digfort: add start() comment

NEWS

@@ -2,6 +2,9 @@ DFHack future
 
  - Is not yet known.
 
+  Misc improvements:
+    - digfort: improved csv parsing, add start() comment handling
+
 DFHack v0.34.11-r4
 
   New commands:

Readme.rst

@@ -2171,7 +2171,12 @@ Unrecognized characters are ignored (eg the 'skip this tile' in the sample).
 Empty lines and data after a ``#`` are ignored as comments.
 To skip a row in your design, use a single ``;``.
 
-The script takes the plan filename, starting from the root df folder.
+One comment in the file may contain the phrase ``start(3,5)``. It is interpreted
+as an offset for the pattern: instead of starting at the cursor, it will start
+3 tiles left and 5 tiles up from the cursor.
+
+The script takes the plan filename, starting from the root df folder (where
+Dwarf Fortress.exe is found).
 
 invasion-now
 ============

scripts/digfort.rb

@@ -4,15 +4,47 @@ raise "usage: digfort <plan filename>" if not $script_args[0]
 planfile = File.read($script_args[0])
 
 if df.cursor.x == -30000
-	raise "place the game cursor to the top-left corner of the design"
+	puts "place the game cursor to the top-left corner of the design"
+	throw :script_finished
 end
 
-tiles = planfile.lines.map { |l|
-	l.sub(/#.*/, '').split(/[;,]/).map { |t| t = t.strip ; ((t[0] == ?") ? t[1..-2] : t) }
+# a sample CSV file
+# empty lines are ignored
+# a special comment with start(dx, dy) means the actual patterns starts at cursor.x-dx, cursor.y-dy
+# the CSV file should be saved in the main DF directory, alongside of Dwarf Fortress.exe
+sample_csv = <<EOS
+# start(3, 4)
+ ,d,d,d,d,d,d
+d, , , , , , ,d
+d, , , , , , ,d
+d, ,d, , ,d, ,d
+h, , , , , , ,h
+h,h,h,h,h,h,h,h
+h,h, ,d,d, ,h,h
+h,h,h,h,h,h,h,h
+ ,h,h,h,h,h,h 
+ , , ,h,h,h
+ , , , ,h,h
+EOS
+
+offset = [0, 0]
+tiles = []
+planfile.each_line { |l|
+	if l =~ /#.*start\s*\(\s*(-?\d+)\s*[,;]\s*(-?\d+)/
+		raise "Error: multiple start() comments" if offset != [0, 0]
+		offset = [$1.to_i, $2.to_i]
+	end
+
+	l = l.chomp.sub(/#.*/, '')
+	next if l == ''
+	tiles << l.split(/[;,]/).map { |t|
+		t = t.strip
+		(t[0] == ?") ? t[1..-2] : t
+	}
 }
 
-x = x0 = df.cursor.x
-y = df.cursor.y
+x = x0 = df.cursor.x - offset[0]
+y = df.cursor.y - offset[1]
 z = df.cursor.z
 
 tiles.each { |line|