FM / base64

/opt/canhelp/node_modules/@stablelib/base64/

/opt/canhelp/node_modules/@stablelib/base64

Name	Size	Mode	Actions
lib/	-	0755	rm
base64.bench.ts	876	0644	edit dl rm
base64.test.ts	2713	0644	edit dl rm
base64.ts	9715	0644	edit dl rm
LICENSE	1110	0644	edit dl rm
package.json	702	0644	edit dl rm
tsconfig.json	610	0644	edit dl rm

Edit: /opt/canhelp/node_modules/@stablelib/base64/base64.ts (9715B)

// Copyright (C) 2016 Dmitry Chestnykh
// MIT License. See LICENSE file for details.

/**
 * Package base64 implements Base64 encoding and decoding.
 */

// Invalid character used in decoding to indicate
// that the character to decode is out of range of
// alphabet and cannot be decoded.
const INVALID_BYTE = 256;

/**
 * Implements standard Base64 encoding.
 *
 * Operates in constant time.
 */
export class Coder {
    // TODO(dchest): methods to encode chunk-by-chunk.

constructor(private _paddingCharacter = "=") { }

encodedLength(length: number): number {
        if (!this._paddingCharacter) {
            return (length * 8 + 5) / 6 | 0;
        }
        return (length + 2) / 3 * 4 | 0;
    }

encode(data: Uint8Array): string {
        let out = "";

let i = 0;
        for (; i < data.length - 2; i += 3) {
            let c = (data[i] << 16) | (data[i + 1] << 8) | (data[i + 2]);
            out += this._encodeByte((c >>> 3 * 6) & 63);
            out += this._encodeByte((c >>> 2 * 6) & 63);
            out += this._encodeByte((c >>> 1 * 6) & 63);
            out += this._encodeByte((c >>> 0 * 6) & 63);
        }

return out;
    }

maxDecodedLength(length: number): number {
        if (!this._paddingCharacter) {
            return (length * 6 + 7) / 8 | 0;
        }
        return length / 4 * 3 | 0;
    }

decodedLength(s: string): number {
        return this.maxDecodedLength(s.length - this._getPaddingLength(s));
    }

decode(s: string): Uint8Array {
        if (s.length === 0) {
            return new Uint8Array(0);
        }
        const paddingLength = this._getPaddingLength(s);
        const length = s.length - paddingLength;
        const out = new Uint8Array(this.maxDecodedLength(length));
        let op = 0;
        let i = 0;
        let haveBad = 0;
        let v0 = 0, v1 = 0, v2 = 0, v3 = 0;
        for (; i < length - 4; i += 4) {
            v0 = this._decodeChar(s.charCodeAt(i + 0));
            v1 = this._decodeChar(s.charCodeAt(i + 1));
            v2 = this._decodeChar(s.charCodeAt(i + 2));
            v3 = this._decodeChar(s.charCodeAt(i + 3));
            out[op++] = (v0 << 2) | (v1 >>> 4);
            out[op++] = (v1 << 4) | (v2 >>> 2);
            out[op++] = (v2 << 6) | v3;
            haveBad |= v0 & INVALID_BYTE;
            haveBad |= v1 & INVALID_BYTE;
            haveBad |= v2 & INVALID_BYTE;
            haveBad |= v3 & INVALID_BYTE;
        }
        if (i < length - 1) {
            v0 = this._decodeChar(s.charCodeAt(i));
            v1 = this._decodeChar(s.charCodeAt(i + 1));
            out[op++] = (v0 << 2) | (v1 >>> 4);
            haveBad |= v0 & INVALID_BYTE;
            haveBad |= v1 & INVALID_BYTE;
        }
        if (i < length - 2) {
            v2 = this._decodeChar(s.charCodeAt(i + 2));
            out[op++] = (v1 << 4) | (v2 >>> 2);
            haveBad |= v2 & INVALID_BYTE;
        }
        if (i < length - 3) {
            v3 = this._decodeChar(s.charCodeAt(i + 3));
            out[op++] = (v2 << 6) | v3;
            haveBad |= v3 & INVALID_BYTE;
        }
        if (haveBad !== 0) {
            throw new Error("Base64Coder: incorrect characters for decoding");
        }
        return out;
    }

// Standard encoding have the following encoded/decoded ranges,
    // which we need to convert between.
    //
    // ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789  +   /
    // Index:   0 - 25                    26 - 51              52 - 61   62  63
    // ASCII:  65 - 90                    97 - 122             48 - 57   43  47
    //

