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|
#pragma once
///@file
#include <cassert>
#include <climits>
#include <cstdint>
#include <cstring>
#include <functional>
#include <limits>
#include <memory>
#include <ranges>
#include <span>
#include <string_view>
#include <type_traits>
#include "lix/libexpr/gc-alloc.hh"
#include "lix/libexpr/value/context.hh"
#include "lix/libutil/logging.hh"
#include "lix/libutil/source-path.hh"
#include "lix/libexpr/print-options.hh"
#include "lix/libutil/checked-arithmetic.hh"
#include "lix/libutil/concepts.hh"
#include "lix/libutil/json-fwd.hh"
namespace nix {
class BindingsBuilder;
class EvalMemory;
class EvalState;
struct Value;
/**
* Function that implements a primop.
*/
using PrimOpImpl = Value(EvalState & state, Value ** args);
/**
* Info about a primitive operation, and its implementation
*/
struct PrimOpDetails
{
/**
* Name of the primop. `__` prefix is treated specially.
*/
std::string name;
/**
* Names of the parameters of a primop, for primops that take a
* fixed number of arguments to be substituted for these parameters.
*/
std::vector<std::string> args;
/**
* Aritiy of the primop.
*
* If `args` is not empty, this field will be computed from that
* field instead, so it doesn't need to be manually set.
*/
size_t arity = 0;
/**
* Optional free-form documentation about the primop.
*/
const char * doc = nullptr;
/**
* Implementation of the primop.
*/
std::function<PrimOpImpl> fun;
/**
* Optional experimental for this to be gated on.
*/
std::optional<ExperimentalFeature> experimentalFeature;
};
// NOTE value.cc contains alignment assertions for pointers tagged thusly.
// *always* ensure that these assertions match the tag types declared here
typedef enum {
// NOTE: tThunk *must* be 0, otherwise invalid value detection breaks
// since invalid values are encoded as thunks with a null thunk state
tThunk = 0,
tApp,
tInt,
tBool,
tString,
tAttrs,
tList,
tAuxiliary,
} InternalType;
/**
* This type abstracts over all actual value types in the language,
* grouping together implementation details like tList*, different function
* types, and types in non-normal form (so thunks and co.)
*/
typedef enum {
nThunk,
nInt,
nFloat,
nBool,
nString,
nPath,
nNull,
nAttrs,
nList,
nFunction,
nExternal
} ValueType;
/**
* Modes of string coercion.
*
* Determines how permissive the coercion functions are when converting
* values to strings.
*
* - Strict: Only allow coercion of values that are already strings,
* paths, or derivations.
* - Interpolation: Additionally allow coercion of unambiguously printable values in a string, for
* now: integers. This mode is meant as a stopgap measure until we get better formatting tools.
* - ToString: Additionally allow coercion of integers, booleans, null,
* and lists to strings.
*/
enum class StringCoercionMode {
Strict,
Interpolation,
ToString,
};
class Bindings;
struct Env;
struct Expr;
struct ExprLambda;
struct ExprBlackHole;
class PosIdx;
struct Pos;
class StorePath;
class Store;
class EvalState;
class XMLWriter;
class Printer;
using NixInt = checked::Checked<int64_t>;
using NixFloat = double;
/**
* External values must descend from ExternalValueBase, so that
* type-agnostic nix functions (e.g. showType) can be implemented
*/
class ExternalValueBase
{
friend std::ostream & operator << (std::ostream & str, const ExternalValueBase & v);
friend class Printer;
protected:
/**
* Print out the value
*/
virtual std::ostream & print(std::ostream & str) const = 0;
public:
/**
* Return a simple string describing the type
*/
virtual std::string showType() const = 0;
/**
* Return a string to be used in builtins.typeOf
*/
virtual std::string typeOf() const = 0;
/**
* Coerce the value to a string. Defaults to uncoercable, i.e. throws an
* error.
*/
virtual std::string coerceToString(EvalState & state, const PosIdx & pos, NixStringContext & context, StringCoercionMode mode, bool copyToStore) const;
/**
* Compare to another value of the same type. Defaults to uncomparable,
* i.e. always false.
