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#include "soc_desc.hpp"
#include <cstdarg>
#include <cstdio>
using namespace soc_desc;
namespace soc_desc
{
namespace
{
struct formula_evaluator
{
std::string formula;
size_t pos;
error_context_t& ctx;
std::string m_loc;
bool err(const char *fmt, ...)
{
char buffer[256];
va_list args;
va_start(args, fmt);
vsnprintf(buffer,sizeof(buffer), fmt, args);
va_end(args);
ctx.add(error_t(error_t::FATAL, m_loc, buffer));
return false;
}
formula_evaluator(const std::string& s, error_context_t& ctx):pos(0),ctx(ctx)
{
for(size_t i = 0; i < s.size(); i++)
if(!isspace(s[i]))
formula.push_back(s[i]);
}
void set_location(const std::string& loc)
{
m_loc = loc;
}
void adv()
{
pos++;
}
char cur()
{
return end() ? 0 : formula[pos];
}
bool end()
{
return pos >= formula.size();
}
bool parse_digit(char c, int basis, soc_word_t& res)
{
c = tolower(c);
if(isdigit(c))
{
res = c - '0';
return true;
}
if(basis == 16 && isxdigit(c))
{
res = c + 10 - 'a';
return true;
}
return false;
}
bool parse_signed(soc_word_t& res)
{
char op = cur();
if(op == '+' || op == '-')
{
adv();
if(!parse_signed(res))
return false;
if(op == '-')
res *= -1;
return true;
}
else if(op == '(')
{
adv();
if(!parse_expression(res))
return false;
if(cur() != ')')
return err("expected ')', got '%c'", cur());
adv();
return true;
}
else if(isdigit(op))
{
res = op - '0';
adv();
int basis = 10;
if(op == '0' && cur() == 'x')
{
basis = 16;
adv();
}
soc_word_t digit = 0;
while(parse_digit(cur(), basis, digit))
{
res = res * basis + digit;
adv();
}
return true;
}
else if(isalpha(op) || op == '_')
{
std::string name;
while(isalnum(cur()) || cur() == '_')
{
name.push_back(cur());
adv();
}
return get_variable(name, res);
}
else
return err("express signed expression, got '%c'", op);
}
bool parse_term(soc_word_t& res)
{
if(!parse_signed(res))
return false;
while(cur() == '*' || cur() == '/' || cur() == '%')
{
char op = cur();
adv();
soc_word_t tmp;
if(!parse_signed(tmp))
return false;
if(op == '*')
res *= tmp;
else if(tmp != 0)
res = op == '/' ? res / tmp : res % tmp;
else
return err("division by 0");
}
return true;
}
bool parse_expression(soc_word_t& res)
{
if(!parse_term(res))
return false;
while(!end() && (cur() == '+' || cur() == '-'))
{
char op = cur();
adv();
soc_word_t tmp;
if(!parse_term(tmp))
return false;
if(op == '+')
res += tmp;
else
res -= tmp;
}
return true;
}
bool parse(soc_word_t& res)
{
bool ok = parse_expression(res);
if(ok && !end())
err("unexpected character '%c'", cur());
return ok && end();
}
virtual bool get_variable(std::string name, soc_word_t& res)
{
return err("unknown variable '%s'", name.c_str());
}
};
struct my_evaluator : public formula_evaluator
{
const std::map< std::string, soc_word_t>& var;
my_evaluator(const std::string& formula, const std::map< std::string, soc_word_t>& _var,
error_context_t& ctx)
:formula_evaluator(formula, ctx), var(_var) {}
virtual bool get_variable(std::string name, soc_word_t& res)
{
std::map< std::string, soc_word_t>::const_iterator it = var.find(name);
if(it == var.end())
return formula_evaluator::get_variable(name, res);
else
{
res = it->second;
return true;
}
}
};
}
bool evaluate_formula(const std::string& formula,
const std::map< std::string, soc_word_t>& var, soc_word_t& result,
const std::string& loc, error_context_t& error)
{
my_evaluator e(formula, var, error);
e.set_location(loc);
return e.parse(result);
}
} // soc_desc
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