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refactor(kernel/constraint): simplify constraint interface, and add choice constraint

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-06-21 08:15:47 -07:00
parent 9e50d5a1b8
commit 67088b130e
4 changed files with 58 additions and 40 deletions
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38
src/kernel/constraint.cpp
View file

@ -11,24 +11,30 @@ struct constraint_cell {
void dealloc();
MK_LEAN_RC()
constraint_kind m_kind;
unsigned m_hash;
justification m_jst;
constraint_cell(constraint_kind k, unsigned h, justification const & j):m_rc(1), m_kind(k), m_hash(h), m_jst(j) {}
constraint_cell(constraint_kind k, justification const & j):m_rc(1), m_kind(k), m_jst(j) {}
};
struct eq_constraint_cell : public constraint_cell {
expr m_lhs;
expr m_rhs;
eq_constraint_cell(expr const & lhs, expr const & rhs, justification const & j):
constraint_cell(constraint_kind::Eq, hash(lhs.hash(), rhs.hash()), j),
constraint_cell(constraint_kind::Eq, j),
m_lhs(lhs), m_rhs(rhs) {}
};
struct level_constraint_cell : public constraint_cell {
level m_lhs;
level m_rhs;
level_constraint_cell(level const & lhs, level const & rhs, justification const & j):
constraint_cell(constraint_kind::Level, hash(hash(lhs), hash(rhs)), j),
constraint_cell(constraint_kind::Level, j),
m_lhs(lhs), m_rhs(rhs) {}
};
struct choice_constraint_cell : public constraint_cell {
expr m_mvar;
choice_fn m_fn;
choice_constraint_cell(expr const & mvar, choice_fn const & fn, justification const & j):
constraint_cell(constraint_kind::Choice, j),
m_mvar(mvar), m_fn(fn) {}
};
void constraint_cell::dealloc() {
switch (m_kind) {
@ -36,6 +42,8 @@ void constraint_cell::dealloc() {
delete static_cast<eq_constraint_cell*>(this); break;
case constraint_kind::Level:
delete static_cast<level_constraint_cell*>(this); break;
case constraint_kind::Choice:
delete static_cast<choice_constraint_cell*>(this); break;
}
}
@ -46,7 +54,6 @@ constraint::~constraint() { if (m_ptr) m_ptr->dec_ref(); }
constraint & constraint::operator=(constraint const & c) { LEAN_COPY_REF(c); }
constraint & constraint::operator=(constraint && c) { LEAN_MOVE_REF(c); }
constraint_kind constraint::kind() const { lean_assert(m_ptr); return m_ptr->m_kind; }
unsigned constraint::hash() const { lean_assert(m_ptr); return m_ptr->m_hash; }
justification const & constraint::get_justification() const { lean_assert(m_ptr); return m_ptr->m_jst; }
constraint mk_eq_cnstr(expr const & lhs, expr const & rhs, justification const & j) {
@ -55,23 +62,19 @@ constraint mk_eq_cnstr(expr const & lhs, expr const & rhs, justification const &
constraint mk_level_cnstr(level const & lhs, level const & rhs, justification const & j) {
return constraint(new level_constraint_cell(lhs, rhs, j));
}
bool operator==(constraint const & c1, constraint const & c2) {
if (c1.kind() != c2.kind() || c1.hash() != c2.hash())
return false;
switch (c1.kind()) {
case constraint_kind::Eq:
return cnstr_lhs_expr(c1) == cnstr_lhs_expr(c2) && cnstr_rhs_expr(c1) == cnstr_rhs_expr(c2);
case constraint_kind::Level:
return cnstr_lhs_level(c1) == cnstr_lhs_level(c2) && cnstr_rhs_level(c1) == cnstr_rhs_level(c2);
}
lean_unreachable(); // LCOV_EXCL_LINE
constraint mk_choice_cnstr(expr const & m, choice_fn const & fn, justification const & j) {
lean_assert(is_meta(m));
return constraint(new choice_constraint_cell(m, fn, j));
}
expr const & cnstr_lhs_expr(constraint const & c) { lean_assert(is_eq_cnstr(c)); return static_cast<eq_constraint_cell*>(c.raw())->m_lhs; }
expr const & cnstr_rhs_expr(constraint const & c) { lean_assert(is_eq_cnstr(c)); return static_cast<eq_constraint_cell*>(c.raw())->m_rhs; }
level const & cnstr_lhs_level(constraint const & c) { lean_assert(is_level_cnstr(c)); return static_cast<level_constraint_cell*>(c.raw())->m_lhs; }
level const & cnstr_rhs_level(constraint const & c) { lean_assert(is_level_cnstr(c)); return static_cast<level_constraint_cell*>(c.raw())->m_rhs; }
expr const & cnstr_mvar(constraint const & c) { lean_assert(is_choice_cnstr(c)); return static_cast<choice_constraint_cell*>(c.raw())->m_mvar; }
choice_fn const & cnstr_choice_fn(constraint const & c) {
lean_assert(is_choice_cnstr(c)); return static_cast<choice_constraint_cell*>(c.raw())->m_fn;
}
constraint updt_eq_cnstr(constraint const & c, expr const & new_lhs, expr const & new_rhs, justification const & new_jst) {
lean_assert(is_eq_cnstr(c));
@ -102,6 +105,9 @@ std::ostream & operator<<(std::ostream & out, constraint const & c) {
case constraint_kind::Level:
out << cnstr_lhs_level(c) << " = " << cnstr_rhs_level(c);
break;
case constraint_kind::Choice:
out << "choice " << cnstr_mvar(c);
break;
}
return out;
}

