From e88f60b63cb05f56a61060a953c726b7a78c0652 Mon Sep 17 00:00:00 2001
From: pacien
Date: Fri, 30 Nov 2018 17:08:01 +0100
Subject: isolate huffman encoding module

---
 src/huffman/huffmandecoder.nim     | 35 ++++++++++++++++++
 src/huffman/huffmanencoder.nim     | 40 +++++++++++++++++++++
 src/huffman/huffmantree.nim        | 74 ++++++++++++++++++++++++++++++++++++++
 src/huffman/huffmantreebuilder.nim | 44 +++++++++++++++++++++++
 src/huffmandecoder.nim             | 34 ------------------
 src/huffmanencoder.nim             | 39 --------------------
 src/huffmantree.nim                | 74 --------------------------------------
 src/huffmantreebuilder.nim         | 44 -----------------------
 src/lzsschain.nim                  |  2 +-
 9 files changed, 194 insertions(+), 192 deletions(-)
 create mode 100644 src/huffman/huffmandecoder.nim
 create mode 100644 src/huffman/huffmanencoder.nim
 create mode 100644 src/huffman/huffmantree.nim
 create mode 100644 src/huffman/huffmantreebuilder.nim
 delete mode 100644 src/huffmandecoder.nim
 delete mode 100644 src/huffmanencoder.nim
 delete mode 100644 src/huffmantree.nim
 delete mode 100644 src/huffmantreebuilder.nim

(limited to 'src')

diff --git a/src/huffman/huffmandecoder.nim b/src/huffman/huffmandecoder.nim
new file mode 100644
index 0000000..9a58b55
--- /dev/null
+++ b/src/huffman/huffmandecoder.nim
@@ -0,0 +1,35 @@
+# 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 ../bitio/bitreader
+import huffmantree
+
+type HuffmanDecoder*[T: SomeUnsignedInt] = object
+  tree: HuffmanTreeNode[T]
+
+proc decoder*[T](tree: HuffmanTreeNode[T]): HuffmanDecoder[T] =
+  HuffmanDecoder[T](tree: tree)
+
+proc decode*[T](decoder: HuffmanDecoder[T], bitReader: BitReader): T =
+  proc walk(node: HuffmanTreeNode[T]): T =
+    case node.kind:
+      of branch:
+        case bitReader.readBool():
+          of false: walk(node.left)
+          of true: walk(node.right)
+      of leaf:
+        node.value
+  walk(decoder.tree)
diff --git a/src/huffman/huffmanencoder.nim b/src/huffman/huffmanencoder.nim
new file mode 100644
index 0000000..3ed41ec
--- /dev/null
+++ b/src/huffman/huffmanencoder.nim
@@ -0,0 +1,40 @@
+# 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
+import ../integers, ../bitio/bitwriter
+import huffmantree
+
+type HuffmanEncoder*[T, U: SomeUnsignedInt] = object
+  codebook: TableRef[T, U]
+
+proc buildCodebook*[T, U](tree: HuffmanTreeNode[T], codeType: typedesc[U]): TableRef[T, U] =
+  var codebook = newTable[T, U]()
+  proc addCode(node: HuffmanTreeNode[T], path: U, depth: int) =
+    case node.kind:
+      of branch:
+        addCode(node.left, path, depth + 1)
+        addCode(node.right, path or (1.U shl depth), depth + 1)
+      of leaf:
+        codebook[node.value] = path
+  addCode(tree, 0.U, 0)
+  codebook
+
+proc encoder*[T, U](tree: HuffmanTreeNode[T], codeType: typedesc[U]): HuffmanEncoder[T, U] =
+  HuffmanEncoder[T, U](codebook: buildCodebook(tree, codeType))
+
+proc encode*[T, U](decoder: HuffmanEncoder[T, U], value: T): U =
+  decoder.codebook[value]
diff --git a/src/huffman/huffmantree.nim b/src/huffman/huffmantree.nim
