blob: 3b0b188834ef39ea6da55b86abb55515625aa604 [file] [log] [blame]
import re
from typing import Match, Optional, Sequence, Mapping
# match $identifier or ${identifier} and replace with value in env
# If this identifier is at the beginning of whitespace on a line
# and its value is a list then it is treated as
# block substitution by indenting to that depth and putting each element
# of the list on its own line
# if the identifier is on a line starting with non-whitespace and a list
# then it is comma separated ${,foo} will insert a comma before the list
# if this list is not empty and ${foo,} will insert one after.
class CodeTemplate:
# Python 2.7.5 has a bug where the leading (^[^\n\S]*)? does not work,
# workaround via appending another [^\n\S]? inside
substitution_str = r'(^[^\n\S]*[^\n\S]?)?\$([^\d\W]\w*|\{,?[^\d\W]\w*\,?})'
# older versions of Python have a bug where \w* does not work,
# so we need to replace with the non-shortened version [a-zA-Z0-9_]*
# https://bugs.python.org/issue18647
substitution_str = substitution_str.replace(r'\w', r'[a-zA-Z0-9_]')
substitution = re.compile(substitution_str, re.MULTILINE)
pattern: str
filename: str
@staticmethod
def from_file(filename: str) -> 'CodeTemplate':
with open(filename, 'r') as f:
return CodeTemplate(f.read(), filename)
def __init__(self, pattern: str, filename: str = "") -> None:
self.pattern = pattern
self.filename = filename
def substitute(self, env: Optional[Mapping[str, object]] = None, **kwargs: object) -> str:
if env is None:
env = {}
def lookup(v: str) -> object:
assert env is not None
return kwargs[v] if v in kwargs else env[v]
def indent_lines(indent: str, v: Sequence[object]) -> str:
return "".join([indent + l + "\n" for e in v for l in str(e).splitlines()]).rstrip()
def replace(match: Match[str]) -> str:
indent = match.group(1)
key = match.group(2)
comma_before = ''
comma_after = ''
if key[0] == "{":
key = key[1:-1]
if key[0] == ",":
comma_before = ', '
key = key[1:]
if key[-1] == ',':
comma_after = ', '
key = key[:-1]
v = lookup(key)
if indent is not None:
if not isinstance(v, list):
v = [v]
return indent_lines(indent, v)
elif isinstance(v, list):
middle = ', '.join([str(x) for x in v])
if len(v) == 0:
return middle
return comma_before + middle + comma_after
else:
return str(v)
return self.substitution.sub(replace, self.pattern)
if __name__ == "__main__":
c = CodeTemplate("""\
int foo($args) {
$bar
$bar
$a+$b
}
int commatest(int a${,stuff})
int notest(int a${,empty,})
""")
print(c.substitute(args=["hi", 8], bar=["what", 7],
a=3, b=4, stuff=["things...", "others"], empty=[]))