lean2/src/library/substitution.cpp

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/*
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include "kernel/replace_fn.h"
#include "kernel/metavar.h"
#include "library/substitution.h"
#include "library/kernel_bindings.h"
namespace lean {
expr find(substitution & s, expr e) {
while (true) {
if (is_metavar(e)) {
expr * it = s.find(metavar_name(e));
if (it == nullptr)
return e;
e = *it;
} else {
return e;
}
}
}
expr apply(substitution & s, expr const & e, optional<ro_metavar_env> const & menv) {
return replace(e, [&](expr const & e, unsigned) -> expr {
if (is_metavar(e)) {
expr r = find(s, e);
if (r != e) {
if (has_metavar(r)) {
r = apply(s, r);
s.insert(metavar_name(e), r);
}
return apply_local_context(r, metavar_lctx(e), menv);
} else {
return e;
}
} else {
return e;
}
});
}
DECL_UDATA(substitution)
static int substitution_size(lua_State * L) {
lua_pushinteger(L, to_substitution(L, 1).size());
return 1;
}
static int substitution_empty(lua_State * L) {
lua_pushboolean(L, to_substitution(L, 1).empty());
return 1;
}
static int substitution_find(lua_State * L) {
substitution & s = to_substitution(L, 1);
expr * it;
if (is_expr(L, 2)) {
expr const & e = to_expr(L, 2);
if (is_metavar(e))
it = s.find(metavar_name(e));
else
throw exception("arg #2 must be a metavariable");
} else {
it = s.find(to_name_ext(L, 2));
}
if (it)
push_expr(L, find(s, *it));
else
lua_pushnil(L);
return 1;
}
static int substitution_apply(lua_State * L) {
return push_expr(L, apply(to_substitution(L, 1), to_expr(L, 2)));
}
static const struct luaL_Reg substitution_m[] = {
{"__gc", substitution_gc}, // never throws
{"__len", safe_function<substitution_size>},
{"find", safe_function<substitution_find>},
{"empty", safe_function<substitution_empty>},
{"size", safe_function<substitution_size>},
{"apply", safe_function<substitution_apply>},
{0, 0}
};
void open_substitution(lua_State * L) {
luaL_newmetatable(L, substitution_mt);
lua_pushvalue(L, -1);
lua_setfield(L, -2, "__index");
setfuncs(L, substitution_m, 0);
SET_GLOBAL_FUN(substitution_pred, "is_substitution");
}
}