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Fix issue test-gen#172 #805

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Apr 12, 2017
Merged

Fix issue test-gen#172 #805

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53 changes: 41 additions & 12 deletions src/solvers/refinement/string_constraint_generator_valueof.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -642,25 +642,35 @@ exprt string_constraint_generatort::add_axioms_for_correct_number_format(
binary_relation_exprt(chr, ID_ge, zero_char),
binary_relation_exprt(chr, ID_le, nine_char));

// TODO: we should have implications in the other direction for correct
// correct => |str| > 0
exprt non_empty=str.axiom_for_is_longer_than(from_integer(1, index_type));
axioms.push_back(implies_exprt(correct, non_empty));

// correct => (str[0] = '+' or '-' || '0' <= str[0] <= '9')
or_exprt correct_first(
or_exprt(starts_with_minus, starts_with_plus), starts_with_digit);
exprt has_first=str.axiom_for_is_longer_than(from_integer(1, index_type));
implies_exprt a1(correct, and_exprt(has_first, correct_first));
axioms.push_back(a1);
axioms.push_back(implies_exprt(correct, correct_first));

exprt not_too_long=str.axiom_for_is_shorter_than(max_size);
axioms.push_back(not_too_long);
// correct => str[0]='+' or '-' ==> |str| > 1
implies_exprt contains_digit(
or_exprt(starts_with_minus, starts_with_plus),
str.axiom_for_is_longer_than(from_integer(2, index_type)));
axioms.push_back(implies_exprt(correct, contains_digit));

symbol_exprt qvar=fresh_univ_index("number_format", index_type);
// correct => |str| < max_size
axioms.push_back(
implies_exprt(correct, str.axiom_for_is_shorter_than(max_size)));

// forall 1 <= qvar < |str| . correct => '0'<= str[qvar] <= '9'
symbol_exprt qvar=fresh_univ_index("number_format", index_type);
and_exprt is_digit(
binary_relation_exprt(str[qvar], ID_ge, zero_char),
binary_relation_exprt(str[qvar], ID_le, nine_char));

string_constraintt a2(
string_constraintt all_digits(
qvar, from_integer(1, index_type), str.length(), correct, is_digit);
axioms.push_back(all_digits);

axioms.push_back(a2);
return correct;
}

Expand Down Expand Up @@ -706,10 +716,29 @@ exprt string_constraint_generatort::add_axioms_for_parse_int(

for(unsigned j=1; j<size; j++)
{
sum=plus_exprt(
mult_exprt(sum, ten),
mult_exprt ten_sum(sum, ten);
if(j>=9)
{
// We have to be careful about overflows
div_exprt div(sum, ten);
equal_exprt no_overflow(div, sum);
axioms.push_back(no_overflow);
}

sum=plus_exprt_with_overflow_check(
ten_sum,
typecast_exprt(minus_exprt(str[j], zero_char), type));
first_value=mult_exprt(first_value, ten);

mult_exprt first(first_value, ten);
if(j>=9)
{
// We have to be careful about overflows
div_exprt div_first(first, ten);
implies_exprt no_overflow_first(
starts_with_digit, equal_exprt(div_first, first_value));
axioms.push_back(no_overflow_first);
}
first_value=first;
}

// If the length is `size`, we add axioms:
Expand Down