public virtual LNode GenerateSwitch(IPGTerminalSet[] branchSets, MSet <int> casesToInclude, LNode[] branchCode, LNode defaultBranch, LNode laVar)
{
Debug.Assert(branchSets.Length == branchCode.Length);
WList <LNode> stmts = new WList <LNode>();
for (int i = 0; i < branchSets.Length; i++)
{
if (casesToInclude.Contains(i))
{
foreach (LNode value in GetCases(branchSets[i]))
{
stmts.Add(F.Call(S.Case, value));
if (stmts.Count > 65535) // sanity check
{
throw new InvalidOperationException("switch is too large to generate");
}
}
AddSwitchHandler(branchCode[i], stmts);
}
}
if (!defaultBranch.IsIdNamed(S.Missing))
{
stmts.Add(F.Call(S.Label, F.Id(S.Default)));
AddSwitchHandler(defaultBranch, stmts);
}
return(F.Call(S.Switch, (LNode)laVar, F.Braces(stmts.ToVList())));
}
public override LNode GenerateMatchExpr(IPGTerminalSet set_, bool savingResult, bool recognizerMode)
{
var set = (PGIntSet)set_;
LNode call;
var type = set.ChooseMatchType(2, 4);
if (type != PGIntSet.Match.Set)
{
var args = new WList <LNode>();
if (type == PGIntSet.Match.Ranges)
{
// Use MatchRange or MatchExceptRange
foreach (var r in set)
{
if (!set.IsInverted || r.Lo != EOF_int || r.Hi != EOF_int)
{
args.Add((LNode)set.MakeLiteral(r.Lo));
args.Add((LNode)set.MakeLiteral(r.Hi));
}
}
var target = recognizerMode
? (set.IsInverted ? _TryMatchExceptRange : _TryMatchRange)
: (set.IsInverted ? _MatchExceptRange : _MatchRange);
call = ApiCall(target, args);
}
else
{
// Use Match or MatchExcept
foreach (var r in set)
{
for (int c = r.Lo; c <= r.Hi; c++)
{
if (!set.IsInverted || c != EOF_int)
{
args.Add((LNode)set.MakeLiteral(c));
}
}
}
var target = recognizerMode
? (set.IsInverted ? _TryMatchExcept : _TryMatch)
: (set.IsInverted ? _MatchExcept : _Match);
call = ApiCall(target, args.ToVList());
}
}
else
{
var setName = GenerateSetDecl(set);
if (set.IsInverted)
{
call = ApiCall(recognizerMode ? _TryMatchExcept : _MatchExcept, F.Id(setName));
}
else
{
call = ApiCall(recognizerMode ? _TryMatch : _Match, F.Id(setName));
}
}
return(call);
}
LNode GetOutputAsLNode()
{
WList <LNode> finalOutput = _handler.ToWList();
for (int end = _output.Count - 1; end >= 0; end--)
{
var tmp_10 = _output[end];
Mode mode = tmp_10.Item1;
LNode code = tmp_10.Item2;
if (mode == Mode.Condition)
{
// Merge adjacent conditions into the same if-statement
int start = end;
for (; start > 0 && _output[start - 1].A == mode; start--)
{
}
LNode cond = _output[start].B;
for (int i = start + 1; i <= end; i++)
{
cond = LNode.Call(CodeSymbols.And, LNode.List(cond, _output[i].B)).SetStyle(NodeStyle.Operator);
}
end = start;
finalOutput = new WList <LNode> {
LNode.Call(CodeSymbols.If, LNode.List(cond, finalOutput.ToVList().AsLNode(S.Braces)))
};
}
else
{
finalOutput.Insert(0, code);
}
}
return(finalOutput.ToVList().AsLNode(S.Braces));
}
public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList <LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces))
{
contents = node.Args[1].Args;
var outputs = new WList <LNode>();
input = MaybeAddTempVarDecl(context, input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i)
{
var @case = contents[case_i];
if (!IsCaseLabel(@case))
{
return(Reject(context, contents[0], "In 'match': expected 'case' statement"));
}
for (next_i = case_i + 1; next_i < contents.Count; next_i++)
{
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
{
break;
}
if (stmt.Calls(S.Break, 0))
{
next_i++;
break;
}
}
var handler = new VList <LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0)
{
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
{
outputs.Add(codeGen.GenCodeForPattern(pattern));
}
}
else // default:
// Note: the extra {braces} around the handler are rarely
// needed. They are added just in case the handler declares a
// variable and a different handler declares another variable
// by the same name, which is illegal unless we add braces.
{
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
{
context.Sink.Error(contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
}
return(LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false))));
}
}
return(null);
}
public static LNode UnpackTuple(LNode node, IMacroContext context)
{
var a = node.Args;
if (a.Count == 2 && a[0].CallsMin(S.Tuple, 1))
{
var output = new WList <LNode>();
var tuple = a[0].Args;
var rhs = a[1];
// Avoid evaluating rhs more than once, if it doesn't look like a simple variable
rhs = MaybeAddTempVarDecl(context, rhs, output);
for (int i = 0; i < tuple.Count; i++)
{
var itemi = F.Dot(rhs, F.Id(GSymbol.Get("Item" + (i + 1))));
if (tuple[i].Calls(S.Var, 2))
{
output.Add(F.Var(tuple[i].Args[0], tuple[i].Args[1], itemi));
}
else
{
output.Add(F.Call(S.Assign, tuple[i], itemi));
}
}
return(F.Call(S.Splice, output.ToVList()));
}
return(null);
}
public void Generate(Rule rule)
{
CGH.BeginRule(rule);
_currentRule = rule;
_target = new WList<LNode>();
_laVarsNeeded = 0;
_separatedMatchCounter = _stopLabelCounter = 0;
_recognizerMode = rule.IsRecognizer;
_labelsInUse.Clear();
Visit(rule.Pred);
if (_laVarsNeeded != 0) {
LNode laVars = F.Call(S.Var, CGH.LAType());
for (int i = 0; _laVarsNeeded != 0; i++, _laVarsNeeded >>= 1)
if ((_laVarsNeeded & 1) != 0)
laVars = laVars.PlusArg(F.Id("la" + i.ToString()));
_target.Insert(0, laVars);
}
LNode method;
if (rule.TryWrapperName != null) {
Debug.Assert(rule.IsRecognizer);
method = F.OnNewLine(CGH.CreateTryWrapperForRecognizer(rule));
_classBody.SpliceAdd(method, S.Splice);
}
method = CGH.CreateRuleMethod(rule, _target.ToVList());
if (!rule.IsRecognizer)
method = F.OnNewLine(method);
_classBody.SpliceAdd(method, S.Splice);
}
[LexicalMacro("match (var) { case ...: ... }; // In LES, use a => b instead of case a: b", "Attempts to match and deconstruct an object against a \"pattern\", such as a tuple or an algebraic data type. Example:\n" + "match (obj) { \n" + " case is Shape(ShapeType.Circle, $size, Location: $p is Point<int>($x, $y)): \n" + " Circle(size, x, y); \n" + "}\n\n" + "This is translated to the following C# code: \n" + "do { \n" + " Point<int> p; \n" + " Shape tmp1; \n" + " if (obj is Shape) { \n" + " var tmp1 = (Shape)obj; \n" + " if (tmp1.Item1 == ShapeType.Circle) { \n" + " var size = tmp1.Item2; \n" + " var tmp2 = tmp1.Location; \n" + " if (tmp2 is Point<int>) { \n" + " var p = (Point<int>)tmp2; \n" + " var x = p.Item1; \n" + " var y = p.Item2; \n" + " Circle(size, x, y); \n" + " break; \n" + " } \n" + " }\n" + " }\n" + "} while(false); \n" + "`break` is not expected at the end of each handler (`case` code block), but it can " + "be used to exit early from a `case`. You can associate multiple patterns with the same " + "handler using `case pattern1, pattern2:` in EC#, but please note that (due to a " + "limitation of plain C#) this causes code duplication since the handler will be repeated " + "for each pattern.")] public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList <LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces))
