initial import

15 files changed, 138 insertions, 0 deletions

diff --git a/lib/sql_algebra/relations/attribute.rb b/lib/sql_algebra/relations/attribute.rb
new file mode 100644
index 0000000000..c0b8df3083
--- /dev/null
+++ b/lib/sql_algebra/relations/attribute.rb
@@ -0,0 +1,35 @@
+class Attribute
+  attr_reader :relation, :attribute_name
+  
+  def initialize(relation, attribute_name)
+    @relation, @attribute_name = relation, attribute_name
+  end
+  
+  def eql?(other)
+    relation == other.relation and attribute_name == other.attribute_name
+  end
+  
+  def ==(other)
+    EqualityPredicate.new(self, other)
+  end
+  
+  def <(other)
+    LessThanPredicate.new(self, other)
+  end
+  
+  def <=(other)
+    LessThanOrEqualToPredicate.new(self, other)
+  end
+  
+  def >(other)
+    GreaterThanPredicate.new(self, other)
+  end
+  
+  def >=(other)
+    GreaterThanOrEqualToPredicate.new(self, other)
+  end
+  
+  def =~(regexp)
+    MatchPredicate.new(self, regexp)
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/join_operation.rb b/lib/sql_algebra/relations/join_operation.rb
new file mode 100644
index 0000000000..dab8e9e6bd
--- /dev/null
+++ b/lib/sql_algebra/relations/join_operation.rb
@@ -0,0 +1,16 @@
+class JoinOperation
+  attr_reader :relation1, :relation2
+  
+  def initialize(relation1, relation2)
+    @relation1, @relation2 = relation1, relation2
+  end
+  
+  def on(*predicates)
+    JoinRelation.new(relation1, relation2, *predicates)
+  end
+  
+  def ==(other)
+    (relation1 == other.relation1 and relation2 == other.relation2) or
+      (relation1 == other.relation2 and relation2 == other.relation1)
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/join_relation.rb b/lib/sql_algebra/relations/join_relation.rb
new file mode 100644
index 0000000000..64db8e0e68
--- /dev/null
+++ b/lib/sql_algebra/relations/join_relation.rb
@@ -0,0 +1,13 @@
+class JoinRelation < Relation
+  attr_reader :relation1, :relation2, :predicates
+  
+  def initialize(relation1, relation2, *predicates)
+    @relation1, @relation2, @predicates = relation1, relation2, predicates
+  end
+  
+  def ==(other)
+    predicates == other.predicates and
+      ((relation1 == other.relation1 and relation2 == other.relation2) or
+      (relation2 == other.relation1 and relation1 == other.relation2))
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/binary_predicate.rb b/lib/sql_algebra/relations/predicates/binary_predicate.rb
new file mode 100644
index 0000000000..d7f4cb20e7
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/binary_predicate.rb
@@ -0,0 +1,12 @@
+class BinaryPredicate < Predicate
+  attr_reader :attribute1, :attribute2
+  
+  def initialize(attribute1, attribute2)
+    @attribute1, @attribute2 = attribute1, attribute2
+  end
+  
+  def ==(other)
+    super and
+      (attribute1.eql?(other.attribute1) and attribute2.eql?(other.attribute2))
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/equality_predicate.rb b/lib/sql_algebra/relations/predicates/equality_predicate.rb
new file mode 100644
index 0000000000..2d206e6c12
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/equality_predicate.rb
@@ -0,0 +1,7 @@
+class EqualityPredicate < BinaryPredicate
+  def ==(other)
+    self.class == other.class and
+      ((attribute1.eql?(other.attribute1) and attribute2.eql?(other.attribute2)) or
+       (attribute1.eql?(other.attribute2) and attribute2.eql?(other.attribute1)))
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/greater_than_or_equal_to_predicate.rb b/lib/sql_algebra/relations/predicates/greater_than_or_equal_to_predicate.rb
new file mode 100644
index 0000000000..49127c312c
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/greater_than_or_equal_to_predicate.rb
@@ -0,0 +1,2 @@
+class GreaterThanOrEqualToPredicate < BinaryPredicate
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/greater_than_predicate.rb b/lib/sql_algebra/relations/predicates/greater_than_predicate.rb
new file mode 100644
index 0000000000..03aecaed62
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/greater_than_predicate.rb
@@ -0,0 +1,2 @@
+class GreaterThanPredicate < BinaryPredicate
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/less_than_or_equal_to_predicate.rb b/lib/sql_algebra/relations/predicates/less_than_or_equal_to_predicate.rb
new file mode 100644
index 0000000000..fee6ea7f35
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/less_than_or_equal_to_predicate.rb
@@ -0,0 +1,2 @@
+class LessThanOrEqualToPredicate < BinaryPredicate
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/less_than_predicate.rb b/lib/sql_algebra/relations/predicates/less_than_predicate.rb
new file mode 100644
index 0000000000..03cbdcf000
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/less_than_predicate.rb
@@ -0,0 +1,2 @@
+class LessThanPredicate < BinaryPredicate
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/match_predicate.rb b/lib/sql_algebra/relations/predicates/match_predicate.rb
new file mode 100644
index 0000000000..90a13090d4
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/match_predicate.rb
@@ -0,0 +1,7 @@
+class MatchPredicate < Predicate
+  attr_reader :attribute, :regexp
+  
+  def initialize(attribute, regexp)
+    @attribute, @regexp = attribute, regexp
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/predicate.rb b/lib/sql_algebra/relations/predicates/predicate.rb
new file mode 100644
index 0000000000..4c395a3fdc
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/predicate.rb
@@ -0,0 +1,5 @@
+class Predicate
+  def ==(other)
+    self.class == other.class
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/predicates/range_inclusion_predicate.rb b/lib/sql_algebra/relations/predicates/range_inclusion_predicate.rb
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/range_inclusion_predicate.rb
diff --git a/lib/sql_algebra/relations/predicates/relation_inclusion_predicate.rb b/lib/sql_algebra/relations/predicates/relation_inclusion_predicate.rb
new file mode 100644
index 0000000000..5881a85d99
--- /dev/null
+++ b/lib/sql_algebra/relations/predicates/relation_inclusion_predicate.rb
@@ -0,0 +1,11 @@
+class RelationInclusionPredicate < Predicate
+  attr_reader :attribute, :relation
+  
+  def initialize(attribute, relation)
+    @attribute, @relation = attribute, relation
+  end
+  
+  def ==(other)
+    super and attribute == other.attribute and relation == other.relation
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/relation.rb b/lib/sql_algebra/relations/relation.rb
new file mode 100644
index 0000000000..f1f8fc5884
--- /dev/null
+++ b/lib/sql_algebra/relations/relation.rb
@@ -0,0 +1,13 @@
+class Relation
+  def *(other)
+    JoinOperation.new(self, other)
+  end
+  
+  def [](attribute_name)
+    Attribute.new(self, attribute_name)
+  end
+  
+  def include?(attribute)
+    RelationInclusionPredicate.new(attribute, self)
+  end
+end
\ No newline at end of file
diff --git a/lib/sql_algebra/relations/table_relation.rb b/lib/sql_algebra/relations/table_relation.rb
new file mode 100644
index 0000000000..dd4987c3e1
--- /dev/null
+++ b/lib/sql_algebra/relations/table_relation.rb
@@ -0,0 +1,11 @@
+class TableRelation < Relation
+  attr_reader :table
+  
+  def initialize(table)
+    @table = table
+  end
+  
+  def to_sql
+    Select.new(:*).from(table)
+  end
+end
\ No newline at end of file