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// Provenance: own design — shared run scripts (spec §3.6)
using System.Globalization;
using System.Text;
namespace Godosa.Core.Runs.Scripts;
public interface IConditionContext
{
bool HasProbe(string name);
RunValue Probe(string name, IReadOnlyList<string> args);
long? Constant(string name);
}
/// <summary>Condition AST: or / and / not / comparison / atom. A bare identifier is a probe without arguments when the
/// game has one by that name, else a game constant.</summary>
public abstract record Cond
{
public abstract RunValue Eval(IConditionContext c);
public bool Test(IConditionContext c) => Truthy(Eval(c));
public abstract IEnumerable<(string Name, IReadOnlyList<string> Args)> Probes();
public abstract IEnumerable<string> Bare();
public static string Describe(Cond cond, IConditionContext c) =>
string.Join(" ", cond.Probes().Where(p => c.HasProbe(p.Name)).Distinct().Select(p =>
{
var label = p.Args.Count == 0 ? p.Name : $"{p.Name}({string.Join(",", p.Args)})";
return $"{label}={c.Probe(p.Name, p.Args)}";
}));
internal static bool Truthy(RunValue v) => v.IsNumber ? v.Number != 0 : !string.IsNullOrEmpty(v.Text);
}
public sealed record OrCond(Cond A, Cond B) : Cond
{
public override RunValue Eval(IConditionContext c) => RunValue.Of(A.Test(c) || B.Test(c));
public override IEnumerable<(string, IReadOnlyList<string>)> Probes() => A.Probes().Concat(B.Probes());
public override IEnumerable<string> Bare() => A.Bare().Concat(B.Bare());
}
public sealed record AndCond(Cond A, Cond B) : Cond
{
public override RunValue Eval(IConditionContext c) => RunValue.Of(A.Test(c) && B.Test(c));
public override IEnumerable<(string, IReadOnlyList<string>)> Probes() => A.Probes().Concat(B.Probes());
public override IEnumerable<string> Bare() => A.Bare().Concat(B.Bare());
}
public sealed record NotCond(Cond A) : Cond
{
public override RunValue Eval(IConditionContext c) => RunValue.Of(!A.Test(c));
public override IEnumerable<(string, IReadOnlyList<string>)> Probes() => A.Probes();
public override IEnumerable<string> Bare() => A.Bare();
}
public sealed record CompareCond(Cond A, string Op, Cond B) : Cond
{
public override RunValue Eval(IConditionContext c)
{
var (a, b) = (A.Eval(c), B.Eval(c));
if (a.IsNumber != b.IsNumber)
throw new ScriptFault($"cannot compare {a} with {b}");
var order = a.IsNumber ? a.Number!.Value.CompareTo(b.Number!.Value) : string.CompareOrdinal(a.Text, b.Text);
if (!a.IsNumber && Op is "<" or "<=" or ">" or ">=")
throw new ScriptFault($"cannot order strings {a} and {b}");
return RunValue.Of(Op switch
{
"=" => order == 0, "!=" => order != 0, "<" => order < 0, "<=" => order <= 0, ">" => order > 0, _ => order >= 0,
});
}
public override IEnumerable<(string, IReadOnlyList<string>)> Probes() => A.Probes().Concat(B.Probes());
public override IEnumerable<string> Bare() => A.Bare().Concat(B.Bare());
}
public sealed record LiteralCond(RunValue Value) : Cond
{
public override RunValue Eval(IConditionContext c) => Value;
public override IEnumerable<(string, IReadOnlyList<string>)> Probes() => [];
public override IEnumerable<string> Bare() => [];
}
/// <summary>A probe call <c>name(args)</c>, or a bare <c>name</c> (probe if the game has it, else a constant).</summary>
public sealed record NameCond(string Name, IReadOnlyList<string> Args, bool HasParens) : Cond
{
