lix/src/libexpr/nixexpr.cc
Eelco Dolstra 0f827cc607 * Prevent repeated wrapping of closed terms
(closed(closed(closed(...)))) since this reduces performance by
  producing bigger terms and killing caching (which incidentally also
  prevents useful infinite recursion detection).
2005-07-19 11:48:05 +00:00

374 lines
8.7 KiB
C++

#include "nixexpr.hh"
#include "derivations.hh"
#include "nixexpr-ast.hh"
#include "nixexpr-ast.cc"
ATermMap::ATermMap(unsigned int initialSize, unsigned int maxLoadPct)
: table(0)
{
this->maxLoadPct = maxLoadPct;
table = ATtableCreate(initialSize, maxLoadPct);
if (!table) throw Error("cannot create ATerm table");
}
ATermMap::ATermMap(const ATermMap & map)
: table(0)
{
copy(map);
}
ATermMap::~ATermMap()
{
free();
}
ATermMap & ATermMap::operator = (const ATermMap & map)
{
if (this == &map) return *this;
free();
copy(map);
return *this;
}
void ATermMap::free()
{
if (table) {
ATtableDestroy(table);
table = 0;
}
}
void ATermMap::copy(const ATermMap & map)
{
ATermList keys = map.keys();
/* !!! adjust allocation for load pct */
maxLoadPct = map.maxLoadPct;
table = ATtableCreate(ATgetLength(keys), maxLoadPct);
if (!table) throw Error("cannot create ATerm table");
add(map, keys);
}
void ATermMap::set(ATerm key, ATerm value)
{
return ATtablePut(table, key, value);
}
void ATermMap::set(const string & key, ATerm value)
{
set(toATerm(key), value);
}
ATerm ATermMap::get(ATerm key) const
{
return ATtableGet(table, key);
}
ATerm ATermMap::get(const string & key) const
{
return get(toATerm(key));
}
void ATermMap::remove(ATerm key)
{
ATtableRemove(table, key);
}
void ATermMap::remove(const string & key)
{
remove(toATerm(key));
}
ATermList ATermMap::keys() const
{
ATermList keys = ATtableKeys(table);
if (!keys) throw Error("cannot query aterm map keys");
return keys;
}
void ATermMap::add(const ATermMap & map)
{
ATermList keys = map.keys();
add(map, keys);
}
void ATermMap::add(const ATermMap & map, ATermList & keys)
{
for (ATermIterator i(keys); i; ++i)
set(*i, map.get(*i));
}
void ATermMap::reset()
{
ATtableReset(table);
}
string showPos(ATerm pos)
{
ATerm path;
int line, column;
if (matchNoPos(pos)) return "undefined position";
if (!matchPos(pos, path, line, column))
throw badTerm("position expected", pos);
return (format("`%1%', line %2%") % aterm2String(path) % line).str();
}
ATerm bottomupRewrite(TermFun & f, ATerm e)
{
checkInterrupt();
if (ATgetType(e) == AT_APPL) {
AFun fun = ATgetAFun(e);
int arity = ATgetArity(fun);
ATermList args = ATempty;
for (int i = arity - 1; i >= 0; i--)
args = ATinsert(args, bottomupRewrite(f, ATgetArgument(e, i)));
e = (ATerm) ATmakeApplList(fun, args);
}
else if (ATgetType(e) == AT_LIST) {
ATermList in = (ATermList) e;
ATermList out = ATempty;
for (ATermIterator i(in); i; ++i)
out = ATinsert(out, bottomupRewrite(f, *i));
e = (ATerm) ATreverse(out);
}
return f(e);
}
void queryAllAttrs(Expr e, ATermMap & attrs, bool withPos)
{
ATermList bnds;
if (!matchAttrs(e, bnds))
throw Error("attribute set expected");
for (ATermIterator i(bnds); i; ++i) {
ATerm name;
Expr e;
ATerm pos;
if (!matchBind(*i, name, e, pos)) abort(); /* can't happen */
attrs.set(name, withPos ? makeAttrRHS(e, pos) : e);
}
}
Expr queryAttr(Expr e, const string & name)
{
ATerm dummy;
return queryAttr(e, name, dummy);
}
Expr queryAttr(Expr e, const string & name, ATerm & pos)
{
ATermList bnds;
if (!matchAttrs(e, bnds))
throw Error("attribute set expected");
for (ATermIterator i(bnds); i; ++i) {
ATerm name2, pos2;
Expr e;
if (!matchBind(*i, name2, e, pos2))
abort(); /* can't happen */
