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substr bugfix

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This commit is contained in:
Murphy Berzish 2017-01-20 17:39:32 -05:00
parent a570149b57
commit 50e2273dbd
2 changed files with 118 additions and 8 deletions
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45
src/ast/rewriter/str_rewriter.cpp
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@ -431,18 +431,47 @@ br_status str_rewriter::mk_str_from_int(expr * arg0, expr_ref & result) {
br_status str_rewriter::mk_str_Substr(expr * base, expr * start, expr * len, expr_ref & result) {
TRACE("t_str_rw", tout << "rewrite (Substr " << mk_pp(base, m()) << " " << mk_pp(start, m()) << " " << mk_pp(len, m()) << ")" << std::endl;);
rational startVal, lenVal;
if (m_strutil.is_string(base) && m_autil.is_numeral(start, startVal) && m_autil.is_numeral(len, lenVal)) {
std::string baseStr = m_strutil.get_string_constant_value(base);
// TODO handling for invalid start/len
if (startVal.is_nonneg() && lenVal.is_nonneg() && startVal.get_unsigned() <= baseStr.length()) {
TRACE("t_str_rw", tout << "rewriting constant Substr expression" << std::endl;);
std::string substr = baseStr.substr(startVal.get_unsigned(), lenVal.get_unsigned());
result = m_strutil.mk_string(substr);
bool constant_base = m_strutil.is_string(base);
std::string baseStr;
if (constant_base) {
baseStr = m_strutil.get_string_constant_value(base);
}
rational startVal;
bool constant_start = m_autil.is_numeral(start, startVal);
rational lenVal;
bool constant_len = m_autil.is_numeral(len, lenVal);
// case 1: start < 0 or len < 0
if ( (constant_start && startVal.is_neg()) || (constant_len && lenVal.is_neg()) ) {
TRACE("t_str_rw", tout << "start/len of substr is negative" << std::endl;);
result = m_strutil.mk_string("");
return BR_DONE;
}
// case 1.1: start >= length(base)
if (constant_start && constant_base) {
rational baseStrlen((unsigned int)baseStr.length());
if (startVal >= baseStrlen) {
TRACE("t_str_rw", tout << "start >= strlen for substr" << std::endl;);
result = m_strutil.mk_string("");
return BR_DONE;
}
}
if (constant_base && constant_start && constant_len) {
rational baseStrlen((unsigned int)baseStr.length());
std::string retval;
if (startVal + lenVal >= baseStrlen) {
// case 2: pos+len goes past the end of the string
retval = baseStr.substr(startVal.get_unsigned(), std::string::npos);
} else {
// case 3: pos+len still within string
retval = baseStr.substr(startVal.get_unsigned(), lenVal.get_unsigned());
}
result = m_strutil.mk_string(retval);
return BR_DONE;
}
return BR_FAILED;
}