206 lines
6.5 KiB
C++
206 lines
6.5 KiB
C++
/*
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Copyright (c) 2013-2014 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 <vector>
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#include "kernel/replace_fn.h"
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#ifndef LEAN_DEFAULT_REPLACE_CACHE_CAPACITY
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#define LEAN_DEFAULT_REPLACE_CACHE_CAPACITY 1024*32
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#endif
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namespace lean {
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struct replace_cache {
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struct entry {
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expr_cell * m_cell;
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unsigned m_offset;
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expr m_result;
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entry():m_cell(nullptr) {}
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};
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unsigned m_capacity;
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std::vector<entry> m_cache;
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std::vector<unsigned> m_used;
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replace_cache(unsigned c):m_capacity(c), m_cache(c) {}
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expr * find(expr const & e, unsigned offset) {
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unsigned i = hash(e.hash_alloc(), offset) % m_capacity;
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if (m_cache[i].m_cell == e.raw())
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return &m_cache[i].m_result;
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else
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return nullptr;
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}
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void insert(expr const & e, unsigned offset, expr const & v) {
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unsigned i = hash(e.hash_alloc(), offset) % m_capacity;
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if (m_cache[i].m_cell == nullptr)
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m_used.push_back(i);
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m_cache[i].m_cell = e.raw();
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m_cache[i].m_offset = offset;
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m_cache[i].m_result = v;
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}
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void clear() {
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for (unsigned i : m_used) {
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m_cache[i].m_cell = nullptr;
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m_cache[i].m_result = expr();
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}
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m_used.clear();
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}
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};
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MK_THREAD_LOCAL_GET(replace_cache, get_replace_cache, LEAN_DEFAULT_REPLACE_CACHE_CAPACITY)
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struct replace_cache_reset {
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~replace_cache_reset() { get_replace_cache().clear(); }
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};
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/**
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\brief Functional for applying <tt>F</tt> to the subexpressions of a given expression.
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The signature of \c F is
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expr const &, unsigned -> optional(expr)
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F is invoked for each subexpression \c s of the input expression e.
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In a call <tt>F(s, n)</tt>, n is the scope level, i.e., the number of
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bindings operators that enclosing \c s. The replaces only visits children of \c e
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if F return none_expr
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*/
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class replace_fn {
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struct frame {
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expr m_expr;
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unsigned m_offset;
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bool m_shared;
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unsigned m_index;
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frame(expr const & e, unsigned o, bool s):m_expr(e), m_offset(o), m_shared(s), m_index(0) {}
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};
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typedef buffer<frame> frame_stack;
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typedef buffer<expr> result_stack;
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std::function<optional<expr>(expr const &, unsigned)> m_f;
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frame_stack m_fs;
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result_stack m_rs;
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replace_cache & m_cache;
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void save_result(expr const & e, expr const & r, unsigned offset, bool shared) {
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if (shared)
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m_cache.insert(e, offset, r);
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m_rs.push_back(r);
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}
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/**
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\brief Visit \c e at the given offset. Return true iff the result is on the
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result stack \c m_rs. Return false iff a new frame was pushed on the stack \c m_fs.
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The idea is that after the frame is processed, the result will be on the result stack.
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*/
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bool visit(expr const & e, unsigned offset) {
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bool shared = false;
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if (is_shared(e)) {
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if (auto r = m_cache.find(e, offset)) {
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m_rs.push_back(*r);
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return true;
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}
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shared = true;
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}
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optional<expr> r = m_f(e, offset);
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if (r) {
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save_result(e, *r, offset, shared);
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return true;
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} else if (is_atomic(e)) {
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save_result(e, e, offset, shared);
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return true;
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} else {
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m_fs.emplace_back(e, offset, shared);
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return false;
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}
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}
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/**
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\brief Return true iff <tt>f.m_index == idx</tt>.
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When the result is true, <tt>f.m_index</tt> is incremented.
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*/
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bool check_index(frame & f, unsigned idx) {
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if (f.m_index == idx) {
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f.m_index++;
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return true;
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} else {
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return false;
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}
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}
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expr const & rs(int i) {
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lean_assert(i < 0);
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return m_rs[m_rs.size() + i];
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}
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void pop_rs(unsigned num) {
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m_rs.shrink(m_rs.size() - num);
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}
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public:
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template<typename F>
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replace_fn(F const & f):m_f(f), m_cache(get_replace_cache()) {}
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expr operator()(expr const & e) {
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replace_cache_reset reset;
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expr r;
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visit(e, 0);
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while (!m_fs.empty()) {
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begin_loop:
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check_interrupted();
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frame & f = m_fs.back();
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expr const & e = f.m_expr;
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unsigned offset = f.m_offset;
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switch (e.kind()) {
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case expr_kind::Constant: case expr_kind::Sort:
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case expr_kind::Var:
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lean_unreachable(); // LCOV_EXCL_LINE
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case expr_kind::Meta: case expr_kind::Local:
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if (check_index(f, 0) && !visit(mlocal_type(e), offset))
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goto begin_loop;
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r = update_mlocal(e, rs(-1));
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pop_rs(1);
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break;
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case expr_kind::App:
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if (check_index(f, 0) && !visit(app_fn(e), offset))
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goto begin_loop;
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if (check_index(f, 1) && !visit(app_arg(e), offset))
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goto begin_loop;
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r = update_app(e, rs(-2), rs(-1));
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pop_rs(2);
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break;
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case expr_kind::Pi: case expr_kind::Lambda:
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if (check_index(f, 0) && !visit(binding_domain(e), offset))
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goto begin_loop;
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if (check_index(f, 1) && !visit(binding_body(e), offset + 1))
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goto begin_loop;
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r = update_binding(e, rs(-2), rs(-1));
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pop_rs(2);
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break;
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case expr_kind::Macro:
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while (f.m_index < macro_num_args(e)) {
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unsigned idx = f.m_index;
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f.m_index++;
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if (!visit(macro_arg(e, idx), offset))
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goto begin_loop;
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}
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r = update_macro(e, macro_num_args(e), &rs(-macro_num_args(e)));
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pop_rs(macro_num_args(e));
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break;
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}
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save_result(e, r, offset, f.m_shared);
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m_fs.pop_back();
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}
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lean_assert(m_rs.size() == 1);
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r = m_rs.back();
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m_rs.pop_back();
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return r;
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}
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};
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expr replace(expr const & e, std::function<optional<expr>(expr const &, unsigned)> const & f) {
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return replace_fn(f)(e);
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}
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}
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