2 using System.Collections;
3 using System.Collections.Generic;
7 namespace System.Xml.Expression
9 public class Xexpression
11 public static int debug_level = 0;
13 public struct Name : IEquatable<Name>
15 private static NameTable nt = new NameTable ();
19 public Name (string str)
24 public static implicit operator Name (string str)
26 return new Name (str);
29 public static implicit operator string (Name name)
34 public static bool operator== (Name n1, Name n2)
36 return (object) n1.name == (object) n2.name;
39 public static bool operator!= (Name n1, Name n2)
41 return (object) n1.name != (object) n2.name;
44 public static bool operator== (Name n1, string n2)
46 return (object) n1.name == (object) n2;
49 public static bool operator!= (Name n1, string n2)
51 return (object) n1.name != (object) n2;
54 public static bool operator== (string n1, Name n2)
56 return (object) n1 == (object) n2.name;
59 public static bool operator!= (string n1, Name n2)
61 return (object) n1 != (object) n2.name;
64 public bool Equals (Name name)
66 return Object.ReferenceEquals (this.name, name.name);
69 public override bool Equals (object obj)
71 return Object.ReferenceEquals (this.name, obj);
74 public override int GetHashCode ()
76 return name.GetHashCode ();
79 public static NameTable Table { get { return nt; } }
81 public override string ToString () { return name; }
84 private static Name Nexpr = "expr";
86 private static Name Nfuncall = "funcall";
87 private static Name Nvariable = "variable";
88 private static Name Ninteger = "integer";
89 private static Name Nstring = "string";
90 private static Name Nsymbol = "symbol";
91 private static Name Nlist = "list";
93 private static Name Ndefun = "defun";
94 private static Name Nfname = "fname";
95 private static Name Nargs = "args";
96 private static Name Nargs_unevalled = "args-unevalled";
97 private static Name Noptional = "optional";
98 private static Name Nrest = "rest";
99 private static Name Nbody = "body";
101 private static Name Ndefvar = "defvar";
102 private static Name Ndescription = "description";
103 private static Name Nrange = "range";
105 private static Name Nprogn = "progn";
107 internal abstract class Function
110 public int min_arg, max_arg;
112 public Function () { }
114 public Function (Name name, int min_arg, int max_arg)
117 this.min_arg = min_arg;
118 this.max_arg = max_arg;
121 public abstract Term Call (Domain domain, Term[] args);
123 public override string ToString ()
128 internal class Subroutine : Function
130 public Builtin builtin;
132 public Subroutine (Builtin builtin, Name name,
133 int min_arg, int max_arg)
134 : base (name, min_arg, max_arg)
136 this.builtin = builtin;
139 public override Term Call (Domain domain, Term[] args)
141 Term[] newargs = new Term[args.Length];
143 for (int i = 0; i < args.Length; i++)
144 newargs[i] = args[i].Eval (domain);
145 return builtin (domain, newargs);
149 internal class SpecialForm : Function
151 public Builtin builtin;
153 public SpecialForm (Builtin builtin, Name name,
154 int min_arg, int max_arg)
155 : base (name, min_arg, max_arg)
157 this.builtin = builtin;
160 public override Term Call (Domain domain, Term[] args)
162 return builtin (domain, args);
166 internal class Lambda : Function
168 internal bool args_evalled;
169 internal Term[] args;
170 internal Term[] body;
172 public Lambda (XmlNode node)
174 int nargs = 0, noptions = 0, nrest = 0;
