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# Copyright 2020 The Pigweed Authors
#
# 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.
"""Defines a class used to write code to an output buffer."""
from typing import List
class OutputFile:
"""A buffer to which data is written.
Example:
```
output = Output("hello.c")
output.write_line('int main(void) {')
with output.indent():
output.write_line('printf("Hello, world");')
output.write_line('return 0;')
output.write_line('}')
print(output.content())
```
Produces:
```
int main(void) {
printf("Hello, world");
return 0;
}
```
"""
INDENT_WIDTH = 2
def __init__(self, filename: str):
self._filename: str = filename
self._content: List[str] = []
self._indentation: int = 0
def write_line(self, line: str = '') -> None:
if line:
self._content.append(' ' * self._indentation)
self._content.append(line)
self._content.append('\n')
def indent(
self,
amount: int = INDENT_WIDTH,
) -> 'OutputFile._IndentationContext':
"""Increases the indentation level of the output."""
return self._IndentationContext(self, amount)
def name(self) -> str:
return self._filename
def content(self) -> str:
return ''.join(self._content)
class _IndentationContext:
"""Context that increases the output's indentation when it is active."""
def __init__(self, output: 'OutputFile', amount: int):
self._output = output
self._amount: int = amount
def __enter__(self):
self._output._indentation += self._amount
def __exit__(self, typ, value, traceback):
self._output._indentation -= self._amount
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