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LibRegex: Make infinite repetitions short-circuit on empty matches

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This makes (addmittedly weird) patterns like `(a*)*` work correctly
without going into an infinite fork loop.
This commit is contained in:
Ali Mohammad Pur 2021-09-06 02:38:47 +04:30 • committed by Ali Mohammad Pur
parent f8570bd773
commit abbe9da255
4 changed files with 131 additions and 69 deletions
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108
Userland/Libraries/LibRegex/RegexByteCode.cpp
View file

@ -46,6 +46,22 @@ char const* execution_result_name(ExecutionResult result)
}
}
char const* opcode_id_name(OpCodeId opcode)
{
switch (opcode) {
#define __ENUMERATE_OPCODE(x) \
case OpCodeId::x: \
return #x;
ENUMERATE_OPCODES
#undef __ENUMERATE_OPCODE
default:
VERIFY_NOT_REACHED();
return "<Unknown>";
}
}
char const* boundary_check_type_name(BoundaryCheckType ty)
{
switch (ty) {
@ -144,60 +160,14 @@ void ByteCode::ensure_opcodes_initialized()
return;
for (u32 i = (u32)OpCodeId::First; i <= (u32)OpCodeId::Last; ++i) {
switch ((OpCodeId)i) {
case OpCodeId::Exit:
s_opcodes[i] = make<OpCode_Exit>();
break;
case OpCodeId::Jump:
s_opcodes[i] = make<OpCode_Jump>();
break;
case OpCodeId::Compare:
s_opcodes[i] = make<OpCode_Compare>();
break;
case OpCodeId::CheckEnd:
s_opcodes[i] = make<OpCode_CheckEnd>();
break;
case OpCodeId::CheckBoundary:
s_opcodes[i] = make<OpCode_CheckBoundary>();
break;
case OpCodeId::ForkJump:
s_opcodes[i] = make<OpCode_ForkJump>();
break;
case OpCodeId::ForkStay:
s_opcodes[i] = make<OpCode_ForkStay>();
break;
case OpCodeId::FailForks:
s_opcodes[i] = make<OpCode_FailForks>();
break;
case OpCodeId::Save:
s_opcodes[i] = make<OpCode_Save>();
break;
case OpCodeId::Restore:
s_opcodes[i] = make<OpCode_Restore>();
break;
case OpCodeId::GoBack:
s_opcodes[i] = make<OpCode_GoBack>();
break;
case OpCodeId::CheckBegin:
s_opcodes[i] = make<OpCode_CheckBegin>();
break;
case OpCodeId::ClearCaptureGroup:
s_opcodes[i] = make<OpCode_ClearCaptureGroup>();
break;
case OpCodeId::SaveLeftCaptureGroup:
s_opcodes[i] = make<OpCode_SaveLeftCaptureGroup>();
break;
case OpCodeId::SaveRightCaptureGroup:
s_opcodes[i] = make<OpCode_SaveRightCaptureGroup>();
break;
case OpCodeId::SaveRightNamedCaptureGroup:
s_opcodes[i] = make<OpCode_SaveRightNamedCaptureGroup>();
break;
case OpCodeId::Repeat:
s_opcodes[i] = make<OpCode_Repeat>();
break;
case OpCodeId::ResetRepeat:
s_opcodes[i] = make<OpCode_ResetRepeat>();
break;
#define __ENUMERATE_OPCODE(OpCode) \
case OpCodeId::OpCode: \
s_opcodes[i] = make<OpCode_##OpCode>(); \
break;
ENUMERATE_OPCODES
#undef __ENUMERATE_OPCODE
}
}
s_opcodes_initialized = true;
@ -901,4 +871,34 @@ ALWAYS_INLINE ExecutionResult OpCode_ResetRepeat::execute(MatchInput const&, Mat
return ExecutionResult::Continue;
}
ALWAYS_INLINE ExecutionResult OpCode_Checkpoint::execute(MatchInput const&, MatchState& state) const
{
state.checkpoints.set(state.instruction_position, state.string_position);
return ExecutionResult::Continue;
}
ALWAYS_INLINE ExecutionResult OpCode_JumpNonEmpty::execute(MatchInput const&, MatchState& state) const
{
auto current_position = state.string_position;
auto checkpoint_ip = state.instruction_position + size() + checkpoint();
if (state.checkpoints.get(checkpoint_ip).value_or(current_position) != current_position) {
auto form = this->form();
if (form == OpCodeId::Jump) {
state.instruction_position += offset();
return ExecutionResult::Continue;
}
state.fork_at_position = state.instruction_position + size() + offset();
if (form == OpCodeId::ForkJump)
return ExecutionResult::Fork_PrioHigh;
if (form == OpCodeId::ForkStay)
return ExecutionResult::Fork_PrioLow;
}
return ExecutionResult::Continue;
}
}