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#--
# $originalId: parser.rb,v 1.8 2006/07/06 11:42:07 aamine Exp $
#
# Copyright (c) 1999-2006 Minero Aoki
#
# This program is free software.
# You can distribute/modify this program under the same terms of ruby.
#
# As a special exception, when this code is copied by Racc
# into a Racc output file, you may use that output file
# without restriction.
#++
module Racc
class ParseError < StandardError; end
end
unless defined?(::ParseError)
ParseError = Racc::ParseError
end
# Racc is a LALR(1) parser generator.
# It is written in Ruby itself, and generates Ruby programs.
#
# == Command-line Reference
#
# racc [-o<var>filename</var>] [--output-file=<var>filename</var>]
# [-e<var>rubypath</var>] [--embedded=<var>rubypath</var>]
# [-v] [--verbose]
# [-O<var>filename</var>] [--log-file=<var>filename</var>]
# [-g] [--debug]
# [-E] [--embedded]
# [-l] [--no-line-convert]
# [-c] [--line-convert-all]
# [-a] [--no-omit-actions]
# [-C] [--check-only]
# [-S] [--output-status]
# [--version] [--copyright] [--help] <var>grammarfile</var>
#
# [+filename+]
# Racc grammar file. Any extension is permitted.
# [-o+outfile+, --output-file=+outfile+]
# A filename for output. default is <+filename+>.tab.rb
# [-O+filename+, --log-file=+filename+]
# Place logging output in file +filename+.
# Default log file name is <+filename+>.output.
# [-e+rubypath+, --executable=+rubypath+]
# output executable file(mode 755). where +path+ is the Ruby interpreter.
# [-v, --verbose]
# verbose mode. create +filename+.output file, like yacc's y.output file.
# [-g, --debug]
# add debug code to parser class. To display debugging information,
# use this '-g' option and set @yydebug true in parser class.
# [-E, --embedded]
# Output parser which doesn't need runtime files (racc/parser.rb).
# [-C, --check-only]
# Check syntax of racc grammar file and quit.
# [-S, --output-status]
# Print messages time to time while compiling.
# [-l, --no-line-convert]
# turns off line number converting.
# [-c, --line-convert-all]
# Convert line number of actions, inner, header and footer.
# [-a, --no-omit-actions]
# Call all actions, even if an action is empty.
# [--version]
# print Racc version and quit.
# [--copyright]
# Print copyright and quit.
# [--help]
# Print usage and quit.
#
# == Generating Parser Using Racc
#
# To compile Racc grammar file, simply type:
#
# $ racc parse.y
#
# This creates Ruby script file "parse.tab.y". The -o option can change the output filename.
#
# == Writing A Racc Grammar File
#
# If you want your own parser, you have to write a grammar file.
# A grammar file contains the name of your parser class, grammar for the parser,
# user code, and anything else.
# When writing a grammar file, yacc's knowledge is helpful.
# If you have not used yacc before, Racc is not too difficult.
#
# Here's an example Racc grammar file.
#
# class Calcparser
# rule
# target: exp { print val[0] }
#
# exp: exp '+' exp
# | exp '*' exp
# | '(' exp ')'
# | NUMBER
# end
#
# Racc grammar files resemble yacc files.
# But (of course), this is Ruby code.
# yacc's $$ is the 'result', $0, $1... is
# an array called 'val', and $-1, $-2... is an array called '_values'.
#
# See the {Grammar File Reference}[rdoc-ref:lib/racc/rdoc/grammar.en.rdoc] for
# more information on grammar files.
#
# == Parser
#
# Then you must prepare the parse entry method. There are two types of
# parse methods in Racc, Racc::Parser#do_parse and Racc::Parser#yyparse
#
# Racc::Parser#do_parse is simple.
#
# It's yyparse() of yacc, and Racc::Parser#next_token is yylex().
# This method must returns an array like [TOKENSYMBOL, ITS_VALUE].
# EOF is [false, false].
# (TOKENSYMBOL is a Ruby symbol (taken from String#intern) by default.
# If you want to change this, see the grammar reference.
#
# Racc::Parser#yyparse is little complicated, but useful.
# It does not use Racc::Parser#next_token, instead it gets tokens from any iterator.
#
# For example, <code>yyparse(obj, :scan)</code> causes
# calling +obj#scan+, and you can return tokens by yielding them from +obj#scan+.
#
# == Debugging
#
# When debugging, "-v" or/and the "-g" option is helpful.
#
# "-v" creates verbose log file (.output).
# "-g" creates a "Verbose Parser".
# Verbose Parser prints the internal status when parsing.
# But it's _not_ automatic.
