133 lines
4.4 KiB
C++
133 lines
4.4 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 <utility>
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#include <vector>
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#include <algorithm>
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#include "util/name_set.h"
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#include "util/buffer.h"
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#include "kernel/for_each_fn.h"
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#include "kernel/replace.h"
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#include "kernel/abstract.h"
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#include "library/type_inferer.h"
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#include "library/tactic/goal.h"
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namespace lean {
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goal::goal(list<std::pair<name, expr>> const & h, expr const & c):m_hypotheses(h), m_conclusion(c) {}
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format goal::pp(formatter const & fmt, options const & opts) const {
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unsigned indent = get_pp_indent(opts);
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bool unicode = get_pp_unicode(opts);
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format turnstile = unicode ? format("\u22A2") /* ⊢ */ : format("|-");
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buffer<std::pair<name, expr>> tmp;
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to_buffer(m_hypotheses, tmp);
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bool first = true;
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format r;
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for (auto const & p : tmp) {
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if (first) {
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first = false;
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} else {
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r += compose(comma(), line());
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}
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r += format{format(p.first), space(), colon(), nest(indent, compose(line(), fmt(p.second, opts)))};
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}
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r = group(r);
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r += format{line(), turnstile, space(), nest(indent, fmt(m_conclusion, opts))};
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return group(r);
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}
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goal_proof_fn::goal_proof_fn(std::vector<expr> && consts):
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m_constants(consts) {
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}
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expr goal_proof_fn::operator()(expr const & pr) const {
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return abstract(pr, m_constants.size(), m_constants.data());
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}
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static name_set collect_used_names(context const & ctx, expr const & t) {
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name_set r;
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auto f = [&r](expr const & e, unsigned) { if (is_constant(e)) r.insert(const_name(e)); return true; };
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for_each_fn<decltype(f)> visitor(f);
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for (auto const & e : ctx) {
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if (expr const & d = e.get_domain())
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visitor(d);
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if (expr const & b = e.get_body())
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visitor(b);
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}
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visitor(t);
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return r;
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}
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static name mk_unique_name(name_set & s, name const & suggestion) {
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unsigned i = 1;
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name n = suggestion;
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while (true) {
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if (s.find(n) == s.end()) {
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s.insert(n);
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return n;
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} else {
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n = name(suggestion, i);
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i++;
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}
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}
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}
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std::pair<goal, goal_proof_fn> to_goal(environment const & env, context const & ctx, expr const & t) {
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type_inferer inferer(env);
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if (!inferer.is_proposition(t, ctx))
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throw exception("to goal failed, type is not a proposition");
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name_set used_names = collect_used_names(ctx, t);
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buffer<context_entry> entries;
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for (auto const & e : ctx)
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entries.push_back(e);
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buffer<std::pair<name, expr>> hypotheses; // normalized names and types of the entries processed so far
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buffer<expr> bodies; // normalized bodies of the entries processed so far
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std::vector<expr> consts; // cached consts[i] == mk_constant(names[i], hypotheses[i])
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auto replace_vars = [&](expr const & e, unsigned offset) -> expr {
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if (is_var(e)) {
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unsigned vidx = var_idx(e);
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if (vidx >= offset) {
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unsigned nvidx = vidx - offset;
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unsigned nfv = consts.size();
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if (nvidx >= nfv)
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throw exception("to_goal failed, unknown free variable");
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unsigned lvl = nfv - nvidx - 1;
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if (bodies[lvl])
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return bodies[lvl];
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else
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return consts[lvl];
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}
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}
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return e;
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};
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replace_fn<decltype(replace_vars)> replacer(replace_vars);
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auto it = entries.end();
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auto begin = entries.begin();
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while (it != begin) {
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--it;
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auto const & e = *it;
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name n = mk_unique_name(used_names, e.get_name());
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expr d = replacer(e.get_domain());
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expr b = replacer(e.get_body());
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replacer.clear();
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if (b && (!d || !inferer.is_proposition(d))) {
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hypotheses.emplace_back(n, expr());
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bodies.push_back(b);
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consts.push_back(expr());
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} else {
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hypotheses.emplace_back(n, d);
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bodies.push_back(expr());
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consts.push_back(mk_constant(n, d));
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}
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}
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expr conclusion = replacer(t);
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std::reverse(consts.begin(), consts.end());
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return mk_pair(goal(reverse_to_list(hypotheses.begin(), hypotheses.end()), conclusion),
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goal_proof_fn(std::move(consts)));
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}
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}
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