{
contents = node.Args[1].Args;
var outputs = new WList <LNode>();
input = MaybeAddTempVarDecl(input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i)
{
var @case = contents[case_i];
if (!IsCaseLabel(@case))
{
return(Reject(context, contents[0], "In 'match': expected 'case' statement"));
}
for (next_i = case_i + 1; next_i < contents.Count; next_i++)
{
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
{
break;
}
if (stmt.Calls(S.Break, 0))
{
next_i++;
break;
}
}
var handler = new VList <LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0)
{
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
{
outputs.Add(codeGen.GenCodeForPattern(pattern));
}
}
else
{
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
{
context.Write(Severity.Error, contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
}
return(LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false))));
}
}
return(null);
}
public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList <LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces))
{
contents = node.Args[1].Args;
var outputs = new WList <LNode>();
input = MaybeAddTempVarDecl(context, input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i)
{
var @case = contents[case_i];
if (!IsCaseLabel(@case))
{
return(Reject(context, contents[0], "In 'match': expected 'case' statement"));
}
for (next_i = case_i + 1; next_i < contents.Count; next_i++)
{
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
{
break;
}
if (stmt.Calls(S.Break, 0))
{
next_i++;
break;
}
}
var handler = new VList <LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0)
{
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
{
outputs.Add(codeGen.GenCodeForPattern(pattern));
}
}
else
{
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
{
context.Write(Severity.Error, contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
}
return(LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false))));
}
}
return(null);
}
// Restructures a VList if it has degraded severely. Time: O(Count)
void AutoOptimize <T>(ref VList <T> v)
{
// Check if the chain length substantially exceeds Sqrt(v.Count)
if ((v.BlockChainLength - 10) * (v.BlockChainLength - 10) > v.Count)
{
WList <T> w = v.ToWList();
int end = w.Count - 1;
w[end] = w[end];
v = w.ToVList();
}
}
public LNode Vars(LNode type, params LNode[] namesWithValues)
{
type = type ?? Missing;
var list = new WList <LNode>()
{
type
};
list.AddRange(namesWithValues);
return(Call(S.Var, list.ToVList()));
}
Mode = MacroMode.ProcessChildrenBefore)] // post-normal-macro-expansion
public static LNode with(LNode fn, IMacroContext context)
{
LNode braces;
if (fn.ArgCount != 2 || !(braces = fn.Args[1]).Calls(S.Braces))
{
return(null);
}
LNode tmp = F.Id(NextTempName(context));
WList <LNode> stmts = braces.Args.ToWList();
stmts = stmts.SmartSelect(stmt =>
stmt.ReplaceRecursive(expr => {
if (expr.Calls(S.Dot, 1))
{
return(expr.WithArgs(new VList <LNode>(tmp, expr.Args.Last)));
}
else if (expr.IsIdNamed("#"))
{
return(tmp);
}
return(null);
}));
stmts.Insert(0, F.Var(null, tmp.Name, fn.Args[0]));
if (IsExpressionContext(context))
{
stmts.Add(tmp);
return(F.Call("#runSequence", stmts.ToVList()));
}
else
{
return(F.Braces(stmts.ToVList()));
}
}
public void Generate(Rule rule)
{
CGH.BeginRule(rule);
_currentRule = rule;
_target = new WList <LNode>();
_laVarsNeeded = 0;
_separatedMatchCounter = _stopLabelCounter = 0;
_recognizerMode = rule.IsRecognizer;
_labelsInUse.Clear();
Visit(rule.Pred);
if (_laVarsNeeded != 0)
{
LNode laVars = F.Call(S.Var, CGH.LAType());
for (int i = 0; _laVarsNeeded != 0; i++, _laVarsNeeded >>= 1)
{
if ((_laVarsNeeded & 1) != 0)
{
laVars = laVars.PlusArg(F.Id("la" + i.ToString()));
}
}
_target.Insert(0, laVars);
}
LNode method;
if (rule.TryWrapperName != null)
{
Debug.Assert(rule.IsRecognizer);
method = F.OnNewLine(CGH.CreateTryWrapperForRecognizer(rule));
_classBody.SpliceAdd(method, S.Splice);
}
method = CGH.CreateRuleMethod(rule, _target.ToVList());
if (!rule.IsRecognizer)
{
method = F.OnNewLine(method);
}
_classBody.SpliceAdd(method, S.Splice);
}
[LexicalMacro("match (var) { case ...: ... }; // In LES, use a => b instead of case a: b", "Attempts to match and deconstruct an object against a \"pattern\", such as a tuple or an algebraic data type. Example:\n" + "match (obj) { \n" + " case is Shape(ShapeType.Circle, $size, Location: $p is Point<int>($x, $y)): \n" + " Circle(size, x, y); \n" + "}\n\n" + "This is translated to the following C# code: \n" + "do { \n" + " Point<int> p; \n" + " Shape tmp1; \n" + " if (obj is Shape) { \n" + " var tmp1 = (Shape)obj; \n" + " if (tmp1.Item1 == ShapeType.Circle) { \n" + " var size = tmp1.Item2; \n" + " var tmp2 = tmp1.Location; \n" + " if (tmp2 is Point<int>) { \n" + " var p = (Point<int>)tmp2; \n" + " var x = p.Item1; \n" + " var y = p.Item2; \n" + " Circle(size, x, y); \n" + " break; \n" + " } \n" + " }\n" + " }\n" + "} while(false); \n" + "`break` is not expected at the end of each handler (`case` code block), but it can " + "be used to exit early from a `case`. You can associate multiple patterns with the same " + "handler using `case pattern1, pattern2:` in EC#, but please note that (due to a " + "limitation of plain C#) this causes code duplication since the handler will be repeated " + "for each pattern.")] public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList<LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces)) {
contents = node.Args[1].Args;
var outputs = new WList<LNode>();
input = MaybeAddTempVarDecl(input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i) {
var @case = contents[case_i];
if (!IsCaseLabel(@case))
return Reject(context, contents[0], "In 'match': expected 'case' statement");
for (next_i = case_i + 1; next_i < contents.Count; next_i++) {
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
break;
if (stmt.Calls(S.Break, 0)) {
next_i++;
break;
}
}
var handler = new VList<LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0) {
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
outputs.Add(codeGen.GenCodeForPattern(pattern));
} else {
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
context.Write(Severity.Error, contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
return LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false)));
}
}
return null;
}
Mode = MacroMode.ProcessChildrenBefore)] // post-normal-macro-expansion
public static LNode with(LNode fn, IMessageSink sink)
{
LNode braces;
if (fn.ArgCount != 2 || !(braces = fn.Args[1]).Calls(S.Braces))
{
return(null);
}
LNode tmp = F.Id(NextTempName());
WList <LNode> stmts = braces.Args.ToWList();
