From 281f1faefb649bf8bef022cf9c1eb99956f2e315 Mon Sep 17 00:00:00 2001
From: Matthew Honnibal <honnibal@gmail.com>
Date: Sun, 12 Jul 2015 23:48:46 +0200
Subject: [PATCH] * Nearly finished huffman coder

---
 spacy/serialize.pyx | 113 +++++++++++++++++++-------------------------
 1 file changed, 48 insertions(+), 65 deletions(-)

diff --git a/spacy/serialize.pyx b/spacy/serialize.pyx
index 9e0cf1935..1880d1a0f 100644
--- a/spacy/serialize.pyx
+++ b/spacy/serialize.pyx
@@ -11,19 +11,12 @@ import numpy
 
 cimport cython
 
-
-#cdef class Serializer:
-#    def __init__(self, Vocab vocab):
-#        pass
-#
-#    def dump(self, Doc tokens, file_):
-#        pass
-#        # Format
-#        # - Total number of bytes in message (32 bit int)
-#        # - Words, terminating in an EOL symbol, huffman coded ~12 bits per word
-#        # - Spaces ~1 bit per word
-#        # - Parse: Huffman coded head offset / dep label / POS tag / entity IOB tag
-#        #          combo. ? bits per word. 40 * 80 * 40 * 12 = 1.5m symbol vocab
+# Format
+# - Total number of bytes in message (32 bit int)
+# - Words, terminating in an EOL symbol, huffman coded ~12 bits per word
+# - Spaces ~1 bit per word
+# - Parse: Huffman coded head offset / dep label / POS tag / entity IOB tag
+#          combo. ? bits per word. 40 * 80 * 40 * 12 = 1.5m symbol vocab
 
 
 cdef struct Node:
@@ -53,21 +46,11 @@ cdef Code bit_append(Code code, bint bit) nogil:
 cdef class HuffmanCodec:
     cdef vector[Node] nodes
     cdef vector[Code] codes
-    cdef float[:] probs
+    cdef readonly float[:] probs
     cdef PreshMap table
-    def __init__(self, symbols, probs):
-        self.table = PreshMap()
-        cdef bytes symb_str
-        cdef uint64_t key
-        cdef uint32_t i
-        for i, symbol in enumerate(symbols):
-            if type(symbol) == unicode or type(symbol) == bytes:
-                symb_str = symbol.encode('utf8')
-                key = hash64(<unsigned char*>symb_str, len(symb_str), 0)
-            else:
-                key = int(symbol)
-            self.table[key] = i+1
-        self.symbols = symbols
+    cdef uint32_t eol
+    def __init__(self, probs, eol):
+        self.eol = eol
         self.probs = probs
         self.codes.resize(len(probs))
         for i in range(len(self.codes)):
@@ -79,47 +62,47 @@ cdef class HuffmanCodec:
         path.length = 0
         assign_codes(self.nodes, self.codes, len(self.nodes) - 1, path)
 
-    def encode(self, sequence):
-        cdef vector[bint] bits
-        cdef uint64_t key
-        cdef uint64_t i
-        for symbol in sequence:
-            if type(symbol) == unicode or type(symbol) == bytes:
-                symb_str = symbol.encode('utf8')
-                key = hash64(<unsigned char*>symb_str, len(symb_str), 0)
-            else:
-                key = int(symbol)
-            i = <uint32_t>self.table.get(key)
-            if i == 0:
-                raise Exception("Unseen symbol: %s" % symbol)
-            else:
-                code = self.codes[i]
-            bits.extend(code)
-        return bits
+    def encode(self, uint32_t[:] sequence):
+        cdef Code code
+        cdef bytes output = b''
+        cdef unsigned char byte = 0
+        cdef uint64_t one = 1
+        cdef unsigned char i_of_byte = 0
+        cdef unsigned char i_of_code = 0
+        for index in sequence:
+            code = self.codes[index]
+            for i_of_code in range(code.length):
+                if code.bits & (one << i_of_code):
+                    byte |= one << i_of_byte
+                else:
+                    byte &= ~(one << i_of_byte)
+                i_of_byte += 1
+                if i_of_byte == 8:
+                    output += chr(byte)
+                    byte = 0
+                    i_of_byte = 0
+        if i_of_byte != 0:
+            output += chr(byte)
+        return output
 
-    def decode(self, unsigned char[:] data):
-        symbols = []
+    def decode(self, bytes data):
         node = self.nodes.back()
-        bits = []
+        symbols = [] 
         cdef unsigned char byte
-        cdef unsigned char one
-        cdef int i = 0
-        for byte_ in data:
-            for i in range(7, -1, -1):
-                bits.append(bool(byte & (one << i)))
-
-        cdef bint bit = 0
-
-        for bit in bits:
-            branch = node.right if bit else node.left
-            if branch >= 0:
-                node = self.nodes.at(branch)
-            else:
-                symbol = self.symbols[-(branch + 1)]
-                if symbol == self.eol_symbol:
-                    break
-                symbols.append(symbol)
-                node = self.nodes.back()
+        cdef unsigned char i = 0
+        cdef unsigned char one = 1
+        for byte in data:
+            for i in range(8):
+                branch = node.right if (byte & (one << i)) else node.left
+                if branch >= 0:
+                    node = self.nodes.at(branch)
+                else:
+                    symbol = -(branch + 1)
+                    if symbol == self.eol:
+                        return symbols
+                    else:
+                        symbols.append(symbol)
+                    node = self.nodes.back()
         return symbols
 
     property strings: