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   OS << "LRTable:\n";
51   for (StateID S = 0; S < StateOffset.size() - 1; ++S) {
52     OS << llvm::formatv("State {0}\n", S);
53     for (uint16_t Terminal = 0; Terminal < NumTerminals; ++Terminal) {
54       SymbolID TokID = tokenSymbol(static_cast<tok::TokenKind>(Terminal));
55       for (auto A : find(S, TokID)) {
56         if (A.kind() == LRTable::Action::Shift)
57           OS.indent(4) << llvm::formatv("'{0}': shift state {1}\n",
58                                         G.symbolName(TokID), A.getShiftState());
59         else if (A.kind() == LRTable::Action::Reduce)
60           OS.indent(4) << llvm::formatv("'{0}': reduce by rule {1} '{2}'\n",
61                                         G.symbolName(TokID), A.getReduceRule(),
62                                         G.dumpRule(A.getReduceRule()));
63         else if (A.kind() == LRTable::Action::Accept)
64           OS.indent(4) << llvm::formatv("'{0}': accept\n", G.symbolName(TokID));
65       }
66     }
67     for (SymbolID NontermID = 0; NontermID < G.table().Nonterminals.size();
68          ++NontermID) {
69       if (find(S, NontermID).empty())
70         continue;
71       OS.indent(4) << llvm::formatv("'{0}': go to state {1}\n",
72                                     G.symbolName(NontermID),
73                                     getGoToState(S, NontermID));
74     }
75   }
76   return OS.str();
77 }
78 
79 llvm::ArrayRef<LRTable::Action> LRTable::getActions(StateID State,
80                                                     SymbolID Terminal) const {
81   assert(pseudo::isToken(Terminal) && "expect terminal symbol!");
82   return find(State, Terminal);
83 }
84 
85 LRTable::StateID LRTable::getGoToState(StateID State,
86                                        SymbolID Nonterminal) const {
87   assert(pseudo::isNonterminal(Nonterminal) && "expected nonterminal symbol!");
88   auto Result = find(State, Nonterminal);
89   assert(Result.size() == 1 && Result.front().kind() == Action::GoTo);
90   return Result.front().getGoToState();
91 }
92 
93 llvm::ArrayRef<LRTable::Action> LRTable::find(StateID Src, SymbolID ID) const {
94   assert(Src + 1 < StateOffset.size());
95   std::pair<size_t, size_t> Range =
96       std::make_pair(StateOffset[Src], StateOffset[Src + 1]);
97   auto SymbolRange = llvm::makeArrayRef(Symbols.data() + Range.first,
98                                         Symbols.data() + Range.second);
99 
100   assert(llvm::is_sorted(SymbolRange) &&
101          "subrange of the Symbols should be sorted!");
102   const LRTable::StateID *Start =
103       llvm::partition_point(SymbolRange, [&ID](SymbolID S) { return S < ID; });
104   if (Start == SymbolRange.end())
105     return {};
106   const LRTable::StateID *End = Start;
107   while (End != SymbolRange.end() && *End == ID)
108     ++End;
109   return llvm::makeArrayRef(&Actions[Start - Symbols.data()],
110                             /*length=*/End - Start);
111 }
112 
113 LRTable::StateID LRTable::getStartState(SymbolID Target) const {
114   assert(llvm::is_sorted(StartStates) && "StartStates must be sorted!");
115   auto It = llvm::partition_point(
116       StartStates, [Target](const std::pair<SymbolID, StateID> &X) {
117         return X.first < Target;
118       });
119   assert(It != StartStates.end() && It->first == Target &&
120          "target symbol doesn't have a start state!");
121   return It->second;
122 }
123 
124 } // namespace pseudo
125 } // namespace clang
126