mistpark 2.0 infrasturcture lands

1 files changed, 254 insertions, 0 deletions

diff --git a/library/HTMLPurifier/UnitConverter.php b/library/HTMLPurifier/UnitConverter.php
new file mode 100644
index 000000000..545d42622
--- /dev/null
+++ b/library/HTMLPurifier/UnitConverter.php
@@ -0,0 +1,254 @@
+<?php
+
+/**
+ * Class for converting between different unit-lengths as specified by
+ * CSS.
+ */
+class HTMLPurifier_UnitConverter
+{
+
+    const ENGLISH = 1;
+    const METRIC = 2;
+    const DIGITAL = 3;
+
+    /**
+     * Units information array. Units are grouped into measuring systems
+     * (English, Metric), and are assigned an integer representing
+     * the conversion factor between that unit and the smallest unit in
+     * the system. Numeric indexes are actually magical constants that
+     * encode conversion data from one system to the next, with a O(n^2)
+     * constraint on memory (this is generally not a problem, since
+     * the number of measuring systems is small.)
+     */
+    protected static $units = array(
+        self::ENGLISH => array(
+            'px' => 3, // This is as per CSS 2.1 and Firefox. Your mileage may vary
+            'pt' => 4,
+            'pc' => 48,
+            'in' => 288,
+            self::METRIC => array('pt', '0.352777778', 'mm'),
+        ),
+        self::METRIC => array(
+            'mm' => 1,
+            'cm' => 10,
+            self::ENGLISH => array('mm', '2.83464567', 'pt'),
+        ),
+    );
+
+    /**
+     * Minimum bcmath precision for output.
+     */
+    protected $outputPrecision;
+
+    /**
+     * Bcmath precision for internal calculations.
+     */
+    protected $internalPrecision;
+
+    /**
+     * Whether or not BCMath is available
+     */
+    private $bcmath;
+
+    public function __construct($output_precision = 4, $internal_precision = 10, $force_no_bcmath = false) {
+        $this->outputPrecision = $output_precision;
+        $this->internalPrecision = $internal_precision;
+        $this->bcmath = !$force_no_bcmath && function_exists('bcmul');
+    }
+
+    /**
+     * Converts a length object of one unit into another unit.
+     * @param HTMLPurifier_Length $length
+     *      Instance of HTMLPurifier_Length to convert. You must validate()
+     *      it before passing it here!
+     * @param string $to_unit
+     *      Unit to convert to.
+     * @note
+     *      About precision: This conversion function pays very special
+     *      attention to the incoming precision of values and attempts
+     *      to maintain a number of significant figure. Results are
+     *      fairly accurate up to nine digits. Some caveats:
+     *          - If a number is zero-padded as a result of this significant
+     *            figure tracking, the zeroes will be eliminated.
+     *          - If a number contains less than four sigfigs ($outputPrecision)
+     *            and this causes some decimals to be excluded, those
+     *            decimals will be added on.
+     */
+    public function convert($length, $to_unit) {
+
+        if (!$length->isValid()) return false;
+
+        $n    = $length->getN();
+        $unit = $length->getUnit();
+
+        if ($n === '0' || $unit === false) {
+            return new HTMLPurifier_Length('0', false);
+        }
+
+        $state = $dest_state = false;
+        foreach (self::$units as $k => $x) {
+            if (isset($x[$unit])) $state = $k;
+            if (isset($x[$to_unit])) $dest_state = $k;
+        }
+        if (!$state || !$dest_state) return false;
+
+        // Some calculations about the initial precision of the number;
+        // this will be useful when we need to do final rounding.
+        $sigfigs = $this->getSigFigs($n);
+        if ($sigfigs < $this->outputPrecision) $sigfigs = $this->outputPrecision;
+
+        // BCMath's internal precision deals only with decimals. Use
+        // our default if the initial number has no decimals, or increase
+        // it by how ever many decimals, thus, the number of guard digits
+        // will always be greater than or equal to internalPrecision.
+        $log = (int) floor(log(abs($n), 10));
+        $cp = ($log < 0) ? $this->internalPrecision - $log : $this->internalPrecision; // internal precision
+
+        for ($i = 0; $i < 2; $i++) {
+
+            // Determine what unit IN THIS SYSTEM we need to convert to
+            if ($dest_state === $state) {
+                // Simple conversion
+                $dest_unit = $to_unit;
+            } else {
+                // Convert to the smallest unit, pending a system shift
+                $dest_unit = self::$units[$state][$dest_state][0];
+            }
+
+            // Do the conversion if necessary
+            if ($dest_unit !== $unit) {
+                $factor = $this->div(self::$units[$state][$unit], self::$units[$state][$dest_unit], $cp);
+                $n = $this->mul($n, $factor, $cp);
+                $unit = $dest_unit;
+            }
+
+            // Output was zero, so bail out early. Shouldn't ever happen.
