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writer.rb
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writer.rb
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# -*- encoding: utf-8 -*-
require 'rdf'
require 'strscan' unless defined?(StringScanner)
require "ostruct"
require 'unicode/types'
##
# Serialize ruleset back to EBNF
module EBNF
class Writer
LINE_LENGTH = 80
LINE_LENGTH_HTML = 200
# UNICODE escape names
# From https://en.wikipedia.org/wiki/List_of_Unicode_characters
UNICODE_ESCAPE_NAMES = {
0x00 => 'null',
0x01 => 'start of heading',
0x02 => 'start of text',
0x03 => 'end of text',
0x04 => 'end of transmission',
0x05 => 'enquiry',
0x06 => 'acknowledge',
0x07 => 'bell',
0x08 => 'backspace',
0x09 => 'horizontal tab',
0x0A => 'new line',
0x0B => 'vertical tab',
0x0C => 'form feed',
0x0D => 'carriage return',
0x0E => 'shift out',
0x0F => 'shift in',
0x10 => 'data link escape',
0x11 => 'device control 1',
0x12 => 'device control 2',
0x13 => 'device control 3',
0x14 => 'device control 4',
0x15 => 'negative acknowledge',
0x16 => 'synchronous idle',
0x17 => 'end of trans. block',
0x18 => 'cancel',
0x19 => 'end of medium',
0x1A => 'substitute',
0x1B => 'escape',
0x1C => 'file separator',
0x1D => 'group separator',
0x1E => 'record separator',
0x1F => 'unit separator',
0x20 => 'space',
0x22 => 'dquote',
0x27 => 'apos',
0x2F => 'solidus',
0x5C => 'reverse solidus',
0x60 => 'grave',
0x7F => 'delete',
0x80 => 'padding character',
0x81 => 'high octet preset',
0x82 => 'break permitted here',
0x83 => 'no break here',
0x84 => 'index',
0x85 => 'next line',
0x86 => 'start of selected area',
0x87 => 'end of selected area',
0x88 => 'character tabulation set',
0x89 => 'character tabulation with justification',
0x8A => 'line tabulation set',
0x8B => 'partial line forward',
0x8C => 'partial line backward',
0x8D => 'reverse line feed',
0x8E => 'single-shift two',
0x8F => 'single-shift three',
0x90 => 'device control string',
0x91 => 'private use 1',
0x92 => 'private use 2',
0x93 => 'set transmit state',
0x94 => 'cancel character',
0x95 => 'message waiting',
0x96 => 'start of protected area',
0x97 => 'end of protected area',
0x98 => 'start of string',
0x99 => 'single graphic character introducer',
0x9A => 'single character intro introducer',
0x9B => 'control sequence introducer',
0x9C => 'string terminator',
0x9D => 'operating system command',
0x9E => 'private message',
0x9F => 'application program command',
}
##
# Format rules to a String
#
# @param [Array<Rule>] rules
# @param [:abnf, :ebnf, :isoebnf] format (:ebnf)
# @return [Object]
def self.string(*rules, format: :ebnf)
require 'stringio' unless defined?(StringIO)
buf = StringIO.new
write(buf, *rules, format: format)
buf.string
end
##
# Format rules to $stdout
#
# @param [Array<Rule>] rules
# @param [:abnf, :ebnf, :isoebnf] format (:ebnf)
# @return [Object]
def self.print(*rules, format: :ebnf)
write($stdout, *rules, format: format)
end
##
# Write formatted rules to an IO like object
#
# @param [Object] out
# @param [Array<Rule>] rules
# @param [:abnf, :ebnf, :isoebnf] format (:ebnf)
# @return [Object]
def self.write(out, *rules, format: :ebnf)
Writer.new(rules, out: out, format: format)
