Services for byte streams and arrays

# Services for byte streams and arrays
module bytes

import kernel
import collection::array
intrude import text::flat

# Any kind of entity which can be searched for in a Sequence of Byte
interface BytePattern
	# Return the first occurence of `self` in `b`, or -1 if not found
	fun first_index_in(b: SequenceRead[Int]): Int do return first_index_in_from(b, 0)

	# Return the first occurence of `self` in `b` starting at `from`, or -1 if not found
	fun first_index_in_from(b: SequenceRead[Int], from: Int): Int is abstract

	# Return the last occurence of `self` in `b`, or -1 if not found
	fun last_index_in(b: SequenceRead[Int]): Int do return last_index_in_from(b, b.length - 1)

	# Return the last occurence of `self` in `b`, or -1 if not found
	fun last_index_in_from(b: SequenceRead[Int], from: Int): Int is abstract

	# Returns the indexes of all the occurences of `self` in `b`
	fun search_all_in(b: SequenceRead[Int]): SequenceRead[Int] is abstract

	# Length of the pattern
	fun pattern_length: Int is abstract

	# Appends `self` to `b`
	fun append_to(b: Sequence[Int]) is abstract

	# Is `self` a prefix for `b` ?
	fun is_prefix(b: SequenceRead[Int]): Bool is abstract

	# Is `self` a suffix for `b` ?
	fun is_suffix(b: SequenceRead[Int]): Bool is abstract
end

redef class Int
	super BytePattern

	# Write self as a string into `ns` at position `pos`
	private fun add_digest_at(ns: CString, pos: Int) do
		var tmp = (0xF0 & self) >> 4
		ns[pos] = if tmp >= 0x0A then tmp + 0x37 else tmp + 0x30
		tmp = 0x0F & self
		ns[pos + 1] = if tmp >= 0x0A then tmp + 0x37 else tmp + 0x30
	end

	# Is `self` a valid hexadecimal digit (in ASCII)
	#
	# ~~~nit
	# intrude import core::bytes
	# assert not u'/'.is_valid_hexdigit
	# assert u'0'.is_valid_hexdigit
	# assert u'9'.is_valid_hexdigit
	# assert not u':'.is_valid_hexdigit
	# assert not u'@'.is_valid_hexdigit
	# assert u'A'.is_valid_hexdigit
	# assert u'F'.is_valid_hexdigit
	# assert not u'G'.is_valid_hexdigit
	# assert not u'`'.is_valid_hexdigit
	# assert u'a'.is_valid_hexdigit
	# assert u'f'.is_valid_hexdigit
	# assert not u'g'.is_valid_hexdigit
	# ~~~
	private fun is_valid_hexdigit: Bool do
		return (self >= 0x30 and self <= 0x39) or
		       (self >= 0x41 and self <= 0x46) or
		       (self >= 0x61 and self <= 0x66)
	end

	# `self` as a hexdigit to its byte value
	#
	# ~~~nit
	# intrude import core::bytes
	# assert 0x39.hexdigit_to_byteval == 0x09
	# assert 0x43.hexdigit_to_byteval == 0x0C
	# ~~~
	#
	# REQUIRE: `self.is_valid_hexdigit`
	private fun hexdigit_to_byteval: Int do
		if self >= 0x30 and self <= 0x39 then
			return self - 0x30
		else if self >= 0x41 and self <= 0x46 then
			return self - 0x37
		else if self >= 0x61 and self <= 0x66 then
			return self - 0x57
		end
		# Happens only if the requirement is not met.
		# i.e. this abort is here to please the compiler
		abort
	end

	redef fun first_index_in_from(b, from) do
		for i in [from .. b.length[ do if b[i] == self then return i
		return -1
	end

	redef fun last_index_in_from(b, from) do
		for i in [0 .. from].step(-1) do if b[i] == self then return i
		return -1
	end

	redef fun search_all_in(b) do
		var ret = new Array[Int]
		var pos = 0
		loop
			pos = first_index_in_from(b, pos)
			if pos == -1 then return ret
			ret.add pos
			pos += 1
		end
	end

	redef fun pattern_length do return 1

	redef fun append_to(b) do b.push self

	#     assert u'b'.is_suffix("baqsdb".to_bytes)
	#     assert not u'b'.is_suffix("baqsd".to_bytes)
	redef fun is_suffix(b) do return b.length != 0 and b.last == self

