add hw2

node_modules/iconv-lite/encodings/utf7.js

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+"use strict";
+var Buffer = require("safer-buffer").Buffer;
+
+// UTF-7 codec, according to https://tools.ietf.org/html/rfc2152
+// See also below a UTF-7-IMAP codec, according to http://tools.ietf.org/html/rfc3501#section-5.1.3
+
+exports.utf7 = Utf7Codec;
+exports.unicode11utf7 = 'utf7'; // Alias UNICODE-1-1-UTF-7
+function Utf7Codec(codecOptions, iconv) {
+    this.iconv = iconv;
+};
+
+Utf7Codec.prototype.encoder = Utf7Encoder;
+Utf7Codec.prototype.decoder = Utf7Decoder;
+Utf7Codec.prototype.bomAware = true;
+
+
+// -- Encoding
+
+var nonDirectChars = /[^A-Za-z0-9'\(\),-\.\/:\? \n\r\t]+/g;
+
+function Utf7Encoder(options, codec) {
+    this.iconv = codec.iconv;
+}
+
+Utf7Encoder.prototype.write = function(str) {
+    // Naive implementation.
+    // Non-direct chars are encoded as "+<base64>-"; single "+" char is encoded as "+-".
+    return Buffer.from(str.replace(nonDirectChars, function(chunk) {
+        return "+" + (chunk === '+' ? '' : 
+            this.iconv.encode(chunk, 'utf16-be').toString('base64').replace(/=+$/, '')) 
+            + "-";
+    }.bind(this)));
+}
+
+Utf7Encoder.prototype.end = function() {
+}
+
+
+// -- Decoding
+
+function Utf7Decoder(options, codec) {
+    this.iconv = codec.iconv;
+    this.inBase64 = false;
+    this.base64Accum = '';
+}
+
+var base64Regex = /[A-Za-z0-9\/+]/;
+var base64Chars = [];
+for (var i = 0; i < 256; i++)
+    base64Chars[i] = base64Regex.test(String.fromCharCode(i));
+
+var plusChar = '+'.charCodeAt(0), 
+    minusChar = '-'.charCodeAt(0),
+    andChar = '&'.charCodeAt(0);
+
+Utf7Decoder.prototype.write = function(buf) {
+    var res = "", lastI = 0,
+        inBase64 = this.inBase64,
+        base64Accum = this.base64Accum;
+
+    // The decoder is more involved as we must handle chunks in stream.
+
+    for (var i = 0; i < buf.length; i++) {
+        if (!inBase64) { // We're in direct mode.
+            // Write direct chars until '+'
+            if (buf[i] == plusChar) {
+                res += this.iconv.decode(buf.slice(lastI, i), "ascii"); // Write direct chars.
+                lastI = i+1;
+                inBase64 = true;
+            }
+        } else { // We decode base64.
+            if (!base64Chars[buf[i]]) { // Base64 ended.
+                if (i == lastI && buf[i] == minusChar) {// "+-" -> "+"
+                    res += "+";
+                } else {
+                    var b64str = base64Accum + this.iconv.decode(buf.slice(lastI, i), "ascii");
+                    res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
+                }
+
+                if (buf[i] != minusChar) // Minus is absorbed after base64.
+                    i--;
+
+                lastI = i+1;
+                inBase64 = false;
+                base64Accum = '';
+            }
+        }
+    }
+
+    if (!inBase64) {
+        res += this.iconv.decode(buf.slice(lastI), "ascii"); // Write direct chars.
+    } else {
+        var b64str = base64Accum + this.iconv.decode(buf.slice(lastI), "ascii");
+
+        var canBeDecoded = b64str.length - (b64str.length % 8); // Minimal chunk: 2 quads -> 2x3 bytes -> 3 chars.
+        base64Accum = b64str.slice(canBeDecoded); // The rest will be decoded in future.
+        b64str = b64str.slice(0, canBeDecoded);
+
+        res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
+    }
+
+    this.inBase64 = inBase64;
+    this.base64Accum = base64Accum;
+
+    return res;
+}
+
+Utf7Decoder.prototype.end = function() {
+    var res = "";
+    if (this.inBase64 && this.base64Accum.length > 0)
+        res = this.iconv.decode(Buffer.from(this.base64Accum, 'base64'), "utf16-be");
+
+    this.inBase64 = false;
+    this.base64Accum = '';
+    return res;
+}
+
+
+// UTF-7-IMAP codec.
+// RFC3501 Sec. 5.1.3 Modified UTF-7 (http://tools.ietf.org/html/rfc3501#section-5.1.3)
+// Differences:
+//  * Base64 part is started by "&" instead of "+"
+//  * Direct characters are 0x20-0x7E, except "&" (0x26)
+//  * In Base64, "," is used instead of "/"
+//  * Base64 must not be used to represent direct characters.
+//  * No implicit shift back from Base64 (should always end with '-')
+//  * String must end in non-shifted position.
+//  * "-&" while in base64 is not allowed.
