Add a primop unsafeGetAttrPos to return the position of an attribute

This commit is contained in:
Eelco Dolstra 2013-11-18 22:22:35 +01:00
parent fc33fd86b7
commit 285df765b9
6 changed files with 44 additions and 6 deletions

View file

@ -410,6 +410,19 @@ void EvalState::mkThunk_(Value & v, Expr * expr)
} }
void EvalState::mkPos(Value & v, Pos * pos)
{
if (pos) {
mkAttrs(v, 3);
mkString(*allocAttr(v, sFile), pos->file);
mkInt(*allocAttr(v, sLine), pos->line);
mkInt(*allocAttr(v, sColumn), pos->column);
v.attrs->sort();
} else
mkNull(v);
}
/* Create a thunk for the delayed computation of the given expression /* Create a thunk for the delayed computation of the given expression
in the given environment. But if the expression is a variable, in the given environment. But if the expression is a variable,
then look it up right away. This significantly reduces the number then look it up right away. This significantly reduces the number
@ -1044,11 +1057,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
void ExprPos::eval(EvalState & state, Env & env, Value & v) void ExprPos::eval(EvalState & state, Env & env, Value & v)
{ {
state.mkAttrs(v, 3); state.mkPos(v, &pos);
mkString(*state.allocAttr(v, state.sFile), pos.file);
mkInt(*state.allocAttr(v, state.sLine), pos.line);
mkInt(*state.allocAttr(v, state.sColumn), pos.column);
v.attrs->sort();
} }

View file

@ -243,6 +243,7 @@ public:
void mkList(Value & v, unsigned int length); void mkList(Value & v, unsigned int length);
void mkAttrs(Value & v, unsigned int expected); void mkAttrs(Value & v, unsigned int expected);
void mkThunk_(Value & v, Expr * expr); void mkThunk_(Value & v, Expr * expr);
void mkPos(Value & v, Pos * pos);
void concatLists(Value & v, unsigned int nrLists, Value * * lists); void concatLists(Value & v, unsigned int nrLists, Value * * lists);

View file

@ -776,6 +776,19 @@ void prim_getAttr(EvalState & state, Value * * args, Value & v)
} }
/* Return position information of the specified attribute. */
void prim_unsafeGetAttrPos(EvalState & state, Value * * args, Value & v)
{
string attr = state.forceStringNoCtx(*args[0]);
state.forceAttrs(*args[1]);
Bindings::iterator i = args[1]->attrs->find(state.symbols.create(attr));
if (i == args[1]->attrs->end())
mkNull(v);
else
state.mkPos(v, i->pos);
}
/* Dynamic version of the `?' operator. */ /* Dynamic version of the `?' operator. */
static void prim_hasAttr(EvalState & state, Value * * args, Value & v) static void prim_hasAttr(EvalState & state, Value * * args, Value & v)
{ {
@ -1201,7 +1214,7 @@ void EvalState::createBaseEnv()
mkBool(v, false); mkBool(v, false);
addConstant("false", v); addConstant("false", v);
v.type = tNull; mkNull(v);
addConstant("null", v); addConstant("null", v);
mkInt(v, time(0)); mkInt(v, time(0));
@ -1252,6 +1265,7 @@ void EvalState::createBaseEnv()
// Sets // Sets
addPrimOp("__attrNames", 1, prim_attrNames); addPrimOp("__attrNames", 1, prim_attrNames);
addPrimOp("__getAttr", 2, prim_getAttr); addPrimOp("__getAttr", 2, prim_getAttr);
addPrimOp("__unsafeGetAttrPos", 2, prim_unsafeGetAttrPos);
addPrimOp("__hasAttr", 2, prim_hasAttr); addPrimOp("__hasAttr", 2, prim_hasAttr);
addPrimOp("__isAttrs", 1, prim_isAttrs); addPrimOp("__isAttrs", 1, prim_isAttrs);
addPrimOp("removeAttrs", 2, prim_removeAttrs); addPrimOp("removeAttrs", 2, prim_removeAttrs);

View file

@ -116,6 +116,13 @@ static inline void mkBool(Value & v, bool b)
} }
static inline void mkNull(Value & v)
{
v.type = tNull;
v.app.left = v.app.right = 00; // scrub
}
static inline void mkApp(Value & v, Value & left, Value & right) static inline void mkApp(Value & v, Value & left, Value & right)
{ {
v.type = tApp; v.type = tApp;

View file

@ -0,0 +1 @@
{ column = 5; file = "eval-okay-getattrpos.nix"; line = 3; }

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@ -0,0 +1,6 @@
let
as = {
foo = "bar";
};
pos = builtins.unsafeGetAttrPos "foo" as;
in { inherit (pos) column line; file = baseNameOf pos.file; }