Add IsSingleType to Descriptors

IsSingleType will return whether the descriptor will give one or multiple scriptPubKeys

Author: achow101

src/script/descriptor.cpp

@@ -575,6 +575,7 @@ class AddressDescriptor final : public DescriptorImpl
             default: return nullopt;
         }
     }
+    bool IsSingleType() const final { return true; }
 };
 
 /** A parsed raw(H) descriptor. */
@@ -602,6 +603,7 @@ class RawDescriptor final : public DescriptorImpl
             default: return nullopt;
         }
     }
+    bool IsSingleType() const final { return true; }
 };
 
 /** A parsed pk(P) descriptor. */
@@ -611,6 +613,7 @@ class PKDescriptor final : public DescriptorImpl
     std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Vector(GetScriptForRawPubKey(keys[0])); }
 public:
     PKDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pk") {}
+    bool IsSingleType() const final { return true; }
 };
 
 /** A parsed pkh(P) descriptor. */
@@ -626,6 +629,7 @@ class PKHDescriptor final : public DescriptorImpl
 public:
     PKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pkh") {}
     Optional<OutputType> GetOutputType() const override { return OutputType::LEGACY; }
+    bool IsSingleType() const final { return true; }
 };
 
 /** A parsed wpkh(P) descriptor. */
@@ -641,6 +645,7 @@ class WPKHDescriptor final : public DescriptorImpl
 public:
     WPKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "wpkh") {}
     Optional<OutputType> GetOutputType() const override { return OutputType::BECH32; }
+    bool IsSingleType() const final { return true; }
 };
 
 /** A parsed combo(P) descriptor. */
@@ -664,6 +669,7 @@ class ComboDescriptor final : public DescriptorImpl
     }
 public:
     ComboDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "combo") {}
+    bool IsSingleType() const final { return false; }
 };
 
 /** A parsed multi(...) or sortedmulti(...) descriptor */
@@ -683,6 +689,7 @@ class MultisigDescriptor final : public DescriptorImpl
     }
 public:
     MultisigDescriptor(int threshold, std::vector<std::unique_ptr<PubkeyProvider>> providers, bool sorted = false) : DescriptorImpl(std::move(providers), {}, sorted ? "sortedmulti" : "multi"), m_threshold(threshold), m_sorted(sorted) {}
+    bool IsSingleType() const final { return true; }
 };
 
 /** A parsed sh(...) descriptor. */
@@ -699,6 +706,7 @@ class SHDescriptor final : public DescriptorImpl
         if (m_subdescriptor_arg->GetOutputType() == OutputType::BECH32) return OutputType::P2SH_SEGWIT;
         return OutputType::LEGACY;
     }
+    bool IsSingleType() const final { return true; }
 };
 
 /** A parsed wsh(...) descriptor. */
@@ -709,6 +717,7 @@ class WSHDescriptor final : public DescriptorImpl
 public:
     WSHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "wsh") {}
     Optional<OutputType> GetOutputType() const override { return OutputType::BECH32; }
+    bool IsSingleType() const final { return true; }
 };
 
 ////////////////////////////////////////////////////////////////////////////

src/script/descriptor.h

@@ -87,6 +87,9 @@ struct Descriptor {
     /** Convert the descriptor back to a string, undoing parsing. */
     virtual std::string ToString() const = 0;
 
+    /** Whether this descriptor will return one scriptPubKey or multiple (aka is or is not combo) */
+    virtual bool IsSingleType() const = 0;
+
     /** Convert the descriptor to a private string. This fails if the provided provider does not have the relevant private keys. */
     virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0;