* Implemented attribute set pattern matches.

This commit is contained in:
Eelco Dolstra 2010-03-24 23:40:00 +00:00
parent 0fd3648d34
commit 7482349fe8

View file

@ -26,7 +26,8 @@ typedef enum {
tInt = 1,
tAttrs,
tThunk,
tLambda
tLambda,
tCopy
} ValueType;
@ -46,6 +47,7 @@ struct Value
Pattern pat;
Expr body;
} lambda;
Value * val;
};
};
@ -65,6 +67,9 @@ std::ostream & operator << (std::ostream & str, Value & v)
case tThunk:
str << "<CODE>";
break;
case tLambda:
str << "<LAMBDA>";
break;
default:
abort();
}
@ -72,13 +77,16 @@ std::ostream & operator << (std::ostream & str, Value & v)
}
void eval(Env * env, Expr e, Value & v);
static void eval(Env * env, Expr e, Value & v);
void forceValue(Value & v)
{
if (v.type != tThunk) return;
eval(v.thunk.env, v.thunk.expr, v);
if (v.type == tThunk) eval(v.thunk.env, v.thunk.expr, v);
else if (v.type == tCopy) {
forceValue(*v.val);
v = *v.val;
}
}
@ -103,7 +111,92 @@ Env * allocEnv()
}
void eval(Env * env, Expr e, Value & v)
static bool patternIsStrict(Pattern pat)
{
ATerm name, ellipsis, pat1, pat2;
ATermList formals;
if (matchVarPat(pat, name)) return false;
else if (matchAttrsPat(pat, formals, ellipsis)) return true;
else if (matchAtPat(pat, pat1, pat2))
return patternIsStrict(pat1) || patternIsStrict(pat2);
else abort();
}
static void bindVarPats(Pattern pat, Env & newEnv,
Env * argEnv, Expr argExpr, Value * & vArg)
{
Pattern pat1, pat2;
if (matchAtPat(pat, pat1, pat2)) {
bindVarPats(pat1, newEnv, argEnv, argExpr, vArg);
bindVarPats(pat2, newEnv, argEnv, argExpr, vArg);
return;
}
ATerm name;
if (!matchVarPat(pat, name)) abort();
if (vArg) {
Value & v = newEnv.bindings[aterm2String(name)];
v.type = tCopy;
v.val = vArg;
} else {
vArg = &newEnv.bindings[aterm2String(name)];
vArg->type = tThunk;
vArg->thunk.env = argEnv;
vArg->thunk.expr = argExpr;
}
}
static void bindAttrPats(Pattern pat, Env & newEnv,
Value & vArg, Value * & vArgInEnv)
{
Pattern pat1, pat2;
if (matchAtPat(pat, pat1, pat2)) {
bindAttrPats(pat1, newEnv, vArg, vArgInEnv);
bindAttrPats(pat2, newEnv, vArg, vArgInEnv);
return;
}
ATerm name;
if (matchVarPat(pat, name)) {
if (vArgInEnv) {
Value & v = newEnv.bindings[aterm2String(name)];
v.type = tCopy;
v.val = vArgInEnv;
} else {
vArgInEnv = &newEnv.bindings[aterm2String(name)];
*vArgInEnv = vArg;
}
return;
}
ATerm ellipsis;
ATermList formals;
if (matchAttrsPat(pat, formals, ellipsis)) {
for (ATermIterator i(formals); i; ++i) {
Expr name, def;
DefaultValue def2;
if (!matchFormal(*i, name, def2)) abort(); /* can't happen */
Bindings::iterator j = vArg.attrs->find(aterm2String(name));
if (j == vArg.attrs->end())
throw TypeError(format("the argument named `%1%' required by the function is missing")
% aterm2String(name));
Value & v = newEnv.bindings[aterm2String(name)];
v.type = tCopy;
v.val = &j->second;
}
return;
}
abort();
}
static void eval(Env * env, Expr e, Value & v)
{
printMsg(lvlError, format("eval: %1%") % e);
@ -182,17 +275,21 @@ void eval(Env * env, Expr e, Value & v)
if (matchCall(e, fun, arg)) {
eval(env, fun, v);
if (v.type != tLambda) throw TypeError("expected function");
if (!matchVarPat(v.lambda.pat, name)) throw Error("not implemented");
Env * env2 = allocEnv();
env2->up = env;
Value & arg_ = env2->bindings[aterm2String(name)];
nrValues++;
arg_.type = tThunk;
arg_.thunk.env = env;
arg_.thunk.expr = arg;
if (patternIsStrict(v.lambda.pat)) {
Value vArg;
eval(env, arg, vArg);
if (vArg.type != tAttrs) throw TypeError("expected attribute set");
Value * vArg2 = 0;
bindAttrPats(v.lambda.pat, *env2, vArg, vArg2);
} else {
Value * vArg = 0;
bindVarPats(v.lambda.pat, *env2, env, arg, vArg);
}
eval(env2, v.lambda.body, v);
return;
}
@ -205,7 +302,7 @@ void doTest(string s)
{
EvalState state;
Expr e = parseExprFromString(state, s, "/");
printMsg(lvlError, format("%1%") % e);
printMsg(lvlError, format(">>>>> %1%") % e);
Value v;
eval(0, e, v);
printMsg(lvlError, format("result: %1%") % v);
@ -222,6 +319,13 @@ void run(Strings args)
doTest("rec { x = 1; y = x; }.y");
doTest("(x: x) 1");
doTest("(x: y: y) 1 2");
doTest("(x@y: x) 1");
doTest("(x@y: y) 2");
doTest("(x@y@z: y) 3");
doTest("x: x");
doTest("({x, y}: x) { x = 1; y = 2; }");
doTest("({x, y}@args: args.x) { x = 1; y = 2; }");
doTest("({x, y}@args@args2: args2.x) { x = 1; y = 2; }");
//Expr e = parseExprFromString(state, "let x = \"a\"; in x + \"b\"", "/");
//Expr e = parseExprFromString(state, "(x: x + \"b\") \"a\"", "/");