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/*
* phc -- the open source PHP compiler
* See doc/license/README.license for licensing information
*
* Once a constant is defined, it cannot be redefined or undefined. Keep a list
* of constants defined before this point.
*
* PHP presents two different behaviors for constants defined as case insensitive.
* When checking it for constant redefinition, it does not consider all constant
* name variations. For the "defined" function and when a constant is translated
* to its value, it considers all variations. To cope with this, we used two functions:
* - can_constant_be_defined -> does not check all variations (should be used before set_constant).
* - is_constant_defined -> checks all variations (should be used in all other situations).
*
* To understand better, consider the following example:
* <?php
* define("Def", "value1", true); // defined as case insensitive (stored as "def" - lowercase).
* define("def", "value2"); // cannot be defined, because "def" (lowercase) is already stored.
* define("Def", "value3"); // can be defined, since "Def" isn't stored.
* define("dEf", "value4", true); // cannot be defined, since "def" (lowercase) is already stored.
* ?>
*
* PS: Current behavior of precedence for constants:
* check for case sensitive constants first, then for case insensitive.
*
* TODO: Conditional constants are not working.
* TODO: Handle unknown constants key name.
* TODO: Handle unknown value of case insensitive.
*
*/
#include "Constant_state.h"
#include "Value_analysis.h"
#include <boost/algorithm/string.hpp> // to_lower
using namespace MIR;
Constant_state::Constant_state (Whole_program* wp)
: WPA_lattice <string, const Absval_cell> (wp)
{
}
// TODO: can be case-insensitive
string
Constant_state::context_merge_key (string key) const
{
// Constant keys have context in them.
return key;
}
// TODO: for conditionally defined constants, this might return true, even
// though its unknown.
bool
Constant_state::can_constant_be_defined (Context* cx, Result_state state, string name, bool case_insensitive) const
{
if (case_insensitive)
boost::to_lower(name);
if (lattices[state][cx].has (name))
return false;
Literal* constant = PHP::fold_constant (new Constant (NULL, new CONSTANT_NAME (s(name))));
if (constant)
return false;
return true;
}
void
Constant_state::set_constant (Context* cx, string name, const Abstract_value* value, bool case_insensitive)
{
// Should be handled in Whole_program.
assert (can_constant_be_defined (cx, R_WORKING, name, case_insensitive));
if (case_insensitive)
boost::to_lower(name);
working[cx][name] = new Absval_cell (value, case_insensitive);
}
void
Constant_state::set_unknown_constant (Context* cx, const Abstract_value* value, bool case_insensitive)
{
phc_TODO ();
phc_optimization_exception ("Adding a new value from a new target unsupported during alias analysis");
}
// TODO: for conditionally defined constants, this might return true, even
// though its unknown.
bool
Constant_state::is_constant_defined (Context* cx, Result_state state, string name) const
{
if (lattices[state][cx].has (name))
return true;
Literal* constant = PHP::fold_constant (new Constant (NULL, new CONSTANT_NAME (s(name))));
if (constant)
return true;
// Try to obtain the case-insensitive constant.
string iname = name;
boost::to_lower(iname);
string key;
const Absval_cell *absval;
foreach (tie(key, absval), lattices[state][cx]) {
if (absval->case_insensitive && key == iname)
return true;
}
return false;
}
const Abstract_value*
Constant_state::get_constant (Context* cx, Result_state state, string name) const
{
if (lattices[state][cx].has (name))
return lattices[state][cx][name]->value;
Literal* constant = PHP::fold_constant (new Constant (NULL, new CONSTANT_NAME (s(name))));
if (constant)
return new Abstract_value (constant);
// Try to obtain the case-insensitive constant.
string iname = name;
boost::to_lower(iname);
string key;
const Absval_cell *absval;
foreach (tie(key, absval), lattices[state][cx]) {
if (absval->case_insensitive && key == iname)
return absval->value;
}
return new Abstract_value (new STRING (s(name)));
}
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