1 //===--- LRTable.cpp - Parsing table for LR parsers --------------*- C++-*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "clang-pseudo/LRTable.h"
10 #include "clang-pseudo/Grammar.h"
11 #include "llvm/ADT/ArrayRef.h"
12 #include "llvm/ADT/STLExtras.h"
13 #include "llvm/Support/ErrorHandling.h"
14 #include "llvm/Support/FormatVariadic.h"
15 #include "llvm/Support/raw_ostream.h"
16 
17 namespace clang {
18 namespace pseudo {
19 
20 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const LRTable::Action &A) {
21   switch (A.kind()) {
22   case LRTable::Action::Shift:
23     return OS << llvm::formatv("shift state {0}", A.getShiftState());
24   case LRTable::Action::Reduce:
25     return OS << llvm::formatv("reduce by rule {0}", A.getReduceRule());
26   case LRTable::Action::GoTo:
27     return OS << llvm::formatv("go to state {0}", A.getGoToState());
28   case LRTable::Action::Accept:
29     return OS << "acc";
30   case LRTable::Action::Sentinel:
31     llvm_unreachable("unexpected Sentinel action kind!");
32   }
33   llvm_unreachable("unexpected action kind!");
34 }
35 
36 std::string LRTable::dumpStatistics() const {
37   return llvm::formatv(R"(
38 Statistics of the LR parsing table:
39     number of states: {0}
40     number of actions: {1}
41     size of the table (bytes): {2}
42 )",
43                        StateOffset.size() - 1, Actions.size(), bytes())
44       .str();
45 }
46 
47 std::string LRTable::dumpForTests(const Grammar &G) const {
48   std::string Result;
49   llvm::raw_string_ostream OS(Result);
50   for (StateID S = 0; S < StateOffset.size() - 1; ++S) {
51     OS << llvm::formatv("State {0}\n", S);
52     for (uint16_t Terminal = 0; Terminal < NumTerminals; ++Terminal) {
53       SymbolID TokID = tokenSymbol(static_cast<tok::TokenKind>(Terminal));
54       for (auto A : find(S, TokID)) {
55         if (A.kind() == LRTable::Action::Shift)
56           OS.indent(4) << llvm::formatv("'{0}': shift state {1}\n",
57                                         G.symbolName(TokID), A.getShiftState());
58         else if (A.kind() == LRTable::Action::Reduce)
59           OS.indent(4) << llvm::formatv("'{0}': reduce by rule {1} '{2}'\n",
60                                         G.symbolName(TokID), A.getReduceRule(),
61                                         G.dumpRule(A.getReduceRule()));
62         else if (A.kind() == LRTable::Action::Accept)
63           OS.indent(4) << llvm::formatv("'{0}': accept\n", G.symbolName(TokID));
64       }
65     }
66     for (SymbolID NontermID = 0; NontermID < G.table().Nonterminals.size();
67          ++NontermID) {
68       if (find(S, NontermID).empty())
69         continue;
70       OS.indent(4) << llvm::formatv("'{0}': go to state {1}\n",
71                                     G.symbolName(NontermID),
72                                     getGoToState(S, NontermID));
73     }
74   }
75   return OS.str();
76 }
77 
78 llvm::ArrayRef<LRTable::Action> LRTable::getActions(StateID State,
79                                                     SymbolID Terminal) const {
80   assert(pseudo::isToken(Terminal) && "expect terminal symbol!");
81   return find(State, Terminal);
82 }
83 
84 LRTable::StateID LRTable::getGoToState(StateID State,
85                                        SymbolID Nonterminal) const {
86   assert(pseudo::isNonterminal(Nonterminal) && "expected nonterminal symbol!");
87   auto Result = find(State, Nonterminal);
88   assert(Result.size() == 1 && Result.front().kind() == Action::GoTo);
89   return Result.front().getGoToState();
90 }
91 
92 llvm::ArrayRef<LRTable::Action> LRTable::find(StateID Src, SymbolID ID) const {
93   assert(Src + 1 < StateOffset.size());
94   std::pair<size_t, size_t> Range =
95       std::make_pair(StateOffset[Src], StateOffset[Src + 1]);
96   auto SymbolRange = llvm::makeArrayRef(Symbols.data() + Range.first,
97                                         Symbols.data() + Range.second);
98 
99   assert(llvm::is_sorted(SymbolRange) &&
100          "subrange of the Symbols should be sorted!");
101   const LRTable::StateID *Start =
102       llvm::partition_point(SymbolRange, [&ID](SymbolID S) { return S < ID; });
103   if (Start == SymbolRange.end())
104     return {};
105   const LRTable::StateID *End = Start;
106   while (End != SymbolRange.end() && *End == ID)
107     ++End;
108   return llvm::makeArrayRef(&Actions[Start - Symbols.data()],
109                             /*length=*/End - Start);
110 }
111 
112 LRTable::StateID LRTable::getStartState(SymbolID Target) const {
113   assert(llvm::is_sorted(StartStates) && "StartStates must be sorted!");
114   auto It = llvm::partition_point(
115       StartStates, [Target](const std::pair<SymbolID, StateID> &X) {
116         return X.first < Target;
117       });
118   assert(It != StartStates.end() && It->first == Target &&
119          "target symbol doesn't have a start state!");
120   return It->second;
121 }
122 
123 } // namespace pseudo
124 } // namespace clang
125