+            if ($n === '') {
+                $n = '0';
+                $unit = $to_unit;
+                break;
+            }
+
+            // It was a simple conversion, so bail out
+            if ($dest_state === $state) {
+                break;
+            }
+
+            if ($i !== 0) {
+                // Conversion failed! Apparently, the system we forwarded
+                // to didn't have this unit. This should never happen!
+                return false;
+            }
+
+            // Pre-condition: $i == 0
+
+            // Perform conversion to next system of units
+            $n = $this->mul($n, self::$units[$state][$dest_state][1], $cp);
+            $unit = self::$units[$state][$dest_state][2];
+            $state = $dest_state;
+
+            // One more loop around to convert the unit in the new system.
+
+        }
+
+        // Post-condition: $unit == $to_unit
+        if ($unit !== $to_unit) return false;
+
+        // Useful for debugging:
+        //echo "<pre>n";
+        //echo "$n\nsigfigs = $sigfigs\nnew_log = $new_log\nlog = $log\nrp = $rp\n</pre>\n";
+
+        $n = $this->round($n, $sigfigs);
+        if (strpos($n, '.') !== false) $n = rtrim($n, '0');
+        $n = rtrim($n, '.');
+
+        return new HTMLPurifier_Length($n, $unit);
+    }
+
+    /**
+     * Returns the number of significant figures in a string number.
+     * @param string $n Decimal number
+     * @return int number of sigfigs
+     */
+    public function getSigFigs($n) {
+        $n = ltrim($n, '0+-');
+        $dp = strpos($n, '.'); // decimal position
+        if ($dp === false) {
+            $sigfigs = strlen(rtrim($n, '0'));
+        } else {
+            $sigfigs = strlen(ltrim($n, '0.')); // eliminate extra decimal character
+            if ($dp !== 0) $sigfigs--;
+        }
+        return $sigfigs;
+    }
+
+    /**
+     * Adds two numbers, using arbitrary precision when available.
+     */
+    private function add($s1, $s2, $scale) {
+        if ($this->bcmath) return bcadd($s1, $s2, $scale);
+        else return $this->scale($s1 + $s2, $scale);
+    }
+
+    /**
+     * Multiples two numbers, using arbitrary precision when available.
+     */
+    private function mul($s1, $s2, $scale) {
+        if ($this->bcmath) return bcmul($s1, $s2, $scale);
+        else return $this->scale($s1 * $s2, $scale);
+    }
+
+    /**
+     * Divides two numbers, using arbitrary precision when available.
+     */
+    private function div($s1, $s2, $scale) {
+        if ($this->bcmath) return bcdiv($s1, $s2, $scale);
+        else return $this->scale($s1 / $s2, $scale);
+    }
+
+    /**
+     * Rounds a number according to the number of sigfigs it should have,
+     * using arbitrary precision when available.
+     */
+    private function round($n, $sigfigs) {
+        $new_log = (int) floor(log(abs($n), 10)); // Number of digits left of decimal - 1
+        $rp = $sigfigs - $new_log - 1; // Number of decimal places needed
+        $neg = $n < 0 ? '-' : ''; // Negative sign
+        if ($this->bcmath) {
+            if ($rp >= 0) {
+                $n = bcadd($n, $neg . '0.' .  str_repeat('0', $rp) . '5', $rp + 1);
+                $n = bcdiv($n, '1', $rp);
+            } else {
+                // This algorithm partially depends on the standardized
+                // form of numbers that comes out of bcmath.
+                $n = bcadd($n, $neg . '5' . str_repeat('0', $new_log - $sigfigs), 0);
+                $n = substr($n, 0, $sigfigs + strlen($neg)) . str_repeat('0', $new_log - $sigfigs + 1);
+            }
+            return $n;
+        } else {
+            return $this->scale(round($n, $sigfigs - $new_log - 1), $rp + 1);
+        }
+    }
+
+    /**
+     * Scales a float to $scale digits right of decimal point, like BCMath.
+     */
+    private function scale($r, $scale) {
+        if ($scale < 0) {
+            // The f sprintf type doesn't support negative numbers, so we
+            // need to cludge things manually. First get the string.
+            $r = sprintf('%.0f', (float) $r);
+            // Due to floating point precision loss, $r will more than likely
+            // look something like 4652999999999.9234. We grab one more digit
+            // than we need to precise from $r and then use that to round
+            // appropriately.
+            $precise = (string) round(substr($r, 0, strlen($r) + $scale), -1);
+            // Now we return it, truncating the zero that was rounded off.
+            return substr($precise, 0, -1) . str_repeat('0', -$scale + 1);
+        }
+        return sprintf('%.' . $scale . 'f', (float) $r);
+    }
+
+}
+
+// vim: et sw=4 sts=4