Add python virtual env support

_powerline_config.lua.sample

@@ -50,4 +50,10 @@ plc_git_conflictSymbol = "!"
 --plc_prompt_gitSymbol = "GIT"
 
 -- OPTIONAL. npm Symbol used in the NPM segment as visual indicator.
---plc_npm_npmSymbol = "NPM"
+--plc_npm_npmSymbol = "NPM"
+
+-- OPTIONAL. Snake Symbol used in the Python segment as visual indicator.
+-- plc_python_pythonSymbol = "🐍"
+
+-- REQUIRED. Only show virtual env in directories which contain a .py file
+plc_python_alwaysShow = false

powerline_python_venv.lua

@@ -0,0 +1,87 @@
+---
+ -- get the virtual env variable
+---
+local function get_virtual_env(env_var)
+
+    local venv_path = false
+    -- return the folder name of the current virtual env, or false
+    local function get_virtual_env_var(var)
+        env_path = clink.get_env(var)
+        if env_path then
+            return string.match(env_path, "[^\\/:]+$")
+        else
+            return false
+        end
+    end
+
+    local venv = get_virtual_env_var(env_var) or get_virtual_env_var('VIRTUAL_ENV') or get_virtual_env_var('CONDA_DEFAULT_ENV') or false
+    return venv
+end
+
+---
+ -- check for python files in current directory
+---
+local function get_py_files(path)
+    local function pathname(path)
+        local prefix = ""
+        local i = path:find("[\\/:][^\\/:]*$")
+        if i then
+                prefix = path:sub(1, i-1)
+        end
+        return prefix
+    end
+
+    local function has_py_files(dir)
+        local pyfile = clink.match_files("*.py", dir)
+        return pyfile
+    end
+
+    if not path or path == '.' then path = clink.get_cwd() end
+
+    dir = pathname(path)
+
+    files = has_py_files(dir) > 0
+    return files
+end
+
+-- * Segment object with these properties:
+---- * isNeeded: sepcifies whether a segment should be added or not. For example: no Git segment is needed in a non-git folder
+---- * text
+---- * textColor: Use one of the color constants. Ex: colorWhite
+---- * fillColor: Use one of the color constants. Ex: colorBlue
+local segment = {
+    isNeeded = false,
+    text = "",
+    textColor = colorWhite,
+    fillColor = colorCyan
+}
+---
+-- Sets the properties of the Segment object, and prepares for a segment to be added
+---
+local function init()
+    if plc_python_virtualEnvVariable then
+        segment.isNeeded = get_virtual_env(plc_python_virtualEnvVariable)
+    else
+        segment.isNeeded = get_virtual_env()
+    end
+
+    if not plc_python_alwaysShow and not get_py_files() then segment.isNeeded = false end
+
+    if segment.isNeeded then
+        if plc_python_pythonSymbol then
+            segment.text = " "..plc_python_pythonSymbol.." ["..segment.isNeeded.."] "
+        else
+            segment.text = " ["..segment.isNeeded.."] "
+        end
+    end
+end
+
+local function addAddonSegment()
+    init()
+    if segment.isNeeded then
+        addSegment(segment.text, segment.textColor, segment.fillColor)
+    end
+end
+
+-- register the filters
+clink.prompt.register_filter(addAddonSegment, 59)