/**
* Converts the current expression into a single matcher, applying
* coordination operators to operands according to their binding rules
*
* @throws \RuntimeException
* @return \Hamcrest_Matcher
*/
public function build()
{
// Apply Shunting Yard algorithm to convert the infix expression
// into Reverse Polish Notation. Since we have a very limited
// set of operators and binding rules, the implementation becomes
// really simple
$ops = new \SplStack();
$rpn = array();
foreach ($this->parts as $token) {
if ($token instanceof Operator) {
while (!$ops->isEmpty() && $token->compare($ops->top()) <= 0) {
$rpn[] = $ops->pop();
}
$ops->push($token);
} else {
$rpn[] = $token;
}
}
// Append the remaining operators
while (!$ops->isEmpty()) {
$rpn[] = $ops->pop();
}
// Walk the RPN expression to create AnyOf and AllOf matchers
$stack = new \splStack();
foreach ($rpn as $token) {
if ($token instanceof Operator) {
// Our operators always need two operands
if ($stack->count() < 2) {
throw new \RuntimeException('Unable to build a valid expression. Not enough operands available.');
}
$operands = array($stack->pop(), $stack->pop());
// Check what kind of matcher we need to create
if ($token->getKeyword() === 'OR') {
$matcher = new \Hamcrest_Core_AnyOf($operands);
} else {
// AND, BUT
$matcher = new \Hamcrest_Core_AllOf($operands);
}
$stack->push($matcher);
} else {
$stack[] = $token;
}
}
if ($stack->count() !== 1) {
throw new \RuntimeException('Unable to build a valid expression. The RPN stack should have just one item.');
}
return $stack->pop();
}
<?php
namespace struct;
//数据结构
//栈
$stack = new \splStack();
$stack->push('one');
//入栈
$stack->push('two');
echo $stack->pop();
//出栈
echo $stack->pop();
//队列
$queue = new \splQueue();
$queue->enqueue('three');
//入队
$queue->enqueue('four');
echo $queue->dequeue();
//出队
echo $queue->dequeue();
//(最小)堆
$heap = new \splMinHeap();
$heap->insert('five');
$heap->insert('six');
echo $heap->extract();
echo $heap->extract();
//固定尺寸的数组
$sarr = new \splFixedArray(10);
$sarr[0] = 'a';
$sarr[8] = 'c';