*/
virtual bool operator ==(const ExternalValueBase & b) const;
/**
* Print the value as JSON. Defaults to unconvertable, i.e. throws an error
*/
virtual JSON printValueAsJSON(EvalState & state, bool strict,
NixStringContext & context, bool copyToStore = true) const;
/**
* Print the value as XML. Defaults to unevaluated
*/
virtual void printValueAsXML(EvalState & state, bool strict, bool location,
XMLWriter & doc, NixStringContext & context, PathSet & drvsSeen,
const PosIdx pos) const;
virtual ~ExternalValueBase()
{
};
};
std::ostream & operator << (std::ostream & str, const ExternalValueBase & v);
struct NewValueAs
{
struct integer_t { };
constexpr static integer_t integer{};
struct floating_t { };
constexpr static floating_t floating{};
struct boolean_t { };
constexpr static boolean_t boolean{};
struct string_t { };
constexpr static string_t string{};
struct path_t { };
constexpr static path_t path{};
struct list_t { };
constexpr static list_t list{};
struct attrs_t { };
constexpr static attrs_t attrs{};
struct thunk_t { };
constexpr static thunk_t thunk{};
struct null_t { };
constexpr static null_t null{};
struct app_t { };
constexpr static app_t app{};
struct primop_t { };
constexpr static primop_t primop{};
struct lambda_t { };
constexpr static lambda_t lambda{};
struct external_t { };
constexpr static external_t external{};
struct blackhole_t { };
constexpr static blackhole_t blackhole{};
};
struct Value
{
private:
mutable uintptr_t raw;
public:
static constexpr size_t TAG_BITS = 3;
static constexpr size_t TAG_ALIGN = 1 << TAG_BITS;
static constexpr uintptr_t TAG_MASK = (1 << TAG_BITS) - 1;
private:
// boehmgc always allocate in two-word chunks, which means 8 bytes on 32 bit architectures.
// ensure that malloc must always use at least 8 byte chunks as well so our tags always fit
static_assert(alignof(std::max_align_t) >= Value::TAG_ALIGN);
static uintptr_t tag(InternalType t, auto v)
{
if constexpr (std::is_null_pointer_v<decltype(v)>) {
return t;
} else if constexpr (std::is_pointer_v<decltype(v)>) {
return (reinterpret_cast<uintptr_t>(v)) | t;
} else {
return (static_cast<uintptr_t>(v) << TAG_BITS) | t;
}
}
template<typename T>
T untag() const
{
if constexpr (std::is_pointer_v<T>) {
return reinterpret_cast<T>(raw & ~TAG_MASK);
} else {
return static_cast<T>((raw & ~TAG_MASK) >> TAG_BITS);
}
}
InternalType internalType() const
{
// NOLINTNEXTLINE(lix-cast-to-non-fixed-enum): TAG_MASK ensures it's in range
return InternalType(raw & TAG_MASK);
}
friend std::string showType(const Value & v);
public:
/**
* Underlying data storage for stringly values (i.e., strings and paths). Stores
* both the length of the string and its contents in a single GC-allocated block
* of memory to reduce overhead in the most common case. This and `String` could
* be merged into a single struct to decrease memory overhead further, but doing
* so precludes us from using atomic allocations that do not need to be scanned,
* increasing GC runtime overhead. We only use this struct to replace C strings.
*/
struct Str
{
struct Deleter
{
void operator()(Str * s)
{
free(s);
}
};
size_t length;
char contents[0];
std::string_view str() const
{
return {contents, length};
}
static Str * gcAlloc(size_t size)
{
auto result = static_cast<Str *>(LIX_GC_MALLOC_ATOMIC(sizeof(Value::Str) + size));
if (result) {
result->length = size;
return result;
}
throw std::bad_alloc();
}
static std::unique_ptr<Str, Deleter> copy(std::string_view s)
{
auto result = alloc(s.size());
memcpy(result->contents, s.data(), s.size());
return {result, {}};
}
static Str * gcCopy(std::string_view s)
{
auto result = gcAlloc(s.size());
memcpy(result->contents, s.data(), s.size());
return result;
}
private:
static Str * alloc(size_t size)
{
if (auto result = static_cast<Str *>(malloc(sizeof(Value::Str) + size))) {
result->length = size;
return result;
}
throw std::bad_alloc();
}
};
/**
* Empty list constant.
