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more rewrites

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2015-12-06 10:44:19 -08:00
parent 4fe0e07080
commit 40e9e4c7f8
4 changed files with 98 additions and 12 deletions
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95
src/ast/rewriter/seq_rewriter.cpp
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@ -115,22 +115,75 @@ br_status seq_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * con
return BR_FAILED;
}
/*
string + string = string
a + (b + c) = (a + b) + c
a + "" = a
"" + a = a
(a + string) + string = a + string
*/
br_status seq_rewriter::mk_str_concat(expr* a, expr* b, expr_ref& result) {
std::string c, d;
if (m_util.str.is_const(a, c) && m_util.str.is_const(b, d)) {
result = m_util.str.mk_string(c + d);
std::string s1, s2;
expr* c, *d;
bool isc1 = m_util.str.is_const(a, s1);
bool isc2 = m_util.str.is_const(b, s2);
if (isc1 && isc2) {
result = m_util.str.mk_string(s1 + s2);
return BR_DONE;
}
if (m_util.str.is_concat(b, c, d)) {
result = m_util.str.mk_concat(m_util.str.mk_concat(a, c), d);
return BR_REWRITE2;
}
if (isc1 && s1.length() == 0) {
result = b;
return BR_DONE;
}
if (isc2 && s2.length() == 0) {
result = a;
return BR_DONE;
}
if (m_util.str.is_concat(a, c, d) &&
m_util.str.is_const(d, s1) && isc2) {
result = m_util.str.mk_string(s1 + s2);
return BR_DONE;
}
return BR_FAILED;
}
br_status seq_rewriter::mk_str_length(expr* a, expr_ref& result) {
std::string b;
if (m_util.str.is_const(a, b)) {
m_es.reset();
m_util.str.get_concat(a, m_es);
unsigned len = 0;
unsigned j = 0;
for (unsigned i = 0; i < m_es.size(); ++i) {
if (m_util.str.is_const(m_es[i], b)) {
len += b.length();
}
else {
m_es[j] = m_es[i];
++j;
}
}
if (j == 0) {
result = m_autil.mk_numeral(rational(b.length()), true);
return BR_DONE;
}
if (j != m_es.size()) {
expr_ref_vector es(m());
for (unsigned i = 0; i < j; ++i) {
es.push_back(m_util.str.mk_length(m_es[i]));
}
if (len != 0) {
es.push_back(m_autil.mk_numeral(rational(len), true));
}
result = m_autil.mk_add(es.size(), es.c_ptr());
return BR_DONE;
}
return BR_FAILED;
}
br_status seq_rewriter::mk_str_substr(expr* a, expr* b, expr* c, expr_ref& result) {
std::string s;
rational pos, len;
@ -151,6 +204,7 @@ br_status seq_rewriter::mk_str_strctn(expr* a, expr* b, expr_ref& result) {
}
return BR_FAILED;
}
br_status seq_rewriter::mk_str_charat(expr* a, expr* b, expr_ref& result) {
std::string c;
rational r;
@ -166,10 +220,14 @@ br_status seq_rewriter::mk_str_charat(expr* a, expr* b, expr_ref& result) {
}
return BR_FAILED;
}
br_status seq_rewriter::mk_str_stridof(expr* a, expr* b, expr* c, expr_ref& result) {
std::string s1, s2;
rational r;
if (m_util.str.is_const(a, s1) && m_util.str.is_const(b, s2) && m_autil.is_numeral(c, r) && r.is_unsigned()) {
bool isc1 = m_util.str.is_const(a, s1);
bool isc2 = m_util.str.is_const(b, s2);
if (isc1 && isc2 && m_autil.is_numeral(c, r) && r.is_unsigned()) {
for (unsigned i = r.get_unsigned(); i < s1.length(); ++i) {
if (strncmp(s1.c_str() + i, s2.c_str(), s2.length()) == 0) {
result = m_autil.mk_numeral(rational(i) - r, true);
@ -179,15 +237,23 @@ br_status seq_rewriter::mk_str_stridof(expr* a, expr* b, expr* c, expr_ref& resu
result = m_autil.mk_numeral(rational(-1), true);
return BR_DONE;
}
if (m_util.str.is_const(b, s2) && s2.length() == 0) {
if (m_autil.is_numeral(c, r) && r.is_neg()) {
result = m_autil.mk_numeral(rational(-1), true);
return BR_DONE;
}
if (isc2 && s2.length() == 0) {
result = c;
return BR_DONE;
}
// Enhancement: walk segments of a, determine which segments must overlap, must not overlap, may overlap.
return BR_FAILED;
}
br_status seq_rewriter::mk_str_strrepl(expr* a, expr* b, expr* c, expr_ref& result) {
std::string s1, s2, s3;
if (m_util.str.is_const(a, s1) && m_util.str.is_const(b, s2) && m_util.str.is_const(c, s3)) {
if (m_util.str.is_const(a, s1) && m_util.str.is_const(b, s2) &&
m_util.str.is_const(c, s3)) {
std::ostringstream buffer;
for (unsigned i = 0; i < s1.length(); ) {
if (strncmp(s1.c_str() + i, s2.c_str(), s2.length()) == 0) {
@ -206,12 +272,14 @@ br_status seq_rewriter::mk_str_strrepl(expr* a, expr* b, expr* c, expr_ref& resu
result = a;
return BR_DONE;
}
return BR_FAILED;
}
br_status seq_rewriter::mk_str_prefix(expr* a, expr* b, expr_ref& result) {
std::string s1, s2;
if (m_util.str.is_const(a, s1) && m_util.str.is_const(b, s2)) {
bool isc1 = m_util.str.is_const(a, s1);
bool isc2 = m_util.str.is_const(b, s2);
if (isc1 && isc2) {
bool prefix = s1.length() <= s2.length();
for (unsigned i = 0; i < s1.length() && prefix; ++i) {
prefix = s1[i] == s2[i];
@ -219,15 +287,17 @@ br_status seq_rewriter::mk_str_prefix(expr* a, expr* b, expr_ref& result) {
result = m().mk_bool_val(prefix);
return BR_DONE;
}
if (m_util.str.is_const(a, s1) && s1.length() == 0) {
if (isc1 && s1.length() == 0) {
result = m().mk_true();
return BR_DONE;
}
return BR_FAILED;
}
br_status seq_rewriter::mk_str_suffix(expr* a, expr* b, expr_ref& result) {
std::string s1, s2;
if (m_util.str.is_const(a, s1) && m_util.str.is_const(b, s2)) {
bool isc1 = m_util.str.is_const(a, s1);
if (isc1 && m_util.str.is_const(b, s2)) {
bool suffix = s1.length() <= s2.length();
for (unsigned i = 0; i < s1.length() && suffix; ++i) {
suffix = s1[s1.length() - i - 1] == s2[s2.length() - i - 1];
@ -235,12 +305,13 @@ br_status seq_rewriter::mk_str_suffix(expr* a, expr* b, expr_ref& result) {
result = m().mk_bool_val(suffix);
return BR_DONE;
}
if (m_util.str.is_const(a, s1) && s1.length() == 0) {
if (isc1 && s1.length() == 0) {
result = m().mk_true();
return BR_DONE;
}
return BR_FAILED;
}
br_status seq_rewriter::mk_str_itos(expr* a, expr_ref& result) {
rational r;
if (m_autil.is_numeral(a, r)) {