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/*
Copyright (C) 2021 Fredrik Johansson
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fexpr.h"
/*
Sets res_view to a view of expr replaced by {xs, ys, len} and returns whether
any replacement has been made.
If no replacement has been made, res_view will refer to the data of expr,
with an alloc field of 0.
If expr as a whole has been replaced with some entry in ys, res_view will
refer to the data of that value in ys, also with an alloc field of 0.
Otherwise, expr will be initialized to a new expression, with a nonzero
alloc field.
*/
static int
_fexpr_replace_vec(fexpr_t res_view, const fexpr_t expr, fexpr_srcptr xs, fexpr_srcptr ys, slong len)
{
slong i, nargs;
fexpr_t func, new_func, arg;
fexpr_struct tmp_args[4];
fexpr_ptr args;
int changed;
for (i = 0; i < len; i++)
{
if (fexpr_equal(expr, xs + i))
{
res_view->data = ys[i].data;
res_view->alloc = 0;
return 1;
}
}
if (fexpr_is_atom(expr))
{
res_view->data = expr->data;
res_view->alloc = 0;
return 0;
}
nargs = fexpr_nargs(expr);
fexpr_view_func(func, expr);
changed = _fexpr_replace_vec(new_func, func, xs, ys, len);
if (nargs >= 5)
args = flint_malloc(sizeof(fexpr_struct) * nargs);
else
args = tmp_args;
if (nargs >= 1)
{
fexpr_view_arg(arg, expr, 0);
for (i = 0; i < nargs; i++)
{
changed |= _fexpr_replace_vec(args + i, arg, xs, ys, len);
if (i < nargs - 1)
fexpr_view_next(arg);
}
}
if (changed)
{
fexpr_init(res_view);
fexpr_call_vec(res_view, new_func, args, nargs);
if (new_func->alloc != 0)
flint_free(new_func->data);
for (i = 0; i < nargs; i++)
{
if (args[i].alloc != 0)
flint_free(args[i].data);
}
}
else
{
res_view->data = expr->data;
res_view->alloc = 0;
}
if (nargs >= 5)
flint_free(args);
return changed;
}
int
fexpr_replace_vec(fexpr_t res, const fexpr_t expr, const fexpr_vec_t xs, const fexpr_vec_t ys)
{
int changed;
slong num_rules;
fexpr_t res_view;
num_rules = xs->length;
if (num_rules != ys->length)
{
flint_throw(FLINT_ERROR, "fexpr_replace_vec: vectors don't match\n");
}
if (num_rules == 0)
{
fexpr_set(res, expr);
return 0;
}
changed = _fexpr_replace_vec(res_view, expr, xs->entries, ys->entries, num_rules);
if (changed)
{
if (res_view->alloc != 0)
{
/* We have new data */
fexpr_swap(res, res_view);
fexpr_clear(res_view);
}
else
{
/* Must be a view of some ys; we assume that res is not aliased
with any entry in ys. */
fexpr_set(res, res_view);
}
}
else
{
fexpr_set(res, expr);
}
return changed;
}
int
fexpr_replace(fexpr_t res, const fexpr_t expr, const fexpr_t x, const fexpr_t y)
{
int changed;
fexpr_t res_view;
changed = _fexpr_replace_vec(res_view, expr, x, y, 1);
if (changed)
{
if (res_view->alloc != 0)
{
/* We have new data */
fexpr_swap(res, res_view);
fexpr_clear(res_view);
}
else
{
/* Must be a view of some ys; we assume that res is not aliased
with any entry in ys. */
fexpr_set(res, res_view);
}
}
else
{
fexpr_set(res, expr);
}
return changed;
}
int
fexpr_replace2(fexpr_t res, const fexpr_t expr, const fexpr_t x1, const fexpr_t y1, const fexpr_t x2, const fexpr_t y2)
{
int changed;
fexpr_t res_view;
fexpr_struct tmp[4];
tmp[0] = *x1;
tmp[1] = *x2;
tmp[2] = *y1;
tmp[3] = *y2;
changed = _fexpr_replace_vec(res_view, expr, tmp, tmp + 2, 2);
if (changed)
{
if (res_view->alloc != 0)
{
/* We have new data */
fexpr_swap(res, res_view);
fexpr_clear(res_view);
}
else
{
/* Must be a view of some ys; we assume that res is not aliased
with any entry in ys. */
fexpr_set(res, res_view);
}
}
else
{
fexpr_set(res, expr);
}
return changed;
}