/* 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 #include "kernel/kernel.h" #include "library/fo_unify.h" #include "library/expr_pair.h" #include "library/kernel_bindings.h" #include "library/equality.h" namespace lean { static void assign(substitution & s, expr const & mvar, expr const & e) { lean_assert(is_metavar(mvar)); s.insert(metavar_name(mvar), e); } static bool is_metavar_wo_local_context(expr const & e) { return is_metavar(e) && !metavar_lctx(e); } optional fo_unify(expr e1, expr e2) { substitution s; unsigned i1, i2; buffer todo; todo.emplace_back(e1, e2); while (!todo.empty()) { auto p = todo.back(); todo.pop_back(); e1 = find(s, p.first); e2 = find(s, p.second); if (e1 != e2) { if (is_metavar_wo_local_context(e1)) { assign(s, e1, e2); } else if (is_metavar_wo_local_context(e2)) { assign(s, e2, e1); } else if (is_equality(e1) && is_equality(e2)) { expr_pair p1 = get_equality_args(e1); expr_pair p2 = get_equality_args(e2); todo.emplace_back(p1.second, p2.second); todo.emplace_back(p1.first, p2.first); } else { if (e1.kind() != e2.kind()) return optional(); switch (e1.kind()) { case expr_kind::Var: case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value: case expr_kind::MetaVar: return optional(); case expr_kind::App: i1 = num_args(e1); i2 = num_args(e2); while (i1 > 0 && i2 > 0) { --i1; --i2; if (i1 == 0 && i2 > 0) { todo.emplace_back(arg(e1, i1), mk_app(i2+1, begin_args(e2))); } else if (i2 == 0 && i1 > 0) { todo.emplace_back(mk_app(i1+1, begin_args(e1)), arg(e2, i2)); } else { todo.emplace_back(arg(e1, i1), arg(e2, i2)); } } break; case expr_kind::Proj: if (proj_first(e1) != proj_first(e2)) return optional(); todo.emplace_back(proj_arg(e1), proj_arg(e2)); break; case expr_kind::Pair: todo.emplace_back(pair_first(e1), pair_first(e2)); todo.emplace_back(pair_second(e1), pair_second(e2)); todo.emplace_back(pair_type(e1), pair_type(e2)); break; case expr_kind::Lambda: case expr_kind::Pi: case expr_kind::Sigma: todo.emplace_back(abst_body(e1), abst_body(e2)); todo.emplace_back(abst_domain(e1), abst_domain(e2)); break; case expr_kind::Let: todo.emplace_back(let_body(e1), let_body(e2)); todo.emplace_back(let_value(e1), let_value(e2)); if (static_cast(let_type(e1)) != static_cast(let_type(e2))) return optional(); if (let_type(e1)) { lean_assert(let_type(e2)); todo.emplace_back(*let_type(e1), *let_type(e2)); } break; } } } } return optional(s); } static int fo_unify(lua_State * L) { optional r = fo_unify(to_expr(L, 1), to_expr(L, 2)); if (!r) { lua_pushnil(L); return 1; } else { return push_substitution(L, *r); } } void open_fo_unify(lua_State * L) { SET_GLOBAL_FUN(fo_unify, "fo_unify"); } }