add type alias

include/remill/Arch/Arch.h

@@ -288,12 +288,15 @@ class Arch {
 
   // The decoder takes contextual information in the form of a DecodingContext, making a copy to produce a ContextMap which is a function that maps
   // a successor to a new context that updates the old context.
-  virtual std::optional<DecodingContext::ContextMap>
+
+  using DecodingResult = std::optional<DecodingContext::ContextMap>;
+
+  virtual DecodingResult
   DecodeInstruction(uint64_t address, std::string_view instr_bytes,
                     Instruction &inst, DecodingContext context) const = 0;
 
   // Decode an instruction that is within a delay slot.
-  std::optional<DecodingContext::ContextMap>
+  DecodingResult
   DecodeDelayedInstruction(uint64_t address, std::string_view instr_bytes,
                            Instruction &inst, DecodingContext context) const {
     inst.in_delay_slot = true;

lib/Arch/Arch.cpp

@@ -855,11 +855,9 @@ DecodingContext DefaultContextAndLifter::CreateInitialContext(void) const {
   return DecodingContext();
 }
 
-std::optional<DecodingContext::ContextMap>
-DefaultContextAndLifter::DecodeInstruction(uint64_t address,
-                                           std::string_view instr_bytes,
-                                           Instruction &inst,
-                                           DecodingContext context) const {
+Arch::DecodingResult DefaultContextAndLifter::DecodeInstruction(
+    uint64_t address, std::string_view instr_bytes, Instruction &inst,
+    DecodingContext context) const {
   inst.SetLifter(std::make_unique<remill::InstructionLifter>(
       this, this->GetInstrinsicTable()));
   if (this->ArchDecodeInstruction(address, instr_bytes, inst)) {

lib/Arch/Sleigh/Arch.cpp

@@ -366,7 +366,7 @@ std::string CustomLoadImage::getArchType(void) const {
 void CustomLoadImage::adjustVma(long) {}
 
 
-std::optional<DecodingContext::ContextMap>
+SleighArch::DecodingResult
 SleighArch::DecodeInstruction(uint64_t address, std::string_view instr_bytes,
                               Instruction &inst,
                               DecodingContext context) const {