stmts = stmts.SmartSelect(stmt =>
stmt.ReplaceRecursive(expr => {
if (expr.Calls(S.Dot, 1))
{
return(expr.WithArgs(new VList <LNode>(tmp, expr.Args.Last)));
}
return(null);
}));
stmts.Insert(0, F.Var(null, tmp.Name, fn.Args[0]));
return(F.Braces(stmts.ToVList()));
}
public virtual LNode GenerateSwitch(IPGTerminalSet[] branchSets, LNode[] branchCode, MSet <int> casesToInclude, LNode defaultBranch, LNode laVar)
{
Debug.Assert(branchSets.Length == branchCode.Length);
Debug.Assert(casesToInclude.Count <= branchCode.Length);
WList <LNode> stmts = new WList <LNode>();
for (int i = 0; i < branchCode.Length; i++)
{
if (casesToInclude.Contains(i))
{
int index = -1;
foreach (LNode value in GetCases(branchSets[i]))
{
var label = F.Call(S.Case, value);
if (++index > 0 && (index % 4) != 0) // write 4 cases per line
{
label = label.PlusAttr(F.Id(S.TriviaAppendStatement));
}
stmts.Add(label);
if (stmts.Count > 65535) // sanity check
{
throw new InvalidOperationException("switch is too large to generate");
}
}
AddSwitchHandler(branchCode[i], stmts);
}
}
if (!defaultBranch.IsIdNamed(GSymbol.Empty))
{
stmts.Add(F.Call(S.Label, F.Id(S.Default)));
AddSwitchHandler(defaultBranch, stmts);
}
return(F.Call(S.Switch, (LNode)laVar, F.Braces(stmts.ToVList())));
}
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));
}
}
protected LNode GeneratePredictionTreeCode(PredictionTree tree, Pair<LNode, string>[] matchingCode, ref Symbol haveLoop)
{
var braces = F.Braces();
Debug.Assert(tree.Children.Count >= 1);
var alts = (Alts)_currentPred;
if (tree.Children.Count == 1)
return GetPredictionSubtreeCode(tree.Children[0], matchingCode, ref haveLoop);
// From the prediction table, we can generate either an if-else chain:
//
// if (la0 >= '0' && la0 <= '7') sub_tree_1();
// else if (la0 == '-') sub_tree_2();
// else break;
//
// or a switch statement:
//
// switch(la0) {
// case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7':
// sub_tree_1();
// break;
// case '-':
// sub_tree_2();
// break;
// default:
// goto breakfor;
// }
//
// Assertion levels always need an if-else chain; lookahead levels
// consider the complexity of switch vs if and decide which is most
// appropriate. Generally "if" is slower, but a switch may require
// too many labels since it doesn't support ranges like "la0 >= 'a'
// && la0 <= 'z'".
//
// This class makes if-else chains directly (using IPGTerminalSet.
// GenerateTest() to generate the test expressions), but the code
// snippet generator (CSG) is used to generate switch statements
// because the required code may be more complex.
//
// We may or may not be generating code inside a for(;;) loop. If we
// decide to generate a switch() statement, one of the branches will
// usually need to break out of the for loop, but "break" can only
// break out of the switch(). In that case, add "stop:" after the
// switch() and use "goto stop" instead of "break".
WList<LNode> block = new WList<LNode>();
LNode laVar = null;
MSet<int> switchCases = new MSet<int>();
IPGTerminalSet[] branchSets = null;
bool should = false;
if (tree.UsesLA()) {
laVar = F.Id("la" + tree.Lookahead.ToString());
if (!tree.IsAssertionLevel) {
IPGTerminalSet covered = CGH.EmptySet;
branchSets = tree.Children.Select(branch => {
var set = branch.Set.Subtract(covered);
covered = covered.Union(branch.Set);
return set;
}).ToArray();
should = CGH.ShouldGenerateSwitch(branchSets, switchCases, tree.Children.Last.IsErrorBranch);
if (!should)
switchCases.Clear();
else if (should && haveLoop == S.For)
// Can't "break" out of the for-loop when there is a nested switch,
haveLoop = GSymbol.Get(NextStopLabel()); // so use "goto stop".
}
}
LNode[] branchCode = new LNode[tree.Children.Count];
for (int i = 0; i < tree.Children.Count; i++)
if (tree.Children[i].IsErrorBranch) {
if (alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value) {
Debug.Assert(matchingCode.Length == alts.Arms.Count + 1);
branchCode[i] = matchingCode[alts.Arms.Count].A;
} else
branchCode[i] = CGH.ErrorBranch(tree.TotalCoverage, tree.Lookahead);
} else
branchCode[i] = GetPredictionSubtreeCode(tree.Children[i], matchingCode, ref haveLoop);
var code = GenerateIfElseChain(tree, branchCode, ref laVar, switchCases);
if (laVar != null) {
block.Insert(0, F.Assign(laVar, CGH.LA(tree.Lookahead)));
_laVarsNeeded |= 1ul << tree.Lookahead;
} else if (should)
laVar = CGH.LA(tree.Lookahead);
if (should) {
Debug.Assert(switchCases.Count != 0);
code = CGH.GenerateSwitch(branchSets, switchCases, branchCode, code, laVar);
}
block.Add(code);
return F.Braces(block.ToVList());
}
public static LNode unroll(LNode var, VList <LNode> cases, LNode body, IMessageSink sink)
{
// Maps identifiers => replacements. The integer counts how many times replacement occurred.
var replacements = InternalList <Triplet <Symbol, LNode, int> > .Empty;
if (var.IsId && !var.HasPAttrs())
{
replacements.Add(Pair.Create(var.Name, (LNode)LNode.Missing, 0));
}
else
{
var vars = var.Args;
if ((var.Calls(S.Tuple) || var.Calls(S.Braces)) && vars.All(a => a.IsId && !a.HasPAttrs()))
{
replacements = new Triplet <Symbol, LNode, int> [vars.Count].AsInternalList();
for (int i = 0; i < vars.Count; i++)
{
replacements.InternalArray[i].A = vars[i].Name;
// Check for duplicate names
for (int j = 0; j < i; j++)
{
if (replacements[i].A == replacements[j].A && replacements[i].A.Name != "_")
{
sink.Error(vars[i], "Duplicate name in the left-hand tuple"); // non-fatal
}
}
}
}
else
{
return(Reject(sink, var, "The left-hand side of 'in' should be a simple identifier or a tuple of simple identifiers."));
}
}
UnrollCtx ctx = new UnrollCtx {
Replacements = replacements
};
WList <LNode> output = new WList <LNode>();
int iteration = 0;
foreach (LNode replacement in cases)
{
iteration++;
bool tuple = replacement.Calls(S.Tuple) || replacement.Calls(S.Braces);
int count = tuple ? replacement.ArgCount : 1;
if (replacements.Count != count)
{
sink.Error(replacement, "iteration {0}: Expected {1} replacement items, got {2}", iteration, replacements.Count, count);
if (count < replacements.Count)
{
continue; // too few
}
}
for (int i = 0; i < replacements.Count; i++)
{
replacements.InternalArray[i].B = tuple ? replacement.Args[i] : replacement;
}
if (body.Calls(S.Braces))
{
foreach (LNode stmt in body.Args)
{
output.Add(ctx.Replace(stmt).Value);
}
}
else
{
output.Add(ctx.Replace(body).Value);
}
}
foreach (var r in replacements)
{
if (r.C == 0 && !r.A.Name.StartsWith("_"))
{
sink.Write(Severity.Warning, var, "Replacement variable '{0}' was never used", r.A);
}
}
return(body.With(S.Splice, output.ToVList()));
}
// GENERATED CODE EXAMPLE: The methods in this region generate
// the for(;;) loop in this example and everything inside it, except
// the calls to Match() which are generated by Visit(TerminalPred).