new file mode 100644
index 0000000..1140694
--- /dev/null
+++ b/src/huffman/huffmantree.nim
@@ -0,0 +1,74 @@
+# 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, heapqueue
+import ../integers, ../bitio/bitreader, ../bitio/bitwriter
+
+const valueLengthFieldBitLength* = 6  # 64
+
+type HuffmanTreeNodeKind* = enum
+  branch,
+  leaf
+
+type HuffmanTreeNode*[T: SomeUnsignedInt] = ref object
+  case kind*: HuffmanTreeNodeKind
+    of branch:
+      left*, right*: HuffmanTreeNode[T]
+      maxChildValue: T
+    of leaf:
+      value*: T
+
+proc huffmanBranch*[T](left, right: HuffmanTreeNode[T]): HuffmanTreeNode[T] =
+  HuffmanTreeNode[T](
+    kind: branch, left: left, right: right,
+    maxChildValue: max(left.maxValue(), right.maxValue()))
+
+proc huffmanLeaf*[T](value: T): HuffmanTreeNode[T] =
+  HuffmanTreeNode[T](kind: leaf, value: value)
+
+proc `==`*[T](a, b: HuffmanTreeNode[T]): bool =
+  if a.kind != b.kind: return false
+  case a.kind:
+    of branch: a.left == b.left and a.right == b.right
+    of leaf: a.value == b.value
+
+proc maxValue*[T](node: HuffmanTreeNode[T]): T =
+  case node.kind:
+    of branch: node.maxChildValue
+    of leaf: node.value
+
+proc deserialise*[T](bitReader: BitReader, valueType: typedesc[T]): HuffmanTreeNode[T] =
+  let valueBitLength = bitReader.readBits(valueLengthFieldBitLength, uint8).int
+  proc readNode(): HuffmanTreeNode[T] =
+    case bitReader.readBool():
+      of false: huffmanBranch(readNode(), readNode())
+      of true: huffmanLeaf(bitReader.readBits(valueBitLength, valueType))
+  readNode()
+
+proc serialise*[T](tree: HuffmanTreeNode[T], bitWriter: BitWriter) =
+  let maxValue = tree.maxValue()
+  let valueBitLength = maxValue.bitLength()
+  proc writeNode(node: HuffmanTreeNode[T]) =
+    case node.kind:
+      of branch:
+        bitWriter.writeBool(false)
+        writeNode(node.left)
+        writeNode(node.right)
+      of leaf:
+        bitWriter.writeBool(true)
+        bitWriter.writeBits(valueBitLength, node.value)
+  bitWriter.writeBits(valueLengthFieldBitLength, valueBitLength.uint8)
+  writeNode(tree)
diff --git a/src/huffman/huffmantreebuilder.nim b/src/huffman/huffmantreebuilder.nim
new file mode 100644
index 0000000..4169099
--- /dev/null
+++ b/src/huffman/huffmantreebuilder.nim
@@ -0,0 +1,44 @@
+# 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, heapqueue
+import huffmantree
+
+type WeighedHuffmanTreeNode[T] = ref object
+  weight: int
+  huffmanTreeNode: HuffmanTreeNode[T]
+
+proc weighedHuffmanBranch[T](left, right: WeighedHuffmanTreeNode[T]): WeighedHuffmanTreeNode[T] =
+  WeighedHuffmanTreeNode[T](
+    weight: left.weight + right.weight,
+    huffmanTreeNode: huffmanBranch(left.huffmanTreeNode, right.huffmanTreeNode))
+
+proc weighedHuffmanLeaf[T](value: T, weight: int): WeighedHuffmanTreeNode[T] =
+  WeighedHuffmanTreeNode[T](
+    weight: weight,
+    huffmanTreeNode: huffmanLeaf(value))
+
+proc `<`*[T](left, right: WeighedHuffmanTreeNode[T]): bool =
+  left.weight < right.weight
+
+proc symbolQueue[T](stats: CountTableRef[T]): HeapQueue[WeighedHuffmanTreeNode[T]] =
