forked from lix-project/lix
138 lines
3.5 KiB
C++
138 lines
3.5 KiB
C++
#include "fix-expr.hh"
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#include "expr.hh"
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ATerm bottomupRewrite(TermFun & f, ATerm e)
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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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ATermList args = ATempty;
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for (int i = arity - 1; i >= 0; i--)
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args = ATinsert(args, bottomupRewrite(f, ATgetArgument(e, i)));
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e = (ATerm) ATmakeApplList(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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while (!ATisEmpty(in)) {
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out = ATinsert(out, bottomupRewrite(f, ATgetFirst(in)));
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in = ATgetNext(in);
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}
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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, Attrs & attrs)
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{
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ATermList bnds;
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if (!ATmatch(e, "Attrs([<list>])", &bnds))
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throw badTerm("expected attribute set", e);
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while (!ATisEmpty(bnds)) {
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char * s;
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Expr e;
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if (!ATmatch(ATgetFirst(bnds), "Bind(<str>, <term>)", &s, &e))
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abort(); /* can't happen */
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attrs[s] = e;
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bnds = ATgetNext(bnds);
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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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Attrs attrs;
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queryAllAttrs(e, attrs);
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Attrs::iterator i = attrs.find(name);
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return i == attrs.end() ? 0 : i->second;
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}
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Expr makeAttrs(const Attrs & attrs)
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{
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ATermList bnds = ATempty;
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for (Attrs::const_iterator i = attrs.begin(); i != attrs.end(); i++)
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bnds = ATinsert(bnds,
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ATmake("Bind(<str>, <term>)", i->first.c_str(), i->second));
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return ATmake("Attrs(<term>)", ATreverse(bnds));
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}
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ATerm substitute(Subs & subs, ATerm e)
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{
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char * s;
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if (ATmatch(e, "Var(<str>)", &s)) {
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Subs::iterator i = subs.find(s);
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if (i == subs.end())
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return e;
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else
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return i->second;
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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;
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if (ATmatch(e, "Function([<list>], <term>)", &formals, &body)) {
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Subs subs2(subs);
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ATermList fs = formals;
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while (!ATisEmpty(fs)) {
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if (!ATmatch(ATgetFirst(fs), "<str>", &s)) abort();
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subs2.erase(s);
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fs = ATgetNext(fs);
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}
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return ATmake("Function(<term>, <term>)", formals,
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substitute(subs2, body));
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}
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/* Idem for a mutually recursive attribute set. */
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ATermList bindings;
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if (ATmatch(e, "Rec([<list>])", &bindings)) {
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Subs subs2(subs);
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ATermList bnds = bindings;
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while (!ATisEmpty(bnds)) {
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Expr e;
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if (!ATmatch(ATgetFirst(bnds), "Bind(<str>, <term>)", &s, &e))
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abort(); /* can't happen */
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subs2.erase(s);
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bnds = ATgetNext(bnds);
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}
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return ATmake("Rec(<term>)", substitute(subs2, (ATerm) bindings));
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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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ATermList args = ATempty;
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for (int i = arity - 1; i >= 0; i--)
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args = ATinsert(args, substitute(subs, ATgetArgument(e, i)));
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return (ATerm) ATmakeApplList(fun, args);
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}
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if (ATgetType(e) == AT_LIST) {
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ATermList in = (ATermList) e;
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ATermList out = ATempty;
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while (!ATisEmpty(in)) {
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out = ATinsert(out, substitute(subs, ATgetFirst(in)));
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in = ATgetNext(in);
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}
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return (ATerm) ATreverse(out);
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}
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return e;
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}
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