From 4ea0083ffcad9b73057951d871bcf2dbd855bc7c Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Sun, 10 Oct 2021 17:17:01 +0200
Subject: Refactoring to test the feel of changing a value object to a ref
 object in nim

---
 src/field.nim   | 33 ++++++++++----------
 tests/field.nim | 96 +++++++++++++++++++++++++++++++--------------------------
 2 files changed, 70 insertions(+), 59 deletions(-)

diff --git a/src/field.nim b/src/field.nim
index e63a64e..215a0e3 100644
--- a/src/field.nim
+++ b/src/field.nim
@@ -1,5 +1,5 @@
 type
-  Line = object
+  Line = ref object
     x, l: int
     columns: seq[int]
 
@@ -11,7 +11,7 @@ type
 func Blank*(f: var Field, x, y: int) =
   if y < f.y or y >= f.y+f.ly: # outside the field
     return
-  var l = addr f.lines[y-f.y]
+  var l = f.lines[y-f.y]
   if x < l.x or x >= l.x+l.l: # outside the field
     return
   if x > l.x and x < l.x+l.l-1: # just set the value
@@ -20,14 +20,14 @@ func Blank*(f: var Field, x, y: int) =
   if l.l == 1: # this was the last character on the line
     if y == f.y: # we need to trim the leading lines
       var i = 1
-      while f.lines[i].l == 0:
+      while f.lines[i] == nil or f.lines[i].l == 0:
         inc i
       f.y += i
       f.lines = f.lines[i..<f.ly]
       f.ly -= i
     elif y == f.y+f.ly-1: # we need to trim the trailing lines
       var i = f.ly-2
-      while f.lines[i].l == 0:
+      while f.lines[i] == nil or f.lines[i].l == 0:
         dec i
       f.ly = i+1
       f.lines = f.lines[0..<f.ly]
@@ -51,7 +51,7 @@ func Blank*(f: var Field, x, y: int) =
   f.x = f.lines[0].x
   var x2 = f.lines[0].l + f.lines[0].x
   for i in 1..<f.ly:
-    if f.lines[i].l == 0:
+    if f.lines[i] == nil or f.lines[i].l == 0:
       continue
     if f.x > f.lines[i].x:
       f.x = f.lines[i].x
@@ -74,10 +74,8 @@ proc Load*(filename: string): ref Field =
   if not open(file, filename):
     return nil
   defer: file.close()
-  var f: ref Field
-  new(f)
-  f.lines.add(Line())
-  var l = addr f.lines[0]
+  var f = new(Field)
+  var l = new(Line)
   var trailingSpaces = 0
   var data: array[4096, char]
   var lastReadIsCR = false
@@ -89,9 +87,10 @@ proc Load*(filename: string): ref Field =
           return nil
         f.x = l.x
       if l.l > 0:
-        inc f.ly
         if f.lx < l.l+l.x-f.x:
           f.lx = l.l+l.x-f.x
+        f.lines.add(l)
+        inc f.ly
       break
     var i = 0
     while i < n:
@@ -107,14 +106,14 @@ proc Load*(filename: string): ref Field =
           if l.l == 0:
             return nil
           f.x = l.x
-        inc f.ly
         if l.l > 0:
           if f.x > l.x:
             f.x = l.x
           if f.lx < l.l+l.x-f.x:
             f.lx = l.l+l.x-f.x
-        f.lines.add(Line())
-        l = addr f.lines[^1]
+        inc f.ly
+        f.lines.add(l)
+        l = new(Line)
         trailingSpaces = 0
         if data[i] == '\r':
           if i+1 < n and data[i+1] == '\n':
@@ -140,7 +139,6 @@ proc Load*(filename: string): ref Field =
             l.columns.add(int(data[i]))
             inc l.l
       inc i
-  f.lines = f.lines[0..<f.ly]
   return f
 
 func Set*(f: var Field, x, y, v: int) =
@@ -148,11 +146,14 @@ func Set*(f: var Field, x, y, v: int) =
     f.Blank(x, y)
   elif y >= f.y:
     if y < f.y+f.ly: # the line exists
-      var l = addr f.lines[y-f.y]
-      if l.l == 0: # An empty line is a special case
+      var l = f.lines[y-f.y]
+      if l == nil or l.l == 0: # An empty line is a special case
+        if l == nil:
+          new(l)
         l.x = x
         l.l = 1
         l.columns = @[v]
+        f.lines[y-f.y] = l
         if f.x > x:
           f.lx = f.lx+f.x-x
           f.x = x
diff --git a/tests/field.nim b/tests/field.nim
index 455d81f..6196d97 100644
--- a/tests/field.nim
+++ b/tests/field.nim
@@ -2,99 +2,109 @@ import unittest
 
