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* After parsing, compute level/displacement pairs for each variable

Browse source 
use site, allowing environments to be stores as vectors of values
  rather than maps.  This should speed up evaluation and reduce the
  number of allocations.
This commit is contained in:
Eelco Dolstra 2010-04-14 14:42:32 +00:00
parent 816dd3f061
commit 9985230c00
7 changed files with 258 additions and 143 deletions
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234
src/libexpr/nixexpr.cc
View file

@ -8,13 +8,14 @@
namespace nix {
/* Displaying abstract syntax trees. */
std::ostream & operator << (std::ostream & str, Expr & e)
{
e.show(str);
return str;
}
void Expr::show(std::ostream & str)
{
abort();
@ -135,103 +136,162 @@ std::ostream & operator << (std::ostream & str, const Pos & pos)
str << (format("`%1%:%2%:%3%'") % pos.file % pos.line % pos.column).str();
return str;
}
#if 0
static void varsBoundByPattern(ATermMap & map, Pattern pat)
/* Computing levels/displacements for variables. */
void Expr::bindVars(const StaticEnv & env)
{
ATerm name;
ATermList formals;
ATermBool ellipsis;
/* Use makeRemoved() so that it can be used directly in
substitute(). */
if (matchVarPat(pat, name))
map.set(name, makeRemoved());
else if (matchAttrsPat(pat, formals, ellipsis, name)) {
if (name != sNoAlias) map.set(name, makeRemoved());
for (ATermIterator i(formals); i; ++i) {
ATerm d1;
if (!matchFormal(*i, name, d1)) abort();
map.set(name, makeRemoved());
abort();
}
void ExprInt::bindVars(const StaticEnv & env)
{
}
void ExprString::bindVars(const StaticEnv & env)
{
}
void ExprPath::bindVars(const StaticEnv & env)
{
}
void ExprVar::bindVars(const StaticEnv & env)
{
/* Check whether the variable appears in the environment. If so,
set its level and displacement. */
const StaticEnv * curEnv;
unsigned int level;
int withLevel = -1;
for (curEnv = &env, level = 0; curEnv; curEnv = curEnv->up, level++) {
if (curEnv->isWith) {
if (withLevel == -1) withLevel = level;
} else {
StaticEnv::Vars::const_iterator i = curEnv->vars.find(name);
if (i != curEnv->vars.end()) {
fromWith = false;
this->level = level;
displ = i->second;
return;
}
}
}
else abort();
/* Otherwise, the variable must be obtained from the nearest
enclosing `with'. If there is no `with', then we can issue an
"undefined variable" error now. */
if (withLevel == -1) throw EvalError(format("undefined variable `%1%'") % name);
fromWith = true;
this->level = withLevel;
}
/* We use memoisation to prevent exponential complexity on heavily
shared ATerms (remember, an ATerm is a graph, not a tree!). Note
that using an STL set is fine here wrt to ATerm garbage collection
since all the ATerms in the set are already reachable from
somewhere else. */
static void checkVarDefs2(set<Expr> & done, const ATermMap & defs, Expr e)
void ExprSelect::bindVars(const StaticEnv & env)
{
if (done.find(e) != done.end()) return;
done.insert(e);
ATerm name, pos, value;
ATerm with, body;
ATermList rbnds, nrbnds;
Pattern pat;
/* Closed terms don't have free variables, so we don't have to
check by definition. */
if (matchClosed(e, value)) return;
else if (matchVar(e, name)) {
if (!defs.get(name))
throw EvalError(format("undefined variable `%1%'")
