N°2226: Add missing files for Scss v1.0.0

lib/scssphp/src/SourceMap/Base64VLQ.php

@@ -0,0 +1,137 @@
+<?php
+/**
+ * SCSSPHP
+ *
+ * @copyright 2012-2019 Leaf Corcoran
+ *
+ * @license http://opensource.org/licenses/MIT MIT
+ *
+ * @link http://scssphp.github.io/scssphp
+ */
+
+namespace ScssPhp\ScssPhp\SourceMap;
+
+use ScssPhp\ScssPhp\SourceMap\Base64;
+
+/**
+ * Base 64 VLQ
+ *
+ * Based on the Base 64 VLQ implementation in Closure Compiler:
+ * https://github.com/google/closure-compiler/blob/master/src/com/google/debugging/sourcemap/Base64VLQ.java
+ *
+ * Copyright 2011 The Closure Compiler Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @author John Lenz <johnlenz@google.com>
+ * @author Anthon Pang <anthon.pang@gmail.com>
+ */
+class Base64VLQ
+{
+    // A Base64 VLQ digit can represent 5 bits, so it is base-32.
+    const VLQ_BASE_SHIFT = 5;
+
+    // A mask of bits for a VLQ digit (11111), 31 decimal.
+    const VLQ_BASE_MASK = 31;
+
+    // The continuation bit is the 6th bit.
+    const VLQ_CONTINUATION_BIT = 32;
+
+    /**
+     * Returns the VLQ encoded value.
+     *
+     * @param integer $value
+     *
+     * @return string
+     */
+    public static function encode($value)
+    {
+        $encoded = '';
+        $vlq = self::toVLQSigned($value);
+
+        do {
+            $digit = $vlq & self::VLQ_BASE_MASK;
+            $vlq >>= self::VLQ_BASE_SHIFT;
+
+            if ($vlq > 0) {
+                $digit |= self::VLQ_CONTINUATION_BIT;
+            }
+
+            $encoded .= Base64::encode($digit);
+        } while ($vlq > 0);
+
+        return $encoded;
+    }
+
+    /**
+     * Decodes VLQValue.
+     *
+     * @param string $str
+     * @param integer $index
+     *
+     * @return integer
+     */
+    public static function decode($str, &$index)
+    {
+        $result = 0;
+        $shift = 0;
+
+        do {
+            $c = $str[$index++];
+            $digit = Base64::decode($c);
+            $continuation = ($digit & self::VLQ_CONTINUATION_BIT) != 0;
+            $digit &= self::VLQ_BASE_MASK;
+            $result = $result + ($digit << $shift);
+            $shift = $shift + self::VLQ_BASE_SHIFT;
+        } while ($continuation);
+
+        return self::fromVLQSigned($result);
+    }
+
+    /**
+     * Converts from a two-complement value to a value where the sign bit is
+     * is placed in the least significant bit.  For example, as decimals:
+     *   1 becomes 2 (10 binary), -1 becomes 3 (11 binary)
+     *   2 becomes 4 (100 binary), -2 becomes 5 (101 binary)
+     *
+     * @param integer $value
+     *
+     * @return integer
+     */
+    private static function toVLQSigned($value)
+    {
+        if ($value < 0) {
+            return ((-$value) << 1) + 1;
+        }
+
+        return ($value << 1) + 0;
+    }
+
+    /**
+     * Converts to a two-complement value from a value where the sign bit is
+     * is placed in the least significant bit.  For example, as decimals:
+     *   2 (10 binary) becomes 1, 3 (11 binary) becomes -1
+     *   4 (100 binary) becomes 2, 5 (101 binary) becomes -2
+     *
+     * @param integer $value
+     *
+     * @return integer
+     */
+    private static function fromVLQSigned($value)
+    {
+        $negate = ($value & 1) === 1;
+        $value = $value >> 1;
+
+        return $negate ? -$value : $value;
+    }
+}