lix/src/libexpr/value.hh
Silvan Mosberger b70d22baca
Replace Value type setters with mk* functions
Move clearValue inside Value

mkInt instead of setInt

mkBool instead of setBool

mkString instead of setString

mkPath instead of setPath

mkNull instead of setNull

mkAttrs instead of setAttrs

mkList instead of setList*

mkThunk instead of setThunk

mkApp instead of setApp

mkLambda instead of setLambda

mkBlackhole instead of setBlackhole

mkPrimOp instead of setPrimOp

mkPrimOpApp instead of setPrimOpApp

mkExternal instead of setExternal

mkFloat instead of setFloat

Add note that the static mk* function should be removed eventually
2020-12-18 21:48:22 +01:00

407 lines
9.8 KiB
C++

#pragma once
#include "symbol-table.hh"
#if HAVE_BOEHMGC
#include <gc/gc_allocator.h>
#endif
namespace nix {
typedef enum {
tInt = 1,
tBool,
tString,
tPath,
tNull,
tAttrs,
tList1,
tList2,
tListN,
tThunk,
tApp,
tLambda,
tBlackhole,
tPrimOp,
tPrimOpApp,
tExternal,
tFloat
} 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;
class Bindings;
struct Env;
struct Expr;
struct ExprLambda;
struct PrimOp;
class Symbol;
struct Pos;
class EvalState;
class XMLWriter;
class JSONPlaceholder;
typedef int64_t NixInt;
typedef double NixFloat;
/* 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);
protected:
/* Print out the value */
virtual std::ostream & print(std::ostream & str) const = 0;
public:
/* Return a simple string describing the type */
virtual string showType() const = 0;
/* Return a string to be used in builtins.typeOf */
virtual string typeOf() const = 0;
/* Coerce the value to a string. Defaults to uncoercable, i.e. throws an
* error
*/
virtual string coerceToString(const Pos & pos, PathSet & context, bool copyMore, 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 void printValueAsJSON(EvalState & state, bool strict,
JSONPlaceholder & out, PathSet & context) const;
/* Print the value as XML. Defaults to unevaluated */
virtual void printValueAsXML(EvalState & state, bool strict, bool location,
XMLWriter & doc, PathSet & context, PathSet & drvsSeen) const;
virtual ~ExternalValueBase()
{
};
};
std::ostream & operator << (std::ostream & str, const ExternalValueBase & v);
struct Value
{
private:
InternalType internalType;
friend std::string showType(const Value & v);
friend void printValue(std::ostream & str, std::set<const Value *> & active, const Value & v);
public:
// 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 { return internalType == tBlackhole; };
// type() == nFunction
inline bool isLambda() const { return internalType == tLambda; };
inline bool isPrimOp() const { return internalType == tPrimOp; };
inline bool isPrimOpApp() const { return internalType == tPrimOpApp; };
union
{
NixInt integer;
bool boolean;
/* 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 {
const char * s;
const char * * context; // must be in sorted order
} string;
const char * path;
Bindings * attrs;
struct {
size_t size;
Value * * elems;
} bigList;
Value * smallList[2];
struct {
Env * env;
Expr * expr;
} thunk;
struct {
Value * left, * right;
} app;
struct {
Env * env;
ExprLambda * fun;
} lambda;
PrimOp * primOp;
struct {
Value * left, * right;
} primOpApp;
ExternalValueBase * external;
NixFloat fpoint;
};
// Returns the normal type of a Value. This only returns nThunk if the
// Value hasn't been forceValue'd
inline ValueType type() const
{
switch (internalType) {
case tInt: return nInt;
case tBool: return nBool;
case tString: return nString;
case tPath: return nPath;
case tNull: return nNull;
case tAttrs: return nAttrs;
case tList1: case tList2: case tListN: return nList;