// The generated code uses "goto" and "match" blocks in some cases
// to avoid code duplication. This occurs when the matching code
// requires multiple statements AND appears more than once in the
// prediction tree. Otherwise, matching is done "inline" during
// prediction. We generate a for(;;) loop for (...)*, and in certain
// cases, we generates a do...while(false) loop for (...)?.
//
// rule Foo @{ (('a'|'A') 'A')* 'a'..'z' 'a'..'z' };
// public void Foo()
// {
// int la0, la1;
// for (;;) {
// la0 = LA(0);
// if (la0 == 'a') {
// la1 = LA(1);
// if (la1 == 'A')
// goto match1;
// else
// break;
// } else if (la0 == 'A')
// goto match1;
// else
// break;
// match1:
// {
// Match('A', 'a');
// Match('A');
// }
// }
// MatchRange('a', 'z');
// MatchRange('a', 'z');
// }
private void GenerateCodeForAlts(Alts alts, Dictionary <int, int> timesUsed, PredictionTree tree)
{
bool needError = LLPG.NeedsErrorBranch(tree, alts);
if (!needError && alts.ErrorBranch != null)
{
LLPG.Output(Warning, alts, "The error branch will not be used because the other alternatives are exhaustive (cover all cases)");
}
bool userDefinedError = needError && !_recognizerMode && alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value;
// Generate matching code for each arm. the "string" in each pair
// becomes non-null if the matching code for that branch needs to be
// split out (separated) from the prediction tree because it appears
// multiple times in the tree. The string is the goto-label name.
Pair <LNode, string>[] matchingCode = new Pair <LNode, string> [alts.Arms.Count + (userDefinedError ? 1: 0)];
MSet <int> unreachable = new MSet <int>();
int separateCount = 0;
for (int i = 0; i < alts.Arms.Count; i++)
{
if (!timesUsed.ContainsKey(i))
{
unreachable.Add(i);
continue;
}
var codeForThisArm = new WList <LNode>();
VisitWithNewTarget(alts.Arms[i], codeForThisArm);
matchingCode[i].A = F.Braces(codeForThisArm.ToVList());
if (timesUsed[i] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A))
{
separateCount++;
matchingCode[i].B = alts.Arms[i].ChooseGotoLabel()
?? "match" + (i + 1).ToString();
}
}
// Add matching code for the error branch, if present. Note: the
// default error branch, which is produced by IPGCodeGenHelper.
// ErrorBranch() is handled differently: default error code can
// differ at each error point in the prediction tree. Therefore
// we generate it later, on-demand.
if (userDefinedError)
{
int i = alts.Arms.Count;
var errorHandler = new WList <LNode>();
VisitWithNewTarget(alts.ErrorBranch, errorHandler);
matchingCode[i].A = F.Braces(errorHandler.ToVList());
if (timesUsed[ErrorAlt] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A))
{
matchingCode[i].B = "error";
separateCount++;
}
}
// Print unreachability warnings
if (unreachable.Count == 1)
{
LLPG.Output(Warning, alts, string.Format("Branch {{{0}}} is unreachable.", alts.AltName(unreachable.First())));
}
else if (unreachable.Count > 1)
{
LLPG.Output(Warning, alts, string.Format("Branches {{{0}}} are unreachable.", unreachable.Select(i => alts.AltName(i)).Join(", ")));
}
if (!timesUsed.ContainsKey(ExitAlt) && alts.Mode != LoopMode.None)
{
LLPG.Output(Warning, alts, "Infinite loop. The exit branch is unreachable.");
}
Symbol loopType = null;
// Choose a loop type for (...)* or (...)?:
if (alts.Mode == LoopMode.Star)
{
loopType = S.For;
}
else if (alts.Mode == LoopMode.Opt)
{
if (alts.HasErrorBranch(LLPG) || alts.NonExitDefaultArmRequested())
{
loopType = S.DoWhile;
}
}
// If the code for an arm is nontrivial and appears multiple times
// in the prediction table, it will have to be split out into a
// labeled block and reached via "goto". I'd rather just do a goto
// from inside one "if" statement to inside another, but in C#
// (unlike in CIL, and unlike in C) that is prohibited :(
DeduplicateLabels(matchingCode);
var extraMatching = GenerateExtraMatchingCode(matchingCode, separateCount, ref loopType);
if (separateCount != 0)
{
loopType = loopType ?? S.DoWhile;
}
Symbol breakMode = loopType; // used to request a "goto" label in addition to the loop
LNode code = GeneratePredictionTreeCode(tree, matchingCode, ref breakMode);
// Add break/continue between prediction tree and extra matching code,
// if necessary.
if (extraMatching.Count != 0 && CodeGenHelperBase.EndMayBeReachable(code))
{
loopType = loopType ?? S.DoWhile;
extraMatching.Insert(0, GetContinueStmt(loopType));
}
if (!extraMatching.IsEmpty)
{
code = LNode.MergeLists(code, F.Braces(extraMatching), S.Braces);
}
if (loopType == S.For)
{
// (...)* => for (;;) {}
code = F.Call(S.For, F.List(), F.Missing, F.List(), code);
}
else if (loopType == S.DoWhile)
{
// (...)? becomes "do {...} while(false);" IF the exit branch is NOT the default.