# You must use -g option and set +@yydebug+ to +true+ in order to get output.
# -g option only creates the verbose parser.
#
# === Racc reported syntax error.
#
# Isn't there too many "end"?
# grammar of racc file is changed in v0.10.
#
# Racc does not use '%' mark, while yacc uses huge number of '%' marks..
#
# === Racc reported "XXXX conflicts".
#
# Try "racc -v xxxx.y".
# It causes producing racc's internal log file, xxxx.output.
#
# === Generated parsers does not work correctly
#
# Try "racc -g xxxx.y".
# This command let racc generate "debugging parser".
# Then set @yydebug=true in your parser.
# It produces a working log of your parser.
#
# == Re-distributing Racc runtime
#
# A parser, which is created by Racc, requires the Racc runtime module;
# racc/parser.rb.
#
# Ruby 1.8.x comes with Racc runtime module,
# you need NOT distribute Racc runtime files.
#
# If you want to include the Racc runtime module with your parser.
# This can be done by using '-E' option:
#
# $ racc -E -omyparser.rb myparser.y
#
# This command creates myparser.rb which `includes' Racc runtime.
# Only you must do is to distribute your parser file (myparser.rb).
#
# Note: parser.rb is LGPL, but your parser is not.
# Your own parser is completely yours.
module Racc
unless defined?(Racc_No_Extensions)
Racc_No_Extensions = false # :nodoc:
end
class Parser
Racc_Runtime_Version = '1.4.6'
Racc_Runtime_Revision = %w$originalRevision: 1.8 $[1]
Racc_Runtime_Core_Version_R = '1.4.6'
Racc_Runtime_Core_Revision_R = %w$originalRevision: 1.8 $[1]
begin
require 'racc/cparse'
# Racc_Runtime_Core_Version_C = (defined in extension)
Racc_Runtime_Core_Revision_C = Racc_Runtime_Core_Id_C.split[2]
unless new.respond_to?(:_racc_do_parse_c, true)
raise LoadError, 'old cparse.so'
end
if Racc_No_Extensions
raise LoadError, 'selecting ruby version of racc runtime core'
end
Racc_Main_Parsing_Routine = :_racc_do_parse_c # :nodoc:
Racc_YY_Parse_Method = :_racc_yyparse_c # :nodoc:
Racc_Runtime_Core_Version = Racc_Runtime_Core_Version_C # :nodoc:
Racc_Runtime_Core_Revision = Racc_Runtime_Core_Revision_C # :nodoc:
Racc_Runtime_Type = 'c' # :nodoc:
rescue LoadError
Racc_Main_Parsing_Routine = :_racc_do_parse_rb
Racc_YY_Parse_Method = :_racc_yyparse_rb
Racc_Runtime_Core_Version = Racc_Runtime_Core_Version_R
Racc_Runtime_Core_Revision = Racc_Runtime_Core_Revision_R
Racc_Runtime_Type = 'ruby'
end
def Parser.racc_runtime_type # :nodoc:
Racc_Runtime_Type
end
def _racc_setup
@yydebug = false unless self.class::Racc_debug_parser
@yydebug = false unless defined?(@yydebug)
if @yydebug
@racc_debug_out = $stderr unless defined?(@racc_debug_out)
@racc_debug_out ||= $stderr
end
arg = self.class::Racc_arg
arg[13] = true if arg.size < 14
arg
end
def _racc_init_sysvars
@racc_state = [0]
@racc_tstack = []
@racc_vstack = []
@racc_t = nil
@racc_val = nil
@racc_read_next = true
@racc_user_yyerror = false
@racc_error_status = 0
end
# The entry point of the parser. This method is used with #next_token.
# If Racc wants to get token (and its value), calls next_token.
#
# Example:
# def parse
# @q = [[1,1],
# [2,2],
# [3,3],
# [false, '$']]
# do_parse
# end
#
# def next_token
# @q.shift
# end
def do_parse
__send__(Racc_Main_Parsing_Routine, _racc_setup(), false)
end
# The method to fetch next token.
# If you use #do_parse method, you must implement #next_token.
#
# The format of return value is [TOKEN_SYMBOL, VALUE].
# +token-symbol+ is represented by Ruby's symbol by default, e.g. :IDENT
# for 'IDENT'. ";" (String) for ';'.
#
# The final symbol (End of file) must be false.
def next_token
raise NotImplementedError, "#{self.class}\#next_token is not defined"
end
def _racc_do_parse_rb(arg, in_debug)
action_table, action_check, action_default, action_pointer,
_, _, _, _,
_, _, token_table, _,
_, _, * = arg
_racc_init_sysvars
tok = act = i = nil
catch(:racc_end_parse) {
while true
if i = action_pointer[@racc_state[-1]]
if @racc_read_next
if @racc_t != 0 # not EOF
tok, @racc_val = next_token()
unless tok # EOF
@racc_t = 0
else
@racc_t = (token_table[tok] or 1) # error token
end
racc_read_token(@racc_t, tok, @racc_val) if @yydebug
@racc_read_next = false
end
end
i += @racc_t
unless i >= 0 and
act = action_table[i] and
action_check[i] == @racc_state[-1]
act = action_default[@racc_state[-1]]
end
else
act = action_default[@racc_state[-1]]
end
while act = _racc_evalact(act, arg)
;