	#     assert u'b'.is_prefix("baqsdb".to_bytes)
	#     assert not u'b'.is_prefix("aqsdb".to_bytes)
	redef fun is_prefix(b) do return b.length != 0 and b.first == self

	# A signed big-endian representation of `self`
	#
	# ~~~
	# assert     1.to_bytes.hexdigest ==     "01"
	# assert   255.to_bytes.hexdigest ==     "FF"
	# assert   256.to_bytes.hexdigest ==   "0100"
	# assert 65535.to_bytes.hexdigest ==   "FFFF"
	# assert 65536.to_bytes.hexdigest == "010000"
	# ~~~
	#
	# Negative values are converted to their two's complement.
	# Be careful as the result can be ambiguous.
	#
	# ~~~
	# assert     (-1).to_bytes.hexdigest ==     "FF"
	# assert    (-32).to_bytes.hexdigest ==     "E0"
	# assert   (-512).to_bytes.hexdigest ==   "FE00"
	# assert (-65794).to_bytes.hexdigest == "FEFEFE"
	# ~~~
	#
	# Optionally, set `n_bytes` to the desired number of bytes in the output.
	# This setting can disambiguate the result between positive and negative
	# integers. Be careful with this parameter as the result may overflow.
	#
	# ~~~
	# assert        1.to_bytes(2).hexdigest ==     "0001"
	# assert    65535.to_bytes(2).hexdigest ==     "FFFF"
	# assert     (-1).to_bytes(2).hexdigest ==     "FFFF"
	# assert   (-512).to_bytes(4).hexdigest == "FFFFFE00"
	# assert 0x123456.to_bytes(2).hexdigest ==     "3456"
	# ~~~
	#
	# For 0, a Bytes object with single nul byte is returned (instead of an empty Bytes object).
	#
	# ~~~
	# assert 0.to_bytes.hexdigest == "00"
	# ~~~
	#
	# For positive integers, `Bytes::to_i` can reverse the operation.
	#
	# ~~~
	# assert 1234.to_bytes.to_i == 1234
	# ~~~
	#
	# Require self >= 0
	fun to_bytes(n_bytes: nullable Int): Bytes do

		# If 0, force using at least one byte
		if self == 0 and n_bytes == null then n_bytes = 1

		# Compute the len (log256)
		var len = 1
		var max = 256
		var s = self.abs
		while s >= max do
			len += 1
			max *= 256
		end

		# Two's complement
		s = self
		if self < 0 then
			var ff = 0
			for j in [0..len[ do
				ff *= 0x100
				ff += 0xFF
			end

			s = ((-self) ^ ff) + 1
		end

		# Cut long values
		if n_bytes != null and len > n_bytes then len = n_bytes

		# Allocate the buffer
		var cap = n_bytes or else len
		var res = new Bytes.with_capacity(cap)

		var filler = if self < 0 then 0xFF else 0
		for i in [0..cap[ do res[i] = filler

		# Fill it starting with the end
		var i = cap
		var sum = s
		while i > cap - len do
			i -= 1
			res[i] = sum % 256
			sum /= 256
		end

		return res
	end
end

# A buffer containing Byte-manipulation facilities
#
# Uses Copy-On-Write when persisted
class Bytes
	super AbstractArray[Int]
	super BytePattern

	# A CString being a char*, it can be used as underlying representation here.
	var items: CString

	# Number of bytes in the array
	redef var length

	# Capacity of the array
	private var capacity: Int

	# Has this buffer been persisted (to_s'd)?
	#
	# Used for Copy-On-Write
	private var persisted = false

	#     var b = new Bytes.empty
	#     assert b.to_s == ""
	init empty do
		var ns = new CString(0)
		init(ns, 0, 0)
	end

	# Init a `Bytes` with capacity `cap`
	init with_capacity(cap: Int) do
		var ns = new CString(cap)
		init(ns, 0, cap)
	end

	redef fun pattern_length do return length

	redef fun is_empty do return length == 0

	#     var b = new Bytes.empty
	#     b.add 101
	#     assert b[0] == 101
	redef fun [](i) do
		assert i >= 0
		assert i < length
		return items[i]
	end

