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refactor(kernel/free_vars): cleanup free_vars procedures

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-02-16 13:36:46 -08:00
parent 533f44e224
commit db31cc37a1
3 changed files with 55 additions and 261 deletions
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4
src/kernel/CMakeLists.txt
View file

@ -1,6 +1,6 @@
add_library(kernel level.cpp diff_cnstrs.cpp expr.cpp expr_eq_fn.cpp
for_each_fn.cpp occurs.cpp replace_fn.cpp
# free_vars.cpp abstract.cpp instantiate.cpp
for_each_fn.cpp occurs.cpp replace_fn.cpp free_vars.cpp
# abstract.cpp instantiate.cpp
# normalizer.cpp context.cpp level.cpp object.cpp environment.cpp
# type_checker.cpp kernel.cpp occurs.cpp metavar.cpp
# justification.cpp unification_constraint.cpp kernel_exception.cpp

244
src/kernel/free_vars.cpp
View file

@ -10,7 +10,6 @@ Author: Leonardo de Moura
#include "kernel/expr_sets.h"
#include "kernel/replace_fn.h"
#include "kernel/for_each_fn.h"
#include "kernel/metavar.h"
namespace lean {
/**
@ -30,19 +29,14 @@ protected:
bool apply(expr const & e, unsigned offset) {
// handle easy cases
switch (e.kind()) {
case expr_kind::Constant:
if (!const_type(e))
return false;
break;
case expr_kind::Type: case expr_kind::Value:
case expr_kind::Constant: case expr_kind::Sort: case expr_kind::Macro:
return false;
case expr_kind::MetaVar:
return true;
case expr_kind::Var:
return var_idx(e) >= offset;
case expr_kind::App: case expr_kind::Lambda:
case expr_kind::Pi: case expr_kind::Let: case expr_kind::Sigma:
case expr_kind::Proj: case expr_kind::Pair: case expr_kind::HEq:
case expr_kind::App: case expr_kind::Let:
case expr_kind::Meta: case expr_kind::Local:
case expr_kind::Lambda: case expr_kind::Pi: case expr_kind::Sigma:
case expr_kind::Pair: case expr_kind::Fst: case expr_kind::Snd:
break;
}
@ -70,28 +64,23 @@ protected:
bool result = false;
switch (e.kind()) {
case expr_kind::Constant:
lean_assert(const_type(e));
result = apply(const_type(e), offset);
break;
case expr_kind::Type: case expr_kind::Value: case expr_kind::Var: case expr_kind::MetaVar:
// easy cases were already handled
case expr_kind::Constant: case expr_kind::Sort: case expr_kind::Macro:
case expr_kind::Var:
lean_unreachable(); // LCOV_EXCL_LINE
case expr_kind::Meta: case expr_kind::Local:
result = apply(mlocal_type(e), offset);
case expr_kind::App:
result = std::any_of(begin_args(e), end_args(e), [=](expr const & arg){ return apply(arg, offset); });
result = apply(app_fn(e), offset) || apply(app_arg(e), offset);
break;
case expr_kind::Fst: case expr_kind::Snd:
result = apply(proj_arg(e), offset);
break;
case expr_kind::Lambda: case expr_kind::Pi: case expr_kind::Sigma:
result = apply(abst_domain(e), offset) || apply(abst_body(e), offset + 1);
result = apply(binder_domain(e), offset) || apply(binder_body(e), offset + 1);
break;
case expr_kind::Let:
result = apply(let_type(e), offset) || apply(let_value(e), offset) || apply(let_body(e), offset + 1);
break;
case expr_kind::HEq:
result = apply(heq_lhs(e), offset) || apply(heq_rhs(e), offset);
break;
case expr_kind::Proj:
result = apply(proj_arg(e), offset);
break;
case expr_kind::Pair:
result = apply(pair_first(e), offset) || apply(pair_second(e), offset) || apply(pair_type(e), offset);
break;
@ -121,47 +110,9 @@ bool has_free_vars(expr const & e) {
*/
class free_var_range_fn {
expr_map<unsigned> m_cached;
optional<ro_metavar_env> const & m_menv;
static unsigned dec(unsigned s) { return (s == 0) ? 0 : s - 1; }
/*
\brief If a metavariable \c m was defined in a context \c ctx and <tt>ctx.size() == R</tt>,
then \c m can only contain free variables in the range <tt>[0, R)</tt>
So, if \c m does not have an associated local context, the answer is just \c R.