end
##
# Write formatted rules to an IO like object as HTML
#
# @param [Array<Rule>] rules
# @param [:abnf, :ebnf, :isoebnf] format (:ebnf)
# @param [Boolean] validate (false) validate generated HTML.
# @return [Object]
def self.html(*rules, format: :ebnf, validate: false)
require 'stringio' unless defined?(StringIO)
buf = StringIO.new
Writer.new(rules, out: buf, html: true, format: format, validate: validate)
buf.string
end
##
# @param [Array<Rule>] rules
# @param [:abnf, :ebnf, :isoebnf] format (:ebnf)
# @param [Boolean] html (false) generate HTML output
# @param [Boolean] validate (false) validate generated HTML.
# @param [Hash{Symbol => Object}] options
# @param [#write] out ($stdout)
def initialize(rules, out: $stdout, html: false, format: :ebnf, validate: false, **options)
@options = options.merge(html: html)
return if rules.empty?
# Determine max LHS length
format_meth = "format_#{format}".to_sym
max_id = rules.max_by {|r| r.id.to_s.length}.id.to_s.length
max_sym = rules.max_by {|r| r.sym.to_s.length}.sym.to_s.length
lhs_length = max_sym + 1
lhs_fmt = case format
when :abnf then "%<sym>-#{max_sym}s = "
when :ebnf then "%<sym>-#{max_sym}s ::= "
when :isoebnf then "%<sym>-#{max_sym}s = "
end
if format == :ebnf && max_id > 0
lhs_fmt = "%<id>-#{max_id+2}s " + lhs_fmt
lhs_length += max_id + 3
end
rhs_length = (html ? LINE_LENGTH_HTML : LINE_LENGTH) - lhs_length
if html
# Output as formatted HTML
begin
require 'erubis'
require 'htmlentities'
@coder = HTMLEntities.new
eruby = Erubis::Eruby.new(ERB_DESC)
formatted_rules = rules.map do |rule|
if rule.kind == :terminals || rule.kind == :pass
OpenStruct.new(id: ("@#{rule.kind}"),
class: :declaration,
sym: rule.kind,
assign: nil,
formatted: (
rule.kind == :terminals ?
"<strong># Productions for terminals</strong>" :
self.send(format_meth, rule.expr)))
else
formatted_expr = self.send(format_meth, rule.expr)
# Measure text without markup
formatted_expr_text = formatted_expr.gsub(%r{</?\w+[^>]*>}, '')
if formatted_expr_text.length > rhs_length && (format != :abnf || rule.alt?)
lines = []
# Can only reasonably split apart alts
self.send(format_meth, rule.expr, sep: "--rule-extensions--").
split(/\s*--rule-extensions--\s*/).each_with_index do |formatted, ndx|
assign = case format
when :ebnf
formatted.sub!(%r{\s*<code[^>]*>\|</code>\s*}, '')
(ndx > 0 ? (rule.alt? ? '<code class="grammar-alt">|</code>' : '') : '::=')
when :abnf
formatted.sub!(%r{\s*<code[^>]>/</code>\s*}, '')
(ndx > 0 ? '<code class="grammar-alt">=/</code>' : '=')
else
formatted.sub!(%r{\s*<code[^>]>\|</code>\s*}, '')
(ndx > 0 ? (rule.alt? ? '<code class="grammar-alt">|</code>' : '') : '=')
end
lines << OpenStruct.new(id: ((ndx == 0 ? "[#{rule.id}]" : "") if rule.id),
sym: (rule.sym if ndx == 0 || format == :abnf),
class: :production,
assign: assign,
formatted: formatted)
end
if format == :isoebnf
lines << OpenStruct.new(assign: ';')
end
lines
else
OpenStruct.new(id: ("[#{rule.id}]" if rule.id),
class: :production,
sym: rule.sym,
assign: (format == :ebnf ? '::=' : '='),
formatted: (formatted_expr + (format == :isoebnf ? ' ;' : '')))
end
end
end.flatten
html_result = eruby.evaluate(format: format, rules: formatted_rules)
if validate
begin
require 'nokogiri'
# Validate the output HTML
doc = ::Nokogiri::HTML5("<!DOCTYPE html>" + html_result, max_errors: 10)
raise EncodingError, "Errors found in generated HTML:\n " +
doc.errors.map(&:to_s).join("\n ") unless doc.errors.empty?
