first commit towards a unified API

type_infer/engines/base.py

@@ -0,0 +1,95 @@
+""" base.py
+
+    Base implementation of engines to infer data type and other
+    useful information from tables.
+"""
+import pandas
+
+
+class ColumnInfo:
+    """ Simple container for important column information
+        like data type, modifiers, length, number of
+        invalid entries, etc.
+    """
+    def __init__(self, column_name: str):
+        """ Initializer
+
+            :param column_name (str)
+                name of column
+        """
+        # base attributes
+        self.name_ = column_name
+        self.length_ = -1
+        self.data_type_ = 'unknown'
+        self.data_type_info_ = {}
+        self.modifier_ = 'unkonwn'
+        self.modifier_info_ = {}
+
+    def set_column_length(self, length: int):
+        """ Set length of column.
+        """
+        self.length_ = length
+
+    def get_column_length(self):
+        """ Returns column length.
+
+            :note
+            if `set_column_length()` hasn't been called, then
+            `get_column_length()` will return -1.
+        """
+        return self.length_
+
+    def get_name(self):
+        """ Return column name.
+        """
+        return self.name_
+
+    def get_data_type(self):
+        """ Returns column data type.
+        """
+        return self.data_type_
+
+    def get_data_type_info(self):
+        """ Returns copy of data type information.
+        """
+        d = {}
+        d.update(self.data_type_info_)
+        return d
+
+    def get_modifier(self):
+        """ Returns column modifier.
+        """
+        return self.modifier_
+
+    def get_modifier_info(self):
+        """ Returns copy of modifier info.
+        """
+        d = {}
+        d.update(self.modifier_info_)
+        return d
+
+
+class TypeInferenceEngine:
+    """ Base implementation for column type inference.
+    """
+    def __init__(self, name: str):
+        """ Initializer
+
+            :param name (str)
+                name of the engine.
+        """
+        self.name_ = name
+        self.dfs_ = []
+
+    def attach_dataframe(self, df: pandas.DataFrame):
+        """ Adds dataframe for analysis.
+
+            :param df (pandas.Dataframe)
+                dataframe to be analyzed.
+
+            :note
+                to avoid side effects, a copy of the original
+                dataframe is made.
+        """
+        self.dfs_.append(df.copy())
+