forked from lix-project/lix
libexpr: implement actual constructors for nix::Value
Change-Id: Iebc2bb4e4ea5e93045afe47677df756de4ec4d05
This commit is contained in:
parent
c347d3df8f
commit
ddfca6e81b
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@ -494,6 +494,14 @@ std::ostream & operator<<(std::ostream & output, PrimOp & primOp)
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}
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Value::Value(primop_t, PrimOp & primop)
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: internalType(tPrimOp)
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, primOp(&primop)
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, _primop_pad(0)
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{
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primop.check();
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}
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PrimOp * Value::primOpAppPrimOp() const
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{
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Value * left = primOpApp.left;
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@ -506,7 +514,6 @@ PrimOp * Value::primOpAppPrimOp() const
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return left->primOp;
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}
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void Value::mkPrimOp(PrimOp * p)
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{
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p->check();
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@ -3,6 +3,9 @@
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#include <cassert>
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#include <climits>
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#include <functional>
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#include <ranges>
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#include <span>
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#include "gc-alloc.hh"
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#include "symbol-table.hh"
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@ -11,6 +14,7 @@
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#include "source-path.hh"
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#include "print-options.hh"
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#include "checked-arithmetic.hh"
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#include "concepts.hh"
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#include <nlohmann/json_fwd.hpp>
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@ -132,6 +136,55 @@ class ExternalValueBase
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std::ostream & operator << (std::ostream & str, const ExternalValueBase & v);
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extern ExprBlackHole eBlackHole;
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struct NewValueAs
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{
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struct integer_t { };
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constexpr static integer_t integer{};
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struct floating_t { };
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constexpr static floating_t floating{};
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struct boolean_t { };
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constexpr static boolean_t boolean{};
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struct string_t { };
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constexpr static string_t string{};
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struct path_t { };
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constexpr static path_t path{};
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struct list_t { };
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constexpr static list_t list{};
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struct attrs_t { };
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constexpr static attrs_t attrs{};
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struct thunk_t { };
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constexpr static thunk_t thunk{};
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struct null_t { };
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constexpr static null_t null{};
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struct app_t { };
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constexpr static app_t app{};
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struct primop_t { };
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constexpr static primop_t primop{};
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struct primOpApp_t { };
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constexpr static primOpApp_t primOpApp{};
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struct lambda_t { };
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constexpr static lambda_t lambda{};
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struct external_t { };
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constexpr static external_t external{};
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struct blackhole_t { };
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constexpr static blackhole_t blackhole{};
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};
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struct Value
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{
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@ -142,6 +195,315 @@ private:
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public:
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// Discount `using NewValueAs::*;`
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#define USING_VALUETYPE(name) using name = NewValueAs::name
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USING_VALUETYPE(integer_t);
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USING_VALUETYPE(floating_t);
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USING_VALUETYPE(boolean_t);
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USING_VALUETYPE(string_t);
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USING_VALUETYPE(path_t);
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USING_VALUETYPE(list_t);
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USING_VALUETYPE(attrs_t);
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USING_VALUETYPE(thunk_t);
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USING_VALUETYPE(primop_t);
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USING_VALUETYPE(app_t);
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USING_VALUETYPE(null_t);
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USING_VALUETYPE(primOpApp_t);
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USING_VALUETYPE(lambda_t);
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USING_VALUETYPE(external_t);
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USING_VALUETYPE(blackhole_t);
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#undef USING_VALUETYPE
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/// Default constructor which is still used in the codebase but should not
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/// be used in new code. Zero initializes its members.
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[[deprecated]] Value()
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: internalType(static_cast<InternalType>(0))
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, _empty{ 0, 0 }
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{ }
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/// Constructs a nix language value of type "int", with the integral value
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/// of @ref i.
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Value(integer_t, NixInt i)
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: internalType(tInt)
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, _empty{ 0, 0 }
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{
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// the NixInt ctor here is is special because NixInt has a ctor too, so
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// we're not allowed to have it as an anonymous aggreagte member. we do
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// however still have the option to clear the data members using _empty
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// and leaving the second word of data cleared by setting only integer.