// If the exit branch is the default, then no loop and no "break" is needed.
code = F.Call(S.DoWhile, code, F.@false);
}
if (breakMode != loopType && breakMode != null)
{
// Add "stop:" label (plus extra ";" for C# compatibility, in
// case the label ends the block in which it is located.)
var stopLabel = F.Call(S.Label, F.Id(breakMode))
.PlusTrailingTrivia(F.Trivia(S.TriviaRawText, ";"));
code = LNode.MergeLists(code, stopLabel, S.Braces);
}
int oldCount = _target.Count;
_target.SpliceAdd(code, S.Braces);
// Add comment before code
if (LLPG.AddComments)
{
var pos = alts.Basis.Range.Start;
var comment = F.Trivia(S.TriviaSLComment, string.Format(" Line {0}: {1}", pos.Line, alts.ToString()));
if (_target.Count > oldCount)
{
_target[oldCount] = _target[oldCount].PlusAttr(comment);
}
}
}
public override LNode GenerateMatchExpr(IPGTerminalSet set_, bool savingResult, bool recognizerMode)
{
var set = (PGIntSet)set_;
LNode call;
var type = set.ChooseMatchType(2, 4);
if (type != PGIntSet.Match.Set) {
var args = new WList<LNode>();
if (type == PGIntSet.Match.Ranges) {
// Use MatchRange or MatchExceptRange
foreach (var r in set) {
if (!set.IsInverted || r.Lo != EOF_int || r.Hi != EOF_int) {
args.Add((LNode)set.MakeLiteral(r.Lo));
args.Add((LNode)set.MakeLiteral(r.Hi));
}
}
var target = recognizerMode
? (set.IsInverted ? _TryMatchExceptRange : _TryMatchRange)
: (set.IsInverted ? _MatchExceptRange : _MatchRange);
call = ApiCall(target, args);
} else {
// Use Match or MatchExcept
foreach (var r in set) {
for (int c = r.Lo; c <= r.Hi; c++) {
if (!set.IsInverted || c != EOF_int)
args.Add((LNode)set.MakeLiteral(c));
}
}
var target = recognizerMode
? (set.IsInverted ? _TryMatchExcept : _TryMatch)
: (set.IsInverted ? _MatchExcept : _Match);
call = ApiCall(target, args.ToVList());
}
} else {
var setName = GenerateSetDecl(set);
if (set.IsInverted)
call = ApiCall(recognizerMode ? _TryMatchExcept : _MatchExcept, F.Id(setName));
else
call = ApiCall(recognizerMode ? _TryMatch : _Match, F.Id(setName));
}
return call;
}
public static LNodeList ToLNodeList(this WList <LNode> list) => new LNodeList(list.ToVList());
public static LNode @try(LNode node, IMessageSink sink)
{
if (!node.IsCall)
{
return(null);
}
// try(code, catch, Exception::e, handler, catch, ..., finally, handler)
// ...becomes...
// #try(#{ stmt1; stmt2; ... }, #catch(#var(Exception, e), handler), #finally(handler))
LNode finallyCode = null;
WList <LNode> clauses = new WList <LNode>();
var parts = node.Args;
for (int i = parts.Count - 2; i >= 1; i -= 2)
{
var p = parts[i];
if (p.IsIdNamed(_finally))
{
if (clauses.Count != 0 || finallyCode != null)
{
sink.Write(Severity.Error, p, "The «finally» clause must come last, there can only be one of them.");
}
finallyCode = parts[i + 1];
}
else if (p.Name == _catch)
{
if (p.ArgCount > 0)
{
if (p.ArgCount > 1)
{
sink.Write(Severity.Error, p, "Expected catch() to take one argument.");
}
// This is a normal catch clause
clauses.Insert(0, F.Call(S.Catch, p.Args[0], F.Missing, parts[i + 1]));
}
else
{
// This is a catch-all clause (the type argument is missing)
if (clauses.Count != 0)
{
sink.Write(Severity.Error, p, "The catch-all clause must be the last «catch» clause.");
}
clauses.Add(F.Call(S.Catch, F.Missing, F.Missing, parts[i + 1]));
}
}
else if (i > 1 && parts[i - 1].IsIdNamed(_catch))
{
// This is a normal catch clause
clauses.Insert(0, F.Call(S.Catch, AutoRemoveParens(p), F.Missing, parts[i + 1]));
i--;
}
else
{
return(Reject(sink, p, "Expected «catch» or «finally» clause here. Clause is missing or malformed."));
}
if (i == 2)
{
return(Reject(sink, parts[1], "Expected «catch» or «finally» clause here. Clause is missing or malformed."));
}
}
if (clauses.Count == 0 && finallyCode == null)
{
Debug.Assert(node.ArgCount <= 1);
return(Reject(sink, node, "Missing «catch, Type, Code» or «finally, Code» clause"));
}
if (finallyCode != null)
{
clauses.Add(F.Call(S.Finally, finallyCode));
}
clauses.Insert(0, node.Args[0]);
return(node.With(S.Try, clauses.ToVList()));
}
public static LNode @var(LNode node, IMessageSink sink)
{
var parts = node.Args;
if (parts.Count == 0)
{
return(Reject(sink, node, "A variable definition must have the form var(Name::Type), var(Name = value), or var(Name::Type = value)"));
}
if (parts[0].IsId)
{
return(null); // e.g. this is true for "static readonly x::Foo"
}
WList <LNode> varStmts = null;
LNode varStmt = null;
for (int i = 0; i < parts.Count; i++)
{
LNode part = parts[i], type = null, init = null;
if (part.Calls(S.Assign, 2))
{
init = part.Args[1];
part = part.Args[0];
}
if (part.Calls(S.ColonColon, 2))
{
type = part.Args[1];
part = part.Args[0];
}
if (init == null && part.Calls(S.Assign, 2))
{
init = part.Args[1];
part = part.Args[0];
}
if (!part.IsId)
{
return(Reject(sink, part, "Expected a simple variable name here"));
}
if (type != null && !IsComplexId(type))
{
return(Reject(sink, type, "Expected a type name here"));
}
type = type ?? F.Missing;
var nameAndInit = init == null ? part : F.Call(S.Assign, part, init);
if (varStmt != null && varStmt.Args[0].Equals(type))
{
// same type used again, e.g. (var x::int y::int) => (#var int x y)
varStmt = varStmt.WithArgs(varStmt.Args.Add(nameAndInit));
}
else
{
// first item (var x::int => #var int x) or type changed (var a::A b::B => #var A a; #var B b)
if (varStmt != null)
{
varStmts = varStmts ?? new WList <LNode>();
varStmts.Add(varStmt);
}
varStmt = node.With(S.Var, type, nameAndInit);
}
}
// Return a single statement or a list of them if necessary
if (varStmts != null)
{
varStmts.Add(varStmt);
return(F.Call(S.Splice, varStmts.ToVList()));
}
else
{
return(varStmt);
}
}
[LexicalMacro("matchCode (var) { case ...: ... }; // In LES, use a => b instead of case a: b", "Attempts to match and deconstruct a Loyc tree against a series of cases with patterns, e.g. " + "`case $a + $b:` expects a tree that calls `+` with two parameters, placed in new variables called a and b. " + "`break` is not required or recognized at the end of each case's handler (code block). " + "Use `$(...x)` to gather zero or more parameters into a list `x`. " + "Use `case pattern1, pattern2:` in EC# to handle multiple cases with the same handler.")] public static LNode matchCode(LNode node, IMacroContext context)
{
var args_body = context.GetArgsAndBody(true);
VList<LNode> 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(args[0], output);
var ifClauses = new List<Pair<LNode,LNode>>();
var cmc = new CodeMatchContext {
Context = context
};
foreach (var @case in cases) {
cmc.ThenClause.Clear();
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 = @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.Write(Severity.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.Call(CodeSymbols.Of, LNode.List(LNode.Id((Symbol) "VList"), LNode.Id((Symbol) "LNode")));
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;
else {
output.Add(ifStmt);
return F.Braces(output.ToVList());
}
}
public virtual LNode GenerateSwitch(IPGTerminalSet[] branchSets, MSet<int> casesToInclude, LNode[] branchCode, LNode defaultBranch, LNode laVar)
{
Debug.Assert(branchSets.Length == branchCode.Length);
WList<LNode> stmts = new WList<LNode>();
for (int i = 0; i < branchSets.Length; i++)
{
if (casesToInclude.Contains(i))
{
foreach (LNode value in GetCases(branchSets[i]))
{
stmts.Add(F.Call(S.Case, value));
if (stmts.Count > 65535) // sanity check
throw new InvalidOperationException("switch is too large to generate");
}
AddSwitchHandler(branchCode[i], stmts);
}
}
if (!defaultBranch.IsIdNamed(S.Missing))
{
stmts.Add(F.Call(S.Label, F.Id(S.Default)));
AddSwitchHandler(defaultBranch, stmts);
}
return F.Call(S.Switch, (LNode)laVar, F.Braces(stmts.ToVList()));
}
public static LNode unroll(LNode var, LNode cases, LNode body, IMessageSink sink)
{
if (!cases.Calls(S.Tuple) && !cases.Calls(S.Braces))
return Reject(sink, cases, "unroll: the right-hand side of 'in' should be a tuple");
// Maps identifiers => replacements. The integer counts how many times replacement occurred.