If \c m has an associated local context, we process it using the following rules
[inst:s v] R ===> if s >= R then R else max(R-1, range_of(v))
[lift:s:n] R ===> if s >= R then R else R + n
*/
unsigned process_metavar(expr const & m) {
lean_assert(is_metavar(m));
if (!m_menv)
return std::numeric_limits<unsigned>::max(); // metavariable environment is not available, assume the worst.
context ctx = (*m_menv)->get_context(metavar_name(m));
unsigned R = ctx.size();
if (has_local_context(m)) {
local_context lctx = metavar_lctx(m);
buffer<local_entry> lentries;
to_buffer(lctx, lentries);
unsigned i = lentries.size();
while (i > 0) {
--i;
local_entry const & entry = lentries[i];
if (entry.is_inst()) {
if (entry.s() < R) {
R = std::max(dec(R), apply(entry.v()));
}
} else {
if (entry.s() < R)
R += entry.n();
}
}
}
return R;
}
unsigned apply(optional<expr> const & e) {
return e ? apply(*e) : 0;
}
@ -169,19 +120,14 @@ class free_var_range_fn {
unsigned apply(expr const & e) {
// handle easy cases
switch (e.kind()) {
case expr_kind::Constant:
if (!const_type(e))
return 0;
break;
case expr_kind::Type: case expr_kind::Value:
case expr_kind::Constant: case expr_kind::Sort: case expr_kind::Macro:
return 0;
case expr_kind::Var:
return var_idx(e) + 1;
case expr_kind::MetaVar: case expr_kind::App:
case expr_kind::Lambda: case expr_kind::Pi:
case expr_kind::Let: case expr_kind::Sigma:
case expr_kind::Proj: case expr_kind::Pair:
case expr_kind::HEq:
case expr_kind::App: case expr_kind::Let:
case expr_kind::Meta: case expr_kind::Local:
case expr_kind::Lambda: case expr_kind::Pi: case expr_kind::Sigma:
case expr_kind::Pair: case expr_kind::Fst: case expr_kind::Snd:
break;
}
@ -199,30 +145,21 @@ class free_var_range_fn {
unsigned result = 0;
switch (e.kind()) {
case expr_kind::Constant:
lean_assert(const_type(e));
result = apply(const_type(e));
break;
case expr_kind::Type: case expr_kind::Value: case expr_kind::Var:
// easy cases were already handled
case expr_kind::Constant: case expr_kind::Sort: case expr_kind::Macro:
case expr_kind::Var:
lean_unreachable(); // LCOV_EXCL_LINE
case expr_kind::MetaVar:
result = process_metavar(e);
break;
case expr_kind::Meta: case expr_kind::Local:
result = apply(mlocal_type(e));
case expr_kind::App:
for (auto const & c : args(e))
result = std::max(result, apply(c));
result = std::max(apply(app_fn(e)), apply(app_arg(e)));
break;
case expr_kind::Lambda: case expr_kind::Pi: case expr_kind::Sigma:
result = std::max(apply(abst_domain(e)), dec(apply(abst_body(e))));
result = std::max(apply(binder_domain(e)), dec(apply(binder_body(e))));
break;
case expr_kind::Let:
result = std::max({apply(let_type(e)), apply(let_value(e)), dec(apply(let_body(e)))});
break;
case expr_kind::HEq:
result = std::max(apply(heq_lhs(e)), apply(heq_rhs(e)));
break;
case expr_kind::Proj:
case expr_kind::Fst: case expr_kind::Snd:
result = apply(proj_arg(e));
break;
case expr_kind::Pair:
@ -236,26 +173,16 @@ class free_var_range_fn {
return result;
}
public:
free_var_range_fn(optional<ro_metavar_env> const & menv):m_menv(menv) {}
free_var_range_fn() {}
unsigned operator()(expr const & e) { return apply(e); }
};
unsigned free_var_range(expr const & e, ro_metavar_env const & menv) {
if (closed(e))
return 0;
else
return free_var_range_fn(some_ro_menv(menv))(e);
}
unsigned free_var_range(expr const & e) {
return free_var_range_fn(none_ro_menv())(e);
return free_var_range_fn()(e);
}
/**
\brief Functional object for checking whether a kernel expression has a free variable in the range <tt>[low, high)</tt> or not.
\remark We assume that a metavariable contains free variables.
This is an approximation, since we don't know how the metavariable will be instantiated.