	# Returns a copy of `self`
	fun clone: Bytes do
		var b = new Bytes.with_capacity(length)
		b.append(self)
		return b
	end

	# Trims off the whitespaces at the beginning and the end of `self`
	#
	#     var b = "102041426E6F1020" .hexdigest_to_bytes
	#     assert b.trim.hexdigest == "41426E6F"
	#
	# NOTE: A whitespace is defined here as a byte whose value is <= 0x20
	fun trim: Bytes do
		var st = 0
		while st < length do
			if self[st] > 0x20 then break
			st += 1
		end
		if st >= length then return new Bytes.empty
		var ed = length - 1
		while ed > 0 do
			if self[ed] > 0x20 then break
			ed -= 1
		end
		return slice(st, ed - st + 1)
	end

	# Copy a subset of `self` starting at `from` and of `count` bytes
	#
	#     var b = "abcd".to_bytes
	#     assert b.slice(1, 2).hexdigest == "6263"
	#     assert b.slice(-1, 2).hexdigest == "61"
	#     assert b.slice(1, 0).hexdigest == ""
	#     assert b.slice(2, 5).hexdigest == "6364"
	fun slice(from, count: Int): Bytes do
		if count <= 0 then return new Bytes.empty

		if from < 0 then
			count += from
			if count < 0 then count = 0
			from = 0
		end

		if (count + from) > length then count = length - from
		if count <= 0 then return new Bytes.empty

		var ret = new Bytes.with_capacity(count)

		ret.append_ns(items.fast_cstring(from), count)
		return ret
	end

	# Copy of `self` starting at `from`
	#
	#     var b = "abcd".to_bytes
	#     assert b.slice_from(1).hexdigest  == "626364"
	#     assert b.slice_from(-1).hexdigest == "61626364"
	#     assert b.slice_from(2).hexdigest  == "6364"
	fun slice_from(from: Int): Bytes do
		if from >= length then return new Bytes.empty
		if from < 0 then from = 0
		return slice(from, length)
	end

	# Reverse the byte array in place
	#
	#     var b = "abcd".to_bytes
	#     b.reverse
	#     assert b.to_s == "dcba"
	fun reverse
	do
		var l = length
		for i in [0..l/2[ do
			var tmp = self[i]
			self[i] = self[l-i-1]
			self[l-i-1] = tmp
		end
	end

	# Returns self as an hexadecimal digest.
	#
	# Also known as plain hexdump or postscript hexdump.
	#
	# ~~~
	# var b = "abcd".to_bytes
	# assert b.hexdigest == "61626364"
	# assert b.hexdigest.hexdigest_to_bytes == b
	# ~~~
	fun hexdigest: String do
		var elen = length * 2
		var ns = new CString(elen)
		var i = 0
		var oi = 0
		while i < length do
			self[i].add_digest_at(ns, oi)
			i += 1
			oi += 2
		end
		return new FlatString.full(ns, elen, 0, elen)
	end

	# Return self as a C hexadecimal digest where bytes are prefixed by `\x`
	#
	# The output is compatible with literal stream of bytes for most languages
	# including C and Nit.
	#
	# ~~~
	# var b = "abcd".to_bytes
	# assert b.chexdigest == "\\x61\\x62\\x63\\x64"
	# assert b.chexdigest.unescape_to_bytes == b
	# ~~~
	fun chexdigest: String do
		var elen = length * 4
		var ns = new CString(elen)
		var i = 0
		var oi = 0
		while i < length do
			ns[oi] = u'\\'
			ns[oi+1] = u'x'
			self[i].add_digest_at(ns, oi+2)
			i += 1
			oi += 4
		end
		return new FlatString.full(ns, elen, 0, elen)
	end


	# Returns self as a stream of bits (0 and 1)
	#
	# ~~~
	# var b = "abcd".to_bytes
	# assert b.binarydigest == "01100001011000100110001101100100"
	# assert b.binarydigest.binarydigest_to_bytes == b
	# ~~~
	fun binarydigest: String do
		var elen = length * 8
		var ns = new CString(elen)
		var i = 0
		var oi = 0
		while i < length do
			var c = self[i]
			var b = 128
			while b > 0 do
				if c & b == 0 then
					ns[oi] = u'0'
				else
					ns[oi] = u'1'
				end
				oi += 1
				b = b >> 1
			end
			i += 1
		end
		return new FlatString.full(ns, elen, 0, elen)
	end

