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nix-gh/src/libexpr/nixexpr.cc

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#include "nixexpr.hh"
#include "derivations.hh"
#include "util.hh"
#include "aterm.hh"
#include "nixexpr-ast.hh"
#include "nixexpr-ast.cc"
#include <cstdlib>
namespace nix {
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);
ATerm args[arity];
for (int i = 0; i < arity; ++i)
args[i] = bottomupRewrite(f, ATgetArgument(e, i));
e = (ATerm) ATmakeApplArray(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 TypeError(format("value is %1% while an attribute set was expected") % showType(e));
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 TypeError(format("value is %1% while an attribute set was expected") % showType(e));
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 (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i) {
Expr e;
ATerm pos;
if (!matchAttrRHS(i->value, e, pos))
abort(); /* can't happen */
bnds = ATinsert(bnds, makeBind(i->key, e, pos));
}
return makeAttrs(bnds);
}
Expr substitute(const Substitution & subs, Expr e)
{
checkInterrupt();
//if (subs.size() == 0) return e;
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.lookup(name);
if (sub == makeRemoved()) sub = 0;
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;
if (matchFunction(e, formals, body, pos)) {
ATermMap map(ATgetLength(formals));
for (ATermIterator i(formals); i; ++i) {
ATerm d1;
if (!matchFormal(*i, name, d1)) abort();
map.set(name, makeRemoved());
}
Substitution subs2(&subs, &map);
return makeFunction(
(ATermList) substitute(subs2, (ATerm) formals),
substitute(subs2, body), pos);
}
if (matchFunction1(e, name, body, pos)) {
ATermMap map(1);
map.set(name, makeRemoved());
return makeFunction1(name, substitute(Substitution(&subs, &map), body), pos);
}
/* Idem for a mutually recursive attribute set. */
ATermList rbnds, nrbnds;
if (matchRec(e, rbnds, nrbnds)) {
ATermMap map(ATgetLength(rbnds) + ATgetLength(nrbnds));
for (ATermIterator i(rbnds); i; ++i)
if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved());
else abort(); /* can't happen */
for (ATermIterator i(nrbnds); i; ++i)
if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved());
else abort(); /* can't happen */
return makeRec(
(ATermList) substitute(Substitution(&subs, &map), (ATerm) rbnds),
(ATermList) substitute(subs, (ATerm) nrbnds));
}
if (ATgetType(e) == AT_APPL) {
AFun fun = ATgetAFun(e);
int arity = ATgetArity(fun);
ATerm args[arity];
bool changed = false;
for (int i = 0; i < arity; ++i) {
ATerm arg = ATgetArgument(e, i);
args[i] = substitute(subs, arg);
if (args[i] != arg) changed = true;
}
return changed ? (ATerm) ATmakeApplArray(fun, args) : e;
}
if (ATgetType(e) == AT_LIST) {
unsigned int len = ATgetLength((ATermList) e);
ATerm es[len];
ATermIterator i((ATermList) e);
for (unsigned int j = 0; i; ++i, ++j)
es[j] = substitute(subs, *i);
ATermList out = ATempty;
for (unsigned int j = len; j; --j)
out = ATinsert(out, es[j - 1]);
return (ATerm) out;
}
return e;
}
/* 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)
{
if (done.find(e) != done.end()) return;
done.insert(e);
ATerm name, pos, value;
ATermList formals;
ATerm with, body;
ATermList rbnds, nrbnds;
/* 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, formals, body, pos)) {
ATermMap defs2(defs);
for (ATermIterator i(formals); i; ++i) {
ATerm d1;
if (!matchFormal(*i, name, d1)) abort();
defs2.set(name, (ATerm) ATempty);
}
for (ATermIterator i(formals); i; ++i) {
ATerm deflt;
set<Expr> done2;
if (!matchFormal(*i, name, deflt)) abort();
checkVarDefs2(done2, defs2, deflt);
}
set<Expr> done2;
checkVarDefs2(done2, defs2, body);
}
else if (matchFunction1(e, name, body, pos)) {
ATermMap defs2(defs);
defs2.set(name, (ATerm) ATempty);
set<Expr> done2;
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);
}
void checkVarDefs(const ATermMap & defs, Expr e)
{
set<Expr> done;
checkVarDefs2(done, defs, e);
}
struct Canonicalise : TermFun
{
ATerm operator () (ATerm e)
{
/* Remove position info. */
ATerm path;
int line, column;
if (matchPos(e, path, line, column))
return makeNoPos();
/* Sort attribute sets. */
ATermList _;
if (matchAttrs(e, _)) {
ATermMap attrs;
queryAllAttrs(e, attrs);
StringSet names;
for (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i)
names.insert(aterm2String(i->key));
ATermList attrs2 = ATempty;
for (StringSet::reverse_iterator i = names.rbegin(); i != names.rend(); ++i)
attrs2 = ATinsert(attrs2,
makeBind(toATerm(*i), attrs.get(toATerm(*i)), makeNoPos()));
return makeAttrs(attrs2);
}
return e;
}
};
Expr canonicaliseExpr(Expr e)
{
Canonicalise canonicalise;
return bottomupRewrite(canonicalise, e);
}
Expr makeBool(bool b)
{
return b ? eTrue : eFalse;
}
bool matchStr(Expr e, string & s, PathSet & context)
{
ATermList l;
ATerm s_;
if (!matchStr(e, s_, l)) return false;
s = aterm2String(s_);
for (ATermIterator i(l); i; ++i)
context.insert(aterm2String(*i));
return true;
}
Expr makeStr(const string & s, const PathSet & context)
{
return makeStr(toATerm(s), toATermList(context));
}
string showType(Expr e)
{
ATerm t1, t2, t3;
ATermList l1;
ATermBlob b1;
int i1;
if (matchStr(e, t1, l1)) return "a string";
if (matchPath(e, t1)) return "a path";
if (matchNull(e)) return "null";
if (matchInt(e, i1)) return "an integer";
if (matchBool(e, t1)) return "a boolean";
if (matchFunction(e, l1, t1, t2)) return "a function";
if (matchFunction1(e, t1, t2, t3)) return "a function";
if (matchAttrs(e, l1)) return "an attribute set";
if (matchList(e, l1)) return "a list";
if (matchPrimOp(e, i1, b1, l1)) return "a partially applied built-in function";
return "an unknown type";
}
string showValue(Expr e)
{
PathSet context;
string s;
ATerm s2;
int i;
if (matchStr(e, s, context)) {
string u;
for (string::iterator i = s.begin(); i != s.end(); ++i)
if (*i == '\"' || *i == '\\') u += "\\" + *i;
else if (*i == '\n') u += "\\n";
else if (*i == '\r') u += "\\r";
else if (*i == '\t') u += "\\t";
else u += *i;
return "\"" + u + "\"";
}
if (matchPath(e, s2)) return aterm2String(s2);
if (matchNull(e)) return "null";
if (matchInt(e, i)) return (format("%1%") % i).str();
if (e == eTrue) return "true";
if (e == eFalse) return "false";
/* !!! incomplete */
return "<unknown>";
}
}
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