Add some docs (#21)

README.md

@@ -19,6 +19,52 @@ stmdency, **sta**tement depen**dency** is a Python library for extracting depend
 python -m pip install --upgrade stmdency
 ```
 
+## Usage
+
+Let's say we have a Python script named  `test.py` with the following content:
+
+```python
+a = 1
+b = 2
+
+def bar():
+   b = a + 3
+   print(a, b)
+
+def foo():
+   bar(b)
+```
+
+We want to extract function `foo` and all its dependencies. `stmdency` can do this for us:
+
+```python
+from stmdency.extractor import Extractor
+
+with open("test.py", "r") as f:
+   source = f.read()
+   extractor = Extractor(source)
+   print(extractor.get_code("foo"))
+```
+
+The output will be:
+
+```python
+a = 1
+
+def bar():
+    b = a + 3
+    print(a, b)
+
+b = 2
+
+def foo():
+    bar(b)
+```
+
 ## Documentation
 
-The documentation host on read the doc and is available at [https://stmdency.readthedocs.io](https://stmdency.readthedocs.io).
+The documentation host read the doc and is available at [https://stmdency.readthedocs.io](https://stmdency.readthedocs.io).
+
+## Who is using stmdency?
+
+- [dolphinscheduler-sdk-python](https://github.com/apache/dolphinscheduler-sdk-python): Python API to manage Dolphinscheduler workflow by code, aka PyDolphinscheduler.

docs/index.rst

@@ -7,7 +7,7 @@ Stmdency's Documentation
 ========================
 
 Stmdency, **ST** ate **M** ents depen **DENCY**, a tool handling python statements' dependencies, can
-extract dependencies from python statements according to the given statement identifier.
+extract dependencies from Python statements according to the given statement identifier.
 
 Installation
 ------------
@@ -16,12 +16,25 @@ Stmdency can be installed from PyPI using pip:
 
 .. code-block:: bash
 
-   python -m pip install stmdency
+   python -m pip install --upgrade stmdency
 
 Usage
 -----
 
-Stmdency can be used as a python module(as a command line tool will comming soon).
+Stmdency can be used as a Python module(as a command line tool will coming soon).
+
+Extract Variable Dependencies
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Let's say we have a python code like below, we define a variable ``a`` and ``b`` and ``b`` depends on ``a``:
+
+.. code-block:: python
+
+   a = 1
+   b = a + 2
+
+Now we want to extract variable ``b`` and all of its dependencies, and we want to make sure our extracted code
+can be executed. Stmdency can help us to do this:
 
 .. code-block:: python
 
@@ -31,13 +44,40 @@ Stmdency can be used as a python module(as a command line tool will comming soon
    a = 1
    b = a + 2
    """
+
    extractor = Extractor(source=statement)
-   print(extractor.get_code("b"))
-   # a = 1
-   #
-   # b = a + 2
+   result = extractor.get_code("b")
+   print(result)
+
+The result will be:
+
+.. code-block:: python
+
+   a = 1
+
+   b = a + 2
+
 
-or for function name:
+Extract Function Dependencies
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Stmdency not only can extract variable dependencies, but also can extract function dependencies. Suppose we
+have the script below.
+
+.. code-block:: python
+
+   a = 1
+   b = 2
+
+   def bar():
+       b = a + 3
+       print(a, b)
+
+   def foo():
+       bar(b)
+
+Now we want to extract function ``foo`` and all of its dependencies, and we want to make our extracted code
+runnable.
 
 .. code-block:: python
 
@@ -54,16 +94,54 @@ or for function name:
    """
    extractor = Extractor(source=statement)
    print(extractor.get_code("foo"))
-   # a = 1
-   #
-   # b = 2
-   #
-   # def bar():
-   #     b = a + 3
-   #     print(a, b)
-   #
-   # def foo():
-   #     bar(b)
+   
+The result will be:
+
+.. code-block:: python
+
+   a = 1
+   
+   b = 2
+   
+   def bar():
+       b = a + 3
+       print(a, b)
+   
+   def foo():
+       bar(b)
+
+Python Code in File
+~~~~~~~~~~~~~~~~~~~
+
+As you can see, we use a string to represent the Python code in the above examples. But in most cases, our code
+is in a file. Stmdency can also handle this situation.
+
+First, we need to create a file named ``test.py`` and write the code below into it:
+
+.. code-block:: bash
+
+   cat <<EOF > test.py
+   a = 1
+   b = 2
+   
+   def bar():
+       b = a + 3
+       print(a, b)
+   
+   def foo():
+       bar(b)
+   EOF
+
+Then we can use the code below to extract function ``foo`` and all of its dependencies:
+
+.. code-block:: python
+
+   from stmdency.extractor import Extractor
+   
+   with open("test.py", "r") as f:
+       source = f.read()
+       extractor = Extractor(source)
+       print(extractor.get_code("foo"))
 
 Indices and tables
 ==================