Lua solution for week 4, part 2

1 files changed, 51 insertions, 0 deletions

diff --git a/challenge-004/abigail/lua/ch-2.lua b/challenge-004/abigail/lua/ch-2.lua
new file mode 100644
index 0000000000..c1214ac67d
--- /dev/null
+++ b/challenge-004/abigail/lua/ch-2.lua
@@ -0,0 +1,51 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-2.lua -f FILE < input-file
+--
+
+--
+-- Parse option, and exit if incorrect
+--
+
+local filename = ""
+if   #arg == 2 and arg [1] == "-f"
+then filename = arg [2]
+end
+
+if   file == ""
+then io . stderr : write ("Requires a '-f FILE' option\n")
+     os . exit (1)
+     end
+
+--
+-- Given a file name, and a set of letters, print
+-- the words from the file which can be made with the letters.
+--
+function extract_words (filename, letters)
+    for word in io . lines (filename) do
+        copy = word : gsub ("\n", "") : lower ()
+        for i = 1, letters : len () do
+            --
+            -- Remove each of the characters of 'letters' from
+            -- 'copy', after lowercasing, and only once.
+            --
+            copy = copy : gsub (letters : sub (i, i) : lower (), "", 1)
+        end
+        --
+        -- If we end up with the empty string, we have a winner.
+        --
+        if (copy : len () == 0)
+        then
+            print (word)
+        end
+    end
+end
+
+for line in io . lines () do
+    extract_words (filename, line : gsub ("\n", ""))
+end