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Small base64.nim refactor (#5755)

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* Small changes (var to let)

* Some additional `var` to `let`

* Fix

* Finally removed immediate
This commit is contained in:
Daniil Yarancev
2017-04-25 21:47:26 +03:00
committed by Dominik Picheta
parent c6a8bd264e
commit 6ac37ee2fb
1 changed files with 23 additions and 18 deletions
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41
lib/pure/base64.nim
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@@ -44,21 +44,23 @@
const
cb64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
template encodeInternal(s: expr, lineLen: int, newLine: string): stmt {.immediate.} =
template encodeInternal(s: typed, lineLen: int, newLine: string): untyped =
## encodes `s` into base64 representation. After `lineLen` characters, a
## `newline` is added.
var total = ((len(s) + 2) div 3) * 4
var numLines = (total + lineLen - 1) div lineLen
let numLines = (total + lineLen - 1) div lineLen
if numLines > 0: inc(total, (numLines - 1) * newLine.len)
result = newString(total)
var i = 0
var r = 0
var currLine = 0
var
i = 0
r = 0
currLine = 0
while i < s.len - 2:
var a = ord(s[i])
var b = ord(s[i+1])
var c = ord(s[i+2])
let
a = ord(s[i])
b = ord(s[i+1])
c = ord(s[i+2])
result[r] = cb64[a shr 2]
result[r+1] = cb64[((a and 3) shl 4) or ((b and 0xF0) shr 4)]
result[r+2] = cb64[((b and 0x0F) shl 2) or ((c and 0xC0) shr 6)]
@@ -74,8 +76,9 @@ template encodeInternal(s: expr, lineLen: int, newLine: string): stmt {.immediat
currLine = 0
if i < s.len-1:
var a = ord(s[i])
var b = ord(s[i+1])
let
a = ord(s[i])
b = ord(s[i+1])
result[r] = cb64[a shr 2]
result[r+1] = cb64[((a and 3) shl 4) or ((b and 0xF0) shr 4)]
result[r+2] = cb64[((b and 0x0F) shl 2)]
@@ -83,7 +86,7 @@ template encodeInternal(s: expr, lineLen: int, newLine: string): stmt {.immediat
if r+4 != result.len:
setLen(result, r+4)
elif i < s.len:
var a = ord(s[i])
let a = ord(s[i])
result[r] = cb64[a shr 2]
result[r+1] = cb64[(a and 3) shl 4]
result[r+2] = '='
@@ -127,15 +130,17 @@ proc decode*(s: string): string =
# total is an upper bound, as we will skip arbitrary whitespace:
result = newString(total)
var i = 0
var r = 0
var
i = 0
r = 0
while true:
while s[i] in Whitespace: inc(i)
if i < s.len-3:
var a = s[i].decodeByte
var b = s[i+1].decodeByte
var c = s[i+2].decodeByte
var d = s[i+3].decodeByte
let
a = s[i].decodeByte
b = s[i+1].decodeByte
c = s[i+2].decodeByte
d = s[i+3].decodeByte
result[r] = chr((a shl 2) and 0xff or ((b shr 4) and 0x03))
result[r+1] = chr((b shl 4) and 0xff or ((c shr 2) and 0x0F))
@@ -169,4 +174,4 @@ when isMainModule:
for t in items(tests):
assert decode(encode(t)) == t
assert decode(encode(t, lineLen=40)) == t
assert decode(encode(t, lineLen=76)) == t
assert decode(encode(t, lineLen=76)) == t