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Implement dots interface #209

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8f30a31
Implement dots interface
shikokuchuo Sep 12, 2025
cb8a76f
Add function to header
shikokuchuo Sep 12, 2025
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17 changes: 17 additions & 0 deletions src/include/Rinternals.h
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Original file line number Diff line number Diff line change
Expand Up @@ -708,6 +708,23 @@ Rboolean R_BindingIsActive(SEXP sym, SEXP env); // envir.c
SEXP R_ActiveBindingFunction(SEXP sym, SEXP env);
Rboolean R_HasFancyBindings(SEXP rho); // envir.c

/* Dots interface */
typedef enum {
R_DotTypeValue = 0,
R_DotTypeMissing = 1,
R_DotTypeDelayed = 2,
R_DotTypeForced = 3
} R_DotType;

Rboolean R_DotsExist(SEXP env); // envir.c
int R_DotsLength(SEXP env);
SEXP R_DotsNames(SEXP env);
SEXP R_DotsElt(int i, SEXP env);

R_DotType R_GetDotType(int i, SEXP env); // envir.c
SEXP R_DotDelayedExpression(int i, SEXP env);
SEXP R_DotDelayedEnvironment(int i, SEXP env);
SEXP R_DotForcedExpression(int i, SEXP env);

/* ../main/errors.c : */
/* needed for R_load/savehistory handling in front ends */
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82 changes: 76 additions & 6 deletions src/main/envir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1425,6 +1425,11 @@ static int ddVal(SEXP symbol)

#define length_DOTS(_v_) (TYPEOF(_v_) == DOTSXP ? length(_v_) : 0)

Rboolean R_DotsExist(SEXP env)
{
return R_findVar(R_DotsSymbol, env) != R_UnboundValue;
}

SEXP ddfind(int i, SEXP rho)
{
if(i <= 0)
Expand Down Expand Up @@ -1453,6 +1458,11 @@ SEXP ddfindVar(SEXP symbol, SEXP rho)
return ddfind(i, rho);
}

SEXP R_DotsElt(int i, SEXP env)
{
return eval(ddfind(i, env), env);
}

attribute_hidden SEXP do_dotsElt(SEXP call, SEXP op, SEXP args, SEXP env)
{
checkArity(op, args);
Expand All @@ -1465,23 +1475,26 @@ attribute_hidden SEXP do_dotsElt(SEXP call, SEXP op, SEXP args, SEXP env)
return eval(ddfind(i, env), env);
}

attribute_hidden SEXP do_dotsLength(SEXP call, SEXP op, SEXP args, SEXP env)
int R_DotsLength(SEXP env)
{
checkArity(op, args);
SEXP vl = R_findVar(R_DotsSymbol, env);
if (vl == R_UnboundValue)
error(_("incorrect context: the current call has no '...' to look in"));
error(_("incorrect context: the current call has no '...' to look in"));
// else
return ScalarInteger(length_DOTS(vl));
return length_DOTS(vl);
}

attribute_hidden SEXP do_dotsNames(SEXP call, SEXP op, SEXP args, SEXP env)
attribute_hidden SEXP do_dotsLength(SEXP call, SEXP op, SEXP args, SEXP env)
{
checkArity(op, args);
return ScalarInteger(R_DotsLength(env));
}

SEXP R_DotsNames(SEXP env) {
SEXP vl = R_findVar(R_DotsSymbol, env);
PROTECT(vl);
if (vl == R_UnboundValue)
error(_("incorrect context: the current call has no '...' to look in"));
error(_("incorrect context: the current call has no '...' to look in"));
// else
SEXP out;
int n = length_DOTS(vl);
Expand All @@ -1504,6 +1517,63 @@ attribute_hidden SEXP do_dotsNames(SEXP call, SEXP op, SEXP args, SEXP env)
return out;
}

attribute_hidden SEXP do_dotsNames(SEXP call, SEXP op, SEXP args, SEXP env)
{
checkArity(op, args);
return R_DotsNames(env);
}

// Dot helpers
// For all helpers:
// - If dots don't exist, should error, as you should use `R_DotsExist()` first
// - OOB indexing should error, as you should use `R_DotsLength()` first

R_DotType R_GetDotType(int i, SEXP env)
{
SEXP value = ddfind(i, env);

if (value == R_MissingArg)
return R_DotTypeMissing;

if (TYPEOF(value) == PROMSXP) {
if (PROMISE_IS_EVALUATED(value))
return R_DotTypeForced;
else
return R_DotTypeDelayed;
}

return R_DotTypeValue;
}

// For `R_DotTypeDelayed`
SEXP R_DotDelayedExpression(int i, SEXP env)
{
SEXP value = ddfind(i, env);
if (TYPEOF(value) != PROMSXP || PROMISE_IS_EVALUATED(value))
error(_("not a delayed promise"));

return R_PromiseExpr(value);
}

SEXP R_DotDelayedEnvironment(int i, SEXP env)
{
SEXP value = ddfind(i, env);
if (TYPEOF(value) != PROMSXP || PROMISE_IS_EVALUATED(value))
error(_("not a delayed promise"));

return PRENV(value);
}

// For `R_DotTypeForced`
SEXP R_DotForcedExpression(int i, SEXP env)
{
SEXP value = ddfind(i, env);
if (TYPEOF(value) != PROMSXP || !PROMISE_IS_EVALUATED(value))
error(_("not a forced promise"));

return R_PromiseExpr(value);
}

#undef length_DOTS

/*----------------------------------------------------------------------
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