*/
class has_free_var_in_range_fn {
protected:
@ -292,23 +219,14 @@ protected:
bool apply(expr const & e, unsigned offset) {
// handle easy cases
switch (e.kind()) {
case expr_kind::Constant:
if (!const_type(e))
return false;
break;
case expr_kind::Type: case expr_kind::Value:
case expr_kind::Constant: case expr_kind::Sort: case expr_kind::Macro:
return false;
case expr_kind::MetaVar:
if (m_range_fn)
break; // it is not cheap
else
return true; // assume that any free variable can occur in the metavariable
case expr_kind::Var:
return in_interval(var_idx(e), offset);
case expr_kind::App: case expr_kind::Lambda: case expr_kind::Pi:
case expr_kind::Let: case expr_kind::Sigma:
case expr_kind::Proj: case expr_kind::Pair:
case expr_kind::HEq:
case expr_kind::App: case expr_kind::Let:
case expr_kind::Meta: case expr_kind::Local:
case expr_kind::Lambda: case expr_kind::Pi: case expr_kind::Sigma:
case expr_kind::Pair: case expr_kind::Fst: case expr_kind::Snd:
break;
}
@ -326,37 +244,21 @@ protected:
bool result = false;
switch (e.kind()) {
case expr_kind::Constant:
lean_assert(const_type(e));
result = apply(const_type(e), offset);
break;
case expr_kind::Type: case expr_kind::Value: case expr_kind::Var:
// easy cases were already handled
case expr_kind::Constant: case expr_kind::Sort: case expr_kind::Macro:
case expr_kind::Var:
lean_unreachable(); // LCOV_EXCL_LINE
case expr_kind::MetaVar: {
lean_assert(m_range_fn);
unsigned R = (*m_range_fn)(e);
if (R > 0) {
unsigned max_fvar_idx = R - 1;
result = ge_lower(max_fvar_idx, offset);
// Remark: Variable #0 may occur in \c e.
// So, we don't have to check the upper bound offset + m_high;
}
break;
}
case expr_kind::Meta: case expr_kind::Local:
result = apply(mlocal_type(e), offset);
case expr_kind::App:
result = std::any_of(begin_args(e), end_args(e), [=](expr const & arg){ return apply(arg, offset); });
result = apply(app_fn(e), offset) || apply(app_arg(e), offset);
break;
case expr_kind::Lambda: case expr_kind::Pi: case expr_kind::Sigma:
result = apply(abst_domain(e), offset) || apply(abst_body(e), offset + 1);
result = apply(binder_domain(e), offset) || apply(binder_body(e), offset + 1);
break;
case expr_kind::Let:
result = apply(let_type(e), offset) || apply(let_value(e), offset) || apply(let_body(e), offset + 1);
break;
case expr_kind::HEq:
result = apply(heq_lhs(e), offset) || apply(heq_rhs(e), offset);
break;
case expr_kind::Proj:
case expr_kind::Fst: case expr_kind::Snd:
result = apply(proj_arg(e), offset);
break;
case expr_kind::Pair:
@ -370,46 +272,28 @@ protected:
return result;
}
public:
has_free_var_in_range_fn(unsigned low, unsigned high, optional<ro_metavar_env> const & menv):
has_free_var_in_range_fn(unsigned low, unsigned high):
m_low(low),
m_high(high) {
lean_assert(low < high);
if (menv)
m_range_fn.reset(new free_var_range_fn(menv));
}
bool operator()(expr const & e) { return apply(e, 0); }
};
bool has_free_var(expr const & e, unsigned low, unsigned high, optional<ro_metavar_env> const & menv) {
return high > low && !closed(e) && has_free_var_in_range_fn(low, high, menv)(e);
bool has_free_var(expr const & e, unsigned low, unsigned high) {
return high > low && !closed(e) && has_free_var_in_range_fn(low, high)(e);
}
bool has_free_var(expr const & e, unsigned low, unsigned high, ro_metavar_env const & menv) { return has_free_var(e, low, high, some_ro_menv(menv)); }
bool has_free_var(expr const & e, unsigned low, unsigned high) { return has_free_var(e, low, high, none_ro_menv()); }
bool has_free_var(expr const & e, unsigned i, optional<ro_metavar_env> const & menv) { return has_free_var(e, i, i+1, menv); }
bool has_free_var(expr const & e, unsigned i, ro_metavar_env const & menv) { return has_free_var(e, i, i+1, menv); }
bool has_free_var(expr const & e, unsigned i) { return has_free_var(e, i, i+1); }
bool has_free_var(context_entry const & e, unsigned low, unsigned high, ro_metavar_env const & menv) {
if (high <= low)
return false;
auto d = e.get_domain();
auto b = e.get_body();