rescue LoadError, NoMethodError
# Skip
end
end
out.write html_result
return
rescue LoadError
$stderr.puts "Generating HTML requires erubis and htmlentities gems to be loaded"
end
end
# Format each rule, considering the available rhs size
rules.each do |rule|
buffer = if rule.pass?
"\n%-#{lhs_length-2}s " % "@pass"
elsif rule.kind == :terminals
"\n%-#{lhs_length-2}s" % "@terminals"
else
lhs_fmt % {id: "[#{rule.id}]", sym: rule.sym}
end
formatted_expr = self.send(format_meth, rule.expr)
if formatted_expr.length > rhs_length && (format != :abnf || rule.alt?)
if format == :abnf
# No whitespace, use =/
self.send(format_meth, rule.expr, sep: "--rule-extensions--").
split(/\s*--rule-extensions--\s*/).each_with_index do |formatted, ndx|
if ndx > 0
buffer << "\n" + lhs_fmt.sub('= ', '=/') % {id: "[#{rule.id}]", sym: rule.sym}
end
buffer << formatted.sub(/\s*\/\s*/, '')
end
else
# Space out past "= "
buffer << self.send(format_meth, rule.expr, sep: ("\n" + " " * (lhs_length + (rule.alt? ? 2 : 4) - (format == :ebnf ? 0 : 2))))
buffer << ("\n" + " " * (lhs_length) + ';') if format == :isoebnf
end
else
buffer << formatted_expr + (format == :isoebnf ? ' ;' : '')
end
buffer << "\n\n" if [:terminals, :pass].include?(rule.kind)
out.puts(buffer)
end
end
protected
##
# W3C EBNF Formatters
##
# Format the expression part of a rule
def format_ebnf(expr, sep: nil, embedded: false)
return (@options[:html] ? %(<a href="#grammar-production-#{@coder.encode expr}">#{@coder.encode expr}</a>) : expr.to_s) if expr.is_a?(Symbol)
if expr.is_a?(String)
return expr.length == 1 ?
format_ebnf_char(expr) :
format_ebnf_string(expr, expr.include?('"') ? "'" : '"')
end
parts = {
alt: (@options[:html] ? %(<code class="grammar-alt">|</code> ) : "| "),
diff: (@options[:html] ? %(<code class="grammar-diff">-</code> ) : "- "),
star: (@options[:html] ? %(<code class="grammar-star">*</code>) : "*"),
plus: (@options[:html] ? %(<code class="grammar-plus">+</code>) : "+"),
opt: (@options[:html] ? %(<code class="grammar-opt">?</code>) : "?")
}
lparen = (@options[:html] ? %[<code class="grammar-paren">(</code>] : "(")
rparen = (@options[:html] ? %[<code class="grammar-paren">)</code>] : ")")