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integer = i;
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}
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/// Constructs a nix language value of type "float", with the floating
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/// point value of @ref f.
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Value(floating_t, NixFloat f)
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: internalType(tFloat)
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, fpoint(f)
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, _float_pad(0)
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{ }
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/// Constructs a nix language value of type "bool", with the boolean
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/// value of @ref b.
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Value(boolean_t, bool b)
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: internalType(tBool)
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, boolean(b)
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, _bool_pad(0)
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{ }
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/// Constructs a nix language value of type "string", with the value of the
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/// C-string pointed to by @ref strPtr, and optionally with an array of
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/// string context pointed to by @ref contextPtr.
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///
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/// Neither the C-string nor the context array are copied; this constructor
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/// assumes suitable memory has already been allocated (with the GC if
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/// enabled), and string and context data copied into that memory.
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Value(string_t, char const * strPtr, char const ** contextPtr = nullptr)
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: internalType(tString)
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, string({ .s = strPtr, .context = contextPtr })
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{ }
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/// Constructx a nix language value of type "string", with a copy of the
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/// string data viewed by @ref copyFrom.
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///
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/// The string data *is* copied from @ref copyFrom, and this constructor
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/// performs a dynamic (GC) allocation to do so.
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Value(string_t, std::string_view copyFrom, NixStringContext const & context = {})
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: internalType(tString)
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, string({ .s = gcCopyStringIfNeeded(copyFrom), .context = nullptr })
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{
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if (context.empty()) {
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// It stays nullptr.
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return;
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}
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// Copy the context.
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this->string.context = gcAllocType<char const *>(context.size() + 1);
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size_t n = 0;
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for (NixStringContextElem const & contextElem : context) {
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this->string.context[n] = gcCopyStringIfNeeded(contextElem.to_string());
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n += 1;
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}
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// Terminator sentinel.
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this->string.context[n] = nullptr;
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}
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/// Constructx a nix language value of type "string", with the value of the
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/// C-string pointed to by @ref strPtr, and optionally with a set of string
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/// context @ref context.
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///
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/// The C-string is not copied; this constructor assumes suitable memory
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/// has already been allocated (with the GC if enabled), and string data
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/// has been copied into that memory. The context data *is* copied from
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/// @ref context, and this constructor performs a dynamic (GC) allocation
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/// to do so.
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Value(string_t, char const * strPtr, NixStringContext const & context)
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: internalType(tString)
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, string({ .s = strPtr, .context = nullptr })
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{
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if (context.empty()) {
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// It stays nullptr
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return;
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}
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// Copy the context.
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this->string.context = gcAllocType<char const *>(context.size() + 1);
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size_t n = 0;
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for (NixStringContextElem const & contextElem : context) {
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this->string.context[n] = gcCopyStringIfNeeded(contextElem.to_string());
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n += 1;
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}
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// Terminator sentinel.
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this->string.context[n] = nullptr;
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}
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/// Constructs a nix language value of type "path", with the value of the
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/// C-string pointed to by @ref strPtr.
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///
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/// The C-string is not copied; this constructor assumes suitable memory
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/// has already been allocated (with the GC if enabled), and string data
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/// has been copied into that memory.
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Value(path_t, char const * strPtr)
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: internalType(tPath)
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, _path(strPtr)
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, _path_pad(0)
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{ }
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/// Constructs a nix language value of type "path", with the path
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/// @ref path.
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///
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/// The data from @ref path *is* copied, and this constructor performs a
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/// dynamic (GC) allocation to do so.
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Value(path_t, SourcePath const & path)
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: internalType(tPath)
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, _path(gcCopyStringIfNeeded(path.path.abs()))
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, _path_pad(0)
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{ }
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/// Constructs a nix language value of type "list", with element array
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/// @ref items.
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///
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/// Generally, the data in @ref items is neither deep copied nor shallow
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/// copied. This construct assumes the std::span @ref items is a region of
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/// memory that has already been allocated (with the GC if enabled), and
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/// an array of valid Value pointers has been copied into that memory.
