Example #1
0
        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);
        }
Example #2
0
            // 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);
                    }
                }
            }
Example #3
0
 public static LNode MergeActions(LNode action, LNode action2)
 {
     return(LNode.MergeLists(action, action2, S.Splice));
 }
Example #4
0
        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));
            }
        }
Example #5
0
        [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()));
            }
        }
Example #6
0
        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()));
            }
        }