+  result = newHeapQueue[WeighedHuffmanTreeNode[T]]()
+  for item, count in stats.pairs: result.push(weighedHuffmanLeaf(item, count))
+
+proc buildHuffmanTree*[T: SomeUnsignedInt](stats: CountTableRef[T]): HuffmanTreeNode[T] =
+  var symbolQueue = symbolQueue(stats)
+  while symbolQueue.len > 1: symbolQueue.push(weighedHuffmanBranch(symbolQueue.pop(), symbolQueue.pop()))
+  symbolQueue[0].huffmanTreeNode
diff --git a/src/huffmandecoder.nim b/src/huffmandecoder.nim
deleted file mode 100644
index 5cf4ca5..0000000
--- a/src/huffmandecoder.nim
+++ /dev/null
@@ -1,34 +0,0 @@
-# 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 huffmantree, bitio/bitreader
-
-type HuffmanDecoder*[T: SomeUnsignedInt] = object
-  tree: HuffmanTreeNode[T]
-
-proc decoder*[T](tree: HuffmanTreeNode[T]): HuffmanDecoder[T] =
-  HuffmanDecoder[T](tree: tree)
-
-proc decode*[T](decoder: HuffmanDecoder[T], bitReader: BitReader): T =
-  proc walk(node: HuffmanTreeNode[T]): T =
-    case node.kind:
-      of branch:
-        case bitReader.readBool():
-          of false: walk(node.left)
-          of true: walk(node.right)
-      of leaf:
-        node.value
-  walk(decoder.tree)
diff --git a/src/huffmanencoder.nim b/src/huffmanencoder.nim
deleted file mode 100644
index 05ed64f..0000000
--- a/src/huffmanencoder.nim
+++ /dev/null
@@ -1,39 +0,0 @@
-# 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
-import integers, huffmantree, bitio/bitwriter
-
-type HuffmanEncoder*[T, U: SomeUnsignedInt] = object
-  codebook: TableRef[T, U]
-
-proc buildCodebook*[T, U](tree: HuffmanTreeNode[T], codeType: typedesc[U]): TableRef[T, U] =
-  var codebook = newTable[T, U]()
-  proc addCode(node: HuffmanTreeNode[T], path: U, depth: int) =
-    case node.kind:
-      of branch:
-        addCode(node.left, path, depth + 1)
-        addCode(node.right, path or (1.U shl depth), depth + 1)
-      of leaf:
-        codebook[node.value] = path
-  addCode(tree, 0.U, 0)
-  codebook
-
-proc encoder*[T, U](tree: HuffmanTreeNode[T], codeType: typedesc[U]): HuffmanEncoder[T, U] =
-  HuffmanEncoder[T, U](codebook: buildCodebook(tree, codeType))
-
-proc encode*[T, U](decoder: HuffmanEncoder[T, U], value: T): U =
-  decoder.codebook[value]
diff --git a/src/huffmantree.nim b/src/huffmantree.nim
deleted file mode 100644
index 6208ecf..0000000
--- a/src/huffmantree.nim
+++ /dev/null
@@ -1,74 +0,0 @@
-# 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, heapqueue
-import integers, bitio/bitreader, bitio/bitwriter
-
-const valueLengthFieldBitLength* = 6  # 64
-
-type HuffmanTreeNodeKind* = enum
-  branch,
-  leaf
-
-type HuffmanTreeNode*[T: SomeUnsignedInt] = ref object
-  case kind*: HuffmanTreeNodeKind
-    of branch:
-      left*, right*: HuffmanTreeNode[T]
-      maxChildValue: T
-    of leaf:
-      value*: T
-
-proc huffmanBranch*[T](left, right: HuffmanTreeNode[T]): HuffmanTreeNode[T] =
-  HuffmanTreeNode[T](
-    kind: branch, left: left, right: right,
-    maxChildValue: max(left.maxValue(), right.maxValue()))
-
-proc huffmanLeaf*[T](value: T): HuffmanTreeNode[T] =
-  HuffmanTreeNode[T](kind: leaf, value: value)