case expr.first
when :istr
# Looses fidelity, but, oh well ...
format_ebnf(expr.last, embedded: true)
when :alt, :diff
this_sep = (sep ? sep : " ") + parts[expr.first.to_sym]
res = expr[1..-1].map {|e| format_ebnf(e, embedded: true)}.join(this_sep)
embedded ? (lparen + res + rparen) : res
when :star, :plus, :opt
char = parts[expr.first.to_sym]
r = format_ebnf(expr[1], embedded: true)
"#{r}#{char}"
when :hex
escape_ebnf_hex(expr.last[2..-1].hex.chr(Encoding::UTF_8))
when :range
format_ebnf_range(expr.last)
when :seq
this_sep = (sep ? sep : " ")
res = expr[1..-1].map do |e|
format_ebnf(e, embedded: true)
end.join(this_sep)
embedded ? (lparen + res + rparen) : res
when :rept
# Expand repetition
min, max, value = expr[1..-1]
if min == 0 && max == 1
format_ebnf([:opt, value], sep: sep, embedded: embedded)
elsif min == 0 && max == '*'
format_ebnf([:star, value], sep: sep, embedded: embedded)
elsif min == 1 && max == '*'
format_ebnf([:plus, value], sep: sep, embedded: embedded)
else
val2 = [:seq]
while min > 0
val2 << value
min -= 1
max -= 1 unless max == '*'
end
if max == '*'
val2 << [:star, value]
else
opt = nil
while max > 0
opt = [:opt, opt ? [:seq, value, opt] : value]
max -= 1
end
val2 << opt if opt
end
format_ebnf(val2, sep: sep, embedded: embedded)
end
else
raise "Unknown operator: #{expr.first}"
end
end
# Format a single-character string, prefering hex for non-main ASCII
def format_ebnf_char(c)
case c.ord
when (0x21) then (@options[:html] ? %("<code class="grammar-literal">#{@coder.encode c}</code>") : %{"#{c}"})
when 0x22 then (@options[:html] ? %('<code class="grammar-literal">"</code>') : %{'"'})
when (0x23..0x7e) then (@options[:html] ? %("<code class="grammar-literal">#{@coder.encode c}</code>") : %{"#{c}"})
when (0x80..0xFFFD) then (@options[:html] ? %("<code class="grammar-literal">#{@coder.encode c}</code>") : %{"#{c}"})
else escape_ebnf_hex(c)
end
end
# Format a range
def format_ebnf_range(string)
lbrac = (@options[:html] ? %(<code class="grammar-brac">[</code>) : "[")
rbrac = (@options[:html] ? %(<code class="grammar-brac">]</code>) : "]")
buffer = lbrac
s = StringScanner.new(string)
while !s.eos?
case
when s.scan(/\A[!"\u0024-\u007e]+/)
buffer << (@options[:html] ? %(<code class="grammar-literal">#{@coder.encode s.matched}</code>) : s.matched)
when s.scan(/\A#x\h+/)
buffer << escape_ebnf_hex(s.matched[2..-1].hex.chr(Encoding::UTF_8))
else
buffer << escape_ebnf_hex(s.getch)
end
end
buffer + rbrac
end
# Escape a string, using as many UTF-8 characters as possible
def format_ebnf_string(string, quote = '"')
string.each_char do |c|
case c.ord
when 0x00..0x19, quote.ord
raise RangeError, "cannot format #{string.inspect} as an EBNF String: #{c.inspect} is out of range" unless
ISOEBNF::TERMINAL_CHARACTER.match?(c)
end
end
res = @options[:html] ? %(<code class="grammar-literal">#{@coder.encode(string)}</code>) : string
res = "#{quote}#{res}#{quote}"
end
def escape_ebnf_hex(u)
fmt = case u.ord
when 0x0000..0x00ff then "#x%02X"
when 0x0100..0xffff then "#x%04X"
else "#x%08X"
end
char = fmt % u.ord
if @options[:html]
char = if UNICODE_ESCAPE_NAMES.include?(u.ord)
%(<abbr title="#{UNICODE_ESCAPE_NAMES[u.ord]}">#{char}</abbr>)
elsif ([::Unicode::Types.of(u)] - %w(Control Private-use Surrogate Noncharacter Reserved)).empty?
