diff options
| -rw-r--r-- | lib/pure/unicode.nim | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/lib/pure/unicode.nim b/lib/pure/unicode.nim index eeb1b607d..5d302c9dc 100644 --- a/lib/pure/unicode.nim +++ b/lib/pure/unicode.nim @@ -183,6 +183,105 @@ proc `$`*(runes: seq[Rune]): string = result = "" for rune in runes: result.add(rune.toUTF8) +proc runeOffset*(s: string, pos:Natural, start: Natural = 0): int = + ## Returns the byte position of unicode character + ## at position pos in s with an optional start byte position. + ## returns the special value -1 if it runs out of the string + ## + ## Beware: This can lead to unoptimized code and slow execution! + ## Most problems are solve more efficient by using an iterator + ## or conversion to a seq of Rune. + var + i = 0 + o = start + while i < pos: + o += runeLenAt(s, o) + if o >= s.len: + return -1 + inc i + return o + +proc runeAtPos*(s: string, pos: int): Rune = + ## Returns the unicode character at position pos + ## + ## Beware: This can lead to unoptimized code and slow execution! + ## Most problems are solve more efficient by using an iterator + ## or conversion to a seq of Rune. + fastRuneAt(s, runeOffset(s, pos), result, false) + +proc runeStrAtPos*(s: string, pos: Natural): string = + ## Returns the unicode character at position pos as UTF8 String + ## + ## Beware: This can lead to unoptimized code and slow execution! + ## Most problems are solve more efficient by using an iterator + ## or conversion to a seq of Rune. + let o = runeOffset(s, pos) + s[o.. (o+runeLenAt(s, o)-1)] + +proc runeReverseOffset*(s: string, rev:Positive): (int, int) = + ## Returns a tuple with the the byte offset of the + ## unicode character at position ``rev`` in s counting + ## from the end (starting with 1) and the total + ## number of runes in the string. Returns a negative value + ## for offset if there are to few runes in the string to + ## satisfy the request. + ## + ## Beware: This can lead to unoptimized code and slow execution! + ## Most problems are solve more efficient by using an iterator + ## or conversion to a seq of Rune. + var + a = rev.int + o = 0 + x = 0 + while o < s.len: + let r = runeLenAt(s, o) + o += r + if a < 0: + x += r + dec a + + if a > 0: + return (-a, rev.int-a) + return (x, -a+rev.int) + +proc runeSubStr*(s: string, pos:int, len:int = int.high): string = + ## Returns the UTF-8 substring starting at codepoint pos + ## with len codepoints. If pos or len is negativ they count from + ## the end of the string. If len is not given it means the longest + ## possible string. + ## + ## (Needs some examples) + if pos < 0: + let (o, rl) = runeReverseOffset(s, -pos) + if len >= rl: + result = s[o.. s.len-1] + elif len < 0: + let e = rl + len + if e < 0: + result = "" + else: + result = s[o.. runeOffset(s, e-(rl+pos) , o)-1] + else: + result = s[o.. runeOffset(s, len, o)-1] + else: + let o = runeOffset(s, pos) + if o < 0: + result = "" + elif len == int.high: + result = s[o.. s.len-1] + elif len < 0: + let (e, rl) = runeReverseOffset(s, -len) + discard rl + if e <= 0: + result = "" + else: + result = s[o.. e-1] + else: + var e = runeOffset(s, len, o) + if e < 0: + e = s.len + result = s[o.. e-1] + const alphaRanges = [ 0x00d8, 0x00f6, # - @@ -1360,3 +1459,38 @@ when isMainModule: const test = "as⃝" doAssert lastRune(test, test.len-1)[1] == 3 doAssert graphemeLen("è", 0) == 2 + + # test for rune positioning and runeSubStr() + let s = "Hänsel ««: 10,00€" + + doAssert(runeReverseOffset(s, 1) == (20, 18)) + doAssert(runeReverseOffset(s, 19) == (-1, 18)) + + doAssert(runeStrAtPos(s, 0) == "H") + doAssert(runeSubStr(s, 0, 1) == "H") + doAssert(runeStrAtPos(s, 10) == ":") + doAssert(runeSubStr(s, 10, 1) == ":") + doAssert(runeStrAtPos(s, 9) == "«") + doAssert(runeSubStr(s, 9, 1) == "«") + doAssert(runeStrAtPos(s, 17) == "€") + doAssert(runeSubStr(s, 17, 1) == "€") + # echo runeStrAtPos(s, 18) # index error + + doAssert(runeSubStr(s, 0) == "Hänsel ««: 10,00€") + doAssert(runeSubStr(s, -18) == "Hänsel ««: 10,00€") + doAssert(runeSubStr(s, 10) == ": 10,00€") + doAssert(runeSubStr(s, 18) == "") + doAssert(runeSubStr(s, 0, 10) == "Hänsel ««") + + doAssert(runeSubStr(s, 12) == "10,00€") + doAssert(runeSubStr(s, -6) == "10,00€") + + doAssert(runeSubStr(s, 12, 5) == "10,00") + doAssert(runeSubStr(s, 12, -1) == "10,00") + doAssert(runeSubStr(s, -6, 5) == "10,00") + doAssert(runeSubStr(s, -6, -1) == "10,00") + + doAssert(runeSubStr(s, 0, 100) == "Hänsel ««: 10,00€") + doAssert(runeSubStr(s, -100, 100) == "Hänsel ««: 10,00€") + doAssert(runeSubStr(s, 0, -100) == "") + doAssert(runeSubStr(s, 100, -100) == "") |