forgot to commit openos

data/openos/lib/transforms.lua

@@ -0,0 +1,79 @@
+local lib={}
+lib.internal={}
+function lib.internal.range_adjust(f,l,s)
+  checkArg(1,f,'number','nil')
+  checkArg(2,l,'number','nil')
+  checkArg(3,s,'number')
+  if f==nil then f=1 elseif f<0 then f=s+f+1 end
+  if l==nil then l=s elseif l<0 then l=s+l+1 end
+  return f,l
+end
+function lib.internal.table_view(tbl,f,l)
+  return setmetatable({},
+  {
+    __index = function(_, key)
+      return (type(key) ~= 'number' or (key >= f and key <= l)) and tbl[key] or nil
+    end,
+    __len = function(_)
+      return l
+    end,
+  })
+end
+local adjust=lib.internal.range_adjust
+local view=lib.internal.table_view
+
+-- first(p1,p2) searches for the first range in p1 that satisfies p2
+function lib.first(tbl,pred,f,l)
+  checkArg(1,tbl,'table')
+  checkArg(2,pred,'function','table')
+  if type(pred)=='table'then
+    local set;set,pred=pred,function(e,fi,tbl)
+      for vi=1,#set do
+        local v=set[vi]
+        if lib.begins(tbl,v,fi) then return true,#v end
+      end
+    end
+  end
+  local s=#tbl
+  f,l=adjust(f,l,s)
+  tbl=view(tbl,f,l)
+  for i=f,l do
+    local si,ei=pred(tbl[i],i,tbl)
+    if si then
+      return i,i+(ei or 1)-1
+    end
+  end
+end
+
+-- returns true if p1 at first p3 equals element for element p2
+function lib.begins(tbl,v,f,l)
+  checkArg(1,tbl,'table')
+  checkArg(2,v,'table')
+  local vs=#v
+  f,l=adjust(f,l,#tbl)
+  if vs>(l-f+1)then return end
+  for i=1,vs do
+    if tbl[f+i-1]~=v[i] then return end
+  end
+  return true
+end
+
+function lib.concat(...)
+  local r,rn,k={},0
+  for _,tbl in ipairs({...})do
+    if type(tbl)~='table'then
+      return nil,'parameter '..tostring(_)..' to concat is not a table'
+    end
+    local n=tbl.n or #tbl
+    k=k or tbl.n
+    for i=1,n do
+      rn=rn+1;r[rn]=tbl[i]
+    end
+  end
+  r.n=k and rn or nil
+  return r
+end
+
+require("package").delay(lib, "/lib/core/full_transforms.lua")
+
+return lib