Merge pull request #401 from shlevy/external-value

Allow external code using libnixexpr to add types
This commit is contained in:
Eelco Dolstra 2014-12-02 17:52:01 +01:00
commit f43a8ede93
5 changed files with 108 additions and 0 deletions

View file

@ -104,6 +104,9 @@ static void printValue(std::ostream & str, std::set<const Value *> & active, con
case tPrimOpApp:
str << "<PRIMOP-APP>";
break;
case tExternal:
str << *v.external;
break;
default:
throw Error("invalid value");
}
@ -136,6 +139,7 @@ string showType(const Value & v)
case tBlackhole: return "a black hole";
case tPrimOp: return "a built-in function";
case tPrimOpApp: return "a partially applied built-in function";
case tExternal: return v.external->showType();
}
abort();
}
@ -1314,6 +1318,9 @@ string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
return coerceToString(pos, *i->value, context, coerceMore, copyToStore);
}
if (v.type == tExternal)
return v.external->coerceToString(pos, context, coerceMore, copyToStore);
if (coerceMore) {
/* Note that `false' is represented as an empty string for
@ -1434,6 +1441,9 @@ bool EvalState::eqValues(Value & v1, Value & v2)
case tPrimOpApp:
return false;
case tExternal:
return *v1.external == *v2.external;
default:
throwEvalError("cannot compare %1% with %2%", showType(v1), showType(v2));
}
@ -1575,6 +1585,11 @@ size_t valueSize(Value & v)
sz += doValue(*v.primOpApp.left);
sz += doValue(*v.primOpApp.right);
break;
case tExternal:
if (seen.find(v.external) != seen.end()) break;
seen.insert(v.external);
sz += v.external->valueSize(seen);
break;
default:
;
}
@ -1601,4 +1616,22 @@ size_t valueSize(Value & v)
}
string ExternalValueBase::coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const
{
throw TypeError(format("cannot coerce %1% to a string, at %2%") %
showType() % pos);
}
bool ExternalValueBase::operator==(const ExternalValueBase & b) const
{
return false;
}
std::ostream & operator << (std::ostream & str, const ExternalValueBase & v) {
return v.print(str);
}
}

View file

@ -187,6 +187,9 @@ static void prim_typeOf(EvalState & state, const Pos & pos, Value * * args, Valu
case tPrimOpApp:
t = "lambda";
break;
case tExternal:
t = args[0]->external->typeOf();
break;
default: abort();
}
mkString(v, state.symbols.create(t));

View file

@ -80,10 +80,21 @@ void printValueAsJSON(EvalState & state, bool strict,
break;
}
case tExternal:
v.external->printValueAsJSON(state, strict, str, context);
break;
default:
throw TypeError(format("cannot convert %1% to JSON") % showType(v));
}
}
void ExternalValueBase::printValueAsJSON(EvalState & state, bool strict,
std::ostream & str, PathSet & context) const
{
throw TypeError(format("cannot convert %1% to JSON") % showType());
}
}

View file

@ -144,12 +144,23 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
break;
}
case tExternal:
v.external->printValueAsXML(state, strict, location, doc, context, drvsSeen);
break;
default:
doc.writeEmptyElement("unevaluated");
}
}
void ExternalValueBase::printValueAsXML(EvalState & state, bool strict,
bool location, XMLWriter & doc, PathSet & context, PathSet & drvsSeen) const
{
doc.writeEmptyElement("unevaluated");
}
void printValueAsXML(EvalState & state, bool strict, bool location,
Value & v, std::ostream & out, PathSet & context)
{

View file

@ -19,6 +19,7 @@ typedef enum {
tBlackhole,
tPrimOp,
tPrimOpApp,
tExternal,
} ValueType;
@ -29,10 +30,58 @@ 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, 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;
/* How much space does this value take up */
virtual size_t valueSize(std::set<const void *> & seen) 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,
std::ostream & str, 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
{
@ -88,6 +137,7 @@ struct Value
struct {
Value * left, * right;
} primOpApp;
ExternalValueBase * external;
};
};