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-rw-r--r--runtime/indent/prolog.vim71
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+" vim: set sw=4 sts=4:
+" Language: Prolog
+" Maintainer: Gergely Kontra <kgergely@mcl.hu> (Invalid email address)
+" Doug Kearns <dougkearns@gmail.com>
+" Revised on: 2002.02.18. 23:34:05
+" Last change by: Takuya Fujiwara, 2018 Sep 23
+" 2022 April: b:undo_indent added by Doug Kearns
+
+" TODO:
+" checking with respect to syntax highlighting
+" ignoring multiline comments
+" detecting multiline strings
+
+" Only load this indent file when no other was loaded.
+if exists("b:did_indent")
+ finish
+endif
+
+let b:did_indent = 1
+
+setlocal indentexpr=GetPrologIndent()
+setlocal indentkeys-=:,0#
+setlocal indentkeys+=0%,-,0;,>,0)
+
+let b:undo_indent = "setl inde< indk<"
+
+" Only define the function once.
+"if exists("*GetPrologIndent")
+" finish
+"endif
+
+function! GetPrologIndent()
+ " Find a non-blank line above the current line.
+ let pnum = prevnonblank(v:lnum - 1)
+ " Hit the start of the file, use zero indent.
+ if pnum == 0
+ return 0
+ endif
+ let line = getline(v:lnum)
+ let pline = getline(pnum)
+
+ let ind = indent(pnum)
+ " Previous line was comment -> use previous line's indent
+ if pline =~ '^\s*%'
+ return ind
+ endif
+ " Previous line was the start of block comment -> +1 after '/*' comment
+ if pline =~ '^\s*/\*'
+ return ind + 1
+ endif
+ " Previous line was the end of block comment -> -1 after '*/' comment
+ if pline =~ '^\s*\*/'
+ return ind - 1
+ endif
+ " Check for clause head on previous line
+ if pline =~ '\%(:-\|-->\)\s*\(%.*\)\?$'
+ let ind = ind + shiftwidth()
+ " Check for end of clause on previous line
+ elseif pline =~ '\.\s*\(%.*\)\?$'
+ let ind = ind - shiftwidth()
+ endif
+ " Check for opening conditional on previous line
+ if pline =~ '^\s*\([(;]\|->\)'
+ let ind = ind + shiftwidth()
+ endif
+ " Check for closing an unclosed paren, or middle ; or ->
+ if line =~ '^\s*\([);]\|->\)'
+ let ind = ind - shiftwidth()
+ endif
+ return ind
+endfunction