130 lines
2.4 KiB
C#
130 lines
2.4 KiB
C#
using System;
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/*
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* This structure contains the stack effect of a word: number of stack
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* element consumed on input, and number of stack element produced on
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* output.
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*/
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struct SType {
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/*
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* Get number of stack elements consumed on input; this is -1 if
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* the stack effect is not known.
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*/
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internal int DataIn {
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get {
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return din;
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}
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}
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/*
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* Get number of stack elements produced on output; this is -1 if
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* either the stack effect is not known, or if the word never
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* exits.
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*/
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internal int DataOut {
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get {
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return dout;
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}
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}
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/*
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* Tell whether the stack effect is known.
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*/
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internal bool IsKnown {
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get {
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return din >= 0;
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}
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}
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/*
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* Tell whether the stack effect is known and the word never exits.
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*/
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internal bool NoExit {
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get {
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return din >= 0 && dout < 0;
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}
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}
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int din, dout;
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internal SType(int din, int dout)
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{
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if (din < 0) {
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din = -1;
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}
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if (dout < 0) {
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dout = -1;
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}
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this.din = din;
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this.dout = dout;
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}
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/*
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* Special value for the unknown stack effect.
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*/
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internal static SType UNKNOWN = new SType(-1, -1);
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/*
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* Constant for the "blank stack effect".
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*/
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internal static SType BLANK = new SType(0, 0);
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public static bool operator ==(SType s1, SType s2)
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{
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return s1.din == s2.din && s1.dout == s2.dout;
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}
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public static bool operator !=(SType s1, SType s2)
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{
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return s1.din != s2.din || s1.dout != s2.dout;
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}
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public override bool Equals(Object obj)
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{
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return (obj is SType) && ((SType)obj == this);
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}
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public override int GetHashCode()
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{
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return din * 31 + dout * 17;
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}
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public override string ToString()
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{
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if (!IsKnown) {
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return "UNKNOWN";
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} else if (NoExit) {
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return string.Format("in:{0},noexit", din);
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} else {
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return string.Format("in:{0},out:{1}", din, dout);
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}
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}
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/*
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* Test whether this stack effect is a sub-effect of the provided
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* stack effect s. Stack effect s1 is a sub-effect of stack-effect
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* s2 if any of the following holds:
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* -- s1 and s2 are known, s1.din <= s2.din and s1 does not exit.
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* -- s1 and s2 are known, s1.din <= s2.din, s1 and s2 exit,
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* and s1.din - s1.dout == s2.din - s2.dout.
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*/
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internal bool IsSubOf(SType s)
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{
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if (!IsKnown || !s.IsKnown) {
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return false;
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}
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if (din > s.din) {
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return false;
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}
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if (NoExit) {
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return true;
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}
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if (s.NoExit) {
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return false;
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}
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return (din - dout) == (s.din - s.dout);
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}
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}
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