-
-proc `==`*[T](a, b: HuffmanTreeNode[T]): bool =
-  if a.kind != b.kind: return false
-  case a.kind:
-    of branch: a.left == b.left and a.right == b.right
-    of leaf: a.value == b.value
-
-proc maxValue*[T](node: HuffmanTreeNode[T]): T =
-  case node.kind:
-    of branch: node.maxChildValue
-    of leaf: node.value
-
-proc deserialise*[T](bitReader: BitReader, valueType: typedesc[T]): HuffmanTreeNode[T] =
-  let valueBitLength = bitReader.readBits(valueLengthFieldBitLength, uint8).int
-  proc readNode(): HuffmanTreeNode[T] =
-    case bitReader.readBool():
-      of false: huffmanBranch(readNode(), readNode())
-      of true: huffmanLeaf(bitReader.readBits(valueBitLength, valueType))
-  readNode()
-
-proc serialise*[T](tree: HuffmanTreeNode[T], bitWriter: BitWriter) =
-  let maxValue = tree.maxValue()
-  let valueBitLength = maxValue.bitLength()
-  proc writeNode(node: HuffmanTreeNode[T]) =
-    case node.kind:
-      of branch:
-        bitWriter.writeBool(false)
-        writeNode(node.left)
-        writeNode(node.right)
-      of leaf:
-        bitWriter.writeBool(true)
-        bitWriter.writeBits(valueBitLength, node.value)
-  bitWriter.writeBits(valueLengthFieldBitLength, valueBitLength.uint8)
-  writeNode(tree)
diff --git a/src/huffmantreebuilder.nim b/src/huffmantreebuilder.nim
deleted file mode 100644
index 5b33d34..0000000
--- a/src/huffmantreebuilder.nim
+++ /dev/null
@@ -1,44 +0,0 @@
-# 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, heapqueue
-import huffmantree, lzssencoder
-
-type WeighedHuffmanTreeNode[T] = ref object
-  weight: int
-  huffmanTreeNode: HuffmanTreeNode[T]
-
-proc weighedHuffmanBranch[T](left, right: WeighedHuffmanTreeNode[T]): WeighedHuffmanTreeNode[T] =
-  WeighedHuffmanTreeNode[T](
-    weight: left.weight + right.weight,
-    huffmanTreeNode: huffmanBranch(left.huffmanTreeNode, right.huffmanTreeNode))
-
-proc weighedHuffmanLeaf[T](value: T, weight: int): WeighedHuffmanTreeNode[T] =
-  WeighedHuffmanTreeNode[T](
-    weight: weight,
-    huffmanTreeNode: huffmanLeaf(value))
-
-proc `<`*[T](left, right: WeighedHuffmanTreeNode[T]): bool =
-  left.weight < right.weight
-
-proc symbolQueue[T](stats: CountTableRef[T]): HeapQueue[WeighedHuffmanTreeNode[T]] =
-  result = newHeapQueue[WeighedHuffmanTreeNode[T]]()
-  for item, count in stats.pairs: result.push(weighedHuffmanLeaf(item, count))
-
-proc buildHuffmanTree*[T: SomeUnsignedInt](stats: CountTableRef[T]): HuffmanTreeNode[T] =
-  var symbolQueue = symbolQueue(stats)
-  while symbolQueue.len > 1: symbolQueue.push(weighedHuffmanBranch(symbolQueue.pop(), symbolQueue.pop()))
-  symbolQueue[0].huffmanTreeNode
diff --git a/src/lzsschain.nim b/src/lzsschain.nim
index 073aa5e..44200f2 100644
--- a/src/lzsschain.nim
+++ b/src/lzsschain.nim
@@ -15,7 +15,7 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 import lists, tables, sugar
-import polyfill, integers, lzssnode, huffmantree
+import polyfill, integers, lzssnode, huffman/huffmantree
 
 const maxChainByteLength = 32_000 * wordBitLength
 
-- 
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