	# Interprets `self` as a big-endian integer (unsigned by default)
	#
	# ~~~
	# var b = "0102".hexdigest_to_bytes
	# assert b.to_i == 258
	#
	# assert   "01".hexdigest_to_bytes.to_i == 1
	# assert   "FF".hexdigest_to_bytes.to_i == 255
	# assert "0000".hexdigest_to_bytes.to_i == 0
	# ~~~
	#
	# If `self.is_empty`, 0 is returned.
	#
	# ~~~
	# assert "".hexdigest_to_bytes.to_i == 0
	# ~~~
	#
	# If `signed == true`, the bytes are read as a signed integer.
	# As usual, the sign bit is the left most bit, no matter the
	# `length` of `self`.
	#
	# ~~~
	# assert     "01".hexdigest_to_bytes.to_i(true) ==      1
	# assert     "FF".hexdigest_to_bytes.to_i(true) ==     -1
	# assert   "00FF".hexdigest_to_bytes.to_i(true) ==    255
	# assert     "E0".hexdigest_to_bytes.to_i(true) ==    -32
	# assert   "FE00".hexdigest_to_bytes.to_i(true) ==   -512
	# assert "FEFEFE".hexdigest_to_bytes.to_i(true) == -65794
	# ~~~
	#
	# `Int::to_bytes` is a loosely reverse method.
	#
	# ~~~
	# assert b.to_i.to_bytes == b
	# assert (b.to_i + 1).to_bytes.hexdigest == "0103"
	# assert "0001".hexdigest_to_bytes.to_i.to_bytes.hexdigest == "01"
	#
	# assert (-32).to_bytes.to_i(true) == -32
	# ~~~
	#
	# Warning: `Int` might overflow for bytes with more than 60 bits.
	fun to_i(signed: nullable Bool): Int do
		var res = 0
		var i = 0
		while i < length do
			res *= 256
			res += self[i].to_i
			i += 1
		end

		# Two's complement is `signed`
		if signed == true and not_empty and first > 0x80 then
			var ff = 0
			for j in [0..length[ do
				ff *= 0x100
				ff += 0xFF
			end

			res = -((res ^ ff) + 1)
		end

		return res
	end

	#     var b = new Bytes.with_capacity(1)
	#     b[0] = 101
	#     assert b.to_s == "e"
	redef fun []=(i, v) do
		if persisted then regen
		assert i >= 0
		assert i <= length
		if i == length then add(v)
		items[i] = v
	end

	#     var b = new Bytes.empty
	#     b.add 101
	#     assert b.to_s == "e"
	redef fun add(c) do
		if persisted then regen
		if length >= capacity then
			enlarge(length)
		end
		items[length] = c
		length += 1
	end

	# Adds the UTF-8 representation of `c` to `self`
	#
	#     var b = new Bytes.empty
	#     b.add_char('A')
	#     b.add_char('キ')
	#     assert b.hexdigest == "41E382AD"
	fun add_char(c: Char) do
		if persisted then regen
		var cln = c.u8char_len
		var ln = length
		enlarge(ln + cln)
		items.set_char_at(length, c)
		length += cln
	end

	redef fun has(c)
	do
		if not c isa Int then return false
		return super(c&255)
	end

	#     var b = new Bytes.empty
	#     b.append([104, 101, 108, 108, 111])
	#     assert b.to_s == "hello"
	redef fun append(arr) do
		if arr isa Bytes then
			append_ns(arr.items, arr.length)
		else
			for i in arr do add i
		end
	end

	#     var b = new Bytes.empty
	#     b.append([0x41, 0x41, 0x18])
	#     b.pop
	#     assert b.to_s == "AA"
	redef fun pop do
		assert length >= 1
		length -= 1
		return items[length]
	end

	redef fun clear do length = 0

	# Regenerates the buffer, necessary when it was persisted
	private fun regen do
		var nns = new CString(capacity)
		items.copy_to(nns, length, 0, 0)
		persisted = false
	end

