118 lines
3.4 KiB
C++
118 lines
3.4 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 "frontends/lean/parser_imp.h"
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namespace lean {
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// ==========================================
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// Support for parsing levels
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static name g_max_name("max");
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static name g_cup_name("\u2294");
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static name g_plus_name("+");
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static unsigned g_level_plus_prec = 10;
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static unsigned g_level_cup_prec = 5;
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// ==========================================
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/*
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Parse Universe levels
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*/
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level parser_imp::parse_level_max() {
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auto p = pos();
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next();
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buffer<level> lvls;
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while (curr_is_identifier() || curr_is_nat()) {
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lvls.push_back(parse_level());
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}
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if (lvls.size() < 2)
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throw parser_error("invalid level expression, max must have at least two arguments", p);
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level r = lvls[0];
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for (unsigned i = 1; i < lvls.size(); i++)
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r = max(r, lvls[i]);
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return r;
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}
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level parser_imp::parse_level_nud_id() {
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name id = curr_name();
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if (id == g_max_name) {
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return parse_level_max();
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} else {
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next();
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return m_env->get_uvar(id);
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}
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}
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level parser_imp::parse_level_nud_int() {
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auto p = pos();
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mpz val = curr_num().get_numerator();
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next();
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if (val < 0)
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throw parser_error("invalid level expression, value is negative", p);
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if (!val.is_unsigned_int())
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throw parser_error("invalid level expression, value does not fit in a machine integer", p);
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return level() + val.get_unsigned_int();
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}
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level parser_imp::parse_level_lparen() {
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next();
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level r = parse_level();
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check_rparen_next("invalid level expression, ')' expected");
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return r;
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}
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level parser_imp::parse_level_nud() {
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switch (curr()) {
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case scanner::token::Id: return parse_level_nud_id();
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case scanner::token::IntVal: return parse_level_nud_int();
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case scanner::token::LeftParen: return parse_level_lparen();
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default:
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throw parser_error("invalid level expression", pos());
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}
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}
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level parser_imp::parse_level_led_plus(level const & left) {
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auto p = pos();
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next();
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level right = parse_level(g_level_plus_prec);
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if (!is_lift(right) || !lift_of(right).is_bottom())
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throw parser_error("invalid level expression, right hand side of '+' (aka universe lift operator) must be a numeral", p);
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return left + lift_offset(right);
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}
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level parser_imp::parse_level_led_cup(level const & left) {
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next();
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level right = parse_level(g_level_cup_prec);
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return max(left, right);
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}
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level parser_imp::parse_level_led(level const & left) {
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switch (curr()) {
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case scanner::token::Id:
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if (curr_name() == g_plus_name) return parse_level_led_plus(left);
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else if (curr_name() == g_cup_name) return parse_level_led_cup(left);
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default:
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throw parser_error("invalid level expression", pos());
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}
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}
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unsigned parser_imp::curr_level_lbp() {
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switch (curr()) {
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case scanner::token::Id: {
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name const & id = curr_name();
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if (id == g_plus_name) return g_level_plus_prec;
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else if (id == g_cup_name) return g_level_cup_prec;
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else return 0;
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}
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default: return 0;
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}
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}
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level parser_imp::parse_level(unsigned rbp) {
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level left = parse_level_nud();
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while (rbp < curr_level_lbp()) {
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left = parse_level_led(left);
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}
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return left;
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}
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}
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