%(<abbr title="unicode '#{@coder.encode u}'">#{char}</abbr>)
else
uni_esc = "U+%04X" % u.ord
%(<abbr title="unicode #{uni_esc}">#{char}</abbr>)
end
%(<code class="grammar-char-escape">#{char}</code>)
else
char
end
end
##
# ABNF Formatters
##
# Format the expression part of a rule
def format_abnf(expr, sep: nil, embedded: false, sensitive: true)
return (@options[:html] ? %(<a href="#grammar-production-#{@coder.encode expr}">#{@coder.encode expr}</a>) : expr.to_s) if expr.is_a?(Symbol)
if expr.is_a?(String)
if expr.length == 1
return format_abnf_char(expr)
elsif expr.start_with?('%')
# Already encoded
return expr
elsif expr =~ /"/
# Split into segments
segments = expr.split('"')
return format_abnf_char(expr) if segments.empty?
seq = segments.inject([]) {|memo, s| memo.concat([[:hex, "#x22"], s])}[1..-1]
seq.unshift(:seq)
return format_abnf(seq, sep: nil, embedded: false)
else
return (@options[:html] ? %("<code class="grammar-literal">#{@coder.encode expr}</code>") : %("#{expr}"))
end
end
parts = {
alt: (@options[:html] ? %(<code class="grammar-alt">/</code>) : "/ "),
star: (@options[:html] ? %(<code class="grammar-star">*</code>) : "*"),
plus: (@options[:html] ? %(<code class="grammar-plus">+</code>) : "1*"),
opt: (@options[:html] ? %(<code class="grammar-opt">?</code>) : "?")
}
lbrac = (@options[:html] ? %(<code class="grammar-brac">[</code>) : "[")
rbrac = (@options[:html] ? %(<code class="grammar-brac">]</code>) : "]")
lparen = (@options[:html] ? %[<code class="grammar-paren">(</code>] : "(")
rparen = (@options[:html] ? %[<code class="grammar-paren">)</code>] : ")")
case expr.first
when :istr
# FIXME: if string part is segmented, need to do something different
format_abnf(expr.last, embedded: true, sensitive: false)
when :alt
this_sep = (sep ? sep : " ") + parts[expr.first.to_sym]
res = expr[1..-1].map {|e| format_abnf(e, embedded: true)}.join(this_sep)
embedded ? (lparen + res + rparen) : res
when :diff
raise RangeError, "ABNF does not support the diff operator"
when :opt
char = parts[expr.first.to_sym]
r = format_abnf(expr[1], embedded: true)
"#{lbrac}#{r}#{rbrac}"
when :plus, :star
char = parts[expr.first.to_sym]
r = format_abnf(expr[1], embedded: true)
"#{char}#{r}"
when :hex
escape_abnf_hex(expr.last[2..-1].hex.chr)
when :range
# Returns an [:alt] or [:not [:alt]] if composed of multiple sequences
# Note: ABNF does not support the `not` operator
res = format_abnf_range(expr.last)
res.is_a?(Array) ?
format_abnf(res, embedded: true) :
res
when :seq
this_sep = (sep ? sep : " ")
res = expr[1..-1].map do |e|
format_abnf(e, embedded: true)
end.join(this_sep)
embedded ? (lparen + res + rparen) : res
when :rept
# Expand repetition
min, max, value = expr[1..-1]
r = format_abnf(value, embedded: true)
if min == max
"#{min}#{r}"
elsif min == 0 && max == '*'
"#{parts[:star]}#{r}"
elsif min > 0 && max == '*'
"#{min}#{parts[:star]}#{r}"
elsif min == 0
"#{parts[:star]}#{max}#{r}"
else
"#{min}#{parts[:star]}#{max}#{r}"
end
else
raise "Unknown operator: #{expr.first}"
end
end
# Format a single-character string, prefering hex for non-main ASCII
def format_abnf_char(c)
if /[\x20-\x21\x23-\x7E]/.match?(c)
@options[:html] ? %("<code class="grammar-literal">#{@coder.encode c}</code>") : c.inspect
else
escape_abnf_hex(c)
end
end
# Format a range
#
# Presumes range has already been validated
def format_abnf_range(string)
alt, o_dash = [:alt], false
raise RangeError, "cannot format #{string.inspect} an ABNF range" if string.start_with?('^')
if string.end_with?('-')
o_dash = true
string = string[0..-2]
end
scanner = StringScanner.new(string)
hexes, deces = [], []
in_range = false
# Build op (alt) from different ranges/enums
while !scanner.eos?
