add util-str

1 files changed, 127 insertions, 0 deletions

diff --git a/lualibs-util-str.lua b/lualibs-util-str.lua
new file mode 100644
index 0000000..377dd16
--- /dev/null
+++ b/lualibs-util-str.lua
@@ -0,0 +1,127 @@
+if not modules then modules = { } end modules ['util-str'] = {
+    version   = 1.001,
+    comment   = "companion to luat-lib.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+utilities         = utilities or {}
+utilities.strings = utilities.strings or { }
+local strings     = utilities.strings
+
+local gsub, rep = string.gsub, string.rep
+local Cs, C, Cp, P, Carg = lpeg.Cs, lpeg.C, lpeg.Cp, lpeg.P, lpeg.Carg
+local patterns, lpegmatch = lpeg.patterns, lpeg.match
+
+-- str = " \n \ntest  \n test\ntest "
+-- print("["..string.gsub(string.collapsecrlf(str),"\n","+").."]")
+
+local rubish     = patterns.spaceortab^0 * patterns.newline
+local anyrubish  = patterns.spaceortab + patterns.newline
+local anything   = patterns.anything
+local stripped   = (patterns.spaceortab^1 / "") * patterns.newline
+local leading    = rubish^0 / ""
+local trailing   = (anyrubish^1 * patterns.endofstring) / ""
+local redundant  = rubish^3 / "\n"
+
+local pattern = Cs(leading * (trailing + redundant + stripped + anything)^0)
+
+function strings.collapsecrlf(str)
+    return lpegmatch(pattern,str)
+end
+
+-- The following functions might end up in another namespace.
+
+local repeaters = { } -- watch how we also moved the -1 in depth-1 to the creator
+
+function strings.newrepeater(str,offset)
+    offset = offset or 0
+    local s = repeaters[str]
+    if not s then
+        s = { }
+        repeaters[str] = s
+    end
+    local t = s[offset]
+    if t then
+        return t
+    end
+    t = { }
+    setmetatable(t, {
+        __index = function(t,k)
+            if not k then
+                return ""
+            end
+            local n = k + offset
+            local s = n > 0 and rep(str,n) or ""
+            t[k] = s
+            return s
+        end
+    } )
+    s[offset] = t
+    return t
+end
+
+-- local dashes = strings.newrepeater("--",-1)
+-- print(dashes[2],dashes[3],dashes[1])
+
+local extra, tab, start = 0, 0, 4, 0
+
+local nspaces = strings.newrepeater(" ")
+
+local pattern =
+    Carg(1) / function(t)
+        extra, tab, start = 0, t or 7, 1
+    end
+  * Cs((
+      Cp() * patterns.tab / function(position)
+          local current = (position - start + 1) + extra
+          local spaces = tab-(current-1) % tab
+          if spaces > 0 then
+              extra = extra + spaces - 1
+              return nspaces[spaces] -- rep(" ",spaces)
+          else
+              return ""
+          end
+      end
+    + patterns.newline * Cp() / function(position)
+          extra, start = 0, position
+      end
+    + patterns.anything
+  )^1)
+
+function strings.tabtospace(str,tab)
+    return lpegmatch(pattern,str,1,tab or 7)
+end
+
+--~ local t = {
+--~     "1234567123456712345671234567",
+--~     "\tb\tc",
+--~     "a\tb\tc",
+--~     "aa\tbb\tcc",
+--~     "aaa\tbbb\tccc",
+--~     "aaaa\tbbbb\tcccc",
+--~     "aaaaa\tbbbbb\tccccc",
+--~     "aaaaaa\tbbbbbb\tcccccc\n       aaaaaa\tbbbbbb\tcccccc",
+--~     "one\n	two\nxxx	three\nxx	four\nx	five\nsix",
+--~ }
+--~ for k=1,#t do
+--~     print(strings.tabtospace(t[k]))
+--~ end
+
+function strings.striplong(str) -- strips all leading spaces
+    str = gsub(str,"^%s*","")
+    str = gsub(str,"[\n\r]+ *","\n")
+    return str
+end
+
+--~ local template = string.striplong([[
+--~   aaaa
+--~   bb
+--~   cccccc
+--~ ]])
+
+function strings.nice(str)
+    str = gsub(str,"[:%-+_]+"," ") -- maybe more
+    return str
+end