175 name = node.Attributes[Nfname].Value;
177 node = node.FirstChild;
179 && (node.Name == Nargs || node.Name == Nargs_unevalled))
182 args_evalled = node.Name == Nargs;
183 for (n = node.FirstChild; n != null; n = n.NextSibling)
185 if (n.Name != Nsymbol)
189 if (n != null && n.Name == Noptional)
190 for (n = n.NextSibling; n != null; n = n.NextSibling)
199 max_arg = nargs + noptions + nrest;
200 args = new Term[max_arg];
202 for (int i = 0; i < max_arg; n = n.NextSibling)
203 if (n.Name == Nsymbol)
204 args[i++] = new Term (n, null);
210 min_arg = max_arg = 0;
214 public void SetBody (XmlNode node, Domain domain)
217 for (node = node.FirstChild; node != null && node.Name != Nbody;
218 node = node.NextSibling);
221 XmlNodeList nlist = node.ChildNodes;
223 body = new Term[nlist.Count];
224 for (int i = 0; i < nlist.Count; i++)
225 body[i] = new Term (nlist[i], domain);
229 public override Term Call (Domain domain, Term[] args)
231 Bindings current = domain.bindings;
238 Term[] newargs = new Term[args.Length];
239 for (i = 0; i < min_arg; i++)
240 newargs[i] = args[i].Eval (domain);
243 for (i = 0; i < min_arg; i++)
245 Variable var = domain.GetVar ((Name) this.args[i]);
246 domain.Bind (var, args[i]);
249 foreach (Term term in body)
250 result = term.Eval (domain);
252 domain.UnboundTo (current);
259 internal abstract class Variable
261 public readonly Name name;
264 public Variable (Name name, Term term)
275 if (! ValueP (value))
276 throw new Exception ("Invalid value of " + name + ": " + value);
281 public abstract bool ValueP (Term term);
283 public override string ToString () { return name + "(" + val + ")"; }
285 internal class Int : Variable
292 public Range[] ranges;
294 public Int (Name name, int i) : base (name, new Term (i)) { }
296 public override bool ValueP (Term term)
300 if (term.objval != null)
305 foreach (Range r in ranges)
306 if (i >= r.from && i <= r.to)
312 internal class Str : Variable
314 public string[] ranges;
316 public Str (Name name, string str) : base (name, new Term (str)) { }
318 public override bool ValueP (Term term)
320 if (! (term.objval is string))
324 string str = (string) term.objval;
325 foreach (string s in ranges)
332 internal class Misc : Variable
334 public Misc (Name name, Term term) : base (name, term) { }
336 public override bool ValueP (Term term) { return true; }
340 internal class Bindings
342 private Variable vari;
343 private Term old_value;
344 private Bindings next;
346 private Bindings (Variable vari)
349 old_value = vari.val;
352 public static Bindings Bind (Bindings bindings, Variable vari, Term val)
354 Bindings b = new Bindings (vari);
361 internal Bindings UnboundTo (Bindings boundary)
363 for (Bindings b = this; b != boundary; b = b.next)
364 b.vari.val = b.old_value;
368 public override string ToString ()
370 string str = "(bindings";
371 for (Bindings b = this; b != null; b = b.next)
372 str += " " + vari.name + "=" + b.old_value;
378 internal class ThrowException : Exception
383 public ThrowException (Name tag, object value) : base ()
393 public object context;
394 public int depth = 0;
396 internal Dictionary<Name, Function> functions;
397 internal Dictionary<Name, Variable> variables;
398 internal Bindings bindings;
402 functions = new Dictionary<Name, Function> ();
403 variables = new Dictionary<Name, Variable> ();
406 public Domain (object context) : this (basic, context)
410 public Domain (Domain parent, object context)
412 functions = new Dictionary<Name, Function> (parent.functions);
413 variables = new Dictionary<Name, Variable> (parent.variables);
414 this.context = context;
417 internal void Bind (Variable vari, Term value)
419 bindings = Bindings.Bind (bindings, vari, value);
422 internal void UnboundTo (Bindings boundary)
424 if (bindings != null)
425 bindings = bindings.UnboundTo (boundary);
428 public void DefSubr (Builtin builtin, string str,
429 int min_arg, int max_arg, params string[] aliases)
432 Function func = new Function.Subroutine (builtin, name,
434 functions[name] = func;
435 foreach (string a in aliases)
436 functions[(Name) a] = func;
439 public void DefSpecial (Builtin builtin, string str,
440 int min_arg, int max_arg,
441 params string[] aliases)
444 Function func = new Function.SpecialForm (builtin, name,
446 functions[name] = func;
447 foreach (string a in aliases)
448 functions[(Name) a] = func;
451 public void DefAlias (string alias, string str)
453 functions[(Name) alias] = functions[(Name) str];
456 internal Function.Lambda RegisterFunction (XmlNode node)
458 Function.Lambda lambda = new Function.Lambda (node);
460 functions[lambda.name] = lambda;
464 internal Function Defun (XmlNode node)
466 Name name = node.Attributes[Nfname].Value;
469 if (! functions.TryGetValue (name, out func))
470 func = RegisterFunction (node);
471 ((Function.Lambda) func).SetBody (node, this);
475 public void Defvar (XmlNode node)
477 Name name = node.Attributes[0].Value;
480 node = node.FirstChild;
481 if (node.Name == Ndescription)
482 node = node.NextSibling;
485 Name type = node.Name;
486 XmlNodeList range_list = null;
488 string val = node.InnerText;
490 node = node.NextSibling;
493 range_list = node.ChildNodes;
494 nranges = range_list.Count;
497 if (type == Ninteger)
499 Variable.Int vi = new Variable.Int (name, parse_integer (val));
500 if (range_list != null)
502 vi.ranges = new Variable.Int.Range[nranges];
504 for (int i = 0; i < nranges; i++)
506 XmlNode n = range_list[i];
508 if (n.Name == Nrange)
511 parse_integer (n.FirstChild.InnerText);
513 parse_integer (n.LastChild.InnerText);
517 int num = parse_integer (n.InnerText);
518 vi.ranges[i].from = vi.ranges[i].to = num;
524 else if (type == Nstring)
526 Variable.Str vs = new Variable.Str (name, val);
527 if (range_list != null)
528 vs.ranges = new string[nranges];
529 for (int i = 0; i < nranges; i++)
530 vs.ranges[i] = range_list[i].Value;
534 throw new Exception ("Unknown type: " + type);
537 vari = new Variable.Misc (name, Zero);
538 variables[name] = vari;
541 internal Function GetFunc (Name name)
545 if (! functions.TryGetValue (name, out func))
546 throw new Exception ("Unknown function: " + name);
550 public bool CopyFunc (Domain domain, Name name)
552 Function func = GetFunc (name);
554 domain.functions[name] = func;
558 public void CopyFunc (Domain domain)
560 foreach (KeyValuePair<Name, Function> kv in functions)
561 domain.functions[kv.Key] = kv.Value;
564 internal Variable GetVar (Name name)
568 if (! variables.TryGetValue (name, out vari))
569 variables[name] = vari = new Variable.Misc (name, Zero);
573 public override string ToString ()
575 string str = "<(functions";
576 foreach (KeyValuePair<Name, Function> kv in functions)
578 str += ") (variabls";
579 foreach (KeyValuePair<Name, Variable> kv in variables)
582 if (bindings != null)
583 str += " " + bindings;
