find_all: return a dictionary isntead of a list

New implementation causes the find_all results to depend on order of
dictionary elements. A dictionary is therefore a more appropriate return type.

README.md

@@ -3,7 +3,7 @@
 ![ci](https://github.com/ptrus/suffix-trees/workflows/ci/badge.svg)
 [![codecov](https://codecov.io/gh/ptrus/suffix-trees/branch/master/graph/badge.svg)](https://codecov.io/gh/ptrus/suffix-trees)
 
-Python implementation of Suffix Trees and Generalized Suffix Trees. Also provided methods with typcal applications of STrees and GSTrees. 
+Python implementation of Suffix Trees and Generalized Suffix Trees. Also provided methods with typcal applications of STrees and GSTrees.
 
 ### Installation
 
@@ -19,7 +19,7 @@ from suffix_trees import STree
 # Suffix-Tree example.
 st = STree.STree("abcdefghab")
 print(st.find("abc")) # 0
-print(st.find_all("ab")) # [0, 8]
+print(st.find_all("ab")) # {0, 8}
 
 # Generalized Suffix-Tree example.
 a = ["xxxabcxxx", "adsaabc", "ytysabcrew", "qqqabcqw", "aaabc"]

setup.py

@@ -3,7 +3,7 @@
 setup(
     name='suffix-trees',
     packages=['suffix_trees'],
-    version='0.2.6',
+    version='0.3.0',
     description='Suffix trees, generalized suffix trees and string processing methods',
     author='Peter Us',
     author_email='[email protected]',

suffix_trees/STree.py

@@ -219,14 +219,14 @@ def find_all(self, y):
                 if i == len(edge) and y != '':
                     pass
                 else:
-                    return []
+                    return {}
 
             node = node._get_transition_link(y[0])
             if not node:
-                return []
+                return {}
 
         leaves = node._get_leaves()
-        return [n.idx for n in leaves]
+        return {n.idx for n in leaves}
 
     def _edgeLabel(self, node, parent):
         """Helper method, returns the edge label between a node and it's parent"""
@@ -276,7 +276,7 @@ def _get_suffix_link(self):
     def _get_transition_link(self, suffix):
         return False if suffix not in self.transition_links else self.transition_links[suffix]
 
-    def _add_transition_link(self, snode, suffix=''):
+    def _add_transition_link(self, snode, suffix):
         self.transition_links[suffix] = snode
 
     def _has_transition(self, suffix):
@@ -291,7 +291,10 @@ def _traverse(self, f):
         f(self)
 
     def _get_leaves(self):
+        # Python <3.6 dicts don't perserve insertion order (and even after, we
+        # shouldn't rely on dicts perserving the order) therefore these can be
+        # out-of-order, so we return a set of leaves.
         if self.is_leaf():
-            return [self]
+            return {self}
         else:
-            return [x for n in self.transition_links.values() for x in n._get_leaves()]
+            return {x for n in self.transition_links.values() for x in n._get_leaves()}

suffix_trees/test/test_gen.py

@@ -42,4 +42,4 @@ def test_find_all_substring_true(self, data):
     @given(data())
     def test_find_all_substring_false(self, data):
         (string, substr) = data.draw(string_and_not_substring())
-        assert STree.STree(string).find_all(substr) == []
+        assert STree.STree(string).find_all(substr) == {}

suffix_trees/test/test_simple.py

@@ -19,4 +19,4 @@ def test_missing():
 def test_find():
     st = STree.STree("abcdefghab")
     assert st.find("abc") == 0
-    assert st.find_all("ab") == [0, 8]
+    assert st.find_all("ab") == {0, 8}