hzhu212 · August 25, 2023 09:22 · Dec 11, 2020 · Nov 27, 2020 · Nov 22, 2020 · Nov 22, 2020
diff --git a/python_stream.md b/python_stream.md
@@ -51,6 +51,14 @@ class Stream(object):
             fun = lambda x: x
         self._iterable = (x for x in self._iterable if fun(x))
         return self
+
+    def stopwhen(self, fun):
+        def gen():
+            for x in self._iterable:
+                if fun(x):
+                    break
+                yield x
+        return Stream(gen())
 
     def reduce(self, fun, initial=None):
         return functools.reduce(fun, self._iterable, initial)

diff --git a/python_stream.md b/python_stream.md
@@ -55,7 +55,7 @@ class Stream(object):
     def reduce(self, fun, initial=None):
         return functools.reduce(fun, self._iterable, initial)
 
-    def for_each(self, fun):
+    def foreach(self, fun):
         for x in self._iterable:
             fun(x)
 

diff --git a/python_stream.md b/python_stream.md
@@ -1,3 +1,5 @@
+Python Stream object act like Java Stream, features include lazy calculating, slicing, chain-call etc.
+
 `stream.py`:
 
 ```python3

diff --git a/iterator_chain_call.md → python_stream.md b/iterator_chain_call.md → python_stream.md
@@ -1,8 +1,10 @@
 `stream.py`:
 
 ```python3
+import functools
 import itertools
 
+
 class Stream(object):
     """
     a stream object for chain-call
@@ -37,17 +39,34 @@ class Stream(object):
     def apply(self, fun, *args, **kwargs):
         self._iterable = (fun(x, *args, **kwargs) for x in self._iterable)
         return self
+
+    def map(self, fun):
+        self._iterable = (fun(x) for x in self._iterable)
+        return self
+
+    def filter(self, fun=None):
+        if fun is None:
+            fun = lambda x: x
+        self._iterable = (x for x in self._iterable if fun(x))
+        return self
+
+    def reduce(self, fun, initial=None):
+        return functools.reduce(fun, self._iterable, initial)
+
+    def for_each(self, fun):
+        for x in self._iterable:
+            fun(x)
 
-    def tolist(self):
-        return list(self)
+    def collect(self):
+        return list(self._iterable)
 ```
 
 Use cases:
 
 ```python
-In [1]: Stream(range(100)).skip(10).step(3).limit(10).apply(lambda x: x//3).tolist()                                                                                       
+In [1]: Stream(range(100)).skip(10).step(3).limit(10).map(lambda x: x//3).collect()                                                                                       
 Out[1]: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
 
-In [2]: Stream(range(100))[10:20:3].apply(lambda x: x+1).tolist()                                                                                                          
+In [2]: Stream(range(100))[10:20:3].map(lambda x: x+1).collect()                                                                                                          
 Out[2]: [11, 14, 17, 20]
 ```
diff --git a/iterator_chain_call.md b/iterator_chain_call.md
@@ -45,8 +45,8 @@ class Stream(object):
 Use cases:
 
 ```python
-In [15]: Stream(range(100)).skip(10).step(3).limit(10).apply(lambda x: x//3).tolist()                                                                                       
-Out[15]: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
+In [1]: Stream(range(100)).skip(10).step(3).limit(10).apply(lambda x: x//3).tolist()                                                                                       
+Out[1]: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
 
 In [2]: Stream(range(100))[10:20:3].apply(lambda x: x+1).tolist()                                                                                                          
 Out[2]: [11, 14, 17, 20]

diff --git a/iterator_chain_call.md b/iterator_chain_call.md
@@ -44,7 +44,7 @@ class Stream(object):
 
 Use cases:
 
-```ipython
+```python
 In [15]: Stream(range(100)).skip(10).step(3).limit(10).apply(lambda x: x//3).tolist()                                                                                       
 Out[15]: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
 

diff --git a/iterator_chain_call.md b/iterator_chain_call.md
@@ -44,7 +44,7 @@ class Stream(object):
 
 Use cases:
 
-```
+```ipython
 In [15]: Stream(range(100)).skip(10).step(3).limit(10).apply(lambda x: x//3).tolist()                                                                                       
 Out[15]: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
 

diff --git a/iterator_chain_call.md b/iterator_chain_call.md
@@ -0,0 +1,53 @@
+`stream.py`:
+
+```python3
+import itertools
+
+class Stream(object):
+    """
+    a stream object for chain-call
+    """
+    def __init__(self, iterable):
+        self._iterable = iterable
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return next(self._iterable)
+
+    def skip(self, n):
+        self._iterable = itertools.islice(self._iterable, n, None, 1)
+        return self
+
+    def limit(self, n):
+        self._iterable = itertools.islice(self._iterable, None, n, 1)
+        return self
+
+    def step(self, n):
+        self._iterable = itertools.islice(self._iterable, None, None, n)
+        return self
+
+    def __getitem__(self, slc):
+        if not isinstance(slc, slice):
+            raise ValueError(f'"[]" operator supports only slice object, but {slc!r} got')
+        self._iterable = itertools.islice(self._iterable, slc.start, slc.stop, slc.step)
+        return self
+
+    def apply(self, fun, *args, **kwargs):
+        self._iterable = (fun(x, *args, **kwargs) for x in self._iterable)
+        return self
+
+    def tolist(self):
+        return list(self)
+```
+
+Use cases:
+
+```
+In [15]: Stream(range(100)).skip(10).step(3).limit(10).apply(lambda x: x//3).tolist()                                                                                       
+Out[15]: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
+
+In [2]: Stream(range(100))[10:20:3].apply(lambda x: x+1).tolist()                                                                                                          
+Out[2]: [11, 14, 17, 20]
+```