	# Appends the `ln` first bytes of `ns` to self
	fun append_ns(ns: CString, ln: Int) do
		if persisted then regen
		var nlen = length + ln
		if nlen > capacity then enlarge(nlen)
		ns.copy_to(items, ln, 0, length)
		length += ln
	end

	# Appends `ln` bytes from `ns` starting at index `from` to self
	fun append_ns_from(ns: CString, ln, from: Int) do
		if persisted then regen
		var nlen = length + ln
		if nlen > capacity then enlarge(nlen)
		ns.copy_to(items, ln, from, length)
		length += ln
	end

	# Appends the bytes of `str` to `self`
	fun append_text(str: Text) do str.append_to_bytes self

	redef fun append_to(b) do b.append self

	redef fun enlarge(sz) do
		if capacity >= sz then return
		persisted = false
		if capacity < 16 then capacity = 16
		while capacity < sz do capacity = capacity * 2 + 2
		var ns = new CString(capacity)
		items.copy_to(ns, length, 0, 0)
		items = ns
	end

	redef fun to_s do
		persisted = true
		var b = self
		var r = b.items.to_s_unsafe(length, copy=false)
		if r != items then persisted = false
		return r
	end

	redef fun iterator do return new BytesIterator.with_buffer(self)

	redef fun first_index_in_from(b, from) do
		if is_empty then return -1
		var fst = self[0]
		var bpos = fst.first_index_in_from(self, from)
		for i in [0 .. length[ do
			if self[i] != b[bpos] then return first_index_in_from(b, bpos + 1)
			bpos += 1
		end
		return bpos
	end

	redef fun last_index_in_from(b, from) do
		if is_empty then return -1
		var lst = self[length - 1]
		var bpos = lst.last_index_in_from(b, from)
		for i in [0 .. length[.step(-1) do
			if self[i] != b[bpos] then return last_index_in_from(b, bpos - 1)
			bpos -= 1
		end
		return bpos
	end

	redef fun search_all_in(b) do
		var ret = new Array[Int]
		var pos = first_index_in_from(b, 0)
		if pos == -1 then return ret
		pos = pos + 1
		ret.add pos
		loop
			pos = first_index_in_from(b, pos)
			if pos == -1 then return ret
			ret.add pos
			pos += length
		end
	end

	# Splits the content on self when encountering `b`
	#
	#     var a = "String is string".to_bytes.split_with(u's')
	#     assert a.length == 3
	#     assert a[0].hexdigest == "537472696E672069"
	#     assert a[1].hexdigest == "20"
	#     assert a[2].hexdigest == "7472696E67"
	fun split_with(b: BytePattern): Array[Bytes] do
		var fst = b.search_all_in(self)
		if fst.is_empty then return [clone]
		var retarr = new Array[Bytes]
		var prev = 0
		for i in fst do
			retarr.add(slice(prev, i - prev))
			prev = i + b.pattern_length
		end
		retarr.add slice_from(prev)
		return retarr
	end

	# Splits `self` in two parts at the first occurence of `b`
	#
	#     var a = "String is string".to_bytes.split_once_on(u's')
	#     assert a[0].hexdigest == "537472696E672069"
	#     assert a[1].hexdigest == "20737472696E67"
	fun split_once_on(b: BytePattern): Array[Bytes] do
		var spl = b.first_index_in(self)
		if spl == -1 then return [clone]
		var ret = new Array[Bytes].with_capacity(2)
		ret.add(slice(0, spl))
		ret.add(slice_from(spl + b.pattern_length))
		return ret
	end

	# Replaces all the occurences of `this` in `self` by `by`
	#
	#     var b = "String is string".to_bytes.replace(0x20, 0x41)
	#     assert b.hexdigest == "537472696E6741697341737472696E67"
	fun replace(pattern: BytePattern, bytes: BytePattern): Bytes do
		if is_empty then return new Bytes.empty
		var pos = pattern.search_all_in(self)
		if pos.is_empty then return clone
		var ret = new Bytes.with_capacity(length)
		var prev = 0
		for i in pos do
			ret.append_ns(items.fast_cstring(prev), i - prev)
			bytes.append_to ret
			prev = i + pattern.pattern_length
		end
		ret.append(slice_from(pos.last + pattern.pattern_length))
		return ret
	end

