forked from lix-project/lix
310 lines
8.7 KiB
C++
310 lines
8.7 KiB
C++
#include "nixexpr.hh"
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#include "derivations.hh"
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#include "nixexpr-ast.hh"
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#include "nixexpr-ast.cc"
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string showPos(ATerm pos)
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{
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ATerm path;
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int line, column;
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if (matchNoPos(pos)) return "undefined position";
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if (!matchPos(pos, path, line, column))
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throw badTerm("position expected", pos);
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return (format("`%1%', line %2%") % aterm2String(path) % line).str();
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}
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ATerm bottomupRewrite(TermFun & f, ATerm e)
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{
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checkInterrupt();
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if (ATgetType(e) == AT_APPL) {
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AFun fun = ATgetAFun(e);
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int arity = ATgetArity(fun);
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ATerm args[arity];
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for (int i = 0; i < arity; ++i)
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args[i] = bottomupRewrite(f, ATgetArgument(e, i));
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e = (ATerm) ATmakeApplArray(fun, args);
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}
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else if (ATgetType(e) == AT_LIST) {
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ATermList in = (ATermList) e;
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ATermList out = ATempty;
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for (ATermIterator i(in); i; ++i)
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out = ATinsert(out, bottomupRewrite(f, *i));
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e = (ATerm) ATreverse(out);
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}
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return f(e);
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}
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void queryAllAttrs(Expr e, ATermMap & attrs, bool withPos)
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{
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ATermList bnds;
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if (!matchAttrs(e, bnds))
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throw TypeError("attribute set expected");
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for (ATermIterator i(bnds); i; ++i) {
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ATerm name;
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Expr e;
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ATerm pos;
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if (!matchBind(*i, name, e, pos)) abort(); /* can't happen */
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attrs.set(name, withPos ? makeAttrRHS(e, pos) : e);
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}
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}
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Expr queryAttr(Expr e, const string & name)
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{
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ATerm dummy;
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return queryAttr(e, name, dummy);
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}
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Expr queryAttr(Expr e, const string & name, ATerm & pos)
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{
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ATermList bnds;
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if (!matchAttrs(e, bnds))
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throw TypeError("attribute set expected");
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for (ATermIterator i(bnds); i; ++i) {
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ATerm name2, pos2;
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Expr e;
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if (!matchBind(*i, name2, e, pos2))
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abort(); /* can't happen */
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if (aterm2String(name2) == name) {
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pos = pos2;
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return e;
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}
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}
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return 0;
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}
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Expr makeAttrs(const ATermMap & attrs)
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{
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ATermList bnds = ATempty;
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for (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i) {
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Expr e;
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ATerm pos;
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if (!matchAttrRHS(i->value, e, pos))
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abort(); /* can't happen */
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bnds = ATinsert(bnds, makeBind(i->key, e, pos));
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}
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return makeAttrs(bnds);
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}
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Expr substitute(const Substitution & subs, Expr e)
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{
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checkInterrupt();
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//if (subs.size() == 0) return e;
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ATerm name, pos, e2;
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/* As an optimisation, don't substitute in subterms known to be
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closed. */
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if (matchClosed(e, e2)) return e;
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if (matchVar(e, name)) {
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Expr sub = subs.lookup(name);
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if (sub == makeRemoved()) sub = 0;
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Expr wrapped;
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/* Add a "closed" wrapper around terms that aren't already
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closed. The check is necessary to prevent repeated
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wrapping, e.g., closed(closed(closed(...))), which kills
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caching. */
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return sub ? (matchClosed(sub, wrapped) ? sub : makeClosed(sub)) : e;
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}
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/* In case of a function, filter out all variables bound by this
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function. */
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ATermList formals;
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ATerm body, def;
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if (matchFunction(e, formals, body, pos)) {
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ATermMap map(ATgetLength(formals));
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for (ATermIterator i(formals); i; ++i) {
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ATerm d1, d2;
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if (!matchFormal(*i, name, d1, d2)) abort();
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map.set(name, makeRemoved());
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}
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Substitution subs2(&subs, &map);
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return makeFunction(
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(ATermList) substitute(subs2, (ATerm) formals),
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substitute(subs2, body), pos);
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}
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if (matchFunction1(e, name, body, pos)) {
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ATermMap map(1);
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map.set(name, makeRemoved());
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return makeFunction1(name, substitute(Substitution(&subs, &map), body), pos);
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}
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/* Idem for a mutually recursive attribute set. */
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ATermList rbnds, nrbnds;
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if (matchRec(e, rbnds, nrbnds)) {
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ATermMap map(ATgetLength(rbnds) + ATgetLength(nrbnds));
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for (ATermIterator i(rbnds); i; ++i)
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if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved());
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else abort(); /* can't happen */
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for (ATermIterator i(nrbnds); i; ++i)
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if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved());
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else abort(); /* can't happen */
