{
    #$::RD_TRACE = 1;
    my (
	$context,      # line or group
	@sections,     # master data structure
	$section_head,
	$section_id,
	@lines,        # lines in each section
	$title,
	$author,
	$description,
	%lists,
	%patterns,
	%subs,         # validation subs
	@group,        # current group
	%groups,       # stored groups of fields
	$type,
	@options,
	$required,
	$list_var,
	$size,
	$maxlength,
	$rows,
	$cols,
    );
    $context = 'line';
}

form_spec: (list_def | description_def | validate_def | group_def | note | line)(s)
    {
	# grab the last section, if there is any
	if (@lines) {
	    push @sections,
		{
		    id   => $section_id,
		    head => $section_head,
		    lines => [ @lines ],
		};
	}
	
	$section_id = $item{identifier};
	$section_head = $item[3];
	@lines = ();
	$return = {
	    title    => $title,
	    author   => $author,
	    description => $description,
	    lists    => \%lists,
	    patterns => \%patterns,
	    subs     => \%subs,
	    groups   => \%groups,
	    sections => \@sections,
	}
    }

list_def: '!list' var_name (static_list | dynamic_list)
    { $lists{$item{var_name}} = [ @options ]; @options = () }

static_list: '{' /\s*/ option(s /\s*,\s*/) /,?/ /\s*/ '}'

dynamic_list: '&' <perl_codeblock>
    {
	warn "[Text::FormBuilder] Dynamic lists have been removed from the formspec grammar";
    }

description_def: '!description' block
    {
	warn "[Text::FormBuilder] Description redefined at input text line $thisline\n" if defined $description;
	$description = $item{block};
    }

validate_def: '!validate' var_name <perl_codeblock>
    { $subs{$item{var_name}} = eval "sub $item[3]" }

group_def: '!group' { $context = 'group' } var_name '{' field_line(s) '}' { $context = 'line' }
    { 
	#warn "$item{var_name} group; context $context\n"
	$groups{$item{var_name}} = [ @group ];
	@group = ();
    }

note: '!note' block  { push @lines, [ 'note', $item{block} ]; }


#TODO: allow \ escape for [] {} in these blocks

# curly-brace delimited block, that can contain properly
# nested curly braces, along with any other characters
# inner blocks return with the '{...}' so that nested
# blocks get the braces treated as literals
block: '{' <skip:''> block_content(s) '}' { join('', @{ $item[3] }) }
inner_block: '{' <skip:''> block_content(s) '}'  { '{' . join('', @{ $item[3] }) . '}' }
block_content: /[^\{\}]+?/ | inner_block

# square brace delimited block, that can contain properly
# nested square brackets, along with any other characters
# inner bracket blocks return with the '[...]' so that nested
# blocks get the braces treated as literals
bracket_block: '[' <skip:''> bracket_block_content(s) ']' { join('', @{ $item[3] }) }
inner_bracket_block: '[' <skip:''> bracket_block_content(s) ']' { '[' . join('', @{ $item[3] }) . ']'; }
bracket_block_content: /[^\[\]]+?/ | inner_bracket_block


# field lines are the subset of lines that are allowed in a !group directive
field_line: <skip:'[ \t]*'> ( field | comment | blank ) "\n"

line: <skip:'[ \t]*'> ( title | author | pattern_def | section_head | heading | group_field | field_group | unknown_directive | field | comment | blank ) "\n"

title: '!title' /.*/
    {
	warn "[Text::FormBuilder] Title redefined at input text line $thisline\n" if defined $title;
	$title = $item[2];
    }

author: '!author' /.*/
    {
	warn "[Text::FormBuilder] Author redefined at input text line $thisline\n" if defined $author;
	$author = $item[2];
    }

pattern_def: '!pattern' var_name pattern
    { $patterns{$item{var_name}} = $item{pattern} }

pattern: /.*/

section_head: '!section' identifier /.*/
    {
	#warn "starting section $item{identifier}\n";
	#warn "  with heading $item[3]\n" if $item[3];
	
	if (@lines) {
	    push @sections,
		{
		    id   => $section_id,
		    head => $section_head,
		    lines => [ @lines ],
		};
	}
	
