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* Use a symbol table to represent identifiers and attribute names

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efficiently.  The symbol table ensures that there is only one copy
  of each symbol, thus allowing symbols to be compared efficiently
  using a pointer equality test.
This commit is contained in:
Eelco Dolstra 2010-04-13 12:25:42 +00:00
parent 10e8b1fd15
commit ac1e8f40d4
15 changed files with 228 additions and 101 deletions
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45
src/libexpr/eval.cc
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@ -43,8 +43,8 @@ std::ostream & operator << (std::ostream & str, Value & v)
break;
case tAttrs:
str << "{ ";
foreach (Bindings::iterator, i, *v.attrs)
str << i->first << " = " << i->second << "; ";
foreach (Bindings::iterator, i, *v.attrs)
str << (string) i->first << " = " << i->second << "; ";
str << "}";
break;
case tList:
@ -91,7 +91,14 @@ string showType(Value & v)
}
EvalState::EvalState() : baseEnv(allocEnv())
EvalState::EvalState()
: sWith(symbols.create("<with>"))
, sOutPath(symbols.create("outPath"))
, sDrvPath(symbols.create("drvPath"))
, sType(symbols.create("type"))
, sMeta(symbols.create("meta"))
, sName(symbols.create("name"))
, baseEnv(allocEnv())
{
nrValues = nrEnvs = nrEvaluated = recursionDepth = maxRecursionDepth = 0;
deepestStack = (char *) -1;
@ -110,9 +117,9 @@ EvalState::~EvalState()
void EvalState::addConstant(const string & name, Value & v)
{
baseEnv.bindings[name] = v;
baseEnv.bindings[symbols.create(name)] = v;
string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
(*baseEnv.bindings["builtins"].attrs)[name2] = v;
(*baseEnv.bindings[symbols.create("builtins")].attrs)[symbols.create(name2)] = v;
nrValues += 2;
}
@ -124,9 +131,9 @@ void EvalState::addPrimOp(const string & name,
v.type = tPrimOp;
v.primOp.arity = arity;
v.primOp.fun = primOp;
baseEnv.bindings[name] = v;
baseEnv.bindings[symbols.create(name)] = v;
string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
(*baseEnv.bindings["builtins"].attrs)[name2] = v;
(*baseEnv.bindings[symbols.create("builtins")].attrs)[symbols.create(name2)] = v;
nrValues += 2;
}
@ -225,12 +232,12 @@ void mkPath(Value & v, const char * s)
}
static Value * lookupWith(Env * env, const Sym & name)
Value * EvalState::lookupWith(Env * env, const Symbol & name)
{
if (!env) return 0;
Value * v = lookupWith(env->up, name);
if (v) return v;
Bindings::iterator i = env->bindings.find("<with>");
Bindings::iterator i = env->bindings.find(sWith);
if (i == env->bindings.end()) return 0;
Bindings::iterator j = i->second.attrs->find(name);
if (j != i->second.attrs->end()) return &j->second;
@ -238,7 +245,7 @@ static Value * lookupWith(Env * env, const Sym & name)
}
static Value * lookupVar(Env * env, const Sym & name)
Value * EvalState::lookupVar(Env * env, const Symbol & name)
{
/* First look for a regular variable binding for `name'. */
for (Env * env2 = env; env2; env2 = env2->up) {
@ -318,7 +325,7 @@ void EvalState::evalFile(const Path & path, Value & v)
Expr * e = parseTrees[path];
if (!e) {
e = parseExprFromFile(path);
e = parseExprFromFile(*this, path);
parseTrees[path] = e;
}
@ -428,9 +435,9 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
/* The inherited attributes, on the other hand, are
evaluated in the original environment. */
foreach (list<string>::iterator, i, inherited) {
foreach (list<Symbol>::iterator, i, inherited) {
Value & v2 = env2.bindings[*i];
mkCopy(v2, *lookupVar(&env, *i));
mkCopy(v2, *state.lookupVar(&env, *i));
}
}
@ -441,9 +448,9 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
mkThunk(v2, env, i->second);
}
foreach (list<string>::iterator, i, inherited) {
foreach (list<Symbol>::iterator, i, inherited) {
Value & v2 = (*v.attrs)[*i];
mkCopy(v2, *lookupVar(&env, *i));
mkCopy(v2, *state.lookupVar(&env, *i));
}
}
}
@ -459,7 +466,7 @@ void ExprList::eval(EvalState & state, Env & env, Value & v)
void ExprVar::eval(EvalState & state, Env & env, Value & v)
{
Value * v2 = lookupVar(&env, name);
Value * v2 = state.lookupVar(&env, name);
state.forceValue(*v2);
v = *v2;
}
@ -631,7 +638,7 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
Env & env2(state.allocEnv());
env2.up = &env;
Value & vAttrs = env2.bindings["<with>"];
Value & vAttrs = env2.bindings[state.sWith];
state.eval(env, attrs, vAttrs);
state.forceAttrs(vAttrs);
@ -871,7 +878,7 @@ string EvalState::forceStringNoCtx(Value & v)
bool EvalState::isDerivation(Value & v)
{
if (v.type != tAttrs) return false;
Bindings::iterator i = v.attrs->find("type");
Bindings::iterator i = v.attrs->find(sType);
return i != v.attrs->end() && forceStringNoCtx(i->second) == "derivation";
}
@ -915,7 +922,7 @@ string EvalState::coerceToString(Value & v, PathSet & context,
}
if (v.type == tAttrs) {
Bindings::iterator i = v.attrs->find("outPath");
Bindings::iterator i = v.attrs->find(sOutPath);
if (i == v.attrs->end())
throwTypeError("cannot coerce an attribute set (except a derivation) to a string");
return coerceToString(i->second, context, coerceMore, copyToStore);