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return makeRec(
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(ATermList) substitute(Substitution(&subs, &map), (ATerm) rbnds),
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(ATermList) substitute(subs, (ATerm) nrbnds));
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}
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if (ATgetType(e) == AT_APPL) {
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AFun fun = ATgetAFun(e);
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int arity = ATgetArity(fun);
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ATerm args[arity];
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bool changed = false;
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for (int i = 0; i < arity; ++i) {
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ATerm arg = ATgetArgument(e, i);
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args[i] = substitute(subs, arg);
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if (args[i] != arg) changed = true;
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}
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return changed ? (ATerm) ATmakeApplArray(fun, args) : e;
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}
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if (ATgetType(e) == AT_LIST) {
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unsigned int len = ATgetLength((ATermList) e);
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ATerm es[len];
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ATermIterator i((ATermList) e);
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for (unsigned int j = 0; i; ++i, ++j)
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es[j] = substitute(subs, *i);
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ATermList out = ATempty;
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for (unsigned int j = len; j; --j)
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out = ATinsert(out, es[j - 1]);
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return (ATerm) out;
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}
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return e;
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}
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/* We use memoisation to prevent exponential complexity on heavily
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shared ATerms (remember, an ATerm is a graph, not a tree!). Note
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that using an STL set is fine here wrt to ATerm garbage collection
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since all the ATerms in the set are already reachable from
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somewhere else. */
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static void checkVarDefs2(set<Expr> & done, const ATermMap & defs, Expr e)
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{
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if (done.find(e) != done.end()) return;
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done.insert(e);
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ATerm name, pos, value;
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ATermList formals;
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ATerm with, body;
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ATermList rbnds, nrbnds;
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if (matchVar(e, name)) {
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if (!defs.get(name))
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throw EvalError(format("undefined variable `%1%'")
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% aterm2String(name));
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}
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else if (matchFunction(e, formals, body, pos)) {
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ATermMap defs2(defs);
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for (ATermIterator i(formals); i; ++i) {
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Expr d1, d2;
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if (!matchFormal(*i, name, d1, d2)) abort();
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defs2.set(name, (ATerm) ATempty);
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}
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for (ATermIterator i(formals); i; ++i) {
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Expr dummy, deflt;
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set<Expr> done2;
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if (matchFormal(*i, name, dummy, deflt)) /* !!! check dummy */
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checkVarDefs2(done2, defs2, deflt);
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}
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set<Expr> done2;
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checkVarDefs2(done2, defs2, body);
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}
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else if (matchFunction1(e, name, body, pos)) {
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ATermMap defs2(defs);
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defs2.set(name, (ATerm) ATempty);
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set<Expr> done2;
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checkVarDefs2(done2, defs2, body);
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}
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else if (matchRec(e, rbnds, nrbnds)) {
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checkVarDefs2(done, defs, (ATerm) nrbnds);
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ATermMap defs2(defs);
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for (ATermIterator i(rbnds); i; ++i) {
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if (!matchBind(*i, name, value, pos)) abort(); /* can't happen */
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defs2.set(name, (ATerm) ATempty);
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}
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for (ATermIterator i(nrbnds); i; ++i) {
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if (!matchBind(*i, name, value, pos)) abort(); /* can't happen */
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defs2.set(name, (ATerm) ATempty);
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}
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set<Expr> done2;
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checkVarDefs2(done2, defs2, (ATerm) rbnds);
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}
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else if (matchWith(e, with, body, pos)) {
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/* We can't check the body without evaluating the definitions
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(which is an arbitrary expression), so we don't do that
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here but only when actually evaluating the `with'. */
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checkVarDefs2(done, defs, with);
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}
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else if (ATgetType(e) == AT_APPL) {
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int arity = ATgetArity(ATgetAFun(e));
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for (int i = 0; i < arity; ++i)
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checkVarDefs2(done, defs, ATgetArgument(e, i));
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}
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else if (ATgetType(e) == AT_LIST)
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for (ATermIterator i((ATermList) e); i; ++i)
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checkVarDefs2(done, defs, *i);
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}
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void checkVarDefs(const ATermMap & defs, Expr e)
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{
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set<Expr> done;
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checkVarDefs2(done, defs, e);
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}
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Expr makeBool(bool b)
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{
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return b ? eTrue : eFalse;
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}
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string showType(Expr e)
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{
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ATerm t1, t2, t3;
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ATermList l1;
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int i1;
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if (matchStr(e, t1)) return "a string";
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if (matchPath(e, t1)) return "a path";
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if (matchUri(e, t1)) return "a path";
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if (matchNull(e)) return "null";
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if (matchInt(e, i1)) return "an integer";
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if (matchBool(e, t1)) return "a boolean";
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if (matchFunction(e, l1, t1, t2)) return "a function";
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if (matchFunction1(e, t1, t2, t3)) return "a function";
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if (matchAttrs(e, l1)) return "an attribute set";
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if (matchList(e, l1)) return "a list";
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if (matchContext(e, l1, t1)) return "a context containing " + showType(t1);
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return "an unknown type";
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}
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