| """ |
| Defines utilities useful for performing standard "configuration" style tasks. |
| """ |
| |
| import re |
| import os |
| |
| def configure_file(input_path, output_path, substitutions): |
| """configure_file(input_path, output_path, substitutions) -> bool |
| |
| Given an input and output path, "configure" the file at the given input path |
| by replacing variables in the file with those given in the substitutions |
| list. Returns true if the output file was written. |
| |
| The substitutions list should be given as a list of tuples (regex string, |
| replacement), where the regex and replacement will be used as in 're.sub' to |
| execute the variable replacement. |
| |
| The output path's parent directory need not exist (it will be created). |
| |
| If the output path does exist and the configured data is not different than |
| it's current contents, the output file will not be modified. This is |
| designed to limit the impact of configured files on build dependencies. |
| """ |
| |
| # Read in the input data. |
| f = open(input_path, "rb") |
| try: |
| data = f.read() |
| finally: |
| f.close() |
| |
| # Perform the substitutions. |
| for regex_string,replacement in substitutions: |
| regex = re.compile(regex_string) |
| data = regex.sub(replacement, data) |
| |
| # Ensure the output parent directory exists. |
| output_parent_path = os.path.dirname(os.path.abspath(output_path)) |
| if not os.path.exists(output_parent_path): |
| os.makedirs(output_parent_path) |
| |
| # If the output path exists, load it and compare to the configured contents. |
| if os.path.exists(output_path): |
| current_data = None |
| try: |
| f = open(output_path, "rb") |
| try: |
| current_data = f.read() |
| except: |
| current_data = None |
| f.close() |
| except: |
| current_data = None |
| |
| if current_data is not None and current_data == data: |
| return False |
| |
| # Write the output contents. |
| f = open(output_path, "wb") |
| try: |
| f.write(data) |
| finally: |
| f.close() |
| |
| return True |
