Added plugin files

Author: ikhomutov

zsh-auto-venv.plugin.zsh

@@ -0,0 +1,2 @@
+source ${0:A:h}/zsh-auto-venv.zsh
+

zsh-auto-venv.zsh

@@ -0,0 +1,49 @@
+function _activate() {
+    local venv_dir="$1"
+
+    # Don't reactivate an already activated virtual environment
+    if [[ -z "$VIRTUAL_ENV" || "$venv_dir" != "$$VIRTUAL_ENV)" ]]; then
+        source "$venv_dir/bin/activate"
+    fi
+}
+
+function _deactivate() {
+    if [[ -n "$VIRTUAL_ENV" ]]; then
+        deactivate
+    fi
+}
+
+# Gives the path to the nearest target file
+function _check_path()
+{
+    local check_dir="$1"
+    local check_file="$2"
+
+    if [[ -d "${check_dir}/$check_file" ]]; then
+        printf "${check_dir}/$check_file"
+        return
+    else
+        # Abort search at file system root or HOME directory (latter is a performance optimisation).
+        if [[ "$check_dir" = "/" || "$check_dir" = "$HOME" ]]; then
+            return
+        fi
+        _check_path "$(dirname "$check_dir")" "$check_file"
+    fi
+}
+
+function _check_venv()
+{
+    local venv_path="$(_check_path "$PWD" "venv")"
+
+    if [[ -n "$venv_path" ]]; then
+        _activate "$venv_path"
+        return
+    else
+        _deactivate
+    fi
+}
+
+autoload -Uz add-zsh-hook
+add-zsh-hook chpwd _check_venv
+
+_check_venv