_ Git - BearSSL/blob - T0/SType.cs

   1 using System;
   2
   3 /*
   4  * This structure contains the stack effect of a word: number of stack
   5  * element consumed on input, and number of stack element produced on
   6  * output.
   7  */
   8
   9 struct SType {
  10
  11         /*
  12          * Get number of stack elements consumed on input; this is -1 if
  13          * the stack effect is not known.
  14          */
  15         internal int DataIn {
  16                 get {
  17                         return din;
  18                 }
  19         }
  20
  21         /*
  22          * Get number of stack elements produced on output; this is -1 if
  23          * either the stack effect is not known, or if the word never
  24          * exits.
  25          */
  26         internal int DataOut {
  27                 get {
  28                         return dout;
  29                 }
  30         }
  31
  32         /*
  33          * Tell whether the stack effect is known.
  34          */
  35         internal bool IsKnown {
  36                 get {
  37                         return din >= 0;
  38                 }
  39         }
  40
  41         /*
  42          * Tell whether the stack effect is known and the word never exits.
  43          */
  44         internal bool NoExit {
  45                 get {
  46                         return din >= 0 && dout < 0;
  47                 }
  48         }
  49
  50         int din, dout;
  51
  52         internal SType(int din, int dout)
  53         {
  54                 if (din < 0) {
  55                         din = -1;
  56                 }
  57                 if (dout < 0) {
  58                         dout = -1;
  59                 }
  60                 this.din = din;
  61                 this.dout = dout;
  62         }
  63
  64         /*
  65          * Special value for the unknown stack effect.
  66          */
  67         internal static SType UNKNOWN = new SType(-1, -1);
  68
  69         /*
  70          * Constant for the "blank stack effect".
  71          */
  72         internal static SType BLANK = new SType(0, 0);
  73
  74         public static bool operator ==(SType s1, SType s2)
  75         {
  76                 return s1.din == s2.din && s1.dout == s2.dout;
  77         }
  78
  79         public static bool operator !=(SType s1, SType s2)
  80         {
  81                 return s1.din != s2.din || s1.dout != s2.dout;
  82         }
  83
  84         public override bool Equals(Object obj)
  85         {
  86                 return (obj is SType) && ((SType)obj == this);
  87         }
  88
  89         public override int GetHashCode()
  90         {
  91                 return din * 31 + dout * 17;
  92         }
  93
  94         public override string ToString()
  95         {
  96                 if (!IsKnown) {
  97                         return "UNKNOWN";
  98                 } else if (NoExit) {
  99                         return string.Format("in:{0},noexit", din);
 100                 } else {
 101                         return string.Format("in:{0},out:{1}", din, dout);
 102                 }
 103         }
 104
 105         /*
 106          * Test whether this stack effect is a sub-effect of the provided
 107          * stack effect s. Stack effect s1 is a sub-effect of stack-effect
 108          * s2 if any of the following holds:
 109          * -- s1 and s2 are known, s1.din <= s2.din and s1 does not exit.
 110          * -- s1 and s2 are known, s1.din <= s2.din, s1 and s2 exit,
 111          *    and s1.din - s1.dout == s2.din - s2.dout.
 112          */
 113         internal bool IsSubOf(SType s)
 114         {
 115                 if (!IsKnown || !s.IsKnown) {
 116                         return false;
 117                 }
 118                 if (din > s.din) {
 119                         return false;
 120                 }
 121                 if (NoExit) {
 122                         return true;
 123                 }
 124                 if (s.NoExit) {
 125                         return false;
 126                 }
 127                 return (din - dout) == (s.din - s.dout);
 128         }
 129 }