*/
static Value EMPTY_LIST;
static Value EMPTY_SET;
static Value VNULL;
struct String;
struct Acb;
struct Null;
struct Lambda;
struct Thunk;
struct Int;
static const Null NULL_ACB;
/** Single, unforceable black hole thunk control block. */
static Thunk blackHole;
// Discount `using NewValueAs::*;`
// NOLINTNEXTLINE(bugprone-macro-parentheses)
#define USING_VALUETYPE(name) using name = NewValueAs::name
USING_VALUETYPE(integer_t);
USING_VALUETYPE(floating_t);
USING_VALUETYPE(boolean_t);
USING_VALUETYPE(string_t);
USING_VALUETYPE(path_t);
USING_VALUETYPE(list_t);
USING_VALUETYPE(attrs_t);
USING_VALUETYPE(thunk_t);
USING_VALUETYPE(primop_t);
USING_VALUETYPE(app_t);
USING_VALUETYPE(null_t);
USING_VALUETYPE(lambda_t);
USING_VALUETYPE(external_t);
USING_VALUETYPE(blackhole_t);
#undef USING_VALUETYPE
struct List;
struct PrimOp;
static bool isTaggableInteger(NixInt i)
{
return i.value <= (std::numeric_limits<intptr_t>::max() >> 3)
&& i.value >= (std::numeric_limits<intptr_t>::min() >> 3);
}
/// Default constructor which is still used in the codebase but should not
/// be used in new code. Zero initializes its members.
[[deprecated]]
Value()
: raw{0}
{
}
/// Constructs a nix language value of type "int", with the integral value
/// of @ref i.
Value(integer_t, NixInt::Inner i) : Value(NewValueAs::integer, NixInt{i}) {}
/// Constructs a nix language value of type "int", with the integral value
/// of @ref i.
Value(integer_t, NixInt i)
{
if (isTaggableInteger(i)) {
raw = tInt | (uintptr_t(i.value) << TAG_BITS);
} else {
auto ip = gcAllocType<Int>();
ip->raw = Acb::tInt;
ip->value = i;
raw = tag(tAuxiliary, ip);
}
}
/// Constructs a nix language value of type "float", with the floating
/// point value of @ref f.
Value(floating_t, NixFloat f)
{
auto fp = gcAllocType<Float>();
fp->raw = Acb::tFloat;
fp->value = f;
raw = tag(tAuxiliary, fp);
}
/// Constructs a nix language value of type "bool", with the boolean
/// value of @ref b.
Value(boolean_t, bool b) : raw(tag(tBool, b)) {}
/// Constructs a nix language value of type "string", with the value of the
/// C-string pointed to by @ref strPtr, and optionally with an array of
/// string context pointed to by @ref contextPtr.
///
/// Neither the C-string nor the context array are copied; this constructor
/// assumes suitable memory has already been allocated (with the GC if
/// enabled), and string and context data copied into that memory.
Value(string_t, const Str * strPtr, char const ** contextPtr = nullptr)
{
auto block = gcAllocType<String>();
*block = {.content = strPtr, .context = contextPtr};
raw = tag(tString, block);
}
/// Constructs a nix language value of type "string", with the value of the
/// C-string pointed to by @ref s, and context from @ref context.
///
/// The C-string is not copied but the data from context is
Value(string_t, Str * s, const NixStringContext & context);
Value(string_t, const String * str) : raw(tag(tString, str)) {}
/// Constructx a nix language value of type "string", with a copy of the
/// string data viewed by @ref copyFrom and context from contextPtr.
///
/// The string data *is* copied from @ref copyFrom, and this constructor
/// performs a dynamic (GC) allocation to do so, but contextPtr is used
/// as-is without copying, and must have been allocated ahead of time.
Value(string_t, std::string_view copyFrom, char const ** contextPtr)
: Value(NewValueAs::string, Str::gcCopy(copyFrom), contextPtr)
{
}
/// Constructx a nix language value of type "string", with a copy of the
/// string data viewed by @ref copyFrom.
///
/// The string data *is* copied from @ref copyFrom, and this constructor
/// performs a dynamic (GC) allocation to do so.
Value(string_t, std::string_view copyFrom, NixStringContext const & context = {});
/// Constructs a nix language value of type "path", with the value of the
/// C-string pointed to by @ref strPtr.
///
/// The C-string is not copied; this constructor assumes suitable memory
/// has already been allocated (with the GC if enabled), and string data
/// has been copied into that memory.
Value(path_t, const String * str) : raw(tag(tString, str))
{
assert(str->isPath());
}
/// Constructs a nix language value of type "path", with the value of the
/// C-string @ref path.
///
/// The data from @ref path *is* copied, and this constructor performs a
/// dynamic (GC) allocation to do so.
Value(path_t, const char * path)
{
auto block = gcAllocType<String>();
*block = {.content = Str::gcCopy(path), .context = String::path};
raw = tag(tString, block);
}
/// Constructs a nix language value of type "path", with the path
/// @ref path.
///
/// The data from @ref path *is* copied, and this constructor performs a
/// dynamic (GC) allocation to do so.
Value(path_t, SourcePath const & path)
{
auto block = gcAllocType<String>();
*block = {.content = Str::gcCopy(path.canonical().abs()), .context = String::path};
raw = tag(tString, block);
}
/// Constructs a nix language value of type "list", with element array
/// @ref items.
///
/// Generally, the data in @ref items is neither deep copied nor shallow
/// copied. This construct assumes the std::span @ref items is a region of
/// memory that has already been allocated (with the GC if enabled), and
/// an array of valid Value pointers has been copied into that memory.
///
/// Howver, as an implementation detail, if @ref items is only 2 items or
/// smaller, the list is stored inline, and the Value pointers in
/// @ref items are shallow copied into this structure, without dynamically
/// allocating memory.
Value(list_t, const List * items) : raw(tag(tList, items)) {}
/// Constructs a nix language value of the singleton type "null".
Value(null_t) : raw(tag(tAuxiliary, &NULL_ACB)) {}
/// Constructs a nix language value of type "set", with the attribute
/// bindings pointed to by @ref bindings.
///
/// The bindings are not not copied; this constructor assumes @ref bindings
/// has already been suitably allocated by something like nix::buildBindings.
Value(attrs_t, Bindings * bindings) : raw(tag(tAttrs, bindings)) {}
Value(attrs_t, BindingsBuilder & bindings);
/// Constructs a nix language lazy delayed computation, or "thunk".
///
/// The thunk stores the environment it will be computed in @ref env, and
/// the expression that will need to be evaluated @ref expr.
Value(thunk_t, EvalMemory & mem, Env & env, Expr & expr);
/// Constructs a nix language value of type "lambda", which represents
/// a builtin, primitive operation ("primop"), from the primop
/// implemented by @ref primop.
Value(primop_t, PrimOp & primop);
/// Constructs a nix language value of type "lambda", which represents a
/// lazy and/or partial application of a function.
Value(app_t, EvalMemory & mem, Value & lhs, Value & rhs);
/// Constructs a nix language value of type "lambda", which represents a
/// lazy and/or partial application of a function.
Value(app_t, EvalMemory & mem, Value & lhs, std::span<Value> args);
/// Constructs a nix language value of type "lambda", which represents a
/// lazy and/or partial application of a function.
Value(app_t, EvalMemory & mem, const Value & lhs, std::span<Value> baseArgs, std::span<Value> moreArgs);
/// Constructs a nix language value of type "external", which is only used
/// by plugins. Do any existing plugins even use this mechanism?
Value(external_t, ExternalValueBase & external)
{
auto ext = gcAllocType<External>();
ext->raw = Acb::tExternal;
ext->external = &external;
raw = tag(tAuxiliary, ext);
}
/// Constructs a nix language value of type "lambda", which represents a
/// run of the mill lambda defined in nix code.
///
/// This takes the environment the lambda is closed over @ref env, and
/// the lambda expression itself @ref lambda, which will not be evaluated
/// until it is applied.
Value(lambda_t, EvalMemory & mem, Env & env, ExprLambda & lambda);
/// Constructs an evil thunk, whose evaluation represents infinite recursion.
explicit Value(blackhole_t) : raw(tag(tThunk, &blackHole)) {}
explicit Value(const Acb & backing) : raw(tag(tAuxiliary, &backing)) {}
Value(Value const & rhs) = default;
/// Move constructor. Does the same thing as the copy constructor, but
/// also zeroes out the other Value.
Value(Value && rhs) : raw(0)
{
*this = std::move(rhs);
}
Value & operator=(Value const & rhs) = default;
/// Move assignment operator.