 include ../src/field
 
-func `==`(a, b: Line): bool = a.x == b.x and a.l == b.l and a.columns == b.columns
-func `==`(a, b: Field): bool = a.x == b.x and a.lx == b.lx and a.y == b.y and a.ly == b.ly and a.lines == b.lines
+func `==`(a, b: Field): bool =
+  if a.x == b.x and a.lx == b.lx and a.y == b.y and a.ly == b.ly:
+    for i in 0..<a.ly:
+      if a.lines[i] == nil and b.lines[i] == nil:
+        continue
+      if a.lines[i] == nil xor b.lines[i] == nil:
+        return false
+      if a.lines[i].x != b.lines[i].x or a.lines[i].l != b.lines[i].l or a.lines[i].columns != b.lines[i].columns:
+        return false
+    return true
+  return false
+
 func cols(a: openarray[char]): seq[int] =
   result.setlen(a.len)
   for i in 0..<a.len:
     result[i] = a[i].int()
 
-const minimal = Field(x: 0, y: 0, lx: 1, ly: 1, lines: @[Line(x: 0, l: 1, columns: @[int('@')])])
+let minimal = Field(x: 0, y: 0, lx: 1, ly: 1, lines: @[Line(x: 0, l: 1, columns: @[int('@')])])
 
 suite "Field":
   test "Blank":
     var f = Field(x: -7, y: -5, lx: 17, ly: 10, lines: @[
       Line(x: -5, l: 1, columns: @[int('x')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), int('z'), 32, 32, int('r')]),
       Line(x: -3, l: 1, columns: @[int('f')]),
       Line(x: 5, l: 1, columns: @[int('d')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -7, l: 1, columns: @[int('y')]),
     ])
-    const moinsz = Field(x: -7, y: -5, lx: 17, ly: 10, lines: @[
+    let moinsz = Field(x: -7, y: -5, lx: 17, ly: 10, lines: @[
       Line(x: -5, l: 1, columns: @[int('x')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 1, columns: @[int('f')]),
       Line(x: 5, l: 1, columns: @[int('d')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -7, l: 1, columns: @[int('y')]),
     ])
     f.Blank(1, 0)
     check f == moinsz
-    const moinsy = Field(x: -5, y: -5, lx: 15, ly: 8, lines: @[
+    let moinsy = Field(x: -5, y: -5, lx: 15, ly: 8, lines: @[
       Line(x: -5, l: 1, columns: @[int('x')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 1, columns: @[int('f')]),
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Blank(-7, 4)
     check f == moinsy
-    const moinsx = Field(x: -3, y: -3, lx: 13, ly: 6, lines: @[
+    let moinsx = Field(x: -3, y: -3, lx: 13, ly: 6, lines: @[
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 1, columns: @[int('f')]),
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Blank(-5, -5)
     check f == moinsx
-    const moinsf = Field(x: -2, y: -3, lx: 12, ly: 6, lines: @[
+    let moinsf = Field(x: -2, y: -3, lx: 12, ly: 6, lines: @[
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 0, columns: @[]),
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Blank(-3, 1)
     check f == moinsf
-    const moinse = Field(x: -2, y: -3, lx: 11, ly: 6, lines: @[
+    let moinse = Field(x: -2, y: -3, lx: 11, ly: 6, lines: @[
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 0, columns: @[]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 0, columns: @[]),
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Blank(9, -2)
     check f == moinse
-    const moinsu = Field(x: -2, y: 0, lx: 8, ly: 3, lines: @[
+    let moinsu = Field(x: -2, y: 0, lx: 8, ly: 3, lines: @[
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 0, columns: @[]),
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Blank(8, -3)
     check f == moinsu
-    const moinsd = Field(x: -2, y: 0, lx: 7, ly: 1, lines: @[Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')])])
+    let moinsd = Field(x: -2, y: 0, lx: 7, ly: 1, lines: @[Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')])])
