# NEdit auto-indent and type-in macros for O'Caml.
# By Nathaniel Gray  <n8gray@caltech.edu>
# 5/21/2002
# Version 0.6 -- fixed to work in the presence of hard tabs.
#
# Drop me an e-mail if you use this stuff!  I suspect that nobody ever will...
#
# The type-in macro just automatically dedents '|' if it is typed as the
# first character on a line.  This follows the style of OCaml indentation that
# I've seen most often.  Note that it doesn't do this if the previous line
# also starts with a '|', since in that case the smart-indent macros should
# already have left the cursor aligned with the previous '|'.
#
# The auto-indent macro increases the indent if the last word (non-ws block) is
# in the $indent_words array.  It adds two extra characters if the current line
# begins with a |.

# INSTALLATION INSTRUCTIONS:
#   1. Put this file wherever you keep your NEdit macros.  I keep mine
#       in a directory called $HOME/nedit_macros
#   2. Start NEdit and go to 
#       Preferences | Default Settings | Auto Indent | Program Smart Indent...
#   3. Put this in the first text field (changing the file name if needed):
#       load_macro_file(getenv("HOME") "/nedit_macros/ocaml_indent_macros.nm")
#   4. Put this in the second text field:
#       return ocaml_indent( $1 )
#   5. Put this in the third text field:
#       ocaml_typein( $1, $2 )
#
# That should do it.  Hit "OK" and load an O'Caml file.  Don't forget to
# Save your preferences too!

# These macros increase the indentation after any line that ends with one of
# these words.  Dedents are basically impossible to figure out without a real 
# parser, so you have to do them manually.
$ocaml_indent_words["->"] = 1
$ocaml_indent_words["try"] = 1
$ocaml_indent_words["with"] = 1
$ocaml_indent_words["begin"] = 1
$ocaml_indent_words["do"] = 1
$ocaml_indent_words["="] = 1
$ocaml_indent_words["then"] = 1
$ocaml_indent_words["else"] = 1
$ocaml_indent_words["struct"] = 1
$ocaml_indent_words["sig"] = 1
$ocaml_indent_words["object"] = 1
$ocaml_indent_words["function"] = 1

$pipe_dedent = 2  # The number of columns to dedent '|' characters.  This is
                    # assumed to be less than one tab character.

# Type-in macro for dedenting | chars
define ocaml_typein
{
    # Only take action when | is typed
    if( $2 != "|" ) {
        return
    } else {
        # Corner cases that might cause trouble
        if( $line == 1 || $column < $pipe_dedent )
        {
            #t_print( "line or column too small: " $line " " $column "\n" )
            return
        }

        # Find out if it's the first char on the line
        beg_of_line = search("^\\s+", $1, "regex", "backward")
        if( $search_end < $1 )
        {
            #t_print( "not the first char: '" $search_end "' < '" $1 "'\n" )
            #t_print( "isfirst: " isfirst "\n" )
            return
        }
        #t_print( "Is the first char.  WS from " isfirst " to " $search_end \
        #         " and | is at " $1 "\n" )
        
        # Find out if there's a | starting the previous line
        beg_of_line2 = search("^", beg_of_line-1, "regex", "backward")
        isfirst2 = search("^\\s*\\|", beg_of_line-1, "regex", "backward")
        if( isfirst2 == beg_of_line2 )
        {
            # Don't adjust, smart indent already matched the prev. pipe
            #t_print( "Already matched by auto-indent\n" )
            return 
        }

        # back the | up $pipe_dedent spaces
        # try not to screw up if there are tabs
        insert_pos = $1
        str = "                "
        for( i = insert_pos-1; i >= insert_pos-$pipe_dedent; i-- ) {
            ch = get_character( i )
            if (ch == "\t") {
                # Replace the tab with spaces
                orig_cursor_pos = $cursor
                set_cursor_pos( i+1 )
                end_tab = $column
                set_cursor_pos( i )
                beg_tab = $column
                set_cursor_pos( orig_cursor_pos )
                tab_width = end_tab - beg_tab
                replace_range(i, i+1, substring(str, 0, tab_width))
                insert_pos += tab_width - 1
            } else if (ch != " ") {
                # Bail out on non-ws (shouldn't be possible, but...)
                return
            }
        }
        # Now delete $pipe_dedent spaces before the insert position
        replace_range(insert_pos-$pipe_dedent, insert_pos, "")
        #t_print( "Done it\n" )
    }
}

define ocaml_indent
{
    # Look backwards for the last chunk of non-whitespace.
    beg_of_line = search("^", $1, "regex", "backward")
    beg_word = search("(?:\\s|^)\\S+", $1, "regex", "backward")
    if (beg_word < 0 || beg_word < beg_of_line) {
        #t_print( "no last word\n" )
        return -1
    }
    end_word = min($search_end, $1)
    last_word = get_range( beg_word, end_word )
    if (search_string(last_word, "\\s", 0, "regex") >= 0)
        last_word = get_range( beg_word+1, end_word )

    if (!(last_word in $ocaml_indent_words)) {
        #t_print( "last word not in dict: " last_word "\n" )
        return -1
    }
    
    def_indent = measureIndent( $1 )
    i = def_indent + defaultIndent("default")
    if( get_character( startOfLine($1) + def_indent ) == "|" )
        i += $pipe_dedent
        
    return i
}