return (d && has_free_var(*d, low, high, menv)) || (b && has_free_var(*b, low, high, menv));
bool has_free_var_ge(expr const & e, unsigned low) {
return has_free_var(e, low, std::numeric_limits<unsigned>::max());
}
bool has_free_var_ge(expr const & e, unsigned low, ro_metavar_env const & menv) {
return has_free_var(e, low, std::numeric_limits<unsigned>::max(), menv);
}
bool has_free_var_ge(expr const & e, unsigned low, optional<ro_metavar_env> const & menv) {
return has_free_var(e, low, std::numeric_limits<unsigned>::max(), menv);
}
bool has_free_var_ge(expr const & e, unsigned low) { return has_free_var(e, low, std::numeric_limits<unsigned>::max()); }
expr lower_free_vars(expr const & e, unsigned s, unsigned d, optional<ro_metavar_env> const & DEBUG_CODE(menv)) {
expr lower_free_vars(expr const & e, unsigned s, unsigned d) {
if (d == 0 || closed(e))
return e;
lean_assert(s >= d);
lean_assert(!has_free_var(e, s-d, s, menv));
lean_assert(!has_free_var(e, s-d, s));
return replace(e, [=](expr const & e, unsigned offset) -> expr {
if (is_var(e) && var_idx(e) >= s + offset) {
lean_assert(var_idx(e) >= offset + d);
@ -419,50 +303,18 @@ expr lower_free_vars(expr const & e, unsigned s, unsigned d, optional<ro_metavar
}
});
}
expr lower_free_vars(expr const & e, unsigned s, unsigned d, ro_metavar_env const & menv) { return lower_free_vars(e, s, d, some_ro_menv(menv)); }
expr lower_free_vars(expr const & e, unsigned s, unsigned d) { return lower_free_vars(e, s, d, none_ro_menv()); }
expr lower_free_vars(expr const & e, unsigned d, optional<ro_metavar_env> const & menv) { return lower_free_vars(e, d, d, menv); }
expr lower_free_vars(expr const & e, unsigned d, ro_metavar_env const & menv) { return lower_free_vars(e, d, d, menv); }
expr lower_free_vars(expr const & e, unsigned d) { return lower_free_vars(e, d, d); }
context_entry lower_free_vars(context_entry const & e, unsigned s, unsigned d, ro_metavar_env const & menv) {
auto domain = e.get_domain();
auto body = e.get_body();
if (domain && body)
return context_entry(e.get_name(), lower_free_vars(*domain, s, d, menv), lower_free_vars(*body, s, d, menv));
else if (domain)
return context_entry(e.get_name(), lower_free_vars(*domain, s, d, menv));
else
return context_entry(e.get_name(), none_expr(), lower_free_vars(*body, s, d, menv));
}
expr lift_free_vars(expr const & e, unsigned s, unsigned d, optional<ro_metavar_env> const & menv) {
expr lift_free_vars(expr const & e, unsigned s, unsigned d) {
if (d == 0 || closed(e))
return e;
return replace(e, [=](expr const & e, unsigned offset) -> expr {
if (is_var(e) && var_idx(e) >= s + offset) {
return mk_var(var_idx(e) + d);
} else if (is_metavar(e)) {
return add_lift(e, s + offset, d, menv);
} else {
return e;
}
});
}
expr lift_free_vars(expr const & e, unsigned s, unsigned d, ro_metavar_env const & menv) { return lift_free_vars(e, s, d, some_ro_menv(menv)); }
expr lift_free_vars(expr const & e, unsigned s, unsigned d) { return lift_free_vars(e, s, d, none_ro_menv()); }
expr lift_free_vars(expr const & e, unsigned d, optional<ro_metavar_env> const & menv) { return lift_free_vars(e, 0, d, menv); }
expr lift_free_vars(expr const & e, unsigned d) { return lift_free_vars(e, 0, d); }
expr lift_free_vars(expr const & e, unsigned d, ro_metavar_env const & menv) { return lift_free_vars(e, 0, d, menv); }
context_entry lift_free_vars(context_entry const & e, unsigned s, unsigned d, ro_metavar_env const & menv) {
auto domain = e.get_domain();
auto body = e.get_body();
if (domain && body)
return context_entry(e.get_name(), lift_free_vars(*domain, s, d, menv), lift_free_vars(*body, s, d, menv));
else if (domain)
return context_entry(e.get_name(), lift_free_vars(*domain, s, d, menv));
else
return context_entry(e.get_name(), none_expr(), lift_free_vars(*body, s, d, menv));
}
}

68
src/kernel/free_vars.h
View file

@ -6,65 +6,26 @@ Author: Leonardo de Moura
*/
#pragma once
#include "kernel/expr.h"
#include "kernel/metavar.h"
namespace lean {
/**
\brief Return true iff the given expression has free variables.