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///
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/// Howver, as an implementation detail, if @ref items is only 2 items or
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/// smaller, the list is stored inline, and the Value pointers in
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/// @ref items are shallow copied into this structure, without dynamically
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/// allocating memory.
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Value(list_t, std::span<Value *> items)
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{
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if (items.size() == 1) {
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this->internalType = tList1;
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this->smallList[0] = items[0];
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this->smallList[1] = nullptr;
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} else if (items.size() == 2) {
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this->internalType = tList2;
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this->smallList[0] = items[0];
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this->smallList[1] = items[1];
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} else {
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this->internalType = tListN;
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this->bigList.size = items.size();
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this->bigList.elems = items.data();
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}
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}
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/// Constructs a nix language value of type "list", with an element array
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/// initialized by applying @ref transformer to each element in @ref items.
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///
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/// This allows "in-place" construction of a nix list when some logic is
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/// needed to get each Value pointer. This constructor dynamically (GC)
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/// allocates memory for the size of @ref items, and the Value pointers
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/// returned by @ref transformer are shallow copied into it.
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template<
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std::ranges::sized_range SizedIterableT,
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InvocableR<Value *, typename SizedIterableT::value_type const &> TransformerT
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>
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Value(list_t, SizedIterableT & items, TransformerT const & transformer)
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{
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if (items.size() == 1) {
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this->internalType = tList1;
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this->smallList[0] = transformer(*items.begin());
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this->smallList[1] = nullptr;
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} else if (items.size() == 2) {
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this->internalType = tList2;
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auto it = items.begin();
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this->smallList[0] = transformer(*it);
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it++;
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this->smallList[1] = transformer(*it);
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} else {
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this->internalType = tListN;
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this->bigList.size = items.size();
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this->bigList.elems = gcAllocType<Value *>(items.size());
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auto it = items.begin();
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for (size_t i = 0; i < items.size(); i++, it++) {
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this->bigList.elems[i] = transformer(*it);
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}
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}
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}
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/// Constructs a nix language value of the singleton type "null".
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Value(null_t)
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: internalType(tNull)
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, _empty{0, 0}
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{ }
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/// Constructs a nix language value of type "set", with the attribute
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/// bindings pointed to by @ref bindings.
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///
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/// The bindings are not not copied; this constructor assumes @ref bindings
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/// has already been suitably allocated by something like nix::buildBindings.
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Value(attrs_t, Bindings * bindings)
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: internalType(tAttrs)
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, attrs(bindings)
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, _attrs_pad(0)
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{ }
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/// Constructs a nix language lazy delayed computation, or "thunk".
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///
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/// The thunk stores the environment it will be computed in @ref env, and
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/// the expression that will need to be evaluated @ref expr.
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Value(thunk_t, Env & env, Expr & expr)
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: internalType(tThunk)
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, thunk({ .env = &env, .expr = &expr })
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{ }
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/// Constructs a nix language value of type "lambda", which represents
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/// a builtin, primitive operation ("primop"), from the primop
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/// implemented by @ref primop.
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Value(primop_t, PrimOp & primop);
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/// Constructs a nix language value of type "lambda", which represents a
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/// partially applied primop.
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Value(primOpApp_t, Value & lhs, Value & rhs)
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: internalType(tPrimOpApp)
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, primOpApp({ .left = &lhs, .right = &rhs })
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{ }
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/// Constructs a nix language value of type "lambda", which represents a
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/// lazy partial application of another lambda.
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Value(app_t, Value & lhs, Value & rhs)
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: internalType(tApp)
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, app({ .left = &lhs, .right = &rhs })
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{ }
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/// Constructs a nix language value of type "external", which is only used
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/// by plugins. Do any existing plugins even use this mechanism?
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Value(external_t, ExternalValueBase & external)
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: internalType(tExternal)
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, external(&external)
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, _external_pad(0)
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{ }
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/// Constructs a nix language value of type "lambda", which represents a
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/// run of the mill lambda defined in nix code.
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///
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/// This takes the environment the lambda is closed over @ref env, and
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/// the lambda expression itself @ref lambda, which will not be evaluated
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/// until it is applied.
