Change relational language to use math symbols

The symbols previously used were a Canadian script, and were looking
good enough, but they might not be installed in every machine.

Besides, all this is to workaround a Qt5 bug that prevents from
rendering those symbols at times.

CHANGELOG

@@ -1,8 +1,12 @@
-1.3
+2.0
 - Fix bug in relational-cli that made it crash when an exception was raised
 - Point to new website
 - Drop support for PySide
 - Switch to Python3 and drop support for Python2
+- Switch to Qt5
+- Radical change of language. The UNICODE symbols used previously were meant for a
+  Canadian Aborigenal script. Now switched them to use UNICODE math symbols.
+- Since the language is changing, take the chance to use better symbols for JOIN
 
 1.2
 - Better tokenizer, gives more indicative errors

relational/parser.py

@@ -50,13 +50,13 @@ BINARY = 2
 
 PRODUCT = u'*'
 DIFFERENCE = u'-'
-UNION = u'ᑌ'
-INTERSECTION = u'ᑎ'
+UNION = u'∪'
+INTERSECTION = u'∩'
 DIVISION = u'÷'
-JOIN = u'ᐅᐊ'
-JOIN_LEFT = u'ᐅLEFTᐊ'
-JOIN_RIGHT = u'ᐅRIGHTᐊ'
-JOIN_FULL = u'ᐅFULLᐊ'
+JOIN = u'⋈'
+JOIN_LEFT = u'⧑'
+JOIN_RIGHT = u'⧒'
+JOIN_FULL = u'⧓'
 PROJECTION = u'π'
 SELECTION = u'σ'
 RENAME = u'ρ'
@@ -330,7 +330,7 @@ def tokenize(expression):
             # Removes the entire parentesis and content from the expression
             expression = expression[end + 1:].strip()
 
-        elif expression.startswith((u"σ", u"π", u"ρ")):  # Unary 2 bytes
+        elif expression.startswith((SELECTION, RENAME, PROJECTION)):  # Unary 2 bytes
             items.append(expression[0:1])
                          # Adding operator in the top of the list
             expression = expression[
@@ -346,17 +346,10 @@ def tokenize(expression):
                          # Inserting parameter of the operator
             expression = expression[
                 par:].strip()  # Removing parameter from the expression
-        elif expression.startswith((u"÷", u"ᑎ", u"ᑌ", u"*", u"-")):
+        elif expression.startswith((DIVISION, INTERSECTION, UNION, PRODUCT, DIFFERENCE, JOIN, JOIN_LEFT, JOIN_RIGHT, JOIN_FULL)):
             items.append(expression[0])
             expression = expression[1:].strip()  # 1 char from the expression
             state = 4
-        elif expression.startswith(u"ᐅ"):  # Binary long
-            i = expression.find(u"ᐊ")
-            if i == -1:
-                raise TokenizerException(u"Expected ᐊ in %s" % (expression,))
-            items.append(expression[:i + 1])
-            expression = expression[i + 1:].strip()
-            state = 4
         elif re.match(r'[_0-9A-Za-z]', expression[0]) == None:  # At this point we only have relation names, so we raise errors for anything else
             raise TokenizerException(
                 "Unexpected '%c' in '%s'" % (expression[0], expression))

test/c_programmers.query

@@ -1 +1 @@
-σ skill=='C'(people ᐅᐊ skills)
+σ skill=='C'(people ⋈ skills)

test/fixed_len_name.query

@@ -1 +1 @@
-σ (len(name)==4)(peopleᐅᐊ skills) 
+σ (len(name)==4)(people ⋈ skills)

test/intersection1.query

@@ -1 +1 @@
-σ name=='eve' (people) ᑎ people
+σ name=='eve' (people) ∩ people

test/intersection2.query

@@ -1 +1 @@
-people ᑎ σ name=='eve' (people)
+people ∩ σ name=='eve' (people)

test/max_rating_in_age_range.query

@@ -1 +1 @@
-(σ age<25(people) ᑌ σ age>30(people)) ᐅᐊ ratings-πid,name,chief,age,rating(σ rating<r((ρid➡i,rating➡r(π id,rating((σ age<25(people) ᑌ σ age>30(people)) ᐅᐊ ratings))) * (σ age<25(people) ᑌ σ age>30(people)) ᐅᐊ ratings))
+(σ age<25(people) ∪ σ age>30(people)) ⋈ ratings-πid,name,chief,age,rating(σ rating<r((ρid➡i,rating➡r(π id,rating((σ age<25(people) ∪ σ age>30(people)) ⋈ ratings))) * (σ age<25(people) ∪ σ age>30(people)) ⋈ ratings))

test/people_join_select_args_on_both_tables.query

@@ -1 +1 @@
-σ skill=='C' and age<25 and skill!=name(people ᐅᐊ skills)
+σ skill=='C' and age<25 and skill!=name(people ⋈ skills)

test/phones_of_people_with_personal_room.query

@@ -1 +1 @@
-πname,phone(((πname,id(people)- π name,id(πid(σ i!=id and room==r(ρ id➡i,room➡r(person_room)*person_room)) ᐅᐊ people)) ᐅᐊ person_room) ᐅᐊ rooms)
+πname,phone(((πname,id(people)- π name,id(πid(σ i!=id and room==r(ρ id➡i,room➡r(person_room)*person_room)) ⋈ people)) ⋈ person_room) ⋈ rooms)

test/php.query

@@ -1 +1 @@
-σ age<30 and skill=='PHP' (people ᐅᐊ skills)
+σ age<30 and skill=='PHP' (people ⋈ skills)

test/redoundant_union_select.query

@@ -1 +1 @@
-σ (id==2) (σ age>5 (people ᑌ people))
+σ (id==2) (σ age>5 (people ∪ people))

test/select_join_opt.query

@@ -1 +1 @@
-σ skill=='C' and chief==0 ((σ age<30 (people) ᑌ σ age>40(people)) ᐅᐊ skills)
+σ skill=='C' and chief==0 ((σ age<30 (people) ∪ σ age>40(people)) ⋈ skills)

test/skill_of_best_person.query

@@ -1 +1 @@
-πname,age,skill((ratings-πid,rating(σ r>rating (ρrating➡r(πrating(ratings )) * ratings)) ᐅᐊ people) ᐅᐊ skills)
+πname,age,skill((ratings-πid,rating(σ r>rating (ρrating➡r(πrating(ratings )) * ratings)) ⋈ people) ⋈ skills)

test/union1.query

@@ -1 +1 @@
-σ age<30 (σ (id%2==0) (people) ᑌ σ age>22(people))
+σ age<30 (σ (id%2==0) (people) ∪ σ age>22(people))

test/union2.query

@@ -1 +1 @@
-people ᑌ σ name=='eve' (people)
+people ∪ σ name=='eve' (people)

test/union3.query

@@ -1 +1 @@
-σ name=='eve' (people) ᑌ people
+σ name=='eve' (people) ∪ people

test/union4.query

@@ -1 +1 @@
-people ᑌ people ᑎ people
+people ∪ people ∩ people

test/union_and_select.query

@@ -1 +1 @@
-σ skill=='C'(skills) ᑎ σ id%2==0 (skills)
+σ skill=='C'(skills) ∩ σ id%2==0 (skills)

test/union_or_select.query

@@ -1 +1 @@
-σ age<21 (people) ᑌ σage >30(people)
+σ age<21 (people) ∪ σage >30(people)