/// Does the same thing as the copy assignment operator, but also zeroes out
/// the rhs.
inline Value & operator=(Value && rhs)
{
*this = static_cast<const Value &>(rhs);
if (this != &rhs) {
// Kill `rhs`, because non-destructive move lol.
rhs.raw = 0;
}
return *this;
}
void print(EvalState &state, std::ostream &str, PrintOptions options = PrintOptions {});
// Functions needed to distinguish the type
// These should be removed eventually, by putting the functionality that's
// needed by callers into methods of this type
// type() == nThunk
inline bool isThunk() const
{
return internalType() == tThunk;
};
inline bool isApp() const
{
return internalType() == tApp;
}
inline bool isBlackhole() const;
inline bool isInvalid() const
{
return raw == 0;
}
// type() == nFunction
inline bool isLambda() const
{
return internalType() == tAuxiliary && auxiliary()->type() == Acb::tLambda;
};
inline bool isPrimOp() const
{
return internalType() == tAuxiliary && auxiliary()->type() == Acb::tPrimOp;
}
inline bool isPrimOpApp() const;
/**
* Strings in the evaluator carry a so-called `context` which
* is a list of strings representing store paths. This is to
* allow users to write things like
* "--with-freetype2-library=" + freetype + "/lib"
* where `freetype` is a derivation (or a source to be copied
* to the store). If we just concatenated the strings without
* keeping track of the referenced store paths, then if the
* string is used as a derivation attribute, the derivation
* will not have the correct dependencies in its inputDrvs and
* inputSrcs.
* The semantics of the context is as follows: when a string
* with context C is used as a derivation attribute, then the
* derivations in C will be added to the inputDrvs of the
* derivation, and the other store paths in C will be added to
* the inputSrcs of the derivations.
* For canonicity, the store paths should be in sorted order.
*/
struct alignas(TAG_ALIGN) String
{
/// marker location for paths, to be used as path context.
static inline const char * path[] = {"\1<path>", nullptr};
const Str * content;
const char ** context; // must be in sorted order
bool isPath() const
{
return context == path;
}
};
struct App;
/// auxiliary control block for values that require more space.
/// these blocks are usually heap-allocated in GC memory space.
struct alignas(TAG_ALIGN) Acb
{
// NOTE value.cc contains alignment assertions for pointers tagged thusly.
// *always* ensure that these assertions match the tag types declared here
enum Type {
tExternal,
tFloat,
tNull,
tPrimOp,
tLambda,
tInt,
};
uintptr_t raw;
static constexpr size_t TAG_BITS = 3;
static constexpr size_t TAG_ALIGN = 1 << TAG_BITS;
static constexpr uintptr_t TAG_MASK = (1 << TAG_BITS) - 1;
static uintptr_t tag(Type t, auto v)
{
if constexpr (std::is_null_pointer_v<decltype(v)>) {
return t;
} else if constexpr (std::is_pointer_v<decltype(v)>) {
return (reinterpret_cast<uintptr_t>(v)) | t;
} else {
return (static_cast<uintptr_t>(v) << TAG_BITS) | t;
}
}
template<typename T>
T untag() const
{
if constexpr (std::is_pointer_v<T>) {
return reinterpret_cast<T>(raw & ~TAG_MASK);
} else {
return static_cast<T>((raw & ~TAG_MASK) >> TAG_BITS);
}
}
Type type() const
{
// TAG_MASK == 7, max enumerator is 5, so all possible values are in range
// NOLINTNEXTLINE(lix-cast-to-non-fixed-enum)
return Type(raw & TAG_MASK);
}
};
struct External : Acb
{
ExternalValueBase * external;
};
struct Float : Acb
{
NixFloat value;
};
struct Null : Acb
{};
struct PrimOp : Acb, PrimOpDetails
{
explicit PrimOp(PrimOpDetails p) : Acb{tPrimOp}, PrimOpDetails(std::move(p)) {}
};
struct Int : Acb
{
NixInt value;
};
struct Lambda : Acb
{
ExprLambda * fun;
Lambda(Env & env, ExprLambda & fun) : Acb{tag(tLambda, &env)}, fun(&fun) {}
Env * env() const
{
return untag<Env *>();
}
};
/**
* Returns the normal type of a Value. This only returns nThunk if
* the Value hasn't been forceValue'd
*
* @param invalidIsThunk Instead of aborting an an invalid (probably
* 0, so uninitialized) internal type, return `nThunk`.
*/
inline ValueType type(bool invalidIsThunk = false) const;
bool isList() const
{
return internalType() == tList;
}
Value * listElems() const;
size_t listSize() const;
/**
* Check whether forcing this value requires a trivial amount of
* computation. In particular, function applications are
* non-trivial.
