static void AddCapture(MMap <Symbol, LNode> captures, Symbol capName, LNode candidate)
{
LNode oldCap = captures.TryGetValue(capName, null);
captures[capName] = LNode.MergeLists(oldCap, candidate, S.Splice);
}
// 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 static LNode MergeActions(LNode action, LNode action2)
{
return(LNode.MergeLists(action, action2, S.Splice));
}
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));
}
}
[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 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()));
}
}