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+" vim: set sw=3 sts=3:
+
+" Awk indent script. It can handle multi-line statements and expressions.
+" It works up to the point where the distinction between correct/incorrect
+" and personal taste gets fuzzy. Drop me an e-mail for bug reports and
+" reasonable style suggestions.
+"
+" Bugs:
+" =====
+" - Some syntax errors may cause erratic indentation.
+" - Same for very unusual but syntacticly correct use of { }
+" - In some cases it's confused by the use of ( and { in strings constants
+" - This version likes the closing brace of a multiline pattern-action be on
+" character position 1 before the following pattern-action combination is
+" formatted
+
+" Author:
+" =======
+" Erik Janssen, ejanssen@itmatters.nl
+"
+" History:
+" ========
+" 26-04-2002 Got initial version working reasonably well
+" 29-04-2002 Fixed problems in function headers and max line width
+" Added support for two-line if's without curly braces
+" Fixed hang: 2011 Aug 31
+" 2022 April: b:undo_indent added by Doug Kearns
+
+" Only load this indent file when no other was loaded.
+if exists("b:did_indent")
+ finish
+endif
+
+let b:did_indent = 1
+
+setlocal indentexpr=GetAwkIndent()
+" Mmm, copied from the tcl indent program. Is this okay?
+setlocal indentkeys-=:,0#
+
+let b:undo_indent = "setl inde< indk<"
+
+" Only define the function once.
+if exists("*GetAwkIndent")
+ finish
+endif
+
+" This function contains a lot of exit points. It checks for simple cases
+" first to get out of the function as soon as possible, thereby reducing the
+" number of possibilities later on in the difficult parts
+
+function! GetAwkIndent()
+
+ " Find previous line and get its indentation
+ let prev_lineno = s:Get_prev_line( v:lnum )
+ if prev_lineno == 0
+ return 0
+ endif
+ let prev_data = getline( prev_lineno )
+ let ind = indent( prev_lineno )
+
+ " Increase indent if the previous line contains an opening brace. Search
+ " for this brace the hard way to prevent errors if the previous line is a
+ " 'pattern { action }' (simple check match on /{/ increases the indent then)
+
+ if s:Get_brace_balance( prev_data, '{', '}' ) > 0
+ return ind + shiftwidth()
+ endif
+
+ let brace_balance = s:Get_brace_balance( prev_data, '(', ')' )
+
+ " If prev line has positive brace_balance and starts with a word (keyword
+ " or function name), align the current line on the first '(' of the prev
+ " line
+
+ if brace_balance > 0 && s:Starts_with_word( prev_data )
+ return s:Safe_indent( ind, s:First_word_len(prev_data), getline(v:lnum))
+ endif
+
+ " If this line starts with an open brace bail out now before the line
+ " continuation checks.
+
+ if getline( v:lnum ) =~ '^\s*{'
+ return ind
+ endif
+
+ " If prev line seems to be part of multiline statement:
+ " 1. Prev line is first line of a multiline statement
+ " -> attempt to indent on first ' ' or '(' of prev line, just like we
+ " indented the positive brace balance case above
+ " 2. Prev line is not first line of a multiline statement
+ " -> copy indent of prev line
+
+ let continue_mode = s:Seems_continuing( prev_data )
+ if continue_mode > 0
+ if s:Seems_continuing( getline(s:Get_prev_line( prev_lineno )) )
+ " Case 2
+ return ind
+ else
+ " Case 1
+ if continue_mode == 1
+ " Need continuation due to comma, backslash, etc
+ return s:Safe_indent( ind, s:First_word_len(prev_data), getline(v:lnum))
+ else
+ " if/for/while without '{'
+ return ind + shiftwidth()
+ endif
+ endif
+ endif
+
+ " If the previous line doesn't need continuation on the current line we are
+ " on the start of a new statement. We have to make sure we align with the
+ " previous statement instead of just the previous line. This is a bit
+ " complicated because the previous statement might be multi-line.
+ "
+ " The start of a multiline statement can be found by:
+ "
+ " 1 If the previous line contains closing braces and has negative brace
+ " balance, search backwards until cumulative brace balance becomes zero,
+ " take indent of that line
+ " 2 If the line before the previous needs continuation search backward
+ " until that's not the case anymore. Take indent of one line down.
