add a persistent storage for word frequency

.gitignore

@@ -3,6 +3,7 @@ GPATH
 GRTAGS
 GSYMS
 GTAGS
+build/*
 *~
 *.pyc
 *.o

lexicon/wordb.py

@@ -0,0 +1,77 @@
+#!/usr/bin/python
+# -*- encoding: utf-8 -*-
+
+from __future__ import with_statement
+import sqlite3
+import collections
+from operator import itemgetter
+
+__all__ = ['error', 'open']
+
+class WordFreqDB(object):
+    def __init__(self, filename):
+        self.conn = sqlite3.connect(filename)
+        MAKE_TABLE = '''create table if not exists 
+                        words (word text primary key, freq integer not null)'''
+        MAKE_INDEX = '''create unique index if not exists keyidx on words (word)'''
+        self.conn.execute(MAKE_TABLE)
+        self.conn.execute(MAKE_INDEX)
+        self.conn.commit()
+
+    def keys(self):
+        GET_KEYS = 'SELECT word FROM words ORDER BY ROWID'
+        return map(itemgetter(0), self.conn.cursor().execute(GET_KEYS))
+
+    def values(self):
+        GET_VALUES = 'SELECT freq FROM words ORDER BY ROWID'
+        return map(itemgetter(0), self.conn.cursor().execute(GET_VALUES))
+
+    def items(self):
+        GET_ITEMS = 'SELECT word, freq FROM words ORDER BY ROWID'
+        return iter(self.conn.cursor().execute(GET_ITEMS))
+
+    def __contains__(self, word):
+        GET_ITEM = '''select freq from words where word = ?'''
+        return self.conn.execute(GET_WORD, word).fetchone() is not None
+
+    def __setitem__(self, word, freq):
+        ADD_ITEM = '''replace into words (word, freq) values (?, ?)'''
+        self.conn.execute(ADD_ITEM, (word, freq))
+        self.conn.commit()
+
+    def __getitem__(self, word):
+        GET_ITEM = '''select freq from words where word = ?'''
+        item = self.conn.execute(GET_ITEM, (word,)).fetchone()
+        if item is None:
+            raise KeyError(word)
+        return item[0]
+
+    def __delitem__(self, word):
+        if word not in self:
+            raise KeyError(word)
+        DEL_ITEM = '''delete from words where key = ?'''
+        self.conn.execute(DEL_ITEM, (key,))
+        self.conn.commit()
+
+    def close(self):
+        if self.conn is not None:
+            self.conn.commit()
+            self.conn.close()
+            self.conn = None
+
+    def __del__(self):
+        self.close()
+
+def open(file=None, *args):
+    if file is not None:
+        return SQLhash(file)
+    return SQLhash()
+
+if __name__ == "__main__":
+    db = WordFreqDB('./wordb.db')
+    words = {u'人间':256,
+             u'大炮':128}
+    for w,f in words.iteritems():
+        db[w] = f
+    for w,f in db.items():
+        print w, f