if hex = scanner.scan(Terminals::HEX)
# Append any decimal values
alt << "%d" + deces.join(".") unless deces.empty?
deces = []
hex = hex.upcase
if in_range
# Add "." sequences for any previous hexes
alt << "%x" + hexes[0..-2].join(".") if hexes.length > 1
alt << "%x#{hexes.last}-#{hex[2..-1]}"
in_range, hexes = false, []
else
hexes << hex[2..-1]
end
elsif dec = scanner.scan(Terminals::R_CHAR)
# Append any hexadecimal values
alt << "%x" + hexes.join(".") unless hexes.empty?
hexes = []
if in_range
# Add "." sequences for any previous hexes
alt << "%d" + deces[0..-2].join(".") if deces.length > 1
alt << "%d#{deces.last}-#{dec.codepoints.first}"
in_range, deces = false, []
else
deces << dec.codepoints.first.to_s
end
end
in_range = true if scanner.scan(/\-/)
end
deces << '45' if o_dash
# Append hexes and deces as "." sequences (should be only one)
alt << "%d" + deces.join(".") unless deces.empty?
alt << "%x" + hexes.join(".") unless hexes.empty?
# FIXME: HTML abbreviations?
if alt.length == 2
# Just return the range or enum
alt.last
else
# Return the alt, which will be further formatted
alt
end
end
def escape_abnf_hex(u)
fmt = case u.ord
when 0x0000..0x00ff then "%02X"
when 0x0100..0xffff then "%04X"
else "%08X"
end
char = "%x" + (fmt % u.ord).upcase
if @options[:html]
char = if UNICODE_ESCAPE_NAMES.include?(u.ord)
%(<abbr title="#{UNICODE_ESCAPE_NAMES[u.ord]}">#{char}</abbr>)
elsif ([::Unicode::Types.of(u)] - %w(Control Private-use Surrogate Noncharacter Reserved)).empty?
%(<abbr title="unicode '#{@coder.encode u}'">#{char}</abbr>)
else
uni_esc = "U+%04X" % u.ord
%(<abbr title="unicode #{uni_esc}">#{char}</abbr>)
end
%(<code class="grammar-char-escape">#{char}</code>)
else
char
end
end
##
# ISO EBNF Formatters
##
# Format the expression part of a rule
def format_isoebnf(expr, sep: nil, embedded: false)
return (@options[:html] ? %(<a href="#grammar-production-#{@coder.encode expr}">#{@coder.encode expr}</a>) : expr.to_s) if expr.is_a?(Symbol)
if expr.is_a?(String)
expr = expr[2..-1].hex.chr if expr =~ /\A#x\h+/
expr.chars.each do |c|
raise RangeError, "cannot format #{expr.inspect} as an ISO EBNF String: #{c.inspect} is out of range" unless
ISOEBNF::TERMINAL_CHARACTER.match?(c)
end
if expr =~ /"/
return (@options[:html] ? %('<code class="grammar-literal">#{@coder.encode expr}</code>') : %('#{expr}'))
else
return (@options[:html] ? %("<code class="grammar-literal">#{@coder.encode expr}</code>") : %("#{expr}"))
end
end
parts = {
alt: (@options[:html] ? %(<code class="grammar-alt">|</code> ) : "| "),
diff: (@options[:html] ? %(<code class="grammar-diff">-</code> ) : "- "),
}
lparen = (@options[:html] ? %[<code class="grammar-paren">(</code>] : "(")
rparen = (@options[:html] ? %[<code class="grammar-paren">)</code>] : ")")
