implement lzss encoding

1 files changed, 32 insertions, 0 deletions

diff --git a/src/matchtable.nim b/src/matchtable.nim
new file mode 100644
index 0000000..5be652c
--- /dev/null
+++ b/src/matchtable.nim
@@ -0,0 +1,32 @@
+# gzip-like LZSS compressor
+# Copyright (C) 2018  Pacien TRAN-GIRARD
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import tables, lists
+import polyfill
+
+type MatchTable*[K, V] =
+  TableRef[K, SinglyLinkedList[V]]
+
+proc initMatchTable*[K, V](keyType: typedesc[K], valueType: typedesc[V]): MatchTable[K, V] =
+  newTable[K, SinglyLinkedList[V]]()
+
+proc matchList*[K, V](matchTable: MatchTable[K, V], pattern: K): SinglyLinkedList[V] =
+  matchTable.getOrDefault(pattern, initSinglyLinkedList[V]())
+
+proc addMatch*[K, V](matchTable: MatchTable[K, V], pattern: K, value: V) =
+  var matchList = matchTable.matchList(pattern)
+  polyfill.prepend(matchList, value)
+  matchTable[pattern] = matchList