*/
bool isTrivial() const;
auto listItems() const
{
struct ListIterable
{
typedef Value * iterator;
iterator _begin, _end;
iterator begin() const { return _begin; }
iterator end() const { return _end; }
};
assert(isList());
auto begin = listElems();
return ListIterable { begin, begin + listSize() };
}
SourcePath path() const
{
assert(internalType() == tString && untag<const String *>()->isPath());
return SourcePath{CanonPath(untag<const String *>()->content->str())};
}
std::string_view str() const
{
assert(internalType() == tString && !untag<const String *>()->isPath());
return std::string_view(untag<const String *>()->content->str());
}
NixInt integer() const
{
if (internalType() == tInt) {
intptr_t tmp;
memcpy(&tmp, &raw, sizeof(tmp));
return NixInt(tmp >> 3);
} else {
assert(internalType() == tAuxiliary && untag<const Acb *>()->type() == Acb::tInt);
return untag<const Int *>()->value;
}
}
bool boolean() const
{
return untag<bool>();
}
const auto & string() const
{
return *untag<const String *>();
}
auto attrs() const
{
return untag<Bindings *>();
}
Thunk & thunk() const
{
return *untag<Thunk *>();
}
App & app() const
{
return *untag<App *>();
}
const auto & lambda() const
{
return *untag<const Lambda *>();
}
const PrimOp * primOp() const
{
assert(internalType() == tAuxiliary && untag<const Acb *>()->type() == Acb::tPrimOp);
return untag<const PrimOp *>();
}
const ExternalValueBase * external() const
{
assert(internalType() == tAuxiliary && untag<const Acb *>()->type() == Acb::tExternal);
return untag<const External *>()->external;
}
NixFloat fpoint() const
{
assert(internalType() == tAuxiliary && untag<const Acb *>()->type() == Acb::tFloat);
return untag<const Float *>()->value;
}
const Acb * auxiliary() const
{
return untag<const Acb *>();
}
uintptr_t pointerEqProxy() const
{
return raw;
}
};
struct alignas(Value::TAG_ALIGN) Value::Thunk
{
union {
Env * _env;
Value _result;
};
Expr * expr;
bool resolved() const
{
return expr == nullptr;
}
void resolve(Value v)
{
_result = v;
expr = nullptr;
}
Env * env() const
{
return _env;
}
Value result() const
{
return _result;
}
};
struct alignas(Value::TAG_ALIGN) Value::List
{
size_t size;
Value elems[0];
std::span<Value> span()
{
return {elems, elems + size};
}
};
struct alignas(Value::TAG_ALIGN) Value::App
{
Value _left;
size_t _n;
Value _args[0];
bool resolved() const
{
return _n == ~size_t(0);
}
void resolve(Value v)
{
_left = v;
_n = ~size_t(0);
}
Value left() const
{
return _left;
}
Value result() const
{
return left();
}
Value target() const
{
return left().isApp() ? left().app().target() : left();
}
std::span<Value> args()
{
return std::span{_args, _n};
}
size_t totalArgs() const
{
return _n + (left().isApp() ? left().app().totalArgs() : 0);
}
};
inline ValueType Value::type(bool invalidIsThunk) const
{
again:
switch (internalType()) {
case tInt:
return nInt;
case tBool:
return nBool;
case tString:
return untag<const String *>()->isPath() ? nPath : nString;
case tAttrs:
return nAttrs;
case tList:
return nList;
case tAuxiliary:
switch (untag<const Acb *>()->type()) {
case Acb::tExternal:
return nExternal;
case Acb::tFloat:
return nFloat;
case Acb::tNull:
return nNull;
case Acb::tPrimOp:
case Acb::tLambda:
return nFunction;
case Acb::tInt:
return nInt;
}
case tThunk:
if (isInvalid()) {
if (invalidIsThunk) {
return nThunk;
} else {
abort();
}
} else if (thunk().resolved()) {
raw = thunk().result().raw;
goto again;
}
return nThunk;
case tApp:
if (app().resolved()) {
raw = app().result().raw;
goto again;
}
return app().target().isPrimOp() ? nFunction : nThunk;
}
}
inline bool Value::isBlackhole() const
{
return internalType() == tThunk && untag<const Thunk *>()->expr == blackHole.expr;
}
inline bool Value::isPrimOpApp() const
{
return internalType() == tApp && !app().resolved() && app().target().isPrimOp();
}
inline Value * Value::listElems() const
{
return untag<List *>()->elems;
}
inline size_t Value::listSize() const
{
return untag<const List *>()->size;
}
using PrimOp = Value::PrimOp;
/**
* A value allocated in traceable memory.
*/
typedef std::shared_ptr<Value> RootValue;
RootValue allocRootValue(Value v);
}
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