Merge_history (from Explicable) and develop_steps (from Expression)

work together

pymath/calculus/expression.py

@@ -252,25 +252,32 @@ class Expression(Explicable):
 
     @classmethod
     def develop_steps(cls, tokenList):
-        """ From a list of tokens, it develops steps of each tokens """
-        tmp_steps = []
-        for t in tokenList:
-            try:
-                with Expression.tmp_render():
-                    steps = [i for i in t.explain()]
-                    if steps:
-                        tmp_steps.append(steps)
-                    else:
-                        tmp_steps.append([t])
-            except AttributeError:
-                tmp_steps.append([t])
+        """ 
+        From a list of tokens, it develops steps of each tokens and transpose it into steps respecting the stucture of the tokenList.
 
-        if max([len(i) for i in tmp_steps]) > 1:
-            tmp_steps = expand_list(tmp_steps)[:-1]
-            steps = [Expression(s) for s in tmp_steps]
-            return steps
+        It try to use 'explain' method for every tokens. After using this methode, tokens becom amnesiac.
+        
+        >>> e = Expression('1+2')
+        >>> e1 = e.simplify()
+        >>> f = Expression('3*4+5')
+        >>> f1 = f.simplify()
+        >>> Expression.develop_steps([e1, f1, op.add])
+        [< <class 'pymath.calculus.expression.Expression'> [1, 2, +, 3, 4, *, 5, +, +] >, < <class 'pymath.calculus.expression.Expression'> [3, 12, 5, +, +] >]
+        >>> e = Expression('1+2')
+        >>> e1 = e.simplify()
+        >>> f = Expression('3*4+5')
+        >>> f1 = f.simplify()
+        >>> g = Expression('6+7')
+        >>> g1 = g.simplify()
+        >>> Expression.develop_steps([e1, f1, op.add, g1, op.mul])
+        [< <class 'pymath.calculus.expression.Expression'> [1, 2, +, 3, 4, *, 5, +, +, 6, 7, +, *] >, < <class 'pymath.calculus.expression.Expression'> [3, 12, 5, +, +, 13, *] >]
+        """
+        with Expression.tmp_render():
+            tmp_steps = list(Explicable().merge_history(tokenList))
 
-        return []
+        tmp_steps = list(tmp_steps)[:-1]
+        steps = [Expression(s) for s in tmp_steps]
+        return steps
 
     @classmethod
     def isExpression(cls, other):