Refactor Day 02

To make it more idiomatic & explore the language

1 files changed, 19 insertions, 14 deletions

diff --git a/02.lua b/02.lua
index ce28bb6..3168f3b 100644
--- a/02.lua
+++ b/02.lua
@@ -1,31 +1,35 @@
 local Report = {}
 Report.__index = Report
 
+function Report:__tostring ()
+    return table.concat(self, ' ')
+end
+
 function Report:new (values)
-    if #values == 0 then error "Cannot construct an empty report." end
+    if #values == 0 then error 'Cannot construct an empty report.' end
     setmetatable(values, Report)
     return values
 end
 
-local function valid_jump (start, finish)
-    local diff = finish - start
-    return diff >= 1 and diff <= 3
-end
+function Report:is_safe_dir (down, allow_dampen)
+    local function valid_jump (start, finish)
+        local diff = down and start - finish or finish - start
+        return diff >= 1 and diff <= 3
+    end
 
-function Report:is_safe_factor (mult, allow_dampen)
-    local prev = self[1] * mult
+    local prev = self[1]
     for i = 2,#self do
-        local cur = self[i] * mult
+        local cur = self[i]
 
         if valid_jump(prev, cur) then
             prev = cur
         elseif not allow_dampen then
             return false
         else
-            local remove_cur = i == #self or valid_jump(prev, self[i+1] * mult)
+            local remove_cur = i == #self or valid_jump(prev, self[i+1])
 
             if not remove_cur then
-                local remove_prev = i == 2 or valid_jump(self[i-2] * mult, cur)
+                local remove_prev = i == 2 or valid_jump(self[i-2], cur)
                 if not remove_prev then return false end
                 prev = cur
             end
@@ -37,15 +41,15 @@ function Report:is_safe_factor (mult, allow_dampen)
 end
 
 function Report:is_safe (allow_dampen)
-    return self:is_safe_factor(1, allow_dampen) or
-        self:is_safe_factor(-1, allow_dampen)
+    return self:is_safe_dir(true, allow_dampen) or
+        self:is_safe_dir(false, allow_dampen)
 end
 
 local input = {}
 
-for line in function () return io.read("*l") end do
+for line in function () return io.read('*l') end do
     local parsed = {}
-    for v in line:gmatch("%d+") do
+    for v in line:gmatch('%d+') do
         table.insert(parsed, tonumber(v))
     end
     table.insert(input, Report:new(parsed))
@@ -60,6 +64,7 @@ function input:sum_safe (allow_dampen)
 end
 
 function input:part1 ()
+    print(self)
     print(self:sum_safe(false))
 end