585 str += " (" + context + ")";
590 public void DebugWrite (bool head, string fmt, params string[] arg)
592 if (debug_level > depth)
596 Console.WriteLine ();
597 for (int i = 0; i < depth; i++)
600 Console.Write (fmt, arg);
605 public delegate Term Builtin (Domain domain, Term[] args);
607 private static Domain basic = new Domain ();
609 internal static Function Fprogn;
611 static Xexpression ()
613 basic.DefSubr (set_value, "set", 2, 2, "=");
614 basic.DefSpecial (and, "and", 1, -1, "&&");
615 basic.DefSpecial (or, "or", 1, -1, "||");
616 basic.DefSubr (not, "not", 1, 1, "!");
617 basic.DefSubr (add, "add", 2, -1, "+");
618 basic.DefSubr (mul, "mul", 2, -1, "*");
619 basic.DefSubr (sub, "sub", 1, -1, "-");
620 basic.DefSubr (div, "div", 2, -1, "/");
621 basic.DefSubr (mod, "mod", 2, 2, "%");
622 basic.DefSubr (logior, "logior", 2, -1, "|");
623 basic.DefSubr (logand, "logand", 2, -1, "&");
624 basic.DefSubr (add_set, "add-set", 2, -1, "+=");
625 basic.DefSubr (mul_set, "mul-set", 2, -1, "*=");
626 basic.DefSubr (sub_set, "sub-set", 2, -1, "-=");
627 basic.DefSubr (div_set, "div-set", 2, -1, "/=");
628 basic.DefSubr (mod_set, "mod-set", 2, 2, "%=");
629 basic.DefSubr (logior_set, "logior-set", 2, -1, "|=");
630 basic.DefSubr (logand_set, "logand-set", 2, -1, "&=");
631 basic.DefSubr (lsh, "lsh", 2, 2, "<<");
632 basic.DefSubr (rsh, "rsh", 2, 2, ">>");
633 basic.DefSubr (lsh_set, "lsh-set", 2, 2, "<<=");
634 basic.DefSubr (rsh_set, "rsh-set", 2, 2, ">>=");
635 basic.DefSubr (eq, "eq", 2, -1, "==");
636 basic.DefSubr (noteq, "noteq", 2, 2, "!=");
637 basic.DefSubr (less_than, "lt", 2, -1, "<");
638 basic.DefSubr (less_eq, "le", 2, -1, "<=");
639 basic.DefSubr (greater_than, "gt", 2, -1, ">");
640 basic.DefSubr (greater_eq, "ge", 2, -1, ">=");
641 basic.DefSubr (copy, "copy", 1, 1);
642 basic.DefSubr (append, "append", 0, -1);
643 basic.DefSubr (concat, "concat", 0, -1);
644 basic.DefSubr (nth, "nth", 2, 2);
645 basic.DefSubr (eval_clause, "eval", 1, 1);
646 basic.DefSpecial (quote_clause, "quote", 1, 1);
647 basic.DefSpecial (progn_clause, "progn", 0, -1, "expr");
648 basic.DefSpecial (if_clause, "if", 2, -1);
649 basic.DefSpecial (when_clause, "when", 1, -1);
650 basic.DefSpecial (while_clause, "while", 1, -1);
652 Fprogn = basic.GetFunc (Nprogn);
655 private static Term set_value (Domain domain, Term[] args)
657 Variable vari = domain.GetVar ((Name) args[0]);
659 vari.Value = args[1];
663 private static Term and (Domain domain, Term[] args)
665 foreach (Term arg in args)
666 if (! arg.Eval (domain).IsTrue)
671 private static Term or (Domain domain, Term[] args)
673 foreach (Term arg in args)
674 if (arg.Eval (domain).IsTrue)
679 private static Term not (Domain domain, Term[] args)
681 return args[0].IsTrue ? Zero : One;
684 private static Term add (Domain domain, Term[] args)
687 foreach (Term arg in args)
692 private static Term mul (Domain domain, Term[] args)
695 foreach (Term arg in args)
700 private static Term sub (Domain domain, Term[] args)
702 int n = (int) args[0];
703 if (args.Length == 1)
705 for (int i = 1; i < args.Length; i++)
710 private static Term div (Domain domain, Term[] args)
712 int n = (int) args[0];
713 for (int i = 1; i < args.Length; i++)
718 private static Term mod (Domain domain, Term[] args)
720 return ((int) args[0] % (int) args[1]);
723 private static Term logior (Domain domain, Term[] args)
726 foreach (Term arg in args)