53
src/kernel/constraint.h
View file

@ -6,8 +6,13 @@ Author: Leonardo de Moura
*/
#pragma once
#include <algorithm>
#include "util/lazy_list.h"
#include "util/list.h"
#include "util/name_generator.h"
#include "kernel/expr.h"
#include "kernel/justification.h"
#include "kernel/metavar.h"
namespace lean {
/**
\brief The lean kernel type checker produces two kinds of constraints:
@ -21,8 +26,31 @@ namespace lean {
metavariables or level metavariables.
Each constraint is associated with a justification object.
\remark We also have choice constraints that are used by elaborator to specify
the possible solutions for a metavariable. The choice constraints are not used by
the kernel.
*/
enum class constraint_kind { Eq, Level };
enum class constraint_kind { Eq, Level, Choice };
class constraint;
typedef list<constraint> constraints;
typedef std::tuple<expr, justification, constraints> choice_fn_result;
/**
\brief A choice_fn is used to enumerate the possible solutions for a metavariable.
The input arguments are:
- an inferred type (if available)
- substitution map (metavar -> value)
- name generator
The result is a lazy_list of choices, i.e., tuples containing:
- an expression representing one of the possible solutions
- a justification for it (this is used to accumulate the justification for the substitutions used).
- a list of new constraints (that is, the solution is only valid if the additional constraints can be solved)
One application of choice constraints is overloaded notation.
*/
typedef std::function<lazy_list<choice_fn_result>(optional<expr> const &, substitution const &, name_generator const &)> choice_fn;
struct constraint_cell;
class constraint {
constraint_cell * m_ptr;
@ -33,7 +61,6 @@ public:
~constraint();
constraint_kind kind() const;
unsigned hash() const;
justification const & get_justification() const;
constraint & operator=(constraint const & c);
@ -44,18 +71,18 @@ public:
friend constraint mk_eq_cnstr(expr const & lhs, expr const & rhs, justification const & j);
friend constraint mk_level_cnstr(level const & lhs, level const & rhs, justification const & j);
friend constraint mk_choice_cnstr(expr const & m, choice_fn const & fn, justification const & j);
constraint_cell * raw() const { return m_ptr; }
};
bool operator==(constraint const & c1, constraint const & c2);
inline bool operator!=(constraint const & c1, constraint const & c2) { return !(c1 == c2); }
constraint mk_eq_cnstr(expr const & lhs, expr const & rhs, justification const & j);
constraint mk_level_cnstr(level const & lhs, level const & rhs, justification const & j);
constraint mk_choice_cnstr(expr const & m, choice_fn const & fn, justification const & j);
inline bool is_eq_cnstr(constraint const & c) { return c.kind() == constraint_kind::Eq; }
inline bool is_level_cnstr(constraint const & c) { return c.kind() == constraint_kind::Level; }
inline bool is_choice_cnstr(constraint const & c) { return c.kind() == constraint_kind::Choice; }
/** \brief Return the lhs of an equality constraint. */
expr const & cnstr_lhs_expr(constraint const & c);
@ -65,19 +92,11 @@ expr const & cnstr_rhs_expr(constraint const & c);
level const & cnstr_lhs_level(constraint const & c);
/** \brief Return the rhs of an level constraint. */
level const & cnstr_rhs_level(constraint const & c);
/** \brief Update equality constraint c with new_lhs, new_rhs and justification. */
constraint updt_eq_cnstr(constraint const & c, expr const & new_lhs, expr const & new_rhs, justification const & new_jst);
/** \brief Update equality constraint c with new_lhs and new_rhs, but keeping the same justification. */
constraint updt_eq_cnstr(constraint const & c, expr const & new_lhs, expr const & new_rhs);
/** \brief Update level constraint c with new_lhs, new_rhs and justification. */
constraint updt_level_cnstr(constraint const & c, level const & new_lhs, level const & new_rhs, justification const & new_jst);
/** \brief Update level constraint c with new_lhs and new_rhs, but keeping the same justification. */
constraint updt_level_cnstr(constraint const & c, level const & new_lhs, level const & new_rhs);
/** \brief Return the metavariable associated with a choice constraint */
expr const & cnstr_mvar(constraint const & c);
/** \brief Return the choice_fn associated with a choice constraint. */
choice_fn const & cnstr_choice_fn(constraint const & c);
/** \brief Printer for debugging purposes */
std::ostream & operator<<(std::ostream & out, constraint const & c);
typedef list<constraint> constraints;
inline constraints add(constraints const & cs, constraint const & c) { return cons(c, cs); }
}