+
+ " Case 1
+ if prev_data =~ ')' && brace_balance < 0
+ while brace_balance != 0 && prev_lineno > 0
+ let prev_lineno = s:Get_prev_line( prev_lineno )
+ let prev_data = getline( prev_lineno )
+ let brace_balance=brace_balance+s:Get_brace_balance(prev_data,'(',')' )
+ endwhile
+ let ind = indent( prev_lineno )
+ else
+ " Case 2
+ if s:Seems_continuing( getline( prev_lineno - 1 ) )
+ let prev_lineno = prev_lineno - 2
+ let prev_data = getline( prev_lineno )
+ while prev_lineno > 0 && (s:Seems_continuing( prev_data ) > 0)
+ let prev_lineno = s:Get_prev_line( prev_lineno )
+ let prev_data = getline( prev_lineno )
+ endwhile
+ let ind = indent( prev_lineno + 1 )
+ endif
+ endif
+
+ " Decrease indent if this line contains a '}'.
+ if getline(v:lnum) =~ '^\s*}'
+ let ind = ind - shiftwidth()
+ endif
+
+ return ind
+endfunction
+
+" Find the open and close braces in this line and return how many more open-
+" than close braces there are. It's also used to determine cumulative balance
+" across multiple lines.
+
+function! s:Get_brace_balance( line, b_open, b_close )
+ let line2 = substitute( a:line, a:b_open, "", "g" )
+ let openb = strlen( a:line ) - strlen( line2 )
+ let line3 = substitute( line2, a:b_close, "", "g" )
+ let closeb = strlen( line2 ) - strlen( line3 )
+ return openb - closeb
+endfunction
+
+" Find out whether the line starts with a word (i.e. keyword or function
+" call). Might need enhancements here.
+
+function! s:Starts_with_word( line )
+ if a:line =~ '^\s*[a-zA-Z_0-9]\+\s*('
+ return 1
+ endif
+ return 0
+endfunction
+
+" Find the length of the first word in a line. This is used to be able to
+" align a line relative to the 'print ' or 'if (' on the previous line in case
+" such a statement spans multiple lines.
+" Precondition: only to be used on lines where 'Starts_with_word' returns 1.
+
+function! s:First_word_len( line )
+ let white_end = matchend( a:line, '^\s*' )
+ if match( a:line, '^\s*func' ) != -1
+ let word_end = matchend( a:line, '[a-z]\+\s\+[a-zA-Z_0-9]\+[ (]*' )
+ else
+ let word_end = matchend( a:line, '[a-zA-Z_0-9]\+[ (]*' )
+ endif
+ return word_end - white_end
+endfunction
+
+" Determine if 'line' completes a statement or is continued on the next line.
+" This one is far from complete and accepts illegal code. Not important for
+" indenting, however.
+
+function! s:Seems_continuing( line )
+ " Unfinished lines
+ if a:line =~ '\(--\|++\)\s*$'
+ return 0
+ endif
+ if a:line =~ '[\\,\|\&\+\-\*\%\^]\s*$'
+ return 1
+ endif
+ " if/for/while (cond) eol
+ if a:line =~ '^\s*\(if\|while\|for\)\s*(.*)\s*$' || a:line =~ '^\s*else\s*'
+ return 2
+ endif
+ return 0
+endfunction
+
+" Get previous relevant line. Search back until a line is that is no
+" comment or blank and return the line number
+
+function! s:Get_prev_line( lineno )
+ let lnum = a:lineno - 1
+ let data = getline( lnum )
+ while lnum > 0 && (data =~ '^\s*#' || data =~ '^\s*$')
+ let lnum = lnum - 1
+ let data = getline( lnum )
+ endwhile
+ return lnum
+endfunction
+
+" This function checks whether an indented line exceeds a maximum linewidth
+" (hardcoded 80). If so and it is possible to stay within 80 positions (or
+" limit num of characters beyond linewidth) by decreasing the indent (keeping
+" it > base_indent), do so.
+
+function! s:Safe_indent( base, wordlen, this_line )
+ let line_base = matchend( a:this_line, '^\s*' )
+ let line_len = strlen( a:this_line ) - line_base
+ let indent = a:base
+ if (indent + a:wordlen + line_len) > 80
+ " Simple implementation good enough for the time being
+ let indent = indent + 3
+ endif
+ return indent + a:wordlen
+endfunction