/**
* Main program.
*
* @param array $args Command-line arguments.
* @return integer Zero on success; non-zero on failure.
*/
public static function main($args)
{
printf("Application program number 6. (expression tree)\n");
$status = 0;
$expression = ExpressionTree::parsePostfix(STDIN);
printf("%s\n", str($expression));
return $status;
}
<body>
<!-- jQuery -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<!-- Bootstrap JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<div class="container">
<h1>Result</h1>
<pre>
<?php
include 'autoloader.php';
$expressionString = filter_input(INPUT_POST, 'expression', FILTER_SANITIZE_SPECIAL_CHARS);
if ($expressionString) {
echo "<br>Processando a expressão: '{$expressionString}'<br>";
try {
$calc = new ExpressionTree($expressionString);
echo "<br>Análise prefix: '{$calc->showPreFix()}'";
echo "<br>Análise postfix: '{$calc->showPostFix()}'";
echo "<br>Análise infix: '{$calc->showInFix()}'";
echo "<br><br>Resultado: '{$calc->evaluate()}'";
} catch (Exception $e) {
echo "<br>{$e->getMessage()}";
}
} else {
echo "Expressão inválida";
}
?>
</pre>
<br>
<button class="btn btn-primary" onclick="voltar()">Voltar</button>
</div>
/**
* Parses a postfix expression read from the specified input stream
* and constructs the corresponding expression tree.
* The postfix expression consists of one-letter symbols,
* one-digit numbers, +, -, * and /.
*
* @param resource $in The input stream.
* @return object ExpressionTree An expression tree.
*/
public static function parsePostfix($in)
{
$stack = new StackAsLinkedList();
while (($c = fgetc($in)) != false) {
if (ord('0') <= ord($c) && ord($c) <= ord('9') || ord('a') <= ord($c) && ord($c) <= ord('z') || ord('A') <= ord($c) && ord($c) <= ord('Z')) {
$stack->push(new ExpressionTree($c));
} elseif ($c == '+' || $c == '-' || $c == '*' || $c == '/') {
$result = new ExpressionTree($c);
$result->attachRight($stack->pop());
$result->attachLeft($stack->pop());
$stack->push($result);
}
}
return $stack->pop();
}