public static LNode matchCode(LNode node, IMacroContext context)
{
if (node.AttrNamed(S.Static) != null)
{
return(null); // this case is handled by static_matchCode macro
}
var args_body = context.GetArgsAndBody(false);
LNodeList args = args_body.Item1, body = args_body.Item2;
if (args.Count != 1 || body.Count < 1)
{
return(null);
}
var cases = GetCases(body, context.Sink);
if (cases.IsEmpty)
{
return(null);
}
var output = new WList <LNode>();
var var = MaybeAddTempVarDecl(context, args[0], output);
var ifClauses = new List <Pair <LNode, LNode> >();
var cmc = new CodeMatchContext {
Context = context
};
foreach (var @case in cases)
{
cmc.ThenClause.Clear();
// e.g. case [$(..._)] Foo($x + 1, $y) =>
// LNode x, y, tmp9;
// if (var.Calls((Symbol) "Foo", 2) && (tmp9 = var.Args[0]).Calls(CodeSymbols.Plus, 2)
// && (x = tmp9.Args[0]) != null // this will never be null, but we want to put it the assignment in the 'if' statement
// && 1.Equals(tmp9.Args[1].Value) && (y = var.Args[1]) != null) { ... }
LNode testExpr = null;
if (@case.Key.Count > 0)
{
if (cmc.IsMultiCase = @case.Key.Count > 1)
{
cmc.UsageCounters.Clear();
testExpr = @case.Key.Aggregate((LNode)null, (test, pattern) => {
test = LNode.MergeBinary(test, cmc.MakeTopTestExpr(pattern, var), S.Or);
return(test);
});
foreach (var pair in cmc.UsageCounters.Where(p => p.Value < @case.Key.Count))
{
if (cmc.NodeVars.ContainsKey(pair.Key))
{
cmc.NodeVars[pair.Key] = true;
}
if (cmc.ListVars.ContainsKey(pair.Key))
{
cmc.ListVars[pair.Key] = true;
}
}
}
else
{
testExpr = cmc.MakeTopTestExpr(@case.Key[0], var);
}
}
var handler = F.Braces(@case.Value);
if (cmc.ThenClause.Count > 0)
{
handler = LNode.MergeLists(F.Braces(cmc.ThenClause), handler, S.Braces);
}
ifClauses.Add(Pair.Create(testExpr, handler));
}
LNode ifStmt = null;
for (int i = ifClauses.Count - 1; i >= 0; i--)
{
if (ifClauses[i].Item1 == null)
{
if (ifStmt == null)
{
ifStmt = ifClauses[i].Item2;
}
else
{
context.Sink.Error(node, "The default case must appear last, and there can be only one.");
}
}
else
{
if (ifStmt == null)
{
ifStmt = F.Call(S.If, ifClauses[i].Item1, ifClauses[i].Item2);
}
else
{
ifStmt = F.Call(S.If, ifClauses[i].Item1, ifClauses[i].Item2, ifStmt);
}
}
}
if (cmc.NodeVars.Count > 0)
{
output.Add(F.Call(S.Var, ListExt.Single(F.Id("LNode")).Concat(
cmc.NodeVars.OrderBy(v => v.Key.Name).Select(kvp => kvp.Value ? F.Call(S.Assign, F.Id(kvp.Key), F.Null) : F.Id(kvp.Key)))));
}
if (cmc.ListVars.Count > 0)
{
LNode type = LNode.Id((Symbol)"LNodeList");
output.Add(F.Call(S.Var, ListExt.Single(type).Concat(
cmc.ListVars.OrderBy(v => v.Key.Name).Select(kvp => kvp.Value ? LNode.Call(CodeSymbols.Assign, LNode.List(F.Id(kvp.Key), LNode.Call(CodeSymbols.Default, LNode.List(type)))).SetStyle(NodeStyle.Operator) : F.Id(kvp.Key)))));
}
if (output.Count == 0)
{
return(ifStmt.IncludingTriviaFrom(node));
}
else
{
output.Add(ifStmt);
return(F.Braces(output.ToVList()).IncludingTriviaFrom(node));
}
}
