lix/src/libexpr/fix-expr.cc
Eelco Dolstra ac68840e79 * Refactoring: put the Nix expression evaluator in its own library so
that it can be used by multiple programs.
2003-11-19 11:35:41 +00:00

216 lines
4.7 KiB
C++

#include "fix-expr.hh"
#include "expr.hh"
ATermMap::ATermMap(unsigned int initialSize, unsigned int maxLoadPct)
{
table = ATtableCreate(initialSize, maxLoadPct);
if (!table) throw Error("cannot create ATerm table");
}
ATermMap::ATermMap(const ATermMap & map)
: table(0)
{
ATermList keys = map.keys();
/* !!! adjust allocation for load pct */
table = ATtableCreate(ATgetLength(keys), map.maxLoadPct);
if (!table) throw Error("cannot create ATerm table");
for (ATermIterator i(keys); i; ++i)
set(*i, map.get(*i));
}
ATermMap::~ATermMap()
{
if (table) ATtableDestroy(table);
}
void ATermMap::set(ATerm key, ATerm value)
{
return ATtablePut(table, key, value);
}
void ATermMap::set(const string & key, ATerm value)
{
set(string2ATerm(key), value);
}
ATerm ATermMap::get(ATerm key) const
{
return ATtableGet(table, key);
}
ATerm ATermMap::get(const string & key) const
{
return get(string2ATerm(key));
}
void ATermMap::remove(ATerm key)
{
ATtableRemove(table, key);
}
void ATermMap::remove(const string & key)
{
remove(string2ATerm(key));
}
ATermList ATermMap::keys() const
{
ATermList keys = ATtableKeys(table);
if (!keys) throw Error("cannot query aterm map keys");
return keys;
}
ATerm string2ATerm(const string & s)
{
return (ATerm) ATmakeAppl0(ATmakeAFun((char *) s.c_str(), 0, ATtrue));
}
string aterm2String(ATerm t)
{
return ATgetName(ATgetAFun(t));
}
ATerm bottomupRewrite(TermFun & f, ATerm e)
{
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)
{
ATMatcher m;
ATermList bnds;
if (!(atMatch(m, e) >> "Attrs" >> bnds))
throw badTerm("expected attribute set", e);
for (ATermIterator i(bnds); i; ++i) {
string s;
Expr e;
if (!(atMatch(m, *i) >> "Bind" >> s >> e))
abort(); /* can't happen */
attrs.set(s, e);
}
}
Expr queryAttr(Expr e, const string & name)
{
ATermMap attrs;
queryAllAttrs(e, attrs);
return attrs.get(name);
}
Expr makeAttrs(const ATermMap & attrs)
{
ATermList bnds = ATempty;
for (ATermIterator i(attrs.keys()); i; ++i)
bnds = ATinsert(bnds,
ATmake("Bind(<term>, <term>)", *i, attrs.get(*i)));
return ATmake("Attrs(<term>)", ATreverse(bnds));
}
Expr substitute(const ATermMap & subs, Expr e)
{
ATMatcher m;
string s;
if (atMatch(m, e) >> "Var" >> s) {
Expr sub = subs.get(s);
return sub ? sub : e;
}
/* In case of a function, filter out all variables bound by this
function. */
ATermList formals;
ATerm body;
if (atMatch(m, e) >> "Function" >> formals >> body) {
ATermMap subs2(subs);
for (ATermIterator i(formals); i; ++i) {
Expr def;
if (!(atMatch(m, *i) >> "NoDefFormal" >> s) &&
!(atMatch(m, *i) >> "DefFormal" >> s >> def))
abort();
subs2.remove(s);
}
return ATmake("Function(<term>, <term>)", formals,
substitute(subs2, body));
}
/* Idem for a mutually recursive attribute set. */
ATermList bindings;
if (atMatch(m, e) >> "Rec" >> bindings) {
ATermMap subs2(subs);
for (ATermIterator i(bindings); i; ++i) {
Expr e;
if (!(atMatch(m, *i) >> "Bind" >> s >> e))
abort(); /* can't happen */
subs2.remove(s);
}
return ATmake("Rec(<term>)", substitute(subs2, (ATerm) bindings));
}
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;
}
Expr makeBool(bool b)
{
return b ? ATmake("Bool(True)") : ATmake("Bool(False)");
}