731 private static Term logand (Domain domain, Term[] args)
733 int n = (int) args[0];
734 for (int i = 1; i < args.Length; i++)
739 private static Term add_set (Domain domain, Term[] args)
741 Variable vari = domain.GetVar ((Name) args[0]);
742 int n = (int) vari.val;
744 for (int i = 1; i < args.Length; i++)
750 private static Term mul_set (Domain domain, Term[] args)
752 Variable vari = domain.GetVar ((Name) args[0]);
753 int n = (int) vari.val;
755 for (int i = 1; i < args.Length; i++)
761 private static Term sub_set (Domain domain, Term[] args)
763 Variable vari = domain.GetVar ((Name) args[0]);
764 int n = (int) vari.val;
766 for (int i = 1; i < args.Length; i++)
772 private static Term div_set (Domain domain, Term[] args)
774 Variable vari = domain.GetVar ((Name) args[0]);
775 int n = (int) vari.val;
777 for (int i = 1; i < args.Length; i++)
783 private static Term mod_set (Domain domain, Term[] args)
785 Variable vari = domain.GetVar ((Name) args[0]);
786 int n = (int) vari.val;
788 for (int i = 1; i < args.Length; i++)
794 private static Term logior_set (Domain domain, Term[] args)
796 Variable vari = domain.GetVar ((Name) args[0]);
797 int n = (int) vari.val;
799 for (int i = 1; i < args.Length; i++)
805 private static Term logand_set (Domain domain, Term[] args)
807 Variable vari = domain.GetVar ((Name) args[0]);
808 int n = (int) vari.val;
810 for (int i = 1; i < args.Length; i++)
816 private static Term lsh (Domain domain, Term[] args)
818 return (int) args[0] << (int) args[1];
821 private static Term lsh_set (Domain domain, Term[] args)
823 Variable vari = domain.GetVar ((Name) args[0]);
824 int n = (int) vari.val;
831 private static Term rsh (Domain domain, Term[] args)
833 return (int) args[0] >> (int) args[1];
836 private static Term rsh_set (Domain domain, Term[] args)
838 Variable vari = domain.GetVar ((Name) args[0]);
839 int n = (int) vari.val;
846 private static Term eq (Domain domain, Term[] args)
850 if (o.objval == null)
852 for (int i = 1; i < args.Length; i++)
853 if (args[i].objval != null || args[i].intval != o.intval)
858 for (int i = 1; i < args.Length; i++)
859 if (o.objval.Equals (args[i].objval))
865 private static Term noteq (Domain domain, Term[] args)
867 return eq (domain, args);
870 private static Term less_than (Domain domain, Term[] args)
872 int n = (int) args[0];
874 for (int i = 1; i < args.Length; i++)
876 int n1 = (int) args[i];
884 private static Term less_eq (Domain domain, Term[] args)
886 int n = (int) args[0];
887 for (int i = 1; i < args.Length; i++)
889 int n1 = (int) args[i];
897 private static Term greater_than (Domain domain, Term[] args)
899 int n = (int) args[0];
900 for (int i = 1; i < args.Length; i++)
902 int n1 = (int) args[i];
910 private static Term greater_eq (Domain domain, Term[] args)
912 int n = (int) args[0];
913 for (int i = 1; i < args.Length; i++)
915 int n1 = (int) args[i];
923 private static Term copy (Domain domain, Term[] args)
925 object obj = args[0].objval;
927 if (! (obj is List<Term>))
928 throw new Exception ("Invalid arg to copy: " + args[0]);
929 return new Term (new List<Term> ((List<Term>) obj));
932 private static Term append (Domain domain, Term[] args)
934 List<Term> list = new List<Term> ();
937 foreach (Term arg in args)
940 list.AddRange ((List<Term>) arg.objval);
945 result.objval = list;
949 private static Term concat (Domain domain, Term[] args)