// Encode 6 bits in b into a new character.
    protected _encodeByte(b: number): string {
        // Encoding uses constant time operations as follows:
        //
        // 1. Define comparison of A with B using (A - B) >>> 8:
        //          if A > B, then result is positive integer
        //          if A <= B, then result is 0
        //
        // 2. Define selection of C or 0 using bitwise AND: X & C:
        //          if X == 0, then result is 0
        //          if X != 0, then result is C
        //
        // 3. Start with the smallest comparison (b >= 0), which is always
        //    true, so set the result to the starting ASCII value (65).
        //
        // 4. Continue comparing b to higher ASCII values, and selecting
        //    zero if comparison isn't true, otherwise selecting a value
        //    to add to result, which:
        //
        //          a) undoes the previous addition
        //          b) provides new value to add
        //
        let result = b;
        // b >= 0
        result += 65;
        // b > 25
        result += ((25 - b) >>> 8) & ((0 - 65) - 26 + 97);
        // b > 51
        result += ((51 - b) >>> 8) & ((26 - 97) - 52 + 48);
        // b > 61
        result += ((61 - b) >>> 8) & ((52 - 48) - 62 + 43);
        // b > 62
        result += ((62 - b) >>> 8) & ((62 - 43) - 63 + 47);

return String.fromCharCode(result);
    }

// Decode a character code into a byte.
    // Must return 256 if character is out of alphabet range.
    protected _decodeChar(c: number): number {
        // Decoding works similar to encoding: using the same comparison
        // function, but now it works on ranges: result is always incremented
        // by value, but this value becomes zero if the range is not
        // satisfied.
        //
        // Decoding starts with invalid value, 256, which is then
        // subtracted when the range is satisfied. If none of the ranges
        // apply, the function returns 256, which is then checked by
        // the caller to throw error.
        let result = INVALID_BYTE; // start with invalid character

// c == 43 (c > 42 and c < 44)
        result += (((42 - c) & (c - 44)) >>> 8) & (-INVALID_BYTE + c - 43 + 62);
        // c == 47 (c > 46 and c < 48)
        result += (((46 - c) & (c - 48)) >>> 8) & (-INVALID_BYTE + c - 47 + 63);
        // c > 47 and c < 58
        result += (((47 - c) & (c - 58)) >>> 8) & (-INVALID_BYTE + c - 48 + 52);
        // c > 64 and c < 91
        result += (((64 - c) & (c - 91)) >>> 8) & (-INVALID_BYTE + c - 65 + 0);
        // c > 96 and c < 123
        result += (((96 - c) & (c - 123)) >>> 8) & (-INVALID_BYTE + c - 97 + 26);

return result;
    }

private _getPaddingLength(s: string): number {
        let paddingLength = 0;
        if (this._paddingCharacter) {
            for (let i = s.length - 1; i >= 0; i--) {
                if (s[i] !== this._paddingCharacter) {
                    break;
                }
                paddingLength++;
            }
            if (s.length < 4 || paddingLength > 2) {
                throw new Error("Base64Coder: incorrect padding");
            }
        }
        return paddingLength;
    }

}

const stdCoder = new Coder();

export function encode(data: Uint8Array): string {
    return stdCoder.encode(data);
}

export function decode(s: string): Uint8Array {
    return stdCoder.decode(s);
}

/**
 * Implements URL-safe Base64 encoding.
 * (Same as Base64, but '+' is replaced with '-', and '/' with '_').
 *
 * Operates in constant time.
 */
export class URLSafeCoder extends Coder {
    // URL-safe encoding have the following encoded/decoded ranges:
    //
    // ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789  -   _
    // Index:   0 - 25                    26 - 51              52 - 61   62  63
    // ASCII:  65 - 90                    97 - 122             48 - 57   45  95
    //

protected _encodeByte(b: number): string {
        let result = b;
        // b >= 0
        result += 65;
        // b > 25
        result += ((25 - b) >>> 8) & ((0 - 65) - 26 + 97);
        // b > 51
        result += ((51 - b) >>> 8) & ((26 - 97) - 52 + 48);
        // b > 61
        result += ((61 - b) >>> 8) & ((52 - 48) - 62 + 45);
        // b > 62
        result += ((62 - b) >>> 8) & ((62 - 45) - 63 + 95);

return String.fromCharCode(result);
    }

protected _decodeChar(c: number): number {
        let result = INVALID_BYTE;

// c == 45 (c > 44 and c < 46)
        result += (((44 - c) & (c - 46)) >>> 8) & (-INVALID_BYTE + c - 45 + 62);
        // c == 95 (c > 94 and c < 96)
        result += (((94 - c) & (c - 96)) >>> 8) & (-INVALID_BYTE + c - 95 + 63);
        // c > 47 and c < 58
        result += (((47 - c) & (c - 58)) >>> 8) & (-INVALID_BYTE + c - 48 + 52);
        // c > 64 and c < 91
        result += (((64 - c) & (c - 91)) >>> 8) & (-INVALID_BYTE + c - 65 + 0);
        // c > 96 and c < 123
        result += (((96 - c) & (c - 123)) >>> 8) & (-INVALID_BYTE + c - 97 + 26);

return result;
    }
}

const urlSafeCoder = new URLSafeCoder();

export function encodeURLSafe(data: Uint8Array): string {
    return urlSafeCoder.encode(data);
}

export function decodeURLSafe(s: string): Uint8Array {
    return urlSafeCoder.decode(s);
}

export const encodedLength = (length: number) =>
    stdCoder.encodedLength(length);

export const maxDecodedLength = (length: number) =>
    stdCoder.maxDecodedLength(length);

export const decodedLength = (s: string) =>
    stdCoder.decodedLength(s);

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