diff options
Diffstat (limited to 'tex/context/base/l-unicode.lua')
| -rw-r--r-- | tex/context/base/l-unicode.lua | 55 |
1 files changed, 53 insertions, 2 deletions
diff --git a/tex/context/base/l-unicode.lua b/tex/context/base/l-unicode.lua index 630c34960..7fd380b88 100644 --- a/tex/context/base/l-unicode.lua +++ b/tex/context/base/l-unicode.lua @@ -12,10 +12,10 @@ if not modules then modules = { } end modules ['l-unicode'] = { local concat = table.concat local type = type -local P, C, R, Cs, Ct = lpeg.P, lpeg.C, lpeg.R, lpeg.Cs, lpeg.Ct +local P, C, R, Cs, Ct, Cmt = lpeg.P, lpeg.C, lpeg.R, lpeg.Cs, lpeg.Ct, lpeg.Cmt local lpegmatch, patterns = lpeg.match, lpeg.patterns local utftype = patterns.utftype -local char, byte, find, bytepairs, utfvalues, format = string.char, string.byte, string.find, string.bytepairs, string.utfvalues, string.format +local char, byte, find, bytepairs, utfvalues, format, sub = string.char, string.byte, string.find, string.bytepairs, string.utfvalues, string.format, string.sub local utfsplitlines = string.utfsplitlines if not unicode then @@ -89,6 +89,57 @@ if not utf.byte then end +if not utf.sub then + + local utf8char = patterns.utf8char + + -- inefficient as lpeg just copies ^n + + -- local function sub(str,start,stop) + -- local pattern = utf8char^-(start-1) * C(utf8char^-(stop-start+1)) + -- inspect(pattern) + -- return lpegmatch(pattern,str) or "" + -- end + + local b, e, n, first, last = 0, 0, 0, 0, 0 + + local function slide(s,p) + n = n + 1 + if n == first then + b = p + if not last then + return nil + end + end + if n == last then + e = p + return nil + else + return p + end + end + + local pattern = Cmt(utf8char,slide)^0 + + function utf.sub(str,start,stop) -- todo: from the end + if not start then + return str + end + b, e, n, first, last = 0, 0, 0, start, stop + lpegmatch(pattern,str) + if not stop then + return sub(str,b) + else + return sub(str,b,e) + end + end + + -- print(utf.sub("Hans Hagen is my name")) + -- print(utf.sub("Hans Hagen is my name",5)) + -- print(utf.sub("Hans Hagen is my name",5,10)) + +end + local utfchar, utfbyte = utf.char, utf.byte -- As we want to get rid of the (unmaintained) utf library we implement our own |