954 foreach (Term arg in args)
957 str += (string) arg.objval;
959 foreach (Term term in (List<Term>) arg.objval)
960 str += (char) term.Intval;
962 str += (char) arg.Intval;
969 private static Term nth (Domain domain, Term[] args)
975 result.intval = ((string) args[1].objval)[args[0].Intval];
976 result.objval = null;
978 else if (args[1].IsList)
981 result.objval = ((List<Term>) args[1].objval)[args[0].Intval];
984 throw new Exception ("Term is not enumelable: " + args[1]);
988 private static Term quote_clause (Domain domain, Term[] args)
990 return new Term (args[0]);
993 private static Term eval_clause (Domain domain, Term[] args)
995 return (args[0].Eval (domain));
998 private static Term progn_clause (Domain domain, Term[] args)
1002 foreach (Term arg in args)
1003 result = arg.Eval (domain);
1007 private static Term if_clause (Domain domain, Term[] args)
1009 if (args[0].Eval (domain).IsTrue)
1010 return args[1].Eval (domain);
1013 for (int i = 2; i < args.Length; i++)
1014 result = args[i].Eval (domain);
1018 private static Term when_clause (Domain domain, Term[] args)
1020 if (! args[0].Eval (domain).IsTrue)
1024 for (int i = 1; i < args.Length; i++)
1025 result = args[i].Eval (domain);
1029 private static Term while_clause (Domain domain, Term[] args)
1031 while (args[0].Eval (domain).IsTrue)
1032 for (int i = 1; i < args.Length; i++)
1033 args[i].Eval (domain);
1040 public object objval;
1042 public Term (int i) { intval = i; objval = null; }
1043 public Term (Name name) { intval = 0; objval = name; }
1044 public Term (string str) { intval = 0; objval = str; }
1045 public Term (List<Term> list) { intval = 0; objval = list; }
1046 public Term (Term term) { intval = 0; objval = term; }
1048 public Term (XmlNode node, Domain domain)
1050 Name name = node.Name;
1052 if (name == Ninteger)
1054 intval = parse_integer (node.InnerText);
1060 if (name == Nsymbol)
1061 objval = (Name) node.InnerText;
1062 else if (name == Nstring)
1063 objval = node.InnerText.Clone ();
1064 else if (name == Nvariable)
1065 objval = domain.GetVar ((Name) node.Attributes[0].Value);
1066 else if (name == Nlist)
1068 List<Term> list = new List<Term> ();
1069 for (node = node.FirstChild; node != null;
1070 node = node.NextSibling)
1071 list.Add (new Term (node, domain));
1076 if (name == Nfuncall)
1077 name = node.Attributes[0].Value;
1079 Function func = domain.GetFunc (name);
1080 XmlNodeList nlist = node.ChildNodes;
1081 int nargs = nlist.Count;
1083 if (nargs < func.min_arg
1084 || (func.max_arg >= 0 && nargs > func.max_arg))
1085 throw new Exception ("Invalid number of arguments to: "
1086 + name + " " + nargs);
1087 Term[] args = new Term[nargs];
1088 for (int i = 0; i < nlist.Count; i++)
1089 args[i] = new Term (nlist[i], domain);
1090 objval = new Funcall (func, args);
1095 private class Funcall
1097 internal Function func;
1098 internal Term[] args;
1100 public Funcall (Function func, Term[] args)
1106 public Term Eval (Domain domain)
1108 domain.DebugWrite (true, "(({0}", func.name);
1109 for (int i = 0; i < args.Length; i++)
1110 domain.DebugWrite (false, " {0}", args[i].ToString ());
1111 domain.DebugWrite (false, ")");
1113 Term result = func.Call (domain, args);
1115 domain.DebugWrite (true, " ==> {0})", result.ToString ());
1119 public override string ToString ()
1121 string str = "<funcall fname=\"" + func.name;
1123 return str + "\"/>";
1125 foreach (Term e in args)
