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#pragma once
#include "symbol-table.hh"
namespace nix {
typedef enum {
tInt = 1,
tBool,
tString,
tPath,
tNull,
tAttrs,
tList,
tThunk,
tApp,
tLambda,
tBlackhole,
tPrimOp,
tPrimOpApp,
tExternal,
} ValueType;
class Bindings;
struct Env;
struct Expr;
struct ExprLambda;
struct PrimOp;
struct PrimOp;
class Symbol;
struct Pos;
class EvalState;
class XMLWriter;
typedef long NixInt;
/* 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, ExternalValueBase & v);
protected:
/* Print out the value */
virtual std::ostream & print(std::ostream & str) = 0;
public:
/* Return a simple string describing the type */
virtual string showType() = 0;
/* Return a string to be used in builtins.typeOf */
virtual string typeOf() = 0;
/* How much space does this value take up */
virtual size_t valueSize(std::set<const void *> & seen) = 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);
/* Compare to another value of the same type. Defaults to uncomparable,
* i.e. always false.
*/
virtual bool operator==(const ExternalValueBase & b);
/* Print the value as JSON. Defaults to unconvertable, i.e. throws an error */
virtual void printValueAsJSON(EvalState & state, bool strict,
std::ostream & str, PathSet & context);
/* Print the value as XML. Defaults to unevaluated */
virtual void printValueAsXML(EvalState & state, bool strict, bool location,
XMLWriter & doc, PathSet & context, PathSet & drvsSeen);
virtual ~ExternalValueBase()
{
};
};
std::ostream & operator << (std::ostream & str, ExternalValueBase & v);
struct Value
{
ValueType type;
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 {
unsigned int length;
Value * * elems;
} list;
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;
};
};
/* After overwriting an app node, be sure to clear pointers in the
Value to ensure that the target isn't kept alive unnecessarily. */
static inline void clearValue(Value & v)
{
v.app.left = v.app.right = 0;
}
static inline void mkInt(Value & v, NixInt n)
{
clearValue(v);
v.type = tInt;
v.integer = n;
}
static inline void mkBool(Value & v, bool b)
{
clearValue(v);
v.type = tBool;
v.boolean = b;
}
static inline void mkNull(Value & v)
{
clearValue(v);
v.type = tNull;
}
static inline void mkApp(Value & v, Value & left, Value & right)
{
v.type = tApp;
v.app.left = &left;
v.app.right = &right;
}
static inline void mkStringNoCopy(Value & v, const char * s)
{
v.type = tString;
v.string.s = s;
v.string.context = 0;
}
static inline void mkString(Value & v, const Symbol & s)
{
mkStringNoCopy(v, ((const string &) s).c_str());
}
void mkString(Value & v, const char * s);
static inline void mkPathNoCopy(Value & v, const char * s)
{
clearValue(v);
v.type = tPath;
v.path = s;
}
void mkPath(Value & v, const char * s);
/* Compute the size in bytes of the given value, including all values
and environments reachable from it. Static expressions (Exprs) are
not included. */
size_t valueSize(Value & v);
}
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