var replacements = InternalList<Triplet<Symbol, LNode, int>>.Empty;
if (var.IsId && !var.HasPAttrs()) {
replacements.Add(Pair.Create(var.Name, (LNode)LNode.Missing, 0));
} else {
var vars = var.Args;
if ((var.Calls(S.Tuple) || var.Calls(S.Braces)) && vars.All(a => a.IsId && !a.HasPAttrs())) {
replacements = new Triplet<Symbol, LNode, int>[vars.Count].AsInternalList();
for (int i = 0; i < vars.Count; i++) {
replacements.InternalArray[i].A = vars[i].Name;
// Check for duplicate names
for (int j = 0; j < i; j++)
if (replacements[i].A == replacements[j].A && replacements[i].A.Name != "_")
sink.Write(Severity.Error, vars[i], "unroll: duplicate name in the left-hand tuple"); // non-fatal
}
} else
return Reject(sink, cases, "unroll: the left-hand side of 'in' should be a simple identifier or a tuple of simple identifiers.");
}
UnrollCtx ctx = new UnrollCtx { Replacements = replacements };
WList<LNode> output = new WList<LNode>();
int iteration = 0;
foreach (LNode replacement in cases.Args)
{
iteration++;
bool tuple = replacement.Calls(S.Tuple) || replacement.Calls(S.Braces);
int count = tuple ? replacement.ArgCount : 1;
if (replacements.Count != count)
{
sink.Write(Severity.Error, replacement, "unroll, iteration {0}: Expected {1} replacement items, got {2}", iteration, replacements.Count, count);
if (count < replacements.Count)
continue; // too few
}
for (int i = 0; i < replacements.Count; i++)
replacements.InternalArray[i].B = tuple ? replacement.Args[i] : replacement;
if (body.Calls(S.Braces)) {
foreach (LNode stmt in body.Args)
output.Add(ctx.Replace(stmt).Value);
} else
output.Add(ctx.Replace(body).Value);
}
foreach (var r in replacements)
if (r.C == 0 && !r.A.Name.StartsWith("_"))
sink.Write(Severity.Warning, var, "Replacement variable '{0}' was never used", r.A);
return body.With(S.Splice, output.ToVList());
}
protected LNode GeneratePredictionTreeCode(PredictionTree tree, Pair <LNode, string>[] matchingCode, ref Symbol haveLoop)
{
var braces = F.Braces();
Debug.Assert(tree.Children.Count >= 1);
var alts = (Alts)_currentPred;
if (tree.Children.Count == 1)
{
return(GetPredictionSubtreeCode(tree.Children[0], matchingCode, ref haveLoop));
}
// From the prediction table, we can generate either an if-else chain:
//
// if (la0 >= '0' && la0 <= '7') sub_tree_1();
// else if (la0 == '-') sub_tree_2();
// else break;
//
// or a switch statement:
//
// switch(la0) {
// case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7':
// sub_tree_1();
// break;
// case '-':
// sub_tree_2();
// break;
// default:
// goto breakfor;
// }
//
// Assertion levels always need an if-else chain; lookahead levels
// consider the complexity of switch vs if and decide which is most
// appropriate. Generally "if" is slower, but a switch may require
// too many labels since it doesn't support ranges like "la0 >= 'a'
// && la0 <= 'z'".
//
// This class makes if-else chains directly (using IPGTerminalSet.
// GenerateTest() to generate the test expressions), but the code
// generation helper (CGH) is used to generate switch statements
// because the required code may be more complex.
//
// We may or may not be generating code inside a for(;;) loop. If we
// decide to generate a switch() statement, one of the branches will
// usually need to break out of the for loop, but "break" can only
// break out of the switch(). In that case, add "stop:" after the
// switch() and use "goto stop" instead of "break".
WList <LNode> block = new WList <LNode>();
LNode laVar = null;
MSet <int> switchCases = new MSet <int>();
IPGTerminalSet[] branchSets = null;
bool should = false;
if (tree.UsesLA())
{
laVar = F.Id("la" + tree.Lookahead.ToString());
if (!tree.IsAssertionLevel)
{
IPGTerminalSet covered = CGH.EmptySet;
branchSets = tree.Children.Select(branch => {
var set = branch.Set.Subtract(covered);
covered = covered.Union(branch.Set);
return(set);
}).ToArray();
should = CGH.ShouldGenerateSwitch(branchSets, switchCases, tree.Children.Last.IsErrorBranch);
if (!should)
{
switchCases.Clear();
}
else if (should && haveLoop == S.For)
{
// Can't "break" out of the for-loop when there is a nested switch,
haveLoop = GSymbol.Get(NextStopLabel()); // so use "goto stop".