+
+
+exports.utf7imap = Utf7IMAPCodec;
+function Utf7IMAPCodec(codecOptions, iconv) {
+    this.iconv = iconv;
+};
+
+Utf7IMAPCodec.prototype.encoder = Utf7IMAPEncoder;
+Utf7IMAPCodec.prototype.decoder = Utf7IMAPDecoder;
+Utf7IMAPCodec.prototype.bomAware = true;
+
+
+// -- Encoding
+
+function Utf7IMAPEncoder(options, codec) {
+    this.iconv = codec.iconv;
+    this.inBase64 = false;
+    this.base64Accum = Buffer.alloc(6);
+    this.base64AccumIdx = 0;
+}
+
+Utf7IMAPEncoder.prototype.write = function(str) {
+    var inBase64 = this.inBase64,
+        base64Accum = this.base64Accum,
+        base64AccumIdx = this.base64AccumIdx,
+        buf = Buffer.alloc(str.length*5 + 10), bufIdx = 0;
+
+    for (var i = 0; i < str.length; i++) {
+        var uChar = str.charCodeAt(i);
+        if (0x20 <= uChar && uChar <= 0x7E) { // Direct character or '&'.
+            if (inBase64) {
+                if (base64AccumIdx > 0) {
+                    bufIdx += buf.write(base64Accum.slice(0, base64AccumIdx).toString('base64').replace(/\//g, ',').replace(/=+$/, ''), bufIdx);
+                    base64AccumIdx = 0;
+                }
+
+                buf[bufIdx++] = minusChar; // Write '-', then go to direct mode.
+                inBase64 = false;
+            }
+
+            if (!inBase64) {
+                buf[bufIdx++] = uChar; // Write direct character
+
+                if (uChar === andChar)  // Ampersand -> '&-'
+                    buf[bufIdx++] = minusChar;
+            }
+
+        } else { // Non-direct character
+            if (!inBase64) {
+                buf[bufIdx++] = andChar; // Write '&', then go to base64 mode.
+                inBase64 = true;
+            }
+            if (inBase64) {
+                base64Accum[base64AccumIdx++] = uChar >> 8;
+                base64Accum[base64AccumIdx++] = uChar & 0xFF;
+
+                if (base64AccumIdx == base64Accum.length) {
+                    bufIdx += buf.write(base64Accum.toString('base64').replace(/\//g, ','), bufIdx);
+                    base64AccumIdx = 0;
+                }
+            }
+        }
+    }
+
+    this.inBase64 = inBase64;
+    this.base64AccumIdx = base64AccumIdx;
+
+    return buf.slice(0, bufIdx);
+}
+
+Utf7IMAPEncoder.prototype.end = function() {
+    var buf = Buffer.alloc(10), bufIdx = 0;
+    if (this.inBase64) {
+        if (this.base64AccumIdx > 0) {
+            bufIdx += buf.write(this.base64Accum.slice(0, this.base64AccumIdx).toString('base64').replace(/\//g, ',').replace(/=+$/, ''), bufIdx);
+            this.base64AccumIdx = 0;
+        }
+
+        buf[bufIdx++] = minusChar; // Write '-', then go to direct mode.
+        this.inBase64 = false;
+    }
+
+    return buf.slice(0, bufIdx);
+}
+
+
+// -- Decoding
+
+function Utf7IMAPDecoder(options, codec) {
+    this.iconv = codec.iconv;
+    this.inBase64 = false;
+    this.base64Accum = '';
+}
+
+var base64IMAPChars = base64Chars.slice();
+base64IMAPChars[','.charCodeAt(0)] = true;
+
+Utf7IMAPDecoder.prototype.write = function(buf) {
+    var res = "", lastI = 0,
+        inBase64 = this.inBase64,
+        base64Accum = this.base64Accum;
+
+    // The decoder is more involved as we must handle chunks in stream.
+    // It is forgiving, closer to standard UTF-7 (for example, '-' is optional at the end).
+
+    for (var i = 0; i < buf.length; i++) {
+        if (!inBase64) { // We're in direct mode.
+            // Write direct chars until '&'
+            if (buf[i] == andChar) {
+                res += this.iconv.decode(buf.slice(lastI, i), "ascii"); // Write direct chars.
+                lastI = i+1;
+                inBase64 = true;
+            }
+        } else { // We decode base64.
+            if (!base64IMAPChars[buf[i]]) { // Base64 ended.
+                if (i == lastI && buf[i] == minusChar) { // "&-" -> "&"
+                    res += "&";
+                } else {
+                    var b64str = base64Accum + this.iconv.decode(buf.slice(lastI, i), "ascii").replace(/,/g, '/');
+                    res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
+                }
+
+                if (buf[i] != minusChar) // Minus may be absorbed after base64.
+                    i--;
+
+                lastI = i+1;
+                inBase64 = false;
+                base64Accum = '';
+            }
+        }
+    }
+
+    if (!inBase64) {
+        res += this.iconv.decode(buf.slice(lastI), "ascii"); // Write direct chars.
+    } else {
+        var b64str = base64Accum + this.iconv.decode(buf.slice(lastI), "ascii").replace(/,/g, '/');
+
+        var canBeDecoded = b64str.length - (b64str.length % 8); // Minimal chunk: 2 quads -> 2x3 bytes -> 3 chars.
+        base64Accum = b64str.slice(canBeDecoded); // The rest will be decoded in future.
+        b64str = b64str.slice(0, canBeDecoded);
+
+        res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
+    }
+
+    this.inBase64 = inBase64;
+    this.base64Accum = base64Accum;
+
+    return res;
+}
+
+Utf7IMAPDecoder.prototype.end = function() {
+    var res = "";
+    if (this.inBase64 && this.base64Accum.length > 0)
+        res = this.iconv.decode(Buffer.from(this.base64Accum, 'base64'), "utf16-be");
+
+    this.inBase64 = false;
+    this.base64Accum = '';
+    return res;
+}
+
+