| # Copyright 2019 Google LLC |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # https://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """A formatter for code templates. |
| |
| Use the format_template function to render a code template. |
| """ |
| |
| import collections |
| import re |
| import string |
| |
| |
| def format_template(template, **kwargs): |
| """format_template acts like str.format, but uses ${name} instead of {name}. |
| |
| format_template acts like a str.format, except that instead of using { and } |
| to delimit substitutions, format_template uses ${name}. This simplifies |
| templates of source code in most languages, which frequently use "{" and "}", |
| but very rarely use "$". |
| |
| See the documentation for string.Template for details about |
| template strings and the format of substitutions. |
| |
| Arguments: |
| template: A template to format. |
| **kwargs: Keyword arguments for string.Template.substitute. |
| |
| Returns: |
| A formatted string. |
| """ |
| return template.substitute(**kwargs) |
| |
| |
| def parse_templates(text): |
| """Parses text into a namedtuple of templates. |
| |
| parse_templates will split its argument into templates by searching for lines |
| of the form: |
| |
| [punctuation] " ** " [name] " ** " [punctuation] |
| |
| e.g.: |
| |
| // ** struct_field_accessor ** //////// |
| |
| Leading and trailing punctuation is ignored, and [name] is used as the name |
| of the template. [name] should match [A-Za-z][A-Za-z0-9_]* -- that is, it |
| should be a valid ASCII Python identifier. |
| |
| Arguments: |
| text: The text to parse into templates. |
| |
| Returns: |
| A namedtuple object whose attributes are the templates from text. |
| """ |
| delimiter_re = re.compile(r"^\W*\*\* ([A-Za-z][A-Za-z0-9_]*) \*\*\W*$") |
| templates = {} |
| name = None |
| template = [] |
| def finish_template(template): |
| return string.Template("\n".join(template)) |
| |
| for line in text.splitlines(): |
| if delimiter_re.match(line): |
| if name: |
| templates[name] = finish_template(template) |
| name = delimiter_re.match(line).group(1) |
| template = [] |
| else: |
| template.append(line) |
| if name: |
| templates[name] = finish_template(template) |
| return collections.namedtuple("Templates", |
| list(templates.keys()))(**templates) |