1127 return (str + "</funcall>");
1134 throw new Exception ("term is not integer: " + this);
1139 public bool IsTrue {
1141 return (objval == null
1143 : objval is List<Term>
1144 ? (((List<Term>) objval).Count != 0)
1148 public bool IsInt { get { return (objval == null); } }
1149 public bool IsStr { get { return (objval is string); } }
1150 public bool IsList { get { return (objval is List<Term>); } }
1152 public Term Eval (Domain domain)
1154 if (objval == null || objval is Name || objval is string)
1156 if (objval is List<Term>)
1157 return new Term ((List<Term>) objval);
1158 if (objval is Funcall)
1159 return ((Funcall) objval).Eval (domain);
1160 if (objval is Variable)
1161 return ((Variable) objval).val;
1163 return (Term) objval;
1164 throw new Exception ("invalid Term object: " + objval);
1167 public static explicit operator int (Term term)
1169 if (term.objval != null)
1170 throw new Exception ("Not an integer term: " + term);
1174 public static explicit operator Name (Term term)
1176 return (Name) term.objval;
1179 public static implicit operator Term (int i)
1181 return new Term (i);
1184 public override string ToString ()
1189 str = "<integer>" + intval + "</integer>";
1190 else if (objval is Name)
1191 str = "<symbol>" + objval + "</symbol>";
1192 else if (objval is string)
1193 str = "<string>" + objval + "</string>";
1194 else if (objval is List<Term>)
1197 foreach (Term e in (List<Term>) objval)
1201 else if (objval is Funcall)
1202 str = "<funcall fname=\"" + ((Funcall) objval).func.name + "\"/>";
1203 else if (objval is Variable)
1204 str = "<variable vname=\"" + ((Variable) objval).name + "\"/>";
1205 else if (objval is Term)
1206 str = "<quote>" + objval + "</quote>";
1208 throw new Exception ("invalid Term object: " + objval);
1213 static Term Zero = new Term (0);
1214 static Term One = new Term (1);
1216 internal static int parse_integer (string str)
1218 int len = str.Length;
1219 bool negative = false;
1222 return (len == 0 ? 0 : str[0] - '0');
1227 if (c == '0' && str[1] == 'x')
1230 for (int idx = 2; idx < len; idx++)
1236 i = i * 16 + (c - '0');
1240 i = i * 16 + (c - 'A');
1244 i = i * 16 + (c - 'a');
1253 for (int idx = 1; idx < len; idx++)
1256 if (c < '0' || c > '9')
1258 i = i * 10 + (c - '0');
1260 return negative ? - i : i;
1263 private Term[] terms;
1265 public Xexpression (string url, Domain domain)
1267 XmlDocument doc = new XmlDocument (Name.Table);
1270 using (XmlTextReader reader = new XmlTextReader (url, Name.Table))
1274 } while (reader.NodeType != XmlNodeType.None
1275 && (reader.NodeType != XmlNodeType.Element
1276 || reader.Name != Nexpr));
1277 if (reader.NodeType == XmlNodeType.None)
1278 throw new Exception ("Node <expr> not found");
1279 node = doc.ReadNode (reader);
1283 for (XmlNode n = node.FirstChild; n != null; n = n.NextSibling)
1284 if (n.NodeType == XmlNodeType.Element)
1286 if (n.Name == Ndefun)
1287 domain.RegisterFunction (n);
1288 else if (n.Name == Ndefvar)
1294 terms = new Term[nterms];
1296 for (XmlNode n = node.FirstChild; n != null; n = n.NextSibling)
1297 if (n.NodeType == XmlNodeType.Element)
1299 if (n.Name == Ndefun)
1301 else if (n.Name != Ndefvar)
1302 terms[i++]= new Term (n, domain);
1306 public Term Eval (Domain domain)
1311 foreach (Term term in terms)
1312 result = term.Eval (domain);
1316 public override string ToString ()
1319 for (int i = 0; i < terms.Length; i++)