85092412c7
@Kha @dselsam: This hack was preventing us from making `Expr` a "real" Lean type. This was bad for a few reasons: - It was hard to extend/modify `Expr` in Lean since we would also have to modify the C++ code that creates the `Expr` objects with the hidden fields. - `Expr.lam` and `Expr.forallE` were not following the Lean layout standard where we sort fields by size. @Kha: recall we used that to avoid a UB. The issue with `Expr.lam` and `Expr.forallE` is that they have a "visible" field (`BinderInfo`), which is smaller than hidden fields such as hash code. - `Expr.fvar` had only one field at `Expr.lean,` but four behind the scenes. I added a new constructor `Local` that is only accessible from C++. It is only used in legacy code we inherited from Lean2. We will eventually delete it. This refactoring was quite painful since many parts of the codebase were mixing the new `Expr.fvar` with the old `Expr.local`. I doubt I would be able to do it without the new staging framework @Kha built. BTW, some of the patches are horrible. I didn't care much since we are going to deleted the super ugly files. That being said, you should expect new weird bevaior due to `Expr.fvar` vs `Expr.local`. Next step: use the new `ExprCachedData` to make all `Expr` hidden visibles accessible from Lean. checkpoint
101 lines
3.5 KiB
C++
101 lines
3.5 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include <algorithm>
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#include <utility>
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#include <vector>
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#include "kernel/abstract.h"
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#include "kernel/replace_fn.h"
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namespace lean {
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expr abstract(expr const & e, unsigned n, expr const * subst) {
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lean_assert(std::all_of(subst, subst+n, [](expr const & e) { return !has_loose_bvars(e) && is_local_or_fvar(e); }));
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if (!has_fvar(e))
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return e;
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return replace(e, [=](expr const & m, unsigned offset) -> optional<expr> {
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if (!has_fvar(m))
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return some_expr(m); // expression m does not contain free variables
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if (is_local_or_fvar(m)) {
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unsigned i = n;
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while (i > 0) {
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--i;
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if (local_or_fvar_name(subst[i]) == local_or_fvar_name(m))
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return some_expr(mk_bvar(offset + n - i - 1));
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}
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return none_expr();
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}
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return none_expr();
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});
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}
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expr abstract(expr const & e, name const & n) {
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expr fvar = mk_fvar(n);
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return abstract(e, 1, &fvar);
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}
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static object * lean_expr_abstract_core(object * e0, size_t n, object * subst) {
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lean_assert(n <= lean_array_size(subst));
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expr const & e = reinterpret_cast<expr const &>(e0);
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if (!has_fvar(e)) {
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lean_inc(e0);
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return e0;
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}
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expr r = replace(e, [=](expr const & m, unsigned offset) -> optional<expr> {
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if (!has_fvar(m))
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return some_expr(m); // expression m does not contain free variables
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if (is_fvar(m)) {
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size_t i = n;
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while (i > 0) {
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--i;
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object * v = lean_array_get_core(subst, i);
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if (is_fvar_core(v) && fvar_name_core(v) == fvar_name(m))
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return some_expr(mk_bvar(offset + n - i - 1));
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}
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return none_expr();
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}
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return none_expr();
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});
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return r.steal();
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}
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extern "C" object * lean_expr_abstract_range(object * e, object * n, object * subst) {
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if (!lean_is_scalar(n))
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return lean_expr_abstract_core(e, lean_array_size(subst), subst);
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else
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return lean_expr_abstract_core(e, std::min(lean_unbox(n), lean_array_size(subst)), subst);
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}
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extern "C" object * lean_expr_abstract(object * e, object * subst) {
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return lean_expr_abstract_core(e, lean_array_size(subst), subst);
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}
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/* ------ LEGACY CODE -------------
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The following API is to support legacy
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code where the type of a local constant (aka free variable)
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was stored in the local constant itself.
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This approach was used in Lean2, and is being abandoned in Lean4.
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TODO(Leo): delete */
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template<bool is_lambda>
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expr mk_binding(unsigned num, expr const * locals, expr const & b) {
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expr r = abstract(b, num, locals);
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unsigned i = num;
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while (i > 0) {
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--i;
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expr const & l = locals[i];
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expr t = abstract(local_type(l), i, locals);
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if (is_lambda)
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r = mk_lambda(local_pp_name(l), t, r, local_info(l));
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else
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r = mk_pi(local_pp_name(l), t, r, local_info(l));
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}
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return r;
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}
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expr Pi(unsigned num, expr const * locals, expr const & b) { return mk_binding<false>(num, locals, b); }
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expr Fun(unsigned num, expr const * locals, expr const & b) { return mk_binding<true>(num, locals, b); }
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}
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