case expr.first
when :istr
# Looses fidelity, but, oh well ...
format_isoebnf(expr.last, embedded: true)
when :alt, :diff
this_sep = (sep ? sep : " ") + parts[expr.first.to_sym]
res = expr[1..-1].map {|e| format_isoebnf(e, embedded: true)}.join(this_sep)
embedded ? (lparen + res + rparen) : res
when :opt
r = format_isoebnf(expr[1], embedded: true)
"[#{r}]"
when :star
r = format_isoebnf(expr[1], embedded: true)
"{#{r}}"
when :plus
r = format_isoebnf(expr[1], embedded: true)
"#{r}, {#{r}}"
when :hex
format_isoebnf(expr[1], embedded: true)
when :range
res = format_isoebnf_range(expr.last)
res.is_a?(Array) ?
format_isoebnf(res, embedded: true) :
res
when :seq
this_sep = "," + (sep ? sep : " ")
res = expr[1..-1].map do |e|
format_isoebnf(e, embedded: true)
end.join(this_sep)
embedded ? (lparen + res + rparen) : res
when :rept
# Expand repetition
min, max, value = expr[1..-1]
if min == 0 && max == 1
format_isoebnf([:opt, value], sep: sep, embedded: embedded)
elsif min == 0 && max == '*'
format_isoebnf([:star, value], sep: sep, embedded: embedded)
elsif min == 1 && max == '*'
format_isoebnf([:plus, value], sep: sep, embedded: embedded)
else
val2 = [:seq]
while min > 0
val2 << value
min -= 1
max -= 1 unless max == '*'
end
if max == '*'
val2 << [:star, value]
else
opt = nil
while max > 0
opt = [:opt, opt ? [:seq, value, opt] : value]
max -= 1
end
val2 << opt if opt
end
format_isoebnf(val2, sep: sep, embedded: embedded)
end
else
raise "Unknown operator: #{expr.first}"
end
end
# Format a range
# Range is formatted as a aliteration of characters
def format_isoebnf_range(string)
chars = []
o_dash = false
raise RangeError, "cannot format #{string.inspect} an ABNF range" if string.start_with?('^')
if string.end_with?('-')
o_dash = true
string = string[0..-2]
end
scanner = StringScanner.new(string)
in_range = false
# Build chars from different ranges/enums
while !scanner.eos?
char = if hex = scanner.scan(Terminals::HEX)
hex[2..-1].hex.ord.char(Encoding::UTF_8)
else scanner.scan(Terminals::R_CHAR)
end
raise RangeError, "cannot format #{string.inspect} as an ISO EBNF Aliteration: #{char.inspect} is out of range" unless
char && ISOEBNF::TERMINAL_CHARACTER.match?(char)
if in_range
# calculate characters from chars.last to this char
raise RangeError, "cannot format #{string.inspect} as an ISO EBNF Aliteration" unless chars.last < char
chars.concat (chars.last..char).to_a[1..-1]
in_range = false
else
chars << char
end
in_range = true if scanner.scan(/\-/)
end
chars << '-' if o_dash
# Possibly only a single character (no character?)
chars.length == 1 ? chars.last.inspect : chars.unshift(:alt)
end
ERB_DESC = %(<!-- Generated with ebnf version #{EBNF::VERSION}. See https://github.com/dryruby/ebnf. -->\n) +
%q(<table class="grammar">
<tbody id="grammar-productions" class="<%= @format %>">
<% for rule in @rules %>
<tr<%= %{ id="grammar-#{rule[:class]}-#{rule.sym}"} unless %w(=/ |).include?(rule.assign) || rule.sym.nil?%>>
<% if rule.id %>
<td<%= " colspan=2" unless rule.sym %>><%= rule.id %></td>
<% end %>
<% if rule.sym %>
<td><code><%== (rule.sym unless rule.class == :declaration) %></code></td>
<% end %>
<td><%= rule.assign %></td>
<td><%= rule.formatted %></td>
</tr>
<% end %>
</tbody>
</table>
).gsub(/^ /, '')
end
end