4
src/library/kernel_bindings.cpp
View file

@ -1595,10 +1595,8 @@ DECL_UDATA(constraint)
#define CNSTR_PRED(P) static int constraint_ ## P(lua_State * L) { check_num_args(L, 1); return push_boolean(L, P(to_constraint(L, 1))); }
CNSTR_PRED(is_eq_cnstr)
CNSTR_PRED(is_level_cnstr)
static int constraint_eq(lua_State * L) { return push_boolean(L, to_constraint(L, 1) == to_constraint(L, 2)); }
static int constraint_is_eqp(lua_State * L) { return push_boolean(L, is_eqp(to_constraint(L, 1), to_constraint(L, 2))); }
static int constraint_get_kind(lua_State * L) { return push_integer(L, static_cast<int>(to_constraint(L, 1).kind())); }
static int constraint_hash(lua_State * L) { return push_integer(L, to_constraint(L, 1).hash()); }
static int constraint_jst(lua_State * L) { return push_justification(L, to_constraint(L, 1).get_justification()); }
static int constraint_lhs(lua_State * L) {
constraint const & c = to_constraint(L, 1);
@ -1629,12 +1627,10 @@ static int mk_level_cnstr(lua_State * L) { return push_constraint(L, mk_level_cn
static const struct luaL_Reg constraint_m[] = {
{"__gc", constraint_gc}, // never throws
{"__tostring", safe_function<constraint_tostring>},
{"__eq", safe_function<constraint_eq>},
{"is_eq", safe_function<constraint_is_eq_cnstr>},
{"is_level", safe_function<constraint_is_level_cnstr>},
{"is_eqp", safe_function<constraint_is_eqp>},
{"kind", safe_function<constraint_get_kind>},
{"hash", safe_function<constraint_hash>},
{"lhs", safe_function<constraint_lhs>},
{"rhs", safe_function<constraint_rhs>},
{"justification", safe_function<constraint_jst>},

3
tests/lua/cnstr1.lua
View file

@ -12,8 +12,5 @@ print(c)
local c3 = mk_level_cnstr(mk_level_zero(), mk_level_one(), j)
assert(c3:is_level())
print(c3)
assert(c ~= c2)
assert(c == mk_eq_cnstr(f(a), m, j))
assert(c:is_eqp(c))
assert(not c:is_eqp(mk_eq_cnstr(f(a), m, j)))
assert(c:hash() == mk_eq_cnstr(f(a), m, j):hash())