add Range:difference

lua/u/pos.lua

@@ -12,8 +12,17 @@ end
 --- @field col number 1-based column index
 --- @field off number
 local Pos = {}
+Pos.__index = Pos
 Pos.MAX_COL = MAX_COL
 
+function Pos.__tostring(self)
+  if self.off ~= 0 then
+    return string.format('Pos(%d:%d){bufnr=%d, off=%d}', self.lnum, self.col, self.bufnr, self.off)
+  else
+    return string.format('Pos(%d:%d){bufnr=%d}', self.lnum, self.col, self.bufnr)
+  end
+end
+
 --- @param bufnr? number
 --- @param lnum number 1-based
 --- @param col number 1-based
@@ -28,31 +37,13 @@ function Pos.new(bufnr, lnum, col, off)
     col = col,
     off = off,
   }
-
-  local function str()
-    if pos.off ~= 0 then
-      return string.format('Pos(%d:%d){bufnr=%d, off=%d}', pos.lnum, pos.col, pos.bufnr, pos.off)
-    else
-      return string.format('Pos(%d:%d){bufnr=%d}', pos.lnum, pos.col, pos.bufnr)
-    end
-  end
-  setmetatable(pos, {
-    __index = Pos,
-    __tostring = str,
-    __lt = Pos.__lt,
-    __le = Pos.__le,
-    __eq = Pos.__eq,
-  })
+  setmetatable(pos, Pos)
   return pos
 end
 
 function Pos.invalid() return Pos.new(0, 0, 0, 0) end
 
-function Pos.is(x)
-  if not type(x) == 'table' then return false end
-  local mt = getmetatable(x)
-  return mt and mt.__index == Pos
-end
+function Pos.is(x) return getmetatable(x) == Pos end
 
 function Pos.__lt(a, b) return a.lnum < b.lnum or (a.lnum == b.lnum and a.col < b.col) end
 function Pos.__le(a, b) return a < b or a == b end

lua/u/range.lua

@@ -12,6 +12,29 @@ end
 --- @field stop u.Pos|nil
 --- @field mode 'v'|'V'
 local Range = {}
+Range.__index = Range
+function Range.__tostring(self)
+  --- @param p u.Pos
+  local function posstr(p)
+    if p == nil then
+      return 'nil'
+    elseif p.off ~= 0 then
+      return string.format('Pos(%d:%d){off=%d}', p.lnum, p.col, p.off)
+    else
+      return string.format('Pos(%d:%d)', p.lnum, p.col)
+    end
+  end
+
+  local _1 = posstr(self.start)
+  local _2 = posstr(self.stop)
+  return string.format(
+    'Range{bufnr=%d, mode=%s, start=%s, stop=%s}',
+    self.start.bufnr,
+    self.mode,
+    _1,
+    _2
+  )
+end
 
 --- @param start u.Pos
 --- @param stop u.Pos|nil
@@ -23,36 +46,12 @@ function Range.new(start, stop, mode)
   end
 
   local r = { start = start, stop = stop, mode = mode or 'v' }
-  local function str()
-    --- @param p u.Pos
-    local function posstr(p)
-      if p == nil then
-        return 'nil'
-      elseif p.off ~= 0 then
-        return string.format('Pos(%d:%d){off=%d}', p.lnum, p.col, p.off)
-      else
-        return string.format('Pos(%d:%d)', p.lnum, p.col)
-      end
-    end
 
-    local _1 = posstr(r.start)
-    local _2 = posstr(r.stop)
-    return string.format(
-      'Range{bufnr=%d, mode=%s, start=%s, stop=%s}',
-      r.start.bufnr,
-      r.mode,
-      _1,
-      _2
-    )
-  end
-  setmetatable(r, { __index = Range, __tostring = str })
+  setmetatable(r, Range)
   return r
 end
 
-function Range.is(x)
-  local mt = getmetatable(x)
-  return mt and mt.__index == Range
-end
+function Range.is(x) return getmetatable(x) == Range end
 
 --- @param lpos string
 --- @param rpos string
@@ -299,8 +298,44 @@ function Range:trim_stop()
   return r
 end
 
---- @param p u.Pos
-function Range:contains(p) return not self:is_empty() and p >= self.start and p <= self.stop end
+--- @param x u.Pos | u.Range
+function Range:contains(x)
+  if getmetatable(x) == Pos then
+    return not self:is_empty() and x >= self.start and x <= self.stop
+  elseif getmetatable(x) == Range then
+    return self:contains(x.start) and self:contains(x.stop)
+  end
+  return false
+end
+
+--- TODO: test
+--- @param other u.Range
+--- @return u.Range|nil, u.Range|nil
+function Range:difference(other)
+  local outer, inner = self, other
+  if not outer:contains(inner) then
+    outer, inner = inner, outer
+  end
+  if not outer:contains(inner) then return nil, nil end
+
+  local left
+  if outer.start ~= inner.start then
+    local stop = inner.start:clone() - 1
+    left = Range.new(outer.start, stop)
+  else
+    left = Range.new(outer.start) -- empty range
+  end
+
+  local right
+  if inner.stop ~= outer.stop then
+    local start = inner.stop:clone() + 1
+    right = Range.new(start, outer.stop)
+  else
+    right = Range.new(inner.stop) -- empty range
+  end
+
+  return left, right
+end
 
 --- @return string[]
 function Range:lines()