if (aterm2String(name2) == name) {
pos = pos2;
return e;
}
}
return 0;
}
Expr makeAttrs(const ATermMap & attrs)
{
ATermList bnds = ATempty;
for (ATermIterator i(attrs.keys()); i; ++i) {
Expr e;
ATerm pos;
if (!matchAttrRHS(attrs.get(*i), e, pos))
abort(); /* can't happen */
bnds = ATinsert(bnds, makeBind(*i, e, pos));
}
return makeAttrs(ATreverse(bnds));
}
Expr substitute(const ATermMap & subs, Expr e)
{
checkInterrupt();
ATerm name, pos, e2;
/* As an optimisation, don't substitute in subterms known to be
closed. */
if (matchClosed(e, e2)) return e;
if (matchVar(e, name)) {
Expr sub = subs.get(name);
Expr wrapped;
/* Add a "closed" wrapper around terms that aren't already
closed. The check is necessary to prevent repeated
wrapping, e.g., closed(closed(closed(...))), which kills
caching. */
return sub ? (matchClosed(sub, wrapped) ? sub : makeClosed(sub)) : e;
}
/* In case of a function, filter out all variables bound by this
function. */
ATermList formals;
ATerm body, def;
if (matchFunction(e, formals, body, pos)) {
ATermMap subs2(subs);
for (ATermIterator i(formals); i; ++i) {
if (!matchNoDefFormal(*i, name) &&
!matchDefFormal(*i, name, def))
abort();
subs2.remove(name);
}
return makeFunction(
(ATermList) substitute(subs, (ATerm) formals),
substitute(subs2, body), pos);
}
if (matchFunction1(e, name, body, pos)) {
ATermMap subs2(subs);
subs2.remove(name);
return makeFunction1(name, substitute(subs2, body), pos);
}
/* Idem for a mutually recursive attribute set. */
ATermList rbnds, nrbnds;
if (matchRec(e, rbnds, nrbnds)) {
ATermMap subs2(subs);
for (ATermIterator i(rbnds); i; ++i)
if (matchBind(*i, name, e2, pos)) subs2.remove(name);
else abort(); /* can't happen */
for (ATermIterator i(nrbnds); i; ++i)
if (matchBind(*i, name, e2, pos)) subs2.remove(name);
else abort(); /* can't happen */
return makeRec(
(ATermList) substitute(subs2, (ATerm) rbnds),
(ATermList) substitute(subs, (ATerm) nrbnds));
}
if (ATgetType(e) == AT_APPL) {
AFun fun = ATgetAFun(e);
int arity = ATgetArity(fun);
ATermList args = ATempty;
for (int i = arity - 1; i >= 0; i--)
args = ATinsert(args, substitute(subs, ATgetArgument(e, i)));
return (ATerm) ATmakeApplList(fun, args);
}
if (ATgetType(e) == AT_LIST) {
ATermList out = ATempty;
for (ATermIterator i((ATermList) e); i; ++i)
out = ATinsert(out, substitute(subs, *i));
return (ATerm) ATreverse(out);
}
return e;
}
void checkVarDefs(const ATermMap & defs, Expr e)
{
ATerm name, pos, value;
ATermList formals;
ATerm with, body;
ATermList rbnds, nrbnds;
if (matchVar(e, name)) {
if (!defs.get(name))
throw Error(format("undefined variable `%1%'")
% aterm2String(name));
}
else if (matchFunction(e, formals, body, pos)) {
ATermMap defs2(defs);
for (ATermIterator i(formals); i; ++i) {
Expr deflt;
if (!matchNoDefFormal(*i, name))
if (matchDefFormal(*i, name, deflt))
checkVarDefs(defs, deflt);
else
abort();
defs2.set(name, (ATerm) ATempty);
}
checkVarDefs(defs2, body);
}
else if (matchFunction1(e, name, body, pos)) {
ATermMap defs2(defs);
defs2.set(name, (ATerm) ATempty);
checkVarDefs(defs2, body);
}
else if (matchRec(e, rbnds, nrbnds)) {
checkVarDefs(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);
}
checkVarDefs(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'. */
checkVarDefs(defs, with);
}
else if (ATgetType(e) == AT_APPL) {
int arity = ATgetArity(ATgetAFun(e));
for (int i = 0; i < arity; ++i)
checkVarDefs(defs, ATgetArgument(e, i));
}
else if (ATgetType(e) == AT_LIST)
for (ATermIterator i((ATermList) e); i; ++i)
checkVarDefs(defs, *i);
}
Expr makeBool(bool b)
{
return b ? eTrue : eFalse;
}