% aterm2String(name));
}
else if (matchFunction(e, pat, body, pos)) {
ATermMap defs2(defs);
varsBoundByPattern(defs2, pat);
set<Expr> done2;
checkVarDefs2(done2, defs2, pat);
checkVarDefs2(done2, defs2, body);
}
else if (matchRec(e, rbnds, nrbnds)) {
checkVarDefs2(done, defs, (ATerm) nrbnds);
ATermMap defs2(defs);
for (ATermIterator i(rbnds); i; ++i) {
if (!matchBind(*i, name, value, pos)) abort(); /* can't happen */
defs2.set(name, (ATerm) ATempty);
}
for (ATermIterator i(nrbnds); i; ++i) {
if (!matchBind(*i, name, value, pos)) abort(); /* can't happen */
defs2.set(name, (ATerm) ATempty);
}
set<Expr> done2;
checkVarDefs2(done2, defs2, (ATerm) rbnds);
}
else if (matchWith(e, with, body, pos)) {
/* We can't check the body without evaluating the definitions
(which is an arbitrary expression), so we don't do that
here but only when actually evaluating the `with'. */
checkVarDefs2(done, defs, with);
}
else if (ATgetType(e) == AT_APPL) {
int arity = ATgetArity(ATgetAFun(e));
for (int i = 0; i < arity; ++i)
checkVarDefs2(done, defs, ATgetArgument(e, i));
}
else if (ATgetType(e) == AT_LIST)
for (ATermIterator i((ATermList) e); i; ++i)
checkVarDefs2(done, defs, *i);
e->bindVars(env);
}
void checkVarDefs(const ATermMap & defs, Expr e)
void ExprOpHasAttr::bindVars(const StaticEnv & env)
{
set<Expr> done;
checkVarDefs2(done, defs, e);
e->bindVars(env);
}
void ExprAttrs::bindVars(const StaticEnv & env)
{
if (recursive) {
StaticEnv newEnv(false, &env);
unsigned int displ = 0;
foreach (ExprAttrs::Attrs::iterator, i, attrs)
newEnv.vars[i->first] = displ++;
foreach (list<Symbol>::iterator, i, inherited)
newEnv.vars[*i] = displ++;
foreach (ExprAttrs::Attrs::iterator, i, attrs)
i->second->bindVars(newEnv);
}
else
foreach (ExprAttrs::Attrs::iterator, i, attrs)
i->second->bindVars(env);
}
void ExprList::bindVars(const StaticEnv & env)
{
foreach (vector<Expr *>::iterator, i, elems)
(*i)->bindVars(env);
}
void ExprLambda::bindVars(const StaticEnv & env)
{
StaticEnv newEnv(false, &env);
unsigned int displ = 0;
if (!arg.empty()) newEnv.vars[arg] = displ++;
if (matchAttrs) {
foreach (Formals::Formals_::iterator, i, formals->formals)
newEnv.vars[i->name] = displ++;
foreach (Formals::Formals_::iterator, i, formals->formals)
if (i->def) i->def->bindVars(newEnv);
}
body->bindVars(newEnv);
}
void ExprLet::bindVars(const StaticEnv & env)
{
StaticEnv newEnv(false, &env);
unsigned int displ = 0;
foreach (ExprAttrs::Attrs::iterator, i, attrs->attrs)
newEnv.vars[i->first] = displ++;
foreach (list<Symbol>::iterator, i, attrs->inherited)
newEnv.vars[*i] = displ++;
foreach (ExprAttrs::Attrs::iterator, i, attrs->attrs)
i->second->bindVars(newEnv);
body->bindVars(newEnv);
}
void ExprWith::bindVars(const StaticEnv & env)
{
attrs->bindVars(env);
StaticEnv newEnv(true, &env);
body->bindVars(newEnv);
}
void ExprIf::bindVars(const StaticEnv & env)
{
cond->bindVars(env);
then->bindVars(env);
else_->bindVars(env);
}
void ExprAssert::bindVars(const StaticEnv & env)
{
cond->bindVars(env);
body->bindVars(env);
}
void ExprOpNot::bindVars(const StaticEnv & env)
{
e->bindVars(env);
}
void ExprConcatStrings::bindVars(const StaticEnv & env)
{
foreach (vector<Expr *>::iterator, i, *es)
(*i)->bindVars(env);
}
#endif
}