public (Value success, Value cost, Value result) CompileMatchCase(Value matchWith, MatchCase matchCase)
{
LabelTarget failLabel = Expression.Label("fail");
LabelTarget finishLabel = Expression.Label("finish");
var successVar = Expression.Parameter(typeof(bool), "success");
var costVar = Expression.Parameter(typeof(int), "cost");
var compiler = new FunctionCompiler(scope);
var matcher = new Matcher(
compiler,
implicitVariables: matchCase.ImplicitVariables
);
var instr = new List <Expression>();
instr.Add(matcher.CompileMatch(matchWith, matchCase.MatchedValue, failLabel, MatchKind.exact));
foreach (var variable in matchCase.ImplicitVariables)
{
if (matcher.implicitVars[variable.name] == null)
{
throw new Exception($"{variable.name} was not instantiated at {matchCase.Location}");
}
var value = matcher.implicitVars[variable.name];
if (variable.type.IsSome())
{
var coerceResult = compiler.CompileCoerce(value, CompileExpr(variable.type.Get()));
// TODO: this should always succeed due to type constraints
instr.Add(Expression.IfThenElse(
coerceResult.success.Expression,
Expression.Block(
Expression.AddAssign(costVar, coerceResult.cost.Expression),
scope.CreateVariable(variable.name, coerceResult.value)),
Expression.Goto(failLabel)));
}
else
{
instr.Add(scope.CreateVariable(variable.name, value));
}
}
instr.Add(Expression.Assign(successVar, Expression.Constant(true)));
instr.Add(Expression.Goto(finishLabel));
instr.Add(Expression.Label(failLabel));
instr.Add(Expression.Assign(successVar, Expression.Constant(false)));
instr.Add(Expression.Label(finishLabel));
return(Value.Seq(instr, Value.Dynamic(successVar)), Value.Dynamic(costVar), compiler.CompileExpr(matchCase.Body));
}
public Matcher(FunctionCompiler compiler, List <(string name, Optional <Expr> type)> implicitVariables)