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std.base64

Encoding / Decoding Base64 format.

Implemented according to RFC 4648 - The Base16.

Example:
ubyte[] data = [0x14, 0xfb, 0x9c, 0x03, 0xd9, 0x7e];

const(char)[] encoded = Base64.encode(data);
assert(encoded == "FPucA9l+");

ubyte[] decoded = Base64.decode("FPucA9l+");
assert(decoded == [0x14, 0xfb, 0x9c, 0x03, 0xd9, 0x7e]);

Support Range interface using Encoder / Decoder.

Example:
// Create MIME Base64 with CRLF, per line 76.
File f = File("./text.txt", "r");
scope(exit) f.close();

Appender!string mime64 = appender!string;

foreach (encoded; Base64.encoder(f.byChunk(57)))
{
    mime64.put(encoded);
    mime64.put("\r\n");
}

writeln(mime64.data);

License:
Boost License 1.0.

Authors:
Masahiro Nakagawa, Daniel Murphy (Single value Encoder and Decoder)

Source:
std/base64.d

alias Base64 = Base64Impl!('+', '/');
The Base64

alias Base64URL = Base64Impl!('-', '_');
The "URL and Filename safe" Base64

template Base64Impl(char Map62th, char Map63th, char Padding = '=')
Core implementation for Base64 format.

Example:
alias Base64Impl!('+', '/')                   Base64;    // The Base64 format(Already defined).
alias Base64Impl!('!', '=', Base64.NoPadding) Base64Re;  // non-standard Base64 format for Regular expression

NOTE:
encoded-string doesn't have padding character if set Padding parameter to NoPadding.

size_t encodeLength(in size_t sourceLength);
Calculates the minimum length for encoding.

Parameters:
size_t sourceLength the length of source array.

Returns:
the calculated length using sourceLength.

char[] encode(R1, R2)(in R1 source, R2 buffer) if (isArray!R1 && is(ElementType!R1 : ubyte) && is(R2 == char[]));
char[] encode(R1, R2)(R1 source, R2 buffer) if (!isArray!R1 && isInputRange!R1 && is(ElementType!R1 : ubyte) && hasLength!R1 && is(R2 == char[]));
Encodes source into buffer.

Parameters:
R1 source an InputRange to encode.
R2 buffer a buffer to store encoded result.

Returns:
the encoded string that slices buffer.

size_t encode(R1, R2)(in R1 source, R2 range) if (isArray!R1 && is(ElementType!R1 : ubyte) && !is(R2 == char[]));
size_t encode(R1, R2)(R1 source, R2 range) if (!isArray!R1 && isInputRange!R1 && is(ElementType!R1 : ubyte) && hasLength!R1 && !is(R2 == char[]) && isOutputRange!(R2, char));
Encodes source into range.

Parameters:
R1 source an InputRange to encode.
R2 range an OutputRange to put encoded result.

Returns:
the number of calling put.

char[] encode(Range)(Range source) if (isArray!Range && is(ElementType!Range : ubyte));
char[] encode(Range)(Range source) if (!isArray!Range && isInputRange!Range && is(ElementType!Range : ubyte) && hasLength!Range);
Encodes source to new buffer.

Shortcut to encode(source, buffer) function.

struct Encoder(Range) if (isInputRange!Range && (is(ElementType!Range : const(ubyte)[]) || is(ElementType!Range : const(char)[])));
Range that encodes chunk data at a time.

bool empty();
Range primitive operation that checks iteration state.

Returns:
true if there are no more elements to be iterated.

char[] front();
Range primitive operation that returns the currently iterated element.

Returns:
the encoded string.

void popFront();
Range primitive operation that advances the range to its next element.

Throws:
an Exception when you try to call popFront on empty range.

typeof(this) save();
Captures a Range state.

Returns:
a copy of this.

struct Encoder(Range) if (isInputRange!Range && is(ElementType!Range : ubyte));
Range that encodes single character at a time.

const bool empty();
Range primitive operation that checks iteration state.

Returns:
true if there are no more elements to be iterated.

ubyte front();
Range primitive operation that returns the currently iterated element.

Returns:
the encoded character.

void popFront();
Range primitive operation that advances the range to its next element.

Throws:
an Exception when you try to call popFront on empty range.

typeof(this) save();
Captures a Range state.

Returns:
a copy of this.

Encoder!Range encoder(Range)(Range range) if (isInputRange!Range);
Iterates through an InputRange at a time by using Encoder.

Default Encoder encodes chunk data.

