165 lines
4.4 KiB
PHP
165 lines
4.4 KiB
PHP
<?php
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include_once("oracles/base.php");
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class calculator extends oracle {
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public $info = [
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"name" => "calculator"
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];
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public function check_query($q) {
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// straight numerics should go to that oracle
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if (is_numeric($q)) {
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return false;
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}
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// all chars should be number-y or operator-y
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$char_whitelist = str_split("1234567890.+-/*^%() ");
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foreach (str_split($q) as $char) {
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if (!in_array($char, $char_whitelist)) {
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return false;
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}
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}
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return true;
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}
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// a custom parser and calculator because FUCK YUO, libraries are
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// gay.
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public function generate_response($q)
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{
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$nums = str_split("1234567890.");
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$ops = str_split("+-/*^%;");
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$grouping = str_split("()");
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$q = str_replace(" ", "", $q);
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// backstop for the parser so it catches the last
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// numeric token
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$q .= ";";
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// the following comments refer to this example input:
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// 21+9*(3+2^9)+1
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// 2-length lists of the following patterns:
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// ["n" (umeric), <some number>]
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// ["o" (perator), "<some operator>"]
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// ["g" (roup explicit), <"(" or ")">]
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// e.g. [["n", 21], ["o", "+"], ["n", 9], ["o", *],
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// ["g", "("], ["n", 3], ["o", "+"], ["n", 2],
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// ["o", "^"], ["n", 9], ["g", ")"], ["o", "+"],
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// ["n", "1"]]
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$tokens = array();
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$dragline = 0;
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foreach(str_split($q) as $i=>$char) {
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if (in_array($char, $nums)) {
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continue;
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}
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elseif (in_array($char, $ops) || in_array($char, $grouping)) {
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// hitting a non-numeric implies everything since the
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// last hit has been part of a number
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$capture = substr($q, $dragline, $i - $dragline);
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// prevent the int cast from creating imaginary
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// ["n", 0] tokens
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if ($capture != "") {
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if (substr_count($capture, ".") > 1) {
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return "";
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}
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array_push($tokens, ["n", (float)$capture]);
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}
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// reset to one past the current (non-numeric) char
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$dragline = $i + 1;
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// the `;' backstop is not a real token and this should
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// never be present in the token list
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if ($char != ";") {
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array_push($tokens, [
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($char == "(" || $char == ")") ? "g" : "o",
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$char
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]);
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}
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}
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else {
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return "";
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}
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}
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// two operators back to back should fail
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for ($i = 1; $i < count($tokens); $i++) {
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if ($tokens[$i][0] == "o" && $tokens[$i-1][0] == "o") {
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return "";
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}
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}
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// no implicit multiplication
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for ($i = 0; $i < count($tokens) - 1; $i++) {
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if ($tokens[$i][0] == "n" && $tokens[$i+1] == ["g", "("]) {
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return "";
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}
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}
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//strategy:
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// traverse to group open (if there is one)
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// - return to start with the internals
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// traverse to ^, attack token previous and after
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// same but for *, then / then + then -
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// poppers all teh way down
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try {
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return [
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substr($q, 0, strlen($q)-1)." = " => $this->executeBlock($tokens)[0][1]
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];
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}
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catch (\Throwable $e) {
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if (get_class($e) == "DivisionByZeroError") {
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return [
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$q." = " => "Division by Zero Error!!"
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];
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}
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return "";
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}
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}
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public function executeBlock($tokens) {
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if (count($tokens) >= 2 && $tokens[0][0] == "o" && $tokens[0][1] == "-" && $tokens[1][0] == "n") {
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array_splice($tokens, 0, 2, [["n", -1 * (float)$tokens[1][1]]]);
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}
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if (count($tokens) > 0 && $tokens[0][0] == "o" || $tokens[count($tokens)-1][0] == "o") {
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throw new Exception("Error Processing Request", 1);
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}
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while (in_array(["g", "("], $tokens)) {
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$first_open = array_search(["g", "("], $tokens);
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$enclosedality = 1;
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for ($i = $first_open+1; $i < count($tokens); $i++) {
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if ($tokens[$i][0] == "g") {
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$enclosedality += ($tokens[$i][1] == "(") ? 1 : -1;
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}
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if ($enclosedality == 0) {
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array_splice($tokens,
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$first_open,
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$i+1 - $first_open,
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$this->executeBlock(
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array_slice($tokens, $first_open+1, $i-1 - $first_open)
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)
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);
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break;
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}
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}
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}
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$operators_in_pemdas_order = [
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"^" => (fn($x, $y) => $x ** $y),
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"*" => (fn($x, $y) => $x * $y),
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"/" => (fn($x, $y) => $x / $y),
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"%" => (fn($x, $y) => $x % $y),
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"+" => (fn($x, $y) => $x + $y),
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"-" => (fn($x, $y) => $x - $y)
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];
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foreach ($operators_in_pemdas_order as $op=>$func) {
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while (in_array(["o", $op], $tokens)) {
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for ($i = 0; $i < count($tokens); $i++) {
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if ($tokens[$i] == ["o", $op]) {
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array_splice(
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$tokens,
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$i-1,
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3,
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[["n", (string)($func((float)$tokens[$i-1][1], (float)$tokens[$i+1][1]))]]
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);
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}
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}
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}
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}
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return $tokens;
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}
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}
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?>
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