public override RunValue Eval(IConditionContext c)
{
if (HasParens || c.HasProbe(Name))
return c.Probe(Name, Args);
return c.Constant(Name) is { } n ? RunValue.Of(n) : throw new ScriptFault($"unknown probe or constant {Name}");
}
public override IEnumerable<(string, IReadOnlyList<string>)> Probes() => [(Name, Args)];
public override IEnumerable<string> Bare() => HasParens ? [] : [Name];
}
public static class ConditionParser
{
public static Cond Parse(string text)
{
var tokens = Lex(text);
var pos = 0;
var cond = Or(tokens, ref pos);
if (pos != tokens.Count)
throw new FormatException($"unexpected '{tokens[pos]}' in condition '{text}'");
return cond;
}
private static Cond Or(List<string> t, ref int pos)
{
var a = And(t, ref pos);
while (pos < t.Count && t[pos] == "or")
{
pos++;
a = new OrCond(a, And(t, ref pos));
}
return a;
}
private static Cond And(List<string> t, ref int pos)
{
var a = Not(t, ref pos);
while (pos < t.Count && t[pos] == "and")
{
pos++;
a = new AndCond(a, Not(t, ref pos));
}
return a;
}
private static Cond Not(List<string> t, ref int pos)
{
if (pos < t.Count && t[pos] == "not")
{
pos++;
return new NotCond(Not(t, ref pos));
}
return Compare(t, ref pos);
}
private static Cond Compare(List<string> t, ref int pos)
{
var a = Atom(t, ref pos);
if (pos < t.Count && t[pos] is "=" or "!=" or "<" or "<=" or ">" or ">=")
{
var op = t[pos++];
return new CompareCond(a, op, Atom(t, ref pos));
}
return a;
}
private static Cond Atom(List<string> t, ref int pos)
{
if (pos >= t.Count)
throw new FormatException("condition ends early");
var tok = t[pos++];
if (tok == "(")
{
var inner = Or(t, ref pos);
if (pos >= t.Count || t[pos] != ")")
throw new FormatException("missing ')'");
pos++;
return inner;
}
if (tok.StartsWith('"'))
return new LiteralCond(RunValue.Of(tok[1..^1]));
if (long.TryParse(tok, NumberStyles.AllowLeadingSign, CultureInfo.InvariantCulture, out var n))
return new LiteralCond(RunValue.Of(n));
if (!char.IsLetter(tok[0]) && tok[0] != '_')
throw new FormatException($"unexpected '{tok}'");
var paren = tok.IndexOf('(');
if (paren < 0)
return new NameCond(tok, [], false);
var args = tok[(paren + 1)..^1].Split(',', StringSplitOptions.TrimEntries).Where(a => a.Length > 0).ToArray();
return new NameCond(tok[..paren], args, true);
}
private static List<string> Lex(string text)
{
var tokens = new List<string>();
var i = 0;
while (i < text.Length)
{
var c = text[i];
if (c == ' ')
{
i++;
continue;
}
if (c is '(' or ')')
{
tokens.Add(c.ToString());
i++;
continue;
}
if (c == '"')
{
var end = text.IndexOf('"', i + 1);
if (end < 0)
throw new FormatException("unterminated quote");
tokens.Add(text[i..(end + 1)]);
i = end + 1;
continue;
}
if (c is '=' or '!' or '<' or '>')
{
var two = i + 1 < text.Length && text[i + 1] == '=';
var op = text.Substring(i, two ? 2 : 1);
if (op == "!")
throw new FormatException("use != or not");
tokens.Add(op);
i += op.Length;
continue;
}
var sb = new StringBuilder();
var depth = 0;
while (i < text.Length && (depth > 0 || (text[i] != ' ' && text[i] != ')' && !(text[i] is '=' or '!' or '<' or '>'))))
{
if (text[i] == '(' && sb.Length == 0)
break;
if (text[i] == '(')
depth++;
else if (text[i] == ')')
depth--;
sb.Append(text[i++]);
}
if (sb.Length == 0)
throw new FormatException($"unexpected '{text[i]}'");
tokens.Add(sb.ToString());
}
return tokens;
}
}
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