Example:
File f = File("text.txt", "r");
scope(exit) f.close();

uint line = 0;
foreach (encoded; Base64.encoder(f.byLine()))
{
    writeln(++line, ". ", encoded);
}

In addition, You can use Encoder that returns encoded single character. This Encoder performs Range-based and lazy encoding.

Example:
ubyte[] data = cast(ubyte[]) "0123456789";

// The ElementType of data is not aggregation type
foreach (encoded; Base64.encoder(data))
{
    writeln(encoded);
}

Parameters:
Range range an InputRange to iterate.

Returns:
a Encoder object instantiated and initialized according to the arguments.

size_t decodeLength(in size_t sourceLength);
Calculates the minimum length for decoding.

Parameters:
size_t sourceLength the length of source array.

Returns:
calculated length using sourceLength.

ubyte[] decode(R1, R2)(in R1 source, R2 buffer) if (isArray!R1 && is(ElementType!R1 : dchar) && is(R2 == ubyte[]) && isOutputRange!(R2, ubyte));
ubyte[] decode(R1, R2)(R1 source, R2 buffer) if (!isArray!R1 && isInputRange!R1 && is(ElementType!R1 : dchar) && hasLength!R1 && is(R2 == ubyte[]) && isOutputRange!(R2, ubyte));
Decodes source into buffer.

Parameters:
R1 source an InputRange to decode.
R2 buffer a buffer to store decoded result.

Returns:
the decoded string that slices buffer.

Throws:
an Exception if source has character outside base-alphabet.

size_t decode(R1, R2)(in R1 source, R2 range) if (isArray!R1 && is(ElementType!R1 : dchar) && !is(R2 == ubyte[]) && isOutputRange!(R2, ubyte));
size_t decode(R1, R2)(R1 source, R2 range) if (!isArray!R1 && isInputRange!R1 && is(ElementType!R1 : dchar) && hasLength!R1 && !is(R2 == ubyte[]) && isOutputRange!(R2, ubyte));
Decodes source into range.

Parameters:
R1 source an InputRange to decode.
R2 range an OutputRange to put decoded result

Returns:
the number of calling put.

Throws:
an Exception if source has character outside base-alphabet.

ubyte[] decode(Range)(Range source) if (isArray!Range && is(ElementType!Range : dchar));
ubyte[] decode(Range)(Range source) if (!isArray!Range && isInputRange!Range && is(ElementType!Range : dchar) && hasLength!Range);
Decodes source into new buffer.

Shortcut to decode(source, buffer) function.

struct Decoder(Range) if (isInputRange!Range && (is(ElementType!Range : const(char)[]) || is(ElementType!Range : const(ubyte)[])));
Range that decodes chunk data at a time.

bool empty();
Range primitive operation that checks iteration state.

Returns:
true if there are no more elements to be iterated.

ubyte[] front();
Range primitive operation that returns the currently iterated element.

Returns:
the decoded result.

void popFront();
Range primitive operation that advances the range to its next element.

Throws:
an Exception when you try to call popFront on empty range.

typeof(this) save();
Captures a Range state.

Returns:
a copy of this.

struct Decoder(Range) if (isInputRange!Range && is(ElementType!Range : char));
Range that decodes single character at a time.

const bool empty();
Range primitive operation that checks iteration state.

Returns:
true if there are no more elements to be iterated.

ubyte front();
Range primitive operation that returns the currently iterated element.

Returns:
the decoded result.

void popFront();
Range primitive operation that advances the range to its next element.

Throws:
an Exception when you try to call popFront on empty range.

typeof(this) save();
Captures a Range state.

Returns:
a copy of this.

Decoder!Range decoder(Range)(Range range) if (isInputRange!Range);
Iterates through an InputRange at a time by using Decoder.

Default Decoder decodes chunk data.

Example:
foreach (decoded; Base64.decoder(stdin.byLine()))
{
    writeln(decoded);
}

In addition, You can use Decoder that returns decoded single character. This Decoder performs Range-based and lazy decoding.

Example:
auto encoded = Base64.encoder(cast(ubyte[])"0123456789");
foreach (n; map!q{a - '0'}(Base64.decoder(encoded)))
{
    writeln(n);
}

NOTE:
If you use ByChunk, chunk-size should be the multiple of 4. Decoder can't judge a encode-boundary.

Parameters:
Range range an InputRange to iterate.

Returns:
a Decoder object instantiated and initialized according to the arguments.

class Base64Exception: object.Exception;
Exception thrown on Base64 errors.