commit 195aa2f5f73e0cd9462afd4f21f3f0dac36bbc82 Author: Nick Mathewson nickm@torproject.org Date: Wed Sep 25 21:27:17 2019 -0400

annotate_ifdef_directives: generate paren-balanced expressions

This algorithm is not fully general, but it strikes a balance between efficiency, simplicity, and correctness. --- scripts/maint/annotate_ifdef_directives | 46 +++++++++++++++++++++++++++------ 1 file changed, 38 insertions(+), 8 deletions(-)

diff --git a/scripts/maint/annotate_ifdef_directives b/scripts/maint/annotate_ifdef_directives index b6bb147ce..f88dd4fdf 100755 --- a/scripts/maint/annotate_ifdef_directives +++ b/scripts/maint/annotate_ifdef_directives @@ -35,7 +35,41 @@ LINE_WIDTH=80 class Problem(Exception): pass

+def close_parens_needed(expr): + """Return the number of left-parentheses needed to make 'expr' + balanced. + """ + return expr.count("(") - expr.count(")") + +def truncate_expression(expr, new_width): + """Given a parenthesized C expression in 'expr', try to return a new + expression that is similar to 'expr', but no more than 'new_width' + characters long. + + Try to return an expression with balanced parentheses. + """ + if len(expr) <= new_width: + # The expression is already short enough. + return expr + + ellipsis = "..." + + # Start this at the minimum that we might truncate. + n_to_remove = len(expr) + len(ellipsis) - new_width + + # Try removing characters, one by one, until we get something where + # re-balancing the parentheses still fits within the limit. + while n_to_remove < len(expr): + truncated = expr[:-n_to_remove] + ellipsis + truncated += ")" * close_parens_needed(truncated) + if len(truncated) <= new_width: + return truncated + n_to_remove += 1 + + return ellipsis + def commented_line(fmt, argument, maxwidth=LINE_WIDTH): + """ Return fmt%argument, for use as a commented line. If the line would be longer than maxwidth, truncate argument. @@ -49,14 +83,10 @@ def commented_line(fmt, argument, maxwidth=LINE_WIDTH): if len(result) <= maxwidth: return result else: - # figure out how much we need to truncate by to fit the argument, - # plus an ellipsis. - ellipsis = "..." - result = fmt % (argument + ellipsis) - overrun = len(result) - maxwidth - truncated_argument = argument[:-overrun] + ellipsis - - result = fmt % truncated_argument + # How long can we let the argument be? Try filling in the + # format with an empty argument to find out. + max_arg_width = maxwidth - len(fmt % "") + result = fmt % truncate_expression(argument, max_arg_width) assert len(result) <= maxwidth return result