     f.Blank(5, 2)
     check f == moinsd
-    const moinsl = Field(x: 0, y: 0, lx: 5, ly: 1, lines: @[Line(x: 0, l: 5, columns: @[int('@'), 32, 32, 32, int('r')])])
+    let moinsl = Field(x: 0, y: 0, lx: 5, ly: 1, lines: @[Line(x: 0, l: 5, columns: @[int('@'), 32, 32, 32, int('r')])])
     f.Blank(-2, 0)
     check f == moinsl
-    const moinsr = Field(x: 0, y: 0, lx: 1, ly: 1, lines: @[Line(x: 0, l: 1, columns: @[int('@')])])
+    let moinsr = Field(x: 0, y: 0, lx: 1, ly: 1, lines: @[Line(x: 0, l: 1, columns: @[int('@')])])
     f.Blank(4, 0)
     check f == moinsr
   test "Get":
@@ -136,71 +146,71 @@ suite "Field":
     check f == minimal
     f.Set(1, 0, int(' '))
     check f == minimal
-    const xappend = Field(x: 0, y: 0, lx: 5, ly: 1, lines: @[Line(x: 0, l: 5, columns: @[int('@'), 32, 32, 32, int('r')])])
+    let xappend = Field(x: 0, y: 0, lx: 5, ly: 1, lines: @[Line(x: 0, l: 5, columns: @[int('@'), 32, 32, 32, int('r')])])
     f.Set(4, 0, int('r'))
     check f == xappend
-    const xprepend = Field(x: -2, y: 0, lx: 7, ly: 1, lines: @[Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')])])
+    let xprepend = Field(x: -2, y: 0, lx: 7, ly: 1, lines: @[Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')])])
     f.Set(-2, 0, int('l'))
     check f == xprepend
-    const yappend = Field(x: -2, y: 0, lx: 8, ly: 3, lines: @[
+    let yappend = Field(x: -2, y: 0, lx: 8, ly: 3, lines: @[
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Set(5, 2, int('d'))
     check f == yappend
-    const yprepend = Field(x: -2, y: -3, lx: 11, ly: 6, lines: @[
+    let yprepend = Field(x: -2, y: -3, lx: 11, ly: 6, lines: @[
       Line(x: 8, l: 1, columns: @[int('u')]),
-      Line(x: 0, l: 0, columns: @[]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Set(8, -3, int('u'))
     check f == yprepend
-    const xappendEmptyline = Field(x: -2, y: -3, lx: 12, ly: 6, lines: @[
+    let xappendEmptyline = Field(x: -2, y: -3, lx: 12, ly: 6, lines: @[
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Set(9, -2, int('e'))
     check f == xappendEmptyline
-    const xprependEmptyline = Field(x: -3, y: -3, lx: 13, ly: 6, lines: @[
+    let xprependEmptyline = Field(x: -3, y: -3, lx: 13, ly: 6, lines: @[
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 1, columns: @[int('f')]),
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Set(-3, 1, int('f'))
     check f == xprependEmptyline
-    const xprependyprepend = Field(x: -5, y: -5, lx: 15, ly: 8, lines: @[
+    let xprependyprepend = Field(x: -5, y: -5, lx: 15, ly: 8, lines: @[
       Line(x: -5, l: 1, columns: @[int('x')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 1, columns: @[int('f')]),
       Line(x: 5, l: 1, columns: @[int('d')]),
     ])
     f.Set(-5, -5, int('x'))
     check f == xprependyprepend
-    const xprependyappend = Field(x: -7, y: -5, lx: 17, ly: 10, lines: @[
+    let xprependyappend = Field(x: -7, y: -5, lx: 17, ly: 10, lines: @[
       Line(x: -5, l: 1, columns: @[int('x')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: 8, l: 1, columns: @[int('u')]),
       Line(x: 9, l: 1, columns: @[int('e')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -2, l: 7, columns: @[int('l'), 32, int('@'), 32, 32, 32, int('r')]),
       Line(x: -3, l: 1, columns: @[int('f')]),
       Line(x: 5, l: 1, columns: @[int('d')]),
-      Line(x: 0, l: 0, columns: @[]),
+      nil,
       Line(x: -7, l: 1, columns: @[int('y')]),
     ])
     f.Set(-7, 4, int('y'))
-- 
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