Add a new json format

driver.py

@@ -57,7 +57,7 @@ def load_relations():
 
             print ("Loading relation %s with name %s..." % (i, relname))
 
-            rels[relname] = relation.Relation.load('%s%s' % (examples_path, i))
+            rels[relname] = relation.Relation.load_csv('%s%s' % (examples_path, i))
             print('done')
 
 
@@ -239,7 +239,7 @@ def run_test(testname):
     o_result = None
 
     try:
-        result_rel = relation.Relation.load('%s%s.result' % (tests_path, testname))
+        result_rel = relation.Relation.load_csv('%s%s.result' % (tests_path, testname))
 
         query = readfile('%s%s.query' % (tests_path, testname)).strip()
         o_query = optimizer.optimize_all(query, rels)

relational/maintenance.py

@@ -90,8 +90,15 @@ class UserInterface:
 
     def load(self, filename: str, name: str) -> None:
         '''Loads a relation from file, and gives it a name to
-        be used in subsequent queries.'''
-        rel = Relation.load(filename)
+        be used in subsequent queries.
+
+        Files ending with .csv are loaded as csv, the others are
+        loaded as json.
+        '''
+        if filename.endswith('.csv'):
+            rel = Relation.load_csv(filename)
+        else:
+            rel = Relation.load(filename)
         self.set_relation(name, rel)
 
     def unload(self, name: str) -> None:
@@ -161,8 +168,12 @@ class UserInterface:
         if len(name) == 0:
             return None
 
-        if (name.endswith(".csv")):  # removes the extension
-            name = name[:-4]
+        # Removing the extension
+        try:
+            pos = name.rindex('.')
+        except ValueError:
+            return None
+        name = name[:pos]
 
         if not is_valid_relation_name(name):
             return None

relational/relation.py

@@ -19,7 +19,6 @@
 # This module provides a classes to represent relations and to perform
 # relational operations on them.
 
-import csv
 from itertools import chain, repeat, product as iproduct
 from collections import deque
 from typing import FrozenSet, Iterable, List, Dict, Tuple
@@ -62,21 +61,62 @@ class Relation:
     content: FrozenSet[Tuple[CastValue, ...]]
 
     @staticmethod
-    def load(filename: Union[str, Path]) -> 'Relation':
+    def load_csv(filename: Union[str, Path]) -> 'Relation':
         '''
         Load a relation object from a csv file.
 
         The 1st row is the header and the other rows are the content.
+
+        Types will be inferred automatically
         '''
+        import csv
         with open(filename) as fp:
             reader = csv.reader(fp)  # Creating a csv reader
             header = Header(next(reader))  # read 1st line
             return Relation.create_from(header, reader)
 
+    @staticmethod
+    def load(filename: Union[str, Path]) -> 'Relation':
+        '''
+        Load a relation object from a json file.
+        '''
+        with open(filename) as fp:
+            from json import load as jload
+            from typedload import load
+            return load(jload(fp), Relation)
+
+    def save(self, filename: Union[Path, str]) -> None:
+        '''
+        Saves the relation in a file.
+        Will save using the json format
+        '''
+        with open(filename, 'w') as fp:
+            from json import dump as jdump
+            from typedload import dump
+            jdump(dump(self), fp)
+
+    def save_csv(self, filename: Union[Path, str]) -> None:
+        '''
+        Saves the relation in a file. Will save using the csv
+        format as defined in RFC4180.
+        '''
+        import csv
+        with open(filename, 'w') as fp:
+            writer = csv.writer(fp)  # Creating csv writer
+
+            # It wants an iterable containing iterables
+            head = (self.header,)
+            writer.writerows(head)
+
+            # Writing content, already in the correct format
+            writer.writerows(self.content)
+
     @staticmethod
     def create_from(header: Iterable[str], content: Iterable[List[str]]) -> 'Relation':
         '''
         Iterator for the header, and iterator for the content.
+
+        This will infer types.
         '''
         header = Header(header)
         r_content = []
@@ -105,22 +145,6 @@ class Relation:
     def __contains__(self, key):
         return key in self.content
 
-    def save(self, filename: Union[Path, str]) -> None:
-        '''
-        Saves the relation in a file. Will save using the csv
-        format as defined in RFC4180.
-        '''
-
-        with open(filename, 'w') as fp:
-            writer = csv.writer(fp)  # Creating csv writer
-
-            # It wants an iterable containing iterables
-            head = (self.header,)
-            writer.writerows(head)
-
-            # Writing content, already in the correct format
-            writer.writerows(self.content)
-
     def _rearrange(self, other: 'Relation') -> 'Relation':
         '''If two relations share the same attributes in a different order, this method
         will use projection to make them have the same attributes' order.
@@ -317,7 +341,7 @@ class Relation:
                     added = True
             # If it didn't partecipate, adds it
             if not added:
-                item = chain(i, repeat(None, len(noid))) #FIXME
+                item = chain(i, repeat(None, len(noid)))
                 content.append(tuple(item))
 
         return Relation(header, frozenset(content))