	# Decode `self` from percent (or URL) encoding to a clear string
	#
	# Invalid '%' are not decoded.
	#
	#     assert "aBc09-._~".to_bytes.from_percent_encoding == "aBc09-._~".to_bytes
	#     assert "%25%28%29%3c%20%3e".to_bytes.from_percent_encoding == "%()< >".to_bytes
	#     assert ".com%2fpost%3fe%3dasdf%26f%3d123".to_bytes.from_percent_encoding == ".com/post?e=asdf&f=123".to_bytes
	#     assert "%25%28%29%3C%20%3E".to_bytes.from_percent_encoding == "%()< >".to_bytes
	#     assert "incomplete %".to_bytes.from_percent_encoding == "incomplete %".to_bytes
	#     assert "invalid % usage".to_bytes.from_percent_encoding == "invalid % usage".to_bytes
	#     assert "%c3%a9%e3%81%82%e3%81%84%e3%81%86".to_bytes.from_percent_encoding == "éあいう".to_bytes
	#     assert "%1 %A %C3%A9A9".to_bytes.from_percent_encoding == "%1 %A éA9".to_bytes
	fun from_percent_encoding: Bytes do
		var tmp = new Bytes.with_capacity(length)
		var pos = 0
		while pos < length do
			var b = self[pos]
			if b != u'%' then
				tmp.add b
				pos += 1
				continue
			end
			if length - pos < 2 then
				tmp.add u'%'
				pos += 1
				continue
			end
			var bn = self[pos + 1]
			var bnn = self[pos + 2]
			if not bn.is_valid_hexdigit or not bnn.is_valid_hexdigit then
				tmp.add u'%'
				pos += 1
				continue
			end
			tmp.add((bn.hexdigit_to_byteval << 4) + bnn.hexdigit_to_byteval)
			pos += 3
		end
		return tmp
	end

	# Is `b` a prefix of `self` ?
	fun has_prefix(b: BytePattern): Bool do return b.is_prefix(self)

	# Is `b` a suffix of `self` ?
	fun has_suffix(b: BytePattern): Bool do return b.is_suffix(self)

	redef fun is_suffix(b) do
		if length > b.length then return false
		var j = b.length - 1
		var i = length - 1
		while i > 0 do
			if self[i] != b[j] then return false
			i -= 1
			j -= 1
		end
		return true
	end

	redef fun is_prefix(b) do
		if length > b.length then return false
		for i in [0 .. length[ do if self[i] != b[i] then return false
		return true
	end
end

private class BytesIterator
	super IndexedIterator[Int]

	var tgt: CString

	redef var index

	var max: Int

	init with_buffer(b: Bytes) do init(b.items, 0, b.length)

	redef fun is_ok do return index < max

	redef fun next do index += 1

	redef fun item do return tgt[index]
end

redef class Text
	# Returns a mutable copy of `self`'s bytes
	#
	# ~~~nit
	# assert "String".to_bytes isa Bytes
	# assert "String".to_bytes == [83, 116, 114, 105, 110, 103]
	# ~~~
	fun to_bytes: Bytes do
		var b = new Bytes.with_capacity(byte_length)
		append_to_bytes b
		return b
	end

	# Is `self` a valid hexdigest ?
	#
	#     assert "0B1d3F".is_valid_hexdigest
	#     assert not "5G".is_valid_hexdigest
	fun is_valid_hexdigest: Bool do
		for i in bytes do if not i.is_valid_hexdigit then return false
		return true
	end

	# Appends `self.bytes` to `b`
	fun append_to_bytes(b: Bytes) do
		for s in substrings do
			var from = if s isa FlatString then s.first_byte else 0
			b.append_ns_from(s.items, s.byte_length, from)
		end
	end

	# Returns a new `Bytes` instance with the digest as content
	#
	#     assert "0B1F4D".hexdigest_to_bytes == [0x0B, 0x1F, 0x4D]
	#     assert "0B1F4D".hexdigest_to_bytes.hexdigest == "0B1F4D"
	#
	# Characters that are not hexadecimal digits are ignored.
	#
	#     assert "z0B1 F4\nD".hexdigest_to_bytes.hexdigest == "0B1F4D"
	#     assert "\\x0b1 \\xf4d".hexdigest_to_bytes.hexdigest == "0B1F4D"
	#
	# When the number of hexadecimal digit is not even, then a leading 0 is
	# implicitly considered to fill the left byte (the most significant one).
	#
	#     assert "1".hexdigest_to_bytes.hexdigest == "01"
	#     assert "FFF".hexdigest_to_bytes.hexdigest == "0FFF"
	#
	# `Bytes::hexdigest` is a loosely reverse method since its
	# results contain only pairs of uppercase hexadecimal digits.
	#
	#     assert "ABCD".hexdigest_to_bytes.hexdigest == "ABCD"
	#     assert "a b c".hexdigest_to_bytes.hexdigest == "0ABC"
	fun hexdigest_to_bytes: Bytes do
		var b = bytes
		var max = byte_length

		var dlength = 0 # Number of hex digits
		var pos = 0
		while pos < max do
			var c = b[pos]
			if c.is_valid_hexdigit then dlength += 1
			pos += 1
		end

		# Allocate the result buffer
		var ret = new Bytes.with_capacity((dlength+1) / 2)

		var i = (dlength+1) % 2 # current hex digit (1=high, 0=low)
		var byte = 0 # current accumulated byte value

		pos = 0
		while pos < max do
			var c = b[pos]
			if c.is_valid_hexdigit then
				byte = byte << 4 | c.hexdigit_to_byteval
				i -= 1
				if i < 0 then
					# Last digit known: store and restart
					ret.add byte
					i = 1
					byte = 0
				end
			end
			pos += 1
		end
		return ret
	end

	# Gets the hexdigest of the bytes of `self`
	#
	#     assert "&lt;STRING&#47;&rt;".hexdigest == "266C743B535452494E47262334373B2672743B"
	fun hexdigest: String do
		var ln = byte_length
		var outns = new CString(ln * 2)
		var oi = 0
		for i in [0 .. ln[ do
			bytes[i].add_digest_at(outns, oi)
			oi += 2
		end
		return new FlatString.with_infos(outns, ln * 2, 0)
	end

	# Return a `Bytes` instance where Nit escape sequences are transformed.
	#
	#     assert "B\\n\\x41\\u0103D3".unescape_to_bytes.hexdigest == "420A41F0908F93"
	#
	# `Bytes::chexdigest` is a loosely reverse methods since its result is only made
	# of `"\x??"` escape sequences.
	#
	#     assert "\\x41\\x42\\x43".unescape_to_bytes.chexdigest == "\\x41\\x42\\x43"
	#     assert "B\\n\\x41\\u0103D3".unescape_to_bytes.chexdigest == "\\x42\\x0A\\x41\\xF0\\x90\\x8F\\x93"
	fun unescape_to_bytes: Bytes do
		var res = new Bytes.with_capacity(self.byte_length)
		var was_slash = false
		var i = 0
		while i < length do
			var c = self[i]
			if not was_slash then
				if c == '\\' then
					was_slash = true
				else
					res.add_char(c)
				end
				i += 1
				continue
			end
			was_slash = false
			if c == 'n' then
				res.add_char('\n')
			else if c == 'r' then
				res.add_char('\r')
			else if c == 't' then
				res.add_char('\t')
			else if c == '0' then
				res.add_char('\0')
			else if c == 'x' or c == 'X' then
				var hx = substring(i + 1, 2)
				if hx.is_hex then
					res.add hx.to_hex
				else
					res.add_char(c)
				end
				i += 2
			else if c == 'u' or c == 'U' then
				var hx = substring(i + 1, 6)
				if hx.is_hex then
					res.add_char(hx.to_hex.code_point)
				else
					res.add_char(c)
				end
				i += 6
			else
				res.add_char(c)
			end
			i += 1
		end
		return res
	end

