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Nasal Ghosts can optionally specify member get/set functions.

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This commit is contained in:
James Turner 2012-04-28 22:25:57 +01:00
parent 2daf895d00
commit a5ca531aac
3 changed files with 56 additions and 13 deletions
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49
simgear/nasal/code.c
View File

@ -424,23 +424,37 @@ static void setSymbol(struct Frame* f, naRef sym, naRef val)
naHash_set(f->locals, sym, val);
}
static const char* ghostGetMember(naContext ctx, naRef obj, naRef field, naRef* out)
{
naGhostType* gtype = PTR(obj).ghost->gtype;
if (!gtype->get_member) return "ghost does not support member access";
return gtype->get_member(ctx, PTR(obj).ghost->ptr, field, out);
}
// Funky API: returns null to indicate no member, an empty string to
// indicate success, or a non-empty error message. Works this way so
// we can generate smart error messages without throwing them with a
// longjmp -- this gets called under naMember_get() from C code.
static const char* getMember_r(naRef obj, naRef field, naRef* out, int count)
static const char* getMember_r(naContext ctx, naRef obj, naRef field, naRef* out, int count)
{
int i;
naRef p;
struct VecRec* pv;
if(--count < 0) return "too many parents";
if(!IS_HASH(obj)) return "non-objects have no members";
if(naHash_get(obj, field, out)) return "";
if(!naHash_get(obj, globals->parentsRef, &p)) return 0;
if(!IS_HASH(obj) && !IS_GHOST(obj)) return "non-objects have no members";
if (IS_GHOST(obj)) {
if (ghostGetMember(ctx, obj, field, out)) return "";
if(!ghostGetMember(ctx, obj, globals->parentsRef, &p)) return 0;
} else {
if(naHash_get(obj, field, out)) return "";
if(!naHash_get(obj, globals->parentsRef, &p)) return 0;
}
if(!IS_VEC(p)) return "object \"parents\" field not vector";
pv = PTR(p).vec->rec;
for(i=0; pv && i<pv->size; i++) {
const char* err = getMember_r(pv->array[i], field, out, count);
const char* err = getMember_r(ctx, pv->array[i], field, out, count);
if(err) return err; /* either an error or success */
}
return 0;
@ -449,14 +463,29 @@ static const char* getMember_r(naRef obj, naRef field, naRef* out, int count)
static void getMember(naContext ctx, naRef obj, naRef fld,
naRef* result, int count)
{
const char* err = getMember_r(obj, fld, result, count);
const char* err = getMember_r(ctx, obj, fld, result, count);
if(!err) naRuntimeError(ctx, "No such member: %s", naStr_data(fld));
if(err[0]) naRuntimeError(ctx, err);
}
int naMember_get(naRef obj, naRef field, naRef* out)
static void setMember(naContext ctx, naRef obj, naRef fld, naRef value)
{
const char* err = getMember_r(obj, field, out, 64);
if (IS_GHOST(obj)) {
naGhostType* gtype = PTR(obj).ghost->gtype;
if (!gtype->set_member) ERR(ctx, "ghost does not support member access");
gtype->set_member(ctx, PTR(obj).ghost->ptr, fld, value);
ctx->opTop -= 2;
return;
}
if(!IS_HASH(obj)) ERR(ctx, "non-objects have no members");
naHash_set(obj, fld, value);
ctx->opTop -= 2;
}
int naMember_get(naContext ctx, naRef obj, naRef field, naRef* out)
{
const char* err = getMember_r(ctx, obj, field, out, 64);
return err && !err[0];
}
@ -619,9 +648,7 @@ static naRef run(naContext ctx)
getMember(ctx, STK(1), CONSTARG(), &STK(1), 64);
break;
case OP_SETMEMBER:
if(!IS_HASH(STK(2))) ERR(ctx, "non-objects have no members");
naHash_set(STK(2), STK(1), STK(3));
ctx->opTop -= 2;
setMember(ctx, STK(2), STK(1), STK(3));
break;
case OP_INSERT:
containerSet(ctx, STK(2), STK(1), STK(3));

12
simgear/nasal/misc.c
View File

@ -121,12 +121,24 @@ naRef naNewFunc(struct Context* c, naRef code)
naRef naNewGhost(naContext c, naGhostType* type, void* ptr)
{
// ensure 'simple' ghost users don't see garbage for these fields
type->get_member = 0;
type->set_member = 0;
naRef ghost = naNew(c, T_GHOST);
PTR(ghost).ghost->gtype = type;
PTR(ghost).ghost->ptr = ptr;
return ghost;
}
naRef naNewGhost2(naContext c, naGhostType* t, void* ptr)
{
naRef ghost = naNew(c, T_GHOST);
PTR(ghost).ghost->gtype = t;
PTR(ghost).ghost->ptr = ptr;
return ghost;
}
naGhostType* naGhost_type(naRef ghost)
{
if(!IS_GHOST(ghost)) return 0;

8
simgear/nasal/nasal.h
View File

@ -99,8 +99,8 @@ void naRethrowError(naContext subc);
// Retrieve the specified member from the object, respecting the
// "parents" array as for "object.field". Returns zero for missing
// fields.
int naMember_get(naRef obj, naRef field, naRef* out);
int naMember_cget(naRef obj, const char* field, naRef* out);
int naMember_get(naContext c, naRef obj, naRef field, naRef* out);
int naMember_cget(naContext c, naRef obj, const char* field, naRef* out);
// Returns a hash containing functions from the Nasal standard library
// Useful for passing as a namespace to an initial function call
@ -181,8 +181,12 @@ void naHash_keys(naRef dst, naRef hash);
typedef struct naGhostType {
void(*destroy)(void*);
const char* name;
const char*(*get_member)(naContext c, void*, naRef key, naRef* out);
void(*set_member)(naContext c, void*, naRef key, naRef val);
} naGhostType;
naRef naNewGhost(naContext c, naGhostType* t, void* ghost);
naRef naNewGhost2(naContext c, naGhostType* t, void* ghost);
naGhostType* naGhost_type(naRef ghost);
void* naGhost_ptr(naRef ghost);
int naIsGhost(naRef r);