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feat(kernel): add max_free_var function

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-01-12 16:45:34 -08:00
parent f2cac0410e
commit 4d9eb4ac6c
2 changed files with 23 additions and 0 deletions
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17
src/kernel/free_vars.cpp
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@ -8,6 +8,7 @@ Author: Leonardo de Moura
#include "kernel/free_vars.h"
#include "kernel/expr_sets.h"
#include "kernel/replace_fn.h"
#include "kernel/for_each_fn.h"
#include "kernel/metavar.h"
namespace lean {
@ -397,4 +398,20 @@ context_entry lift_free_vars(context_entry const & e, unsigned s, unsigned d, me
else
return context_entry(e.get_name(), none_expr(), lift_free_vars(*body, s, d, menv));
}
optional<unsigned> max_free_var(expr const & e) {
optional<unsigned> r;
for_each(e, [&](expr const & v, unsigned offset) {
if (is_var(v)) {
unsigned vidx = var_idx(v);
if (vidx >= offset) {
vidx -= offset;
if (!r || vidx > *r)
r = vidx;
}
}
return true;
});
return r;
}
}

6
src/kernel/free_vars.h
View file

@ -88,4 +88,10 @@ expr lift_free_vars(expr const & e, unsigned d, 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, metavar_env const & menv);
/**
\brief Return the index of the max free var occurring in \c e.
Return none if \c e does not contain free variables.
*/
optional<unsigned> max_free_var(expr const & e);
}