* Reduce the number of value allocations in eval() by moving

responsibility for allocation of the result to the caller.
This commit is contained in:
Eelco Dolstra 2010-03-24 12:11:38 +00:00
parent d31c59eb17
commit b70bd8fe56

View file

@ -73,14 +73,13 @@ std::ostream & operator << (std::ostream & str, Value_ & v)
}
Value eval(Env env, Expr e);
void eval(Env env, Expr e, Value v);
void forceValue(Value v)
{
if (v->type != tThunk) return;
Value v2 = eval(v->thunk.env, v->thunk.expr);
*v = *v2; // !!! slightly inefficient
eval(v->thunk.env, v->thunk.expr, v);
}
@ -94,40 +93,48 @@ Value lookupVar(Env env, const string & name)
}
Value eval(Env env, Expr e)
unsigned long nrValues = 0;
Value allocValue()
{
nrValues++;
return new Value_;
}
void eval(Env env, Expr e, Value v)
{
printMsg(lvlError, format("eval: %1%") % e);
ATerm name;
if (matchVar(e, name)) {
Value v = lookupVar(env, aterm2String(name));
forceValue(v);
return v;
Value v2 = lookupVar(env, aterm2String(name));
forceValue(v2);
*v = *v2;
return;
}
int n;
if (matchInt(e, n)) {
Value v = new Value_;
v->type = tInt;
v->integer = n;
return v;
return;
}
ATermList es;
if (matchAttrs(e, es)) {
Value v = new Value_;
v->type = tAttrs;
v->attrs = new Bindings;
ATerm e2, pos;
for (ATermIterator i(es); i; ++i) {
if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
Value v2 = new Value_;
Value v2 = allocValue();
v2->type = tThunk;
v2->thunk.env = env;
v2->thunk.expr = e2;
(*v->attrs)[aterm2String(name)] = v2;
}
return v;
return;
}
ATermList rbnds, nrbnds;
@ -135,48 +142,48 @@ Value eval(Env env, Expr e)
Env env2 = new Env_;
env2->up = env;
Value v = new Value_;
v->type = tAttrs;
v->attrs = &env2->bindings;
ATerm name, e2, pos;
for (ATermIterator i(rbnds); i; ++i) {
if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
Value v2 = new Value_;
Value v2 = allocValue();
v2->type = tThunk;
v2->thunk.env = env2;
v2->thunk.expr = e2;
env2->bindings[aterm2String(name)] = v2;
}
return v;
return;
}
Expr e2;
if (matchSelect(e, e2, name)) {
Value v = eval(env, e2);
eval(env, e2, v);
if (v->type != tAttrs) throw TypeError("expected attribute set");
Value v2 = (*v->attrs)[aterm2String(name)];
if (!v2) throw TypeError("attribute not found");
forceValue(v2);
return v2;
*v = *v2;
return;
}
Pattern pat; Expr body; Pos pos;
if (matchFunction(e, pat, body, pos)) {
Value v = new Value_;
v->type = tLambda;
v->lambda.env = env;
v->lambda.pat = pat;
v->lambda.body = body;
return v;
return;
}
Expr fun, arg;
if (matchCall(e, fun, arg)) {
Value fun_ = eval(env, fun);
if (fun_->type != tLambda) throw TypeError("expected function");
if (!matchVarPat(fun_->lambda.pat, name)) throw Error("not implemented");
eval(env, fun, v);
if (v->type != tLambda) throw TypeError("expected function");
if (!matchVarPat(v->lambda.pat, name)) throw Error("not implemented");
Value arg_ = new Value_;
Value arg_ = allocValue();
arg_->type = tThunk;
arg_->thunk.env = env;
arg_->thunk.expr = arg;
@ -185,7 +192,8 @@ Value eval(Env env, Expr e)
env2->up = env;
env2->bindings[aterm2String(name)] = arg_;
return eval(env2, fun_->lambda.body);
eval(env2, v->lambda.body, v);
return;
}
abort();
@ -197,8 +205,9 @@ void doTest(string s)
EvalState state;
Expr e = parseExprFromString(state, s, "/");
printMsg(lvlError, format("%1%") % e);
Value v = eval(0, e);
printMsg(lvlError, format("result: %1%") % *v);
Value_ v;
eval(0, e, &v);
printMsg(lvlError, format("result: %1%") % v);
}
@ -212,10 +221,13 @@ void run(Strings args)
doTest("rec { x = 1; y = x; }.y");
doTest("(x: x) 1");
doTest("(x: y: y) 1 2");
//Expr e = parseExprFromString(state, "let x = \"a\"; in x + \"b\"", "/");
//Expr e = parseExprFromString(state, "(x: x + \"b\") \"a\"", "/");
//Expr e = parseExprFromString(state, "\"a\" + \"b\"", "/");
//Expr e = parseExprFromString(state, "\"a\" + \"b\"", "/");
printMsg(lvlError, format("alloced %1% values") % nrValues);
}