	# Return a `Bytes` by reading 0 and 1.
	#
	#     assert "1010101100001101".binarydigest_to_bytes.hexdigest == "AB0D"
	#
	# Note that characters that are neither 0 or 1 are just ignored.
	#
	#     assert "a1B01 010\n1100あ001101".binarydigest_to_bytes.hexdigest == "AB0D"
	#     assert "hello".binarydigest_to_bytes.is_empty
	#
	# When the number of bits is not divisible by 8, then leading 0 are
	# implicitly considered to fill the left byte (the most significant one).
	#
	#     assert "1".binarydigest_to_bytes.hexdigest == "01"
	#     assert "1111111".binarydigest_to_bytes.hexdigest == "7F"
	#     assert "1000110100".binarydigest_to_bytes.hexdigest == "0234"
	#
	# `Bytes::binarydigest` is a loosely reverse method since its
	# results contain only 1 and 0 by blocks of 8.
	#
	#     assert "1010101100001101".binarydigest_to_bytes.binarydigest == "1010101100001101"
	#     assert "1".binarydigest_to_bytes.binarydigest == "00000001"
	fun binarydigest_to_bytes: Bytes
	do
		var b = bytes
		var max = byte_length

		# Count bits
		var bitlen = 0
		var pos = 0
		while pos < max do
			var c = b[pos]
			pos += 1
			if c == u'0' or c == u'1' then bitlen += 1
		end

		# Allocate (and take care of the padding)
		var ret = new Bytes.with_capacity((bitlen+7) / 8)

		var i = (bitlen+7) % 8 # current bit (7th=128, 0th=1)
		var byte = 0 # current accumulated byte value

		pos = 0
		while pos < max do
			var c = b[pos]
			pos += 1
			if c == u'0' then
				byte = byte << 1
			else if c == u'1' then
				byte = byte << 1 | 1
			else
				continue
			end

			i -= 1
			if i < 0 then
				# Last bit known: store and restart
				ret.add byte
				i = 7
				byte = 0
			end
		end
		return ret
	end
end

redef class FlatText
	redef fun append_to_bytes(b) do
		var from = if self isa FlatString then first_byte else 0
		if isset _items then b.append_ns_from(items, byte_length, from)
	end
end

redef class CString
	# Creates a new `Bytes` object from `self` with `len` as length
	#
	# If `len` is null, strlen will determine the length of the Bytes
	fun to_bytes(len: nullable Int): Bytes do
		if len == null then len = cstring_length
		return new Bytes(self, len, len)
	end

	# Creates a new `Bytes` object from a copy of `self` with `len` as length
	#
	# If `len` is null, strlen will determine the length of the Bytes
	fun to_bytes_with_copy(len: nullable Int): Bytes do
		if len == null then len = cstring_length
		var nns = new CString(len)
		copy_to(nns, len, 0, 0)
		return new Bytes(nns, len, len)
	end
end

# Joins an array of bytes `arr` separated by `sep`
#
#     assert join_bytes(["String".to_bytes, "is".to_bytes, "string".to_bytes], u' ').hexdigest == "537472696E6720697320737472696E67"
fun join_bytes(arr: Array[Bytes], sep: nullable BytePattern): Bytes do
	if arr.is_empty then return new Bytes.empty
	sep = sep or else new Bytes.empty
	var endln = sep.pattern_length * (arr.length - 1)
	for i in arr do endln += i.length
	var ret = new Bytes.with_capacity(endln)
	ret.append(arr.first)
	for i in  [1 .. arr.length[ do
		sep.append_to(ret)
		ret.append arr[i]
	end
	return ret
end

lib/core/bytes.nit:15,1--1057,3

module bytes

Summary

Services for byte streams and arrays

Introduced classes

BytePattern

Bytes

BytesIterator

Redefined classes

CString

FlatText

Int

Sys

Text

Services for byte streams and arrays

Introduced classes

interface BytePattern

class Bytes

private class BytesIterator

Redefined classes

redef extern class CString

redef abstract class FlatText

redef enum Int

redef class Sys

redef abstract class Text

Summary

All class definitions

BytePattern

Bytes

BytesIterator

CString

FlatText

Int

Sys

Text

All class definitions

interface BytePattern

class Bytes

private class BytesIterator

redef extern class CString

redef abstract class FlatText

redef enum Int

redef class Sys

redef abstract class Text

Summary

Ancestors

abstract_collection

abstract_text

array

circular_array

collection

fixed_ints

hash_collection

kernel

list

math

native

range

sorter

union_find

Parents

flat

Children

codec_base

Descendants

a_star

a_star-m

abstract_compiler

abstract_tree

activities

actors

actors_generation_phase

actors_injection_phase

agent_simulation

ai

all

android

android

android19

android_annotations

angles