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Value(lambda_t, Env & env, ExprLambda & lambda)
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: internalType(tLambda)
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, lambda({ .env = &env, .fun = &lambda })
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{ }
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/// Constructs an evil thunk, whose evaluation represents infinite recursion.
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explicit Value(blackhole_t)
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: internalType(tThunk)
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, thunk({ .env = nullptr, .expr = reinterpret_cast<Expr *>(&eBlackHole) })
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{ }
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Value(Value const & rhs) = default;
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/// Move constructor. Does the same thing as the copy constructor, but
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/// also zeroes out the other Value.
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Value(Value && rhs)
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: internalType(rhs.internalType)
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, _empty{ 0, 0 }
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{
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*this = std::move(rhs);
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}
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Value & operator=(Value const & rhs) = default;
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/// Move assignment operator.
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/// Does the same thing as the copy assignment operator, but also zeroes out
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/// the rhs.
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inline Value & operator=(Value && rhs)
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{
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*this = static_cast<const Value &>(rhs);
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if (this != &rhs) {
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// Kill `rhs`, because non-destructive move lol.
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rhs.internalType = static_cast<InternalType>(0);
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rhs._empty[0] = 0;
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rhs._empty[1] = 0;
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}
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return *this;
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}
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void print(EvalState &state, std::ostream &str, PrintOptions options = PrintOptions {});
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// Functions needed to distinguish the type
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@ -160,8 +522,15 @@ public:
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union
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{
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/// Dummy field, which takes up as much space as the largest union variants
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/// to set the union's memory to zeroed memory.
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uintptr_t _empty[2];
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NixInt integer;
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struct {
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bool boolean;
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uintptr_t _bool_pad;
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};
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/**
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* Strings in the evaluator carry a so-called `context` which
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@ -190,8 +559,14 @@ public:
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const char * * context; // must be in sorted order
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} string;
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struct {
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const char * _path;
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uintptr_t _path_pad;
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};
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struct {
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Bindings * attrs;
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uintptr_t _attrs_pad;
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};
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struct {
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size_t size;
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Value * * elems;
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@ -208,12 +583,21 @@ public:
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Env * env;
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ExprLambda * fun;
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} lambda;
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struct {
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PrimOp * primOp;
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uintptr_t _primop_pad;
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};
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struct {
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Value * left, * right;
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} primOpApp;
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struct {
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ExternalValueBase * external;
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uintptr_t _external_pad;
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};
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struct {
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NixFloat fpoint;
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uintptr_t _float_pad;
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};
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};
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/**
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@ -449,8 +833,6 @@ public:
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};
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extern ExprBlackHole eBlackHole;
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bool Value::isBlackhole() const
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{
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return internalType == tThunk && thunk.expr == (Expr*) &eBlackHole;
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22
src/libutil/concepts.hh
Normal file
22
src/libutil/concepts.hh
Normal file
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@ -0,0 +1,22 @@
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#pragma once
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/// @file Defines C++ 20 concepts that std doesn't have.
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#include <type_traits>
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namespace nix
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{
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/// Like std::invocable<>, but also constrains the return type as well.
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///
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/// Somehow, there is no std concept to do this, even though there is a type trait
|
||||
/// for it.
|
||||
///
|
||||
/// @tparam CallableT The type you want to constrain to be callable, and to return
|
||||
/// @p ReturnT when called with @p Args as arguments.
|
||||
///
|
||||
/// @tparam ReturnT The type the callable should return when called.
|
||||
/// @tparam Args The arguments the callable should accept to return @p ReturnT.
|
||||
template<typename CallableT, typename ReturnT, typename ...Args>
|
||||
concept InvocableR = std::is_invocable_r_v<ReturnT, CallableT, Args...>;
|
||||
|
||||
}
|
||||
|
|
@ -58,6 +58,7 @@ libutil_headers = files(
|
|||
'comparator.hh',
|
||||
'compression.hh',
|
||||
'compute-levels.hh',
|
||||
'concepts.hh',
|
||||
'config-impl.hh',
|
||||
'config.hh',
|
||||
'current-process.hh',
|
||||
|
|
|
|||
Loading…
Reference in a new issue