Merge #16889: Add some general std::vector utility functions

7d8d3e6a2ad827fa916e3909a18dedb9f7fdce43 Add tests for util/vector.h's Cat and Vector (Pieter Wuille)
e65e61c812df90a56e3ce4a8e76c4b746766f387 Add some general std::vector utility functions (Pieter Wuille)

Pull request description:

  This is another general improvement extracted from #16800 .

  Two functions are added are:

  * Vector(arg1,arg2,arg3,...) constructs a vector with the specified arguments as elements. The vector's type is derived from the arguments. If some of the arguments are rvalue references, they will be moved into place rather than copied (which can't be achieved using list initialization).
  * Cat(vector1,vector2) returns a concatenation of the two vectors, efficiently moving elements when relevant.

  Vector generalizes (and replaces) the `Singleton` function in src/descriptor.cpp, and `Cat` replaces the function in bech32.cpp

ACKs for top commit:
  laanwj:
    ACK 7d8d3e6a2ad827fa916e3909a18dedb9f7fdce43
  MarcoFalke:
    ACK 7d8d3e6a2ad827fa916e3909a18dedb9f7fdce43 (enjoyed reading the tests, but did not compile)

Tree-SHA512: 92325f14e90d7e7d9d920421979aec22bb0d730e0291362b4326cccc76f9c2d865bec33a797c5c0201773468c3773cb50ce52c8eee4c1ec1a4d10db5cf2b9d2a

1 files changed, 14 insertions, 22 deletions

diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index ed1bd4cda9..536807e1d8 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -14,6 +14,7 @@
 #include <util/spanparsing.h>
 #include <util/system.h>
 #include <util/strencodings.h>
+#include <util/vector.h>
 
 #include <memory>
 #include <string>
@@ -501,22 +502,13 @@ public:
     }
 };
 
-/** Construct a vector with one element, which is moved into it. */
-template<typename T>
-std::vector<T> Singleton(T elem)
-{
-    std::vector<T> ret;
-    ret.emplace_back(std::move(elem));
-    return ret;
-}
-
 /** A parsed addr(A) descriptor. */
 class AddressDescriptor final : public DescriptorImpl
 {
     const CTxDestination m_destination;
 protected:
     std::string ToStringExtra() const override { return EncodeDestination(m_destination); }
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(m_destination)); }
+    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Vector(GetScriptForDestination(m_destination)); }
 public:
     AddressDescriptor(CTxDestination destination) : DescriptorImpl({}, {}, "addr"), m_destination(std::move(destination)) {}
     bool IsSolvable() const final { return false; }
@@ -528,7 +520,7 @@ class RawDescriptor final : public DescriptorImpl
     const CScript m_script;
 protected:
     std::string ToStringExtra() const override { return HexStr(m_script.begin(), m_script.end()); }
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Singleton(m_script); }
+    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Vector(m_script); }
 public:
     RawDescriptor(CScript script) : DescriptorImpl({}, {}, "raw"), m_script(std::move(script)) {}
     bool IsSolvable() const final { return false; }
@@ -538,9 +530,9 @@ public:
 class PKDescriptor final : public DescriptorImpl
 {
 protected:
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Singleton(GetScriptForRawPubKey(keys[0])); }
+    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(Singleton(std::move(prov)), {}, "pk") {}
+    PKDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pk") {}
 };
 
 /** A parsed pkh(P) descriptor. */
@@ -551,10 +543,10 @@ protected:
     {
         CKeyID id = keys[0].GetID();
         out.pubkeys.emplace(id, keys[0]);
-        return Singleton(GetScriptForDestination(PKHash(id)));
+        return Vector(GetScriptForDestination(PKHash(id)));
     }
 public:
-    PKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "pkh") {}
+    PKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pkh") {}
 };
 
 /** A parsed wpkh(P) descriptor. */
@@ -565,10 +557,10 @@ protected:
     {
         CKeyID id = keys[0].GetID();
         out.pubkeys.emplace(id, keys[0]);
-        return Singleton(GetScriptForDestination(WitnessV0KeyHash(id)));
+        return Vector(GetScriptForDestination(WitnessV0KeyHash(id)));
     }
 public:
-    WPKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "wpkh") {}
+    WPKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "wpkh") {}
 };
 
 /** A parsed combo(P) descriptor. */
@@ -591,7 +583,7 @@ protected:
         return ret;
     }
 public:
-    ComboDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "combo") {}
+    ComboDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "combo") {}
 };
 
 /** A parsed multi(...) or sortedmulti(...) descriptor */
@@ -605,9 +597,9 @@ protected:
         if (m_sorted) {
             std::vector<CPubKey> sorted_keys(keys);
             std::sort(sorted_keys.begin(), sorted_keys.end());
-            return Singleton(GetScriptForMultisig(m_threshold, sorted_keys));
+            return Vector(GetScriptForMultisig(m_threshold, sorted_keys));
         }
-        return Singleton(GetScriptForMultisig(m_threshold, keys));
+        return Vector(GetScriptForMultisig(m_threshold, keys));
     }
 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) {}
@@ -617,7 +609,7 @@ public:
 class SHDescriptor final : public DescriptorImpl
 {
 protected:
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(ScriptHash(*script))); }
+    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Vector(GetScriptForDestination(ScriptHash(*script))); }
 public:
     SHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "sh") {}
 };
@@ -626,7 +618,7 @@ public:
 class WSHDescriptor final : public DescriptorImpl
 {
 protected:
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(WitnessV0ScriptHash(*script))); }
+    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Vector(GetScriptForDestination(WitnessV0ScriptHash(*script))); }
 public:
     WSHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "wsh") {}
 };