1 files changed, 190 insertions, 0 deletions
diff --git a/runtime/indent/occam.vim b/runtime/indent/occam.vim
new file mode 100644
index 0000000..673940a
--- /dev/null
+++ b/runtime/indent/occam.vim
@@ -0,0 +1,190 @@
+" Vim indent file
+" Language:	occam
+" Maintainer:	Mario Schweigler <ms44@kent.ac.uk> (Invalid email address)
+" 		Doug Kearns <dougkearns@gmail.com>
+" Last Change:	2022 Apr 06
+
+" Only load this indent file when no other was loaded.
+if exists("b:did_indent")
+  finish
+endif
+let b:did_indent = 1
+
+"{{{  Settings
+" Set the occam indent function
+setlocal indentexpr=GetOccamIndent()
+" Indent after new line and after initial colon
+setlocal indentkeys=o,O,0=:
+"}}}
+
+let b:undo_indent = "setl inde< indk<"
+
+" Only define the function once
+if exists("*GetOccamIndent")
+  finish
+endif
+let s:keepcpo= &cpo
+set cpo&vim
+
+"{{{  Indent definitions
+" Define carriage return indent
+let s:FirstLevelIndent = '^\C\s*\(IF\|ALT\|PRI\s\+ALT\|PAR\|SEQ\|PRI\s\+PAR\|WHILE\|VALOF\|CLAIM\|FORKING\)\>\|\(--.*\)\@<!\(\<PROC\>\|??\|\<CASE\>\s*\(--.*\)\=\_$\)'
+let s:FirstLevelNonColonEndIndent = '^\C\s*PROTOCOL\>\|\(--.*\)\@<!\<\(\(CHAN\|DATA\)\s\+TYPE\|FUNCTION\)\>'
+let s:SecondLevelIndent = '^\C\s*\(IF\|ALT\|PRI\s\+ALT\)\>\|\(--.*\)\@<!?\s*\<CASE\>\s*\(--.*\)\=\_$'
+let s:SecondLevelNonColonEndIndent = '\(--.*\)\@<!\<\(CHAN\|DATA\)\s\+TYPE\>'
+
+" Define colon indent
+let s:ColonIndent = '\(--.*\)\@<!\<PROC\>'
+let s:ColonNonColonEndIndent = '^\C\s*PROTOCOL\>\|\(--.*\)\@<!\<\(\(CHAN\|DATA\)\s\+TYPE\|FUNCTION\)\>'
+
+let s:ColonEnd = '\(--.*\)\@<!:\s*\(--.*\)\=$'
+let s:ColonStart = '^\s*:\s*\(--.*\)\=$'
+
+" Define comment
+let s:CommentLine = '^\s*--'
+"}}}
+
+"{{{  function GetOccamIndent()
+" Auxiliary function to get the correct indent for a line of occam code
+function GetOccamIndent()
+
+  " Ensure magic is on
+  let save_magic = &magic
+  setlocal magic
+
+  " Get reference line number
+  let linenum = prevnonblank(v:lnum - 1)
+  while linenum > 0 && getline(linenum) =~ s:CommentLine
+    let linenum = prevnonblank(linenum - 1)
+  endwhile
+
+  " Get current indent
+  let curindent = indent(linenum)
+
+  " Get current line
+  let line = getline(linenum)
+
+  " Get previous line number
+  let prevlinenum = prevnonblank(linenum - 1)
+  while prevlinenum > 0 && getline(prevlinenum) =~ s:CommentLine
+    let prevlinenum = prevnonblank(prevlinenum - 1)
+  endwhile
+
+  " Get previous line
+  let prevline = getline(prevlinenum)
+
+  " Colon indent
+  if getline(v:lnum) =~ s:ColonStart
+
+    let found = 0
+
+    while found < 1
+
+      if line =~ s:ColonStart
+	let found = found - 1
+      elseif line =~ s:ColonIndent || (line =~ s:ColonNonColonEndIndent && line !~ s:ColonEnd)
+	let found = found + 1
+      endif
+
+      if found < 1
+	let linenum = prevnonblank(linenum - 1)
+	if linenum > 0
+	  let line = getline(linenum)
+	else
+	  let found = 1
+	endif
+      endif
+
+    endwhile
+
+    if linenum > 0
+      let curindent = indent(linenum)
+    else
+      let colonline = getline(v:lnum)
+      let tabstr = ''
+      while strlen(tabstr) < &tabstop
+	let tabstr = ' ' . tabstr
+      endwhile
+      let colonline = substitute(colonline, '\t', tabstr, 'g')
+      let curindent = match(colonline, ':')
+    endif
+
+    " Restore magic
+    if !save_magic|setlocal nomagic|endif
+
+    return curindent
+  endif
+
+  if getline(v:lnum) =~ '^\s*:'
+    let colonline = getline(v:lnum)
+    let tabstr = ''
+    while strlen(tabstr) < &tabstop
+      let tabstr = ' ' . tabstr
+    endwhile
+    let colonline = substitute(colonline, '\t', tabstr, 'g')
+    let curindent = match(colonline, ':')
+
+    " Restore magic
+    if !save_magic|setlocal nomagic|endif
+
+    return curindent
+  endif
+
+  " Carriage return indenat
+  if line =~ s:FirstLevelIndent || (line =~ s:FirstLevelNonColonEndIndent && line !~ s:ColonEnd)
+	\ || (line !~ s:ColonStart && (prevline =~ s:SecondLevelIndent
+	\ || (prevline =~ s:SecondLevelNonColonEndIndent && prevline !~ s:ColonEnd)))
+    let curindent = curindent + shiftwidth()
+
+    " Restore magic
+    if !save_magic|setlocal nomagic|endif
+
+    return curindent
+  endif
+
+  " Commented line
+  if getline(prevnonblank(v:lnum - 1)) =~ s:CommentLine
+
+    " Restore magic
+    if !save_magic|setlocal nomagic|endif
+
+    return indent(prevnonblank(v:lnum - 1))
+  endif
+
+  " Look for previous second level IF / ALT / PRI ALT
+  let found = 0
+
+  while !found
+
+    if indent(prevlinenum) == curindent - shiftwidth()
+      let found = 1
+    endif
+
+    if !found
+      let prevlinenum = prevnonblank(prevlinenum - 1)
+      while prevlinenum > 0 && getline(prevlinenum) =~ s:CommentLine
+	let prevlinenum = prevnonblank(prevlinenum - 1)
+      endwhile
+      if prevlinenum == 0
+	let found = 1
+      endif
+    endif
+
+  endwhile
+
+  if prevlinenum > 0
+    if getline(prevlinenum) =~ s:SecondLevelIndent
+      let curindent = curindent + shiftwidth()
+    endif
+  endif
+
+  " Restore magic
+  if !save_magic|setlocal nomagic|endif
+
+  return curindent
+
+endfunction
+"}}}
+
+let &cpo = s:keepcpo
+unlet s:keepcpo