}
}
}
LNode[] branchCode = new LNode[tree.Children.Count];
for (int i = 0; i < tree.Children.Count; i++)
{
if (tree.Children[i].IsErrorBranch)
{
if (_recognizerMode)
{
branchCode[i] = F.Call(S.Return, F.False);
}
else if (alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value)
{
Debug.Assert(matchingCode.Length == alts.Arms.Count + 1);
branchCode[i] = matchingCode[alts.Arms.Count].A;
}
else
{
branchCode[i] = CGH.ErrorBranch(tree.TotalCoverage, tree.Lookahead);
}
}
else
{
branchCode[i] = GetPredictionSubtreeCode(tree.Children[i], matchingCode, ref haveLoop);
}
}
var code = GenerateIfElseChain(tree, branchCode, ref laVar, switchCases);
if (laVar != null)
{
block.Insert(0, F.Assign(laVar, CGH.LA(tree.Lookahead)));
_laVarsNeeded |= 1ul << tree.Lookahead;
}
else if (should)
{
laVar = CGH.LA(tree.Lookahead);
}
if (should)
{
Debug.Assert(switchCases.Count != 0);
code = CGH.GenerateSwitch(branchSets, branchCode, switchCases, code ?? F.Missing, laVar);
}
block.Add(code);
return(F.Braces(block.ToVList()));
}
public LNode Vars(LNode type, params LNode[] namesWithValues)
{
type = type ?? Missing;
var list = new WList<LNode>() { type };
list.AddRange(namesWithValues);
return Call(S.Var, list.ToVList());
}
public void ScanClassBody(VList <LNode> body)
{
foreach (var stmt in body)
{
int i;
{
LNode altName;
VList <LNode> attrs, childBody = default(VList <LNode>), parts, rest;
if ((attrs = stmt.Attrs).IsEmpty | true && stmt.Calls(CodeSymbols.Fn, 3) && stmt.Args[0].IsIdNamed((Symbol)"alt") && (altName = stmt.Args[1]) != null && stmt.Args[2].Calls(CodeSymbols.AltList) && (parts = stmt.Args[2].Args).IsEmpty | true || (attrs = stmt.Attrs).IsEmpty | true && stmt.Calls(CodeSymbols.Fn, 4) && stmt.Args[0].IsIdNamed((Symbol)"alt") && (altName = stmt.Args[1]) != null && stmt.Args[2].Calls(CodeSymbols.AltList) && (parts = stmt.Args[2].Args).IsEmpty | true && stmt.Args[3].Calls(CodeSymbols.Braces) && (childBody = stmt.Args[3].Args).IsEmpty | true)
{
LNode genericAltName = altName;
if (altName.CallsMin(CodeSymbols.Of, 1))
{
}
else if (_genericArgs.Count > 0)
{
genericAltName = LNode.Call(CodeSymbols.Of, LNode.List().Add(altName).AddRange(_genericArgs.ToVList())).SetStyle(NodeStyle.Operator);
}
var child = new AltType(attrs, genericAltName, LNode.List(), this);
child.AddParts(parts);
child.ScanClassBody(childBody);
_children.Add(child);
}
else if ((attrs = stmt.Attrs).IsEmpty | true && (i = attrs.IndexWhere(a => a.IsIdNamed(__alt))) > -1 && stmt.CallsMin(CodeSymbols.Constructor, 3) && stmt.Args[1].IsIdNamed((Symbol)"#this") && stmt.Args[2].Calls(CodeSymbols.AltList) && (rest = new VList <LNode>(stmt.Args.Slice(3))).IsEmpty | true && rest.Count <= 1)
{
parts = stmt.Args[2].Args;
attrs.RemoveAt(i);
_constructorAttrs.AddRange(attrs);
if (rest.Count > 0 && rest[0].Calls(S.Braces))
{
_extraConstrLogic.AddRange(rest[0].Args);
}
AddParts(parts);
}
else
{
_classBody.Add(stmt);
}
}
}
}
public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList<LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces)) {
contents = node.Args[1].Args;
var outputs = new WList<LNode>();
input = MaybeAddTempVarDecl(context, input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i) {
var @case = contents[case_i];
if (!IsCaseLabel(@case))
return Reject(context, contents[0], "In 'match': expected 'case' statement");
for (next_i = case_i + 1; next_i < contents.Count; next_i++) {
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
break;
if (stmt.Calls(S.Break, 0)) {
next_i++;
break;
}
}
var handler = new VList<LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0) {
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
outputs.Add(codeGen.GenCodeForPattern(pattern));
} else { // default:
// Note: the extra {braces} around the handler are rarely
// needed. They are added just in case the handler declares a
// variable and a different handler declares another variable
// by the same name, which is illegal unless we add braces.
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
context.Sink.Error(contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
return LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false)));
}
}
return null;
}
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);
VList<LNode> 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 = @case.Value.AsLNode(S.Braces);
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.Call(CodeSymbols.Of, LNode.List(LNode.Id((Symbol) "VList"), LNode.Id((Symbol) "LNode"))).SetStyle(NodeStyle.Operator);
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;
else {
output.Add(ifStmt);
return F.Braces(output.ToVList());
}
}
[LexicalMacro("matchCode (var) { case ...: ... }; // In LES, use a => b instead of case a: b", "Attempts to match and deconstruct a Loyc tree against a series of cases with patterns, e.g. " + "`case $a + $b:` expects a tree that calls `+` with two parameters, placed in new variables called a and b. " + "`break` is not required or recognized at the end of each case's handler (code block). " + "Use `$(...x)` to gather zero or more parameters into a list `x`. " + "Use `case pattern1, pattern2:` in EC# to handle multiple cases with the same handler.")] public static LNode matchCode(LNode node, IMacroContext context)
{
var args_body = context.GetArgsAndBody(true);
VList <LNode> 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(args[0], output);
var ifClauses = new List <Pair <LNode, LNode> >();
var cmc = new CodeMatchContext {
Context = context
};
foreach (var @case in cases)
{
cmc.ThenClause.Clear();
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 = @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.Write(Severity.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.Call(CodeSymbols.Of, LNode.List(LNode.Id((Symbol)"VList"), LNode.Id((Symbol)"LNode")));
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);
}
else
{
output.Add(ifStmt);
return(F.Braces(output.ToVList()));
}
}
// GENERATED CODE EXAMPLE: The methods in this region generate
// the for(;;) loop in this example and everything inside it, except
// the calls to Match() which are generated by Visit(TerminalPred).
// The generated code uses "goto" and "match" blocks in some cases
// to avoid code duplication. This occurs when the matching code
// requires multiple statements AND appears more than once in the
// prediction tree. Otherwise, matching is done "inline" during
// prediction. We generate a for(;;) loop for (...)*, and in certain
// cases, we generates a do...while(false) loop for (...)?.
//
// rule Foo @{ (('a'|'A') 'A')* 'a'..'z' 'a'..'z' };
// public void Foo()
// {
// int la0, la1;
// for (;;) {
// la0 = LA(0);
// if (la0 == 'a') {
// la1 = LA(1);
// if (la1 == 'A')
// goto match1;
// else
// break;
// } else if (la0 == 'A')
// goto match1;
// else
// break;
// match1:
// {
// Match('A', 'a');
// Match('A');
// }
// }
// MatchRange('a', 'z');
// MatchRange('a', 'z');
// }
private void GenerateCodeForAlts(Alts alts, Dictionary<int, int> timesUsed, PredictionTree tree)
{
bool needError = LLPG.NeedsErrorBranch(tree, alts);
if (!needError && alts.ErrorBranch != null)
LLPG.Output(Warning, alts, "The error branch will not be used because the other alternatives are exhaustive (cover all cases)");
bool userDefinedError = needError && alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value;
// Generate matching code for each arm. the "string" in each pair
// becomes non-null if the matching code for that branch needs to be
// split out (separated) from the prediction tree because it appears
// multiple times in the tree. The string is the goto-label name.
Pair<LNode, string>[] matchingCode = new Pair<LNode, string>[alts.Arms.Count + (userDefinedError ? 1 : 0)];
MSet<int> unreachable = new MSet<int>();
int separateCount = 0;
for (int i = 0; i < alts.Arms.Count; i++) {
if (!timesUsed.ContainsKey(i)) {
unreachable.Add(i);
continue;
}
var codeForThisArm = new WList<LNode>();
VisitWithNewTarget(alts.Arms[i], codeForThisArm);
matchingCode[i].A = F.Braces(codeForThisArm.ToVList());
if (timesUsed[i] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A)) {
separateCount++;
matchingCode[i].B = alts.Arms[i].ChooseGotoLabel()
?? "match" + (i + 1).ToString();
}
}
// Add matching code for the error branch, if present. Note: the
// default error branch, which is produced by IPGCodeGenHelper.