*/
/** \brief Return true iff the given expression has free variables. */
bool has_free_vars(expr const & a);
/**
\brief Return true iff the given expression does not have free variables.
*/
/** \brief Return true iff the given expression does not have free variables. */
inline bool closed(expr const & a) { return !has_free_vars(a); }
class metavar_env;
/**
\brief Return \c R s.t. the de Bruijn index of all free variables
occurring in \c e is in the interval <tt>[0, R)</tt>.
\pre All metavariables occurring in \c e must have been created
at \c menv.
\remark Regarding metavariables, if a metavariable \c m was defined
in a context \c ctx and <tt>ctx.size() == R</tt>, then \c m can
only contain free variables in the range <tt>[0, R)</tt>
So, if \c m does not have an associated local context, the answer is just \c R.
If \c m has an associated local context, we process it using the following rules
[inst:s v] R ===> if s >= R then R else max(R-1, range_of(v))
[lift:s:n] R ===> if s >= R then R else R + n
*/
unsigned free_var_range(expr const & e, ro_metavar_env const & menv);
unsigned free_var_range(expr const & e);
/**
\brief Return true iff \c e constains a free variable <tt>(var i)</tt> s.t. \c i in <tt>[low, high)</tt>.
\pre low < high
\remark If menv is not none, then we use \c free_var_range to compute the free variables that may
occur in a metavariable.
*/
bool has_free_var(expr const & e, unsigned low, unsigned high, optional<ro_metavar_env> const & menv);
bool has_free_var(expr const & e, unsigned low, unsigned high, ro_metavar_env const & menv);
bool has_free_var(expr const & e, unsigned low, unsigned high);
/**
\brief Return true iff \c e contains the free variable <tt>(var i)</tt>.
*/
bool has_free_var(expr const & e, unsigned i, optional<ro_metavar_env> const & menv);
bool has_free_var(expr const & e, unsigned i, ro_metavar_env const & menv);
/** \brief Return true iff \c e contains the free variable <tt>(var i)</tt>. */
bool has_free_var(expr const & e, unsigned i);
bool has_free_var(context_entry const & e, unsigned low, unsigned high, ro_metavar_env const & menv);
/**
\brief Return true iff \c e contains a free variable >= low.
\remark If menv is provided, then we use \c free_var_range to compute the free variables that may
occur in a metavariable.
*/
bool has_free_var_ge(expr const & e, unsigned low, ro_metavar_env const & menv);
bool has_free_var_ge(expr const & e, unsigned low, optional<ro_metavar_env> const & menv);
/** \brief Return true iff \c e contains a free variable >= low. */
bool has_free_var_ge(expr const & e, unsigned low);
/**
@ -73,30 +34,11 @@ bool has_free_var_ge(expr const & e, unsigned low);
\pre s >= d
\pre !has_free_var(e, s-d, s, menv)
\remark The parameter menv is only used for debugging purposes
*/
expr lower_free_vars(expr const & e, unsigned s, unsigned d, optional<ro_metavar_env> const & menv);
expr lower_free_vars(expr const & e, unsigned s, unsigned d, ro_metavar_env const & menv);
expr lower_free_vars(expr const & e, unsigned s, unsigned d);
expr lower_free_vars(expr const & e, unsigned d, optional<ro_metavar_env> const & menv);
expr lower_free_vars(expr const & e, unsigned d, ro_metavar_env const & menv);
expr lower_free_vars(expr const & e, unsigned d);
context_entry lower_free_vars(context_entry const & e, unsigned s, unsigned d, ro_metavar_env const & menv);
/**
\brief Lift free variables >= s in \c e by d.
\remark When the parameter menv is not none, this function will minimize the use
of the local entry lift in metavariables occurring in \c e.
*/
expr lift_free_vars(expr const & e, unsigned s, unsigned d, optional<ro_metavar_env> const & menv);
/** \brief Lift free variables >= s in \c e by d. */
expr lift_free_vars(expr const & e, unsigned s, unsigned d);
expr lift_free_vars(expr const & e, unsigned s, unsigned d, ro_metavar_env const & menv);
expr lift_free_vars(expr const & e, unsigned d, optional<ro_metavar_env> const & menv);
expr lift_free_vars(expr const & e, unsigned d, ro_metavar_env const & menv);
expr lift_free_vars(expr const & e, unsigned d);
context_entry lift_free_vars(context_entry const & e, unsigned s, unsigned d, ro_metavar_env const & menv);
}