90 lines
3.1 KiB
C++
90 lines
3.1 KiB
C++
/*
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Copyright (c) 2016 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 "util/fresh_name.h"
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#include "kernel/abstract.h"
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#include "library/placeholder.h"
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#include "library/aux_match.h"
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#include "library/equations_compiler/equations.h"
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#include "frontends/lean/tokens.h"
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#include "frontends/lean/util.h"
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#include "frontends/lean/parser.h"
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#include "frontends/lean/decl_util.h"
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namespace lean {
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/** \brief Use equations compiler infrastructure to implement match-with */
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expr parse_match(parser & p, unsigned, expr const *, pos_info const & pos) {
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parser::local_scope scope1(p);
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match_definition_scope scope2(p.env());
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equations_header header = mk_match_header(scope2.get_name(), scope2.get_actual_name());
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buffer<expr> eqns;
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buffer<expr> ts;
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try {
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ts.push_back(p.parse_expr());
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while (p.curr_is_token(get_comma_tk())) {
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p.next();
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ts.push_back(p.parse_expr());
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}
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expr fn;
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/* Parse optional type */
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if (p.curr_is_token(get_colon_tk())) {
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p.next();
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expr type = p.parse_expr();
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fn = mk_local(p.next_name(), get_aux_match_suffix(), type, mk_rec_info());
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} else {
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fn = mk_local(p.next_name(), get_aux_match_suffix(), mk_expr_placeholder(), mk_rec_info());
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}
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p.check_token_next(get_with_tk(), "invalid 'match' expression, 'with' expected");
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if (p.curr_is_token(get_end_tk())) {
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/* Empty match */
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p.next();
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eqns.push_back(Fun(fn, mk_no_equation()));
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expr f = p.save_pos(mk_equations(header, eqns.size(), eqns.data()), pos);
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return p.mk_app(f, ts, pos);
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}
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if (is_eqn_prefix(p))
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p.next(); // optional '|' in the first case
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while (true) {
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auto lhs_pos = p.pos();
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buffer<expr> lhs_args;
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lhs_args.push_back(p.parse_pattern_or_expr());
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while (p.curr_is_token(get_comma_tk())) {
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p.next();
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lhs_args.push_back(p.parse_pattern_or_expr());
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}
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expr lhs = p.mk_app(fn, lhs_args, lhs_pos);
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buffer<expr> locals;
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bool skip_main_fn = true;
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lhs = p.patexpr_to_pattern(lhs, skip_main_fn, locals);
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auto assign_pos = p.pos();
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p.check_token_next(get_assign_tk(), "invalid 'match' expression, ':=' expected");
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{
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parser::local_scope scope2(p);
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for (expr const & local : locals)
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p.add_local(local);
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expr rhs = p.parse_expr();
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eqns.push_back(Fun(fn, Fun(locals, p.save_pos(mk_equation(lhs, rhs), assign_pos), p), p));
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}
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if (!is_eqn_prefix(p))
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break;
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p.next();
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}
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} catch (exception & ex) {
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consume_until_end_or_command(p);
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throw;
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}
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expr f = p.save_pos(mk_equations(header, eqns.size(), eqns.data()), pos);
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return p.mk_app(f, ts, pos);
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}
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void initialize_match_expr() {
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}
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void finalize_match_expr() {
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}
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}
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