case tLambda: case tPrimOp: case tPrimOpApp: return nFunction;
case tExternal: return nExternal;
case tFloat: return nFloat;
case tThunk: case tApp: case tBlackhole: return nThunk;
}
abort();
}
/* After overwriting an app node, be sure to clear pointers in the
Value to ensure that the target isn't kept alive unnecessarily. */
inline void clearValue()
{
app.left = app.right = 0;
}
inline void mkInt(NixInt n)
{
clearValue();
internalType = tInt;
integer = n;
}
inline void mkBool(bool b)
{
clearValue();
internalType = tBool;
boolean = b;
}
inline void mkString(const char * s, const char * * context = 0)
{
internalType = tString;
string.s = s;
string.context = context;
}
inline void mkPath(const char * s)
{
clearValue();
internalType = tPath;
path = s;
}
inline void mkNull()
{
clearValue();
internalType = tNull;
}
inline void mkAttrs(Bindings * a)
{
clearValue();
internalType = tAttrs;
attrs = a;
}
inline void mkList(size_t size)
{
clearValue();
if (size == 1)
internalType = tList1;
else if (size == 2)
internalType = tList2;
else {
internalType = tListN;
bigList.size = size;
}
}
inline void mkThunk(Env * e, Expr * ex)
{
internalType = tThunk;
thunk.env = e;
thunk.expr = ex;
}
inline void mkApp(Value * l, Value * r)
{
internalType = tApp;
app.left = l;
app.right = r;
}
inline void mkLambda(Env * e, ExprLambda * f)
{
internalType = tLambda;
lambda.env = e;
lambda.fun = f;
}
inline void mkBlackhole()
{
internalType = tBlackhole;
// Value will be overridden anyways
}
inline void mkPrimOp(PrimOp * p)
{
clearValue();
internalType = tPrimOp;
primOp = p;
}
inline void mkPrimOpApp(Value * l, Value * r)
{
internalType = tPrimOpApp;
app.left = l;
app.right = r;
}
inline void mkExternal(ExternalValueBase * e)
{
clearValue();
internalType = tExternal;
external = e;
}
inline void mkFloat(NixFloat n)
{
clearValue();
internalType = tFloat;
fpoint = n;
}
bool isList() const
{
return internalType == tList1 || internalType == tList2 || internalType == tListN;
}
Value * * listElems()
{
return internalType == tList1 || internalType == tList2 ? smallList : bigList.elems;
}
const Value * const * listElems() const
{
return internalType == tList1 || internalType == tList2 ? smallList : bigList.elems;
}
size_t listSize() const
{
return internalType == tList1 ? 1 : internalType == tList2 ? 2 : bigList.size;
}
/* Check whether forcing this value requires a trivial amount of
computation. In particular, function applications are
non-trivial. */
bool isTrivial() const;
std::vector<std::pair<Path, std::string>> getContext();
};
// TODO: Remove these static functions, replace call sites with v.mk* instead
static inline void mkInt(Value & v, NixInt n)
{
v.mkInt(n);
}
static inline void mkFloat(Value & v, NixFloat n)
{
v.mkFloat(n);
}
static inline void mkBool(Value & v, bool b)
{
v.mkBool(b);
}
static inline void mkNull(Value & v)
{
v.mkNull();
}
static inline void mkApp(Value & v, Value & left, Value & right)
{
v.mkApp(&left, &right);
}
static inline void mkString(Value & v, const Symbol & s)
{
v.mkString(((const string &) s).c_str());
}
void mkString(Value & v, const char * s);
void mkPath(Value & v, const char * s);
#if HAVE_BOEHMGC
typedef std::vector<Value *, traceable_allocator<Value *> > ValueVector;
typedef std::map<Symbol, Value *, std::less<Symbol>, traceable_allocator<std::pair<const Symbol, Value *> > > ValueMap;
#else
typedef std::vector<Value *> ValueVector;
typedef std::map<Symbol, Value *> ValueMap;
#endif
/* A value allocated in traceable memory. */
typedef std::shared_ptr<Value *> RootValue;
RootValue allocRootValue(Value * v);
}