private function reduce(Context $ctx, $model = null)
{
$this->reset();
$this->stack = array();
$len = 0;
// While there are input tokens left
// Read the next token from input.
while ($t = array_shift($this->queue)) {
//var_dump ($t->type);
switch ($t->type) {
case self::OP_FIELD:
// If the token is a value or identifier
// Push it onto the stack.
$this->stack[] = $t;
++$len;
break;
case self::OP_EQUALS:
case self::OP_CONTAINS:
case self::OP_AND:
case self::OP_OR:
case self::OP_NOT:
// It is known a priori that the operator takes n arguments.
$na = $this->argc($t);
// If there are fewer than n values on the stack
if ($len < $na) {
throw new RuntimeError('run-time error: too few paramter for operator "' . $t->value . '" (' . $na . ' -> ' . $len . ')');
}
$rhs = array_pop($this->stack);
$lhs = null;
if ($na > 1) {
$lhs = array_pop($this->stack);
}
// Values!
if ($ctx->hasField($rhs->value)) {
$rhs = new Token(self::OP_FIELD, $ctx->getField($rhs->value));
}
if ($na > 1 && $ctx->hasField($lhs->value)) {
$lhs = new Token(self::OP_FIELD, $ctx->getField($lhs->value));
}
// if ($lhs) print "{$lhs->value} {$t->value} {$rhs->value}\n";
// else print "{$t->value} {$rhs->value}\n";
$len -= $na - 1;
// Push the returned results, if any, back onto the stack.
$this->stack[] = new Token(self::OP_FIELD, $this->op($t->type, $lhs, $rhs, $model));
break;
/*
case self::OP_FUNCTION:
// function
$argc = $t->argc;
$argv = array();
$len -= $argc - 1;
for (; $argc > 0; --$argc)
array_unshift($argv, array_pop($this->stack)->value);
// Push the returned results, if any, back onto the stack.
$this->stack[] = new Token(self::OP_FIELD, $ctx->fn($t->value, $argv));
break;
*/
/*
case self::OP_FUNCTION:
// function
$argc = $t->argc;
$argv = array();
$len -= $argc - 1;
for (; $argc > 0; --$argc)
array_unshift($argv, array_pop($this->stack)->value);
// Push the returned results, if any, back onto the stack.
$this->stack[] = new Token(self::OP_FIELD, $ctx->fn($t->value, $argv));
break;
*/
default:
throw new RuntimeError('run-time error: unexpected token`' . $t->value . '`');
}
}
// If there is only one value in the stack
// That value is the result of the calculation.
if (count($this->stack) === 1) {
return array_pop($this->stack)->value;
}
// If there are more values in the stack
// (Error) The user input has too many values.
throw new RuntimeError('run-time error: too many values in the stack');
}
