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#include "nixexpr.hh"
#include "parser.hh"
#include "hash.hh"
#include "util.hh"
#include "nixexpr-ast.hh"
#include <cstdlib>
using namespace nix;
struct Env;
struct Value;
typedef std::map<string, Value> Bindings;
struct Env
{
Env * up;
Bindings bindings;
};
typedef enum {
tInt = 1,
tAttrs,
tThunk,
tLambda
} ValueType;
struct Value
{
ValueType type;
union
{
int integer;
Bindings * attrs;
struct {
Env * env;
Expr expr;
} thunk;
struct {
Env * env;
Pattern pat;
Expr body;
} lambda;
};
};
std::ostream & operator << (std::ostream & str, Value & v)
{
switch (v.type) {
case tInt:
str << v.integer;
break;
case tAttrs:
str << "{ ";
foreach (Bindings::iterator, i, *v.attrs)
str << i->first << " = " << i->second << "; ";
str << "}";
break;
case tThunk:
str << "<CODE>";
break;
default:
abort();
}
return str;
}
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);
}
Value * lookupVar(Env * env, const string & name)
{
for ( ; env; env = env->up) {
Bindings::iterator i = env->bindings.find(name);
if (i != env->bindings.end()) return &i->second;
}
throw Error("undefined variable");
}
unsigned long nrValues = 0;
unsigned long nrEnvs = 0;
Env * allocEnv()
{
nrEnvs++;
return new Env;
}
void eval(Env * env, Expr e, Value & v)
{
printMsg(lvlError, format("eval: %1%") % e);
ATerm name;
if (matchVar(e, name)) {
Value * v2 = lookupVar(env, aterm2String(name));
forceValue(*v2);
v = *v2;
return;
}
int n;
if (matchInt(e, n)) {
v.type = tInt;
v.integer = n;
return;
}
ATermList es;
if (matchAttrs(e, es)) {
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 = (*v.attrs)[aterm2String(name)];
nrValues++;
v2.type = tThunk;
v2.thunk.env = env;
v2.thunk.expr = e2;
}
return;
}
ATermList rbnds, nrbnds;
if (matchRec(e, rbnds, nrbnds)) {
Env * env2 = allocEnv();
env2->up = env;
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 = env2->bindings[aterm2String(name)];
nrValues++;
v2.type = tThunk;
v2.thunk.env = env2;
v2.thunk.expr = e2;
}
return;
}
Expr e2;
if (matchSelect(e, e2, name)) {
eval(env, e2, v);
if (v.type != tAttrs) throw TypeError("expected attribute set");
Bindings::iterator i = v.attrs->find(aterm2String(name));
if (i == v.attrs->end()) throw TypeError("attribute not found");
forceValue(i->second);
v = i->second;
return;
}
Pattern pat; Expr body; Pos pos;
if (matchFunction(e, pat, body, pos)) {
v.type = tLambda;
v.lambda.env = env;
v.lambda.pat = pat;
v.lambda.body = body;
return;
}
Expr fun, arg;
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;
eval(env2, v.lambda.body, v);
return;
}
abort();
}
void doTest(string s)
{
EvalState state;
Expr e = parseExprFromString(state, s, "/");
printMsg(lvlError, format("%1%") % e);
Value v;
eval(0, e, v);
printMsg(lvlError, format("result: %1%") % v);
}
void run(Strings args)
{
printMsg(lvlError, format("size of value: %1% bytes") % sizeof(Value));
doTest("123");
doTest("{ x = 1; y = 2; }");
doTest("{ x = 1; y = 2; }.y");
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);
printMsg(lvlError, format("alloced %1% environments") % nrEnvs);
}
void printHelp()
{
}
string programId = "eval-test";
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