	$section_id = $item{identifier};
	$section_head = $item[3];
	@lines = ();
    }

heading: '!head' /.*/    { push @lines, [ 'head', $item[2] ] }

group_field: '!field' group_name name label(?)
    { 
	push @lines, [ 'group', { name => $item{name}, label => $item{'label(?)'}[0], group => $item{group_name} } ];
    }

group_name: /%[A-Z_]+/

field_group: name label(?) group_type
    { 
	#warn "[$thisline] field $item{name} is $item{group_type}\n";
	push @lines, [ 'group', { name => $item{name}, label => $item{'label(?)'}[0], group => $item{group_type} } ];
    }

group_type: ':' var_name

# this is the real heart of the thing
field: name field_size(?) growable(?) label(?) hint(?) type(?) other(?) default(?) option_list(?) validate(?) comment(?)
    {
	my $field = {
	    name     => $item{name},
	    growable => $item{'growable(?)'}[0],
	    label    => $item{'label(?)'}[0],
	    comment  => $item{'hint(?)'}[0],
	    type     => $item{'type(?)'}[0],
	    other    => $item{'other(?)'}[0],
	    value    => $item{'default(?)'}[0],
	    list     => $list_var,
	    validate => $item{'validate(?)'}[0],
	    required => $required,
	};
	
	$$field{options} = [ @options ] if @options;
	
	$$field{rows} = $rows if defined $rows;
	$$field{cols} = $cols if defined $cols;
	$$field{size} = $size if defined $size;
	$$field{maxlength} = $maxlength if defined $maxlength;
	
	#warn "[$thisline] field $item{name}; context $context\n";
	if ($context eq 'group') {
	    push @group, $field;
	} else {
	    push @lines, [ 'field', $field ];
	}
	
	$type = undef;
	$required = undef;
	$list_var = undef;
	$size = undef;
	$rows = undef;
	$cols = undef;
	$maxlength = undef;
	@options = ();
	
	$field;
    }
    
name: identifier

var_name: /[A-Z_]+/

field_size: '[' ( row_col | size ) ']'

size: /\d+/ bang(?)
    { $maxlength = $item[1] if $item[2][0]; $size = $item[1] }

bang: '!'

row_col: /\d+/ /,\s*/ /\d+/
    { $rows = $item[1]; $cols = $item[3] }

growable: '*' limit(?) { $item{'limit(?)'}[0] || 1 }

limit: /\d+/

label: '|' (simple_multiword | quoted_string) { $item[2] }

hint: bracket_block

type: ':' builtin_field

builtin_field: /textarea|text|password|file|checkbox|radio|select|hidden|static/

other: '+' 'other' { 1 }

default: '=' (simple_multiword | quoted_string) { $item[2] }

# for simple multiword values not involving punctuation
simple_multiword: <skip:''> /\w[\w\t ]*/ { $item[2] }

# my attempt at a single-quoted, non-interpolating string
# where the backslash can escape literal single quotes
quoted_string: <skip:''> "'" /(\\'|[^'])*/ "'"
    { $item[3] =~ s/\\'/'/g; $item[3] }

option_list: options | list_var
    
options: '{' option(s /,/) '}'

list_var: /@[A-Z_]+/ { $list_var = $item[1] }

option: (simple_multiword | quoted_string) display_text(?)
    { push @options, { $item[1] => $item{'display_text(?)'}[0] } }

value: identifier

display_text: bracket_block


validate: '//' (optional_pattern | required_pattern)

optional_pattern: var_name '?'	{ $required = 0; $item[1] }

required_pattern: var_name { $required = 1; $item[1] }

comment: '#' /.*/
blank:

identifier: /\w+/

# skip unknown directives with a warning
unknown_directive: /\!\S*/ /.*/
    { warn "[Text::Formbuilder] Skipping unknown directive '$item[1]' at input text line $thisline\n"; }