97 lines
2.8 KiB
Python
97 lines
2.8 KiB
Python
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import re
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from typing import Mapping, Match, Optional, Sequence
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# match $identifier or ${identifier} and replace with value in env
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# If this identifier is at the beginning of whitespace on a line
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# and its value is a list then it is treated as
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# block substitution by indenting to that depth and putting each element
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# of the list on its own line
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# if the identifier is on a line starting with non-whitespace and a list
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# then it is comma separated ${,foo} will insert a comma before the list
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# if this list is not empty and ${foo,} will insert one after.
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class CodeTemplate:
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substitution_str = r"(^[^\n\S]*)?\$([^\d\W]\w*|\{,?[^\d\W]\w*\,?})"
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substitution = re.compile(substitution_str, re.MULTILINE)
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pattern: str
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filename: str
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@staticmethod
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def from_file(filename: str) -> "CodeTemplate":
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with open(filename) as f:
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return CodeTemplate(f.read(), filename)
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def __init__(self, pattern: str, filename: str = "") -> None:
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self.pattern = pattern
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self.filename = filename
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def substitute(
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self, env: Optional[Mapping[str, object]] = None, **kwargs: object
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) -> str:
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if env is None:
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env = {}
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def lookup(v: str) -> object:
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assert env is not None
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return kwargs[v] if v in kwargs else env[v]
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def indent_lines(indent: str, v: Sequence[object]) -> str:
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return "".join(
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[indent + l + "\n" for e in v for l in str(e).splitlines()]
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).rstrip()
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def replace(match: Match[str]) -> str:
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indent = match.group(1)
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key = match.group(2)
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comma_before = ""
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comma_after = ""
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if key[0] == "{":
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key = key[1:-1]
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if key[0] == ",":
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comma_before = ", "
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key = key[1:]
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if key[-1] == ",":
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comma_after = ", "
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key = key[:-1]
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v = lookup(key)
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if indent is not None:
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if not isinstance(v, list):
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v = [v]
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return indent_lines(indent, v)
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elif isinstance(v, list):
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middle = ", ".join([str(x) for x in v])
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if len(v) == 0:
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return middle
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return comma_before + middle + comma_after
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else:
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return str(v)
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return self.substitution.sub(replace, self.pattern)
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if __name__ == "__main__":
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c = CodeTemplate(
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"""\
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int foo($args) {
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$bar
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$bar
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$a+$b
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}
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int commatest(int a${,stuff})
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int notest(int a${,empty,})
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"""
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)
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print(
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c.substitute(
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args=["hi", 8],
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bar=["what", 7],
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a=3,
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b=4,
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stuff=["things...", "others"],
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empty=[],
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)
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)
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