatement(Operation op, LogicStatement left) {
  32         if (op != NOT) {
  33             throw new IllegalArgumentException("Must be a NOT expression.");
  34         }
  35
  36         this.op = op;
  37         this.left = left;
  38         this.right = null;
  39     }
  40
  41     protected LogicStatement() {
  42         this.op = null;
  43         this.left = null;
  44         this.right = null;
  45     }
  46
  47     public Set getRequiredDescriptors() {
  48         Set v = left.getRequiredDescriptors();
  49         if (right != null) {
  50             v.addAll(right.getRequiredDescriptors());
  51         }
  52         return v;
  53     }
  54
  55     public void generate(CodeWriter writer, VarDescriptor dest) {
  56
  57         writer.outputline("int " + dest.getSafeSymbol() + ";");
  58
  59         if (op == NOT) {
  60
  61             VarDescriptor leftd = VarDescriptor.makeNew("leftboolean");
  62             left.generate(writer, leftd);
  63
  64             writer.outputline("// 3-valued NOT");
  65             writer.outputline("if (!maybe)");
  66             writer.startblock();
  67             writer.outputline(dest.getSafeSymbol() + " =  !" + leftd.getSafeSymbol() + ";");
  68             writer.endblock();
  69
  70         } else { // two operands
  71
  72             VarDescriptor leftd = VarDescriptor.makeNew("leftboolean");
  73             String lm = (VarDescriptor.makeNew("leftmaybe")).getSafeSymbol();
  74             left.generate(writer, leftd);
  75             writer.outputline("int " + lm + " = maybe;");
  76
  77             VarDescriptor rightd = VarDescriptor.makeNew("rightboolean");
  78             String rm = (VarDescriptor.makeNew("rightmaybe")).getSafeSymbol();
  79             assert right != null;
  80             right.generate(writer, rightd);
  81             writer.outputline("int " + rm + " = maybe;");
  82
  83             String l = leftd.getSafeSymbol();
  84             String r = rightd.getSafeSymbol();
  85
  86             if (op == AND) {
  87
  88                 /*
  89                  * 3-value AND LOGIC
  90                  *
  91                  * LRLR
  92                  * MM    M O
  93                  * ----  ---
  94                  * 0000  0 0
  95                  * 0001  0 0
  96                  * 0010  0 0
  97                  * 0011  0 1
  98                  * 0100  0 0
  99                  * 0101  0 0
 100                  * 0110  1 X
 101                  * 0111  1 X
 102                  * 1000  0 0
 103                  * 1001  1 X
 104                  * 1010  0 0
 105                  * 1011  1 X
 106                  * 1100  1 X
 107                  * 1101  1 X
 108                  * 1110  1 X
 109                  * 1111  1 X
 110                  *
 111                  * M = (L*RM) + (R*LM) + (LM*RM)
 112                  * O = (L*R)
 113                  */
 114
 115                 // maybe = (l && rm) || (r && lm) || (lm && rm)
 116                 writer.outputline("maybe = (" + l + " && " + rm + ") || (" + r + " && " + lm + ") || (" + lm + " && " + rm + ");");
 117                 writer.outputline(dest.getSafeSymbol() + " = " + l + " && " + r + ";");
 118
 119             } else if (op == OR) {
 120
 121                 /*
 122                  * 3-value OR LOGIC
 123                  *
 124                  * LRLR
 125                  * MM    M O
 126                  * ----  ---
 127                  * 0000  0 0
 128                  * 0001  0 1
 129                  * 0010  0 1
 130                  * 0011  0 1
 131                  * 0100  1 X
 132                  * 0101  1 X
 133                  * 0110  0 1
 134                  * 0111  0 1
 135                  * 1000  1 X
 136                  * 1001  0 1
 137                  * 1010  1 X
 138                  * 1011  0 1
 139                  * 1100  1 X
 140                  * 1101  1 X
 141                  * 1110  1 X
 142                  * 1111  1 X
 143                  *
 144                  * M = (!L*RM) + (!R*LM) + (LM*RM)
 145                  * O = L+R
 146                  */
 147
 148                 // maybe = (!l && rm) || (!r && lm) || (lm && rm)
 149                 writer.outputline("maybe = (!" + l + " && " + rm + ") || (!" + r + " && " + lm + ") || (" + lm + " && " + rm + ");");
 150                 writer.outputline(dest.getSafeSymbol() + " = " + l + " || " + r + ";");
 151             } else {
 152                 throw new IRException();
 153             }
 154         }
 155     }
 156 }
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