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   1 /* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
   2  * Use of this file is governed by the BSD 3-clause license that
   3  * can be found in the LICENSE.txt file in the project root.
   4  */
   5
   6 #include "misc/MurmurHash.h"
   7 #include "atn/LexerIndexedCustomAction.h"
   8 #include "support/CPPUtils.h"
   9 #include "support/Arrays.h"
  10
  11 #include "atn/LexerActionExecutor.h"
  12
  13 using namespace antlr4;
  14 using namespace antlr4::atn;
  15 using namespace antlr4::misc;
  16 using namespace antlrcpp;
  17
  18 LexerActionExecutor::LexerActionExecutor(const std::vector<Ref<LexerAction>> &lexerActions)
  19   : _lexerActions(lexerActions), _hashCode(generateHashCode()) {
  20 }
  21
  22 LexerActionExecutor::~LexerActionExecutor() {
  23 }
  24
  25 Ref<LexerActionExecutor> LexerActionExecutor::append(Ref<LexerActionExecutor> const& lexerActionExecutor,
  26                                                      Ref<LexerAction> const& lexerAction) {
  27   if (lexerActionExecutor == nullptr) {
  28     return std::make_shared<LexerActionExecutor>(std::vector<Ref<LexerAction>> { lexerAction });
  29   }
  30
  31   std::vector<Ref<LexerAction>> lexerActions = lexerActionExecutor->_lexerActions; // Make a copy.
  32   lexerActions.push_back(lexerAction);
  33   return std::make_shared<LexerActionExecutor>(lexerActions);
  34 }
  35
  36 Ref<LexerActionExecutor> LexerActionExecutor::fixOffsetBeforeMatch(int offset) {
  37   std::vector<Ref<LexerAction>> updatedLexerActions;
  38   for (size_t i = 0; i < _lexerActions.size(); i++) {
  39     if (_lexerActions[i]->isPositionDependent() && !is<LexerIndexedCustomAction>(_lexerActions[i])) {
  40       if (updatedLexerActions.empty()) {
  41         updatedLexerActions = _lexerActions; // Make a copy.
  42       }
  43
  44       updatedLexerActions[i] = std::make_shared<LexerIndexedCustomAction>(offset, _lexerActions[i]);
  45     }
  46   }
  47
  48   if (updatedLexerActions.empty()) {
  49     return shared_from_this();
  50   }
  51
  52   return std::make_shared<LexerActionExecutor>(updatedLexerActions);
  53 }
  54
  55 std::vector<Ref<LexerAction>> LexerActionExecutor::getLexerActions() const {
  56   return _lexerActions;
  57 }
  58
  59 void LexerActionExecutor::execute(Lexer *lexer, CharStream *input, size_t startIndex) {
  60   bool requiresSeek = false;
  61   size_t stopIndex = input->index();
  62
  63   auto onExit = finally([requiresSeek, input, stopIndex]() {
  64     if (requiresSeek) {
  65       input->seek(stopIndex);
  66     }
  67   });
  68   for (auto lexerAction : _lexerActions) {
  69     if (is<LexerIndexedCustomAction>(lexerAction)) {
  70       int offset = (std::static_pointer_cast<LexerIndexedCustomAction>(lexerAction))->getOffset();
  71       input->seek(startIndex + offset);
  72       lexerAction = std::static_pointer_cast<LexerIndexedCustomAction>(lexerAction)->getAction();
  73       requiresSeek = (startIndex + offset) != stopIndex;
  74     } else if (lexerAction->isPositionDependent()) {
  75       input->seek(stopIndex);
  76       requiresSeek = false;
  77     }
  78
  79     lexerAction->execute(lexer);
  80   }
  81 }
  82
  83 size_t LexerActionExecutor::hashCode() const {
  84   return _hashCode;
  85 }
  86
  87 bool LexerActionExecutor::operator == (const LexerActionExecutor &obj) const {
  88   if (&obj == this) {
  89     return true;
  90   }
  91
  92   return _hashCode == obj._hashCode && Arrays::equals(_lexerActions, obj._lexerActions);
  93 }
  94
  95 bool LexerActionExecutor::operator != (const LexerActionExecutor &obj) const {
  96   return !operator==(obj);
  97 }
  98
  99 size_t LexerActionExecutor::generateHashCode() const {
 100   size_t hash = MurmurHash::initialize();
 101   for (auto lexerAction : _lexerActions) {
 102     hash = MurmurHash::update(hash, lexerAction);
 103   }
 104   hash = MurmurHash::finish(hash, _lexerActions.size());
 105
 106   return hash;
 107 }