end
end
}
end
# Another entry point for the parser.
# If you use this method, you must implement RECEIVER#METHOD_ID method.
#
# RECEIVER#METHOD_ID is a method to get next token.
# It must 'yield' the token, which format is [TOKEN-SYMBOL, VALUE].
def yyparse(recv, mid)
__send__(Racc_YY_Parse_Method, recv, mid, _racc_setup(), true)
end
def _racc_yyparse_rb(recv, mid, arg, c_debug)
action_table, action_check, action_default, action_pointer,
_, _, _, _,
_, _, token_table, _,
_, _, * = arg
_racc_init_sysvars
act = nil
i = nil
catch(:racc_end_parse) {
until i = action_pointer[@racc_state[-1]]
while act = _racc_evalact(action_default[@racc_state[-1]], arg)
;
end
end
recv.__send__(mid) do |tok, val|
unless tok
@racc_t = 0
else
@racc_t = (token_table[tok] or 1) # error token
end
@racc_val = val
@racc_read_next = false
i += @racc_t
unless i >= 0 and
act = action_table[i] and
action_check[i] == @racc_state[-1]
act = action_default[@racc_state[-1]]
end
while act = _racc_evalact(act, arg)
;
end
while not(i = action_pointer[@racc_state[-1]]) or
not @racc_read_next or
@racc_t == 0 # $
unless i and i += @racc_t and
i >= 0 and
act = action_table[i] and
action_check[i] == @racc_state[-1]
act = action_default[@racc_state[-1]]
end
while act = _racc_evalact(act, arg)
;
end
end
end
}
end
###
### common
###
def _racc_evalact(act, arg)
action_table, action_check, _, action_pointer,
_, _, _, _,
_, _, _, shift_n, reduce_n,
_, _, * = arg
nerr = 0 # tmp
if act > 0 and act < shift_n
#
# shift
#
if @racc_error_status > 0
@racc_error_status -= 1 unless @racc_t == 1 # error token
end
@racc_vstack.push @racc_val
@racc_state.push act
@racc_read_next = true
if @yydebug
@racc_tstack.push @racc_t
racc_shift @racc_t, @racc_tstack, @racc_vstack
end
elsif act < 0 and act > -reduce_n
#
# reduce
#
code = catch(:racc_jump) {
@racc_state.push _racc_do_reduce(arg, act)
false
}
if code
case code
when 1 # yyerror
@racc_user_yyerror = true # user_yyerror
return -reduce_n
when 2 # yyaccept
return shift_n
else
raise '[Racc Bug] unknown jump code'
end
end
elsif act == shift_n
#
# accept
#
racc_accept if @yydebug
throw :racc_end_parse, @racc_vstack[0]
elsif act == -reduce_n
#
# error
#
case @racc_error_status
when 0
unless arg[21] # user_yyerror
nerr += 1
on_error @racc_t, @racc_val, @racc_vstack
end
when 3
if @racc_t == 0 # is $
throw :racc_end_parse, nil
end
@racc_read_next = true
end
@racc_user_yyerror = false
@racc_error_status = 3
while true
if i = action_pointer[@racc_state[-1]]
i += 1 # error token
if i >= 0 and
(act = action_table[i]) and
action_check[i] == @racc_state[-1]
break
end
end
throw :racc_end_parse, nil if @racc_state.size <= 1
@racc_state.pop
@racc_vstack.pop
if @yydebug
@racc_tstack.pop
racc_e_pop @racc_state, @racc_tstack, @racc_vstack
end
end
return act
else
raise "[Racc Bug] unknown action #{act.inspect}"
end
racc_next_state(@racc_state[-1], @racc_state) if @yydebug
nil
end
def _racc_do_reduce(arg, act)
_, _, _, _,
goto_table, goto_check, goto_default, goto_pointer,
nt_base, reduce_table, _, _,
_, use_result, * = arg
state = @racc_state
vstack = @racc_vstack
tstack = @racc_tstack
i = act * -3
len = reduce_table[i]
reduce_to = reduce_table[i+1]
method_id = reduce_table[i+2]
void_array = []
tmp_t = tstack[-len, len] if @yydebug
tmp_v = vstack[-len, len]
tstack[-len, len] = void_array if @yydebug
vstack[-len, len] = void_array
state[-