// ErrorBranch() is handled differently: default error code can
// differ at each error point in the prediction tree. Therefore
// we generate it later, on-demand.
if (userDefinedError) {
int i = alts.Arms.Count;
var errorHandler = new WList<LNode>();
VisitWithNewTarget(alts.ErrorBranch, errorHandler);
matchingCode[i].A = F.Braces(errorHandler.ToVList());
if (timesUsed[ErrorAlt] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A)) {
matchingCode[i].B = "error";
separateCount++;
}
}
// Print unreachability warnings
if (unreachable.Count == 1)
LLPG.Output(Warning, alts, string.Format("Branch {{{0}}} is unreachable.", alts.AltName(unreachable.First())));
else if (unreachable.Count > 1)
LLPG.Output(Warning, alts, string.Format("Branches {{{0}}} are unreachable.", unreachable.Select(i => alts.AltName(i)).Join(", ")));
if (!timesUsed.ContainsKey(ExitAlt) && alts.Mode != LoopMode.None)
LLPG.Output(Warning, alts, "Infinite loop. The exit branch is unreachable.");
Symbol loopType = null;
// Choose a loop type for (...)* or (...)?:
if (alts.Mode == LoopMode.Star)
loopType = S.For;
else if (alts.Mode == LoopMode.Opt) {
if (alts.HasErrorBranch(LLPG) || alts.NonExitDefaultArmRequested())
loopType = S.DoWhile;
}
// If the code for an arm is nontrivial and appears multiple times
// in the prediction table, it will have to be split out into a
// labeled block and reached via "goto". I'd rather just do a goto
// from inside one "if" statement to inside another, but in C#
// (unlike in CIL, and unlike in C) that is prohibited :(
DeduplicateLabels(matchingCode);
var extraMatching = GenerateExtraMatchingCode(matchingCode, separateCount, ref loopType);
if (separateCount != 0)
loopType = loopType ?? S.DoWhile;
Symbol breakMode = loopType; // used to request a "goto" label in addition to the loop
LNode code = GeneratePredictionTreeCode(tree, matchingCode, ref breakMode);
// Add break/continue between prediction tree and extra matching code,
// if necessary.
if (extraMatching.Count != 0 && CodeGenHelperBase.EndMayBeReachable(code)) {
loopType = loopType ?? S.DoWhile;
extraMatching.Insert(0, GetContinueStmt(loopType));
}
if (!extraMatching.IsEmpty)
code = LNode.MergeLists(code, F.Braces(extraMatching), S.Braces);
if (loopType == S.For) {
// (...)* => for (;;) {}
code = F.Call(S.For, F.List(), F.Missing, F.List(), code);
} else if (loopType == S.DoWhile) {
// (...)? becomes "do {...} while(false);" IF the exit branch is NOT the default.
// If the exit branch is the default, then no loop and no "break" is needed.
code = F.Call(S.DoWhile, code, F.@false);
}
if (breakMode != loopType && breakMode != null) {
// Add "stop:" label (plus extra ";" for C# compatibility, in
// case the label ends the block in which it is located.)
var stopLabel = F.Call(S.Label, F.Id(breakMode))
.PlusTrailingTrivia(F.Trivia(S.TriviaRawText, ";"));
code = LNode.MergeLists(code, stopLabel, S.Braces);
}
int oldCount = _target.Count;
_target.SpliceAdd(code, S.Braces);
// Add comment before code
if (LLPG.AddComments) {
var pos = alts.Basis.Range.Start;
var comment = F.Trivia(S.TriviaSLComment, string.Format(" Line {0}: {1}", pos.Line, alts.ToString()));
if (_target.Count > oldCount)
_target[oldCount] = _target[oldCount].PlusAttr(comment);
}
}
public static LNode @try(LNode node, IMessageSink sink)
{
if (!node.IsCall)
return null;
// try(code, catch, Exception::e, handler, catch, ..., finally, handler)
// ...becomes...
// #try(#{ stmt1; stmt2; ... }, #catch(#var(Exception, e), handler), #finally(handler))
LNode finallyCode = null;
WList<LNode> clauses = new WList<LNode>();
var parts = node.Args;
for (int i = parts.Count-2; i >= 1; i -= 2)
{
var p = parts[i];
if (p.IsIdNamed(_finally)) {
if (clauses.Count != 0 || finallyCode != null)
sink.Write(Severity.Error, p, "The «finally» clause must come last, there can only be one of them.");
finallyCode = parts[i+1];
} else if (p.Name == _catch) {
if (p.ArgCount > 0) {
if (p.ArgCount > 1)
sink.Write(Severity.Error, p, "Expected catch() to take one argument.");
// This is a normal catch clause
clauses.Insert(0, F.Call(S.Catch, p.Args[0], F.Missing, parts[i + 1]));
} else {
// This is a catch-all clause (the type argument is missing)
if (clauses.Count != 0)
sink.Write(Severity.Error, p, "The catch-all clause must be the last «catch» clause.");
clauses.Add(F.Call(S.Catch, F.Missing, F.Missing, parts[i + 1]));
}
} else if (i > 1 && parts[i-1].IsIdNamed(_catch)) {
// This is a normal catch clause
clauses.Insert(0, F.Call(S.Catch, AutoRemoveParens(p), F.Missing, parts[i+1]));
i--;
} else {
return Reject(sink, p, "Expected «catch» or «finally» clause here. Clause is missing or malformed.");
}
if (i == 2)
return Reject(sink, parts[1], "Expected «catch» or «finally» clause here. Clause is missing or malformed.");
}
if (clauses.Count == 0 && finallyCode == null) {
Debug.Assert(node.ArgCount <= 1);
return Reject(sink, node, "Missing «catch, Type, Code» or «finally, Code» clause");
}
if (finallyCode != null)
clauses.Add(F.Call(S.Finally, finallyCode));
clauses.Insert(0, node.Args[0]);
return node.With(S.Try, clauses.ToVList());
}
public static LNode matchCode(LNode node, IMacroContext context)
{
var args_body = context.GetArgsAndBody(true);
VList <LNode> 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();
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 = @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.Write(Severity.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.Call(CodeSymbols.Of, LNode.List(LNode.Id((Symbol)"VList"), LNode.Id((Symbol)"LNode")));
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);
}
else
{
output.Add(ifStmt);
return(F.Braces(output.ToVList()));
}
}
public static LNode UnpackTuple(LNode node, IMessageSink sink)
{
var a = node.Args;
if (a.Count == 2 && a[0].CallsMin(S.Tuple, 1)) {
var output = new WList<LNode>();
var tuple = a[0].Args;
var rhs = a[1];
// Avoid evaluating rhs more than once, if it doesn't look like a simple variable
rhs = MaybeAddTempVarDecl(rhs, output);
for (int i = 0; i < tuple.Count; i++) {
var itemi = F.Dot(rhs, F.Id(GSymbol.Get("Item" + (i + 1))));
if (tuple[i].Calls(S.Var, 2))
output.Add(F.Var(tuple[i].Args[0], tuple[i].Args[1], itemi));
else
output.Add(F.Call(S.Assign, tuple[i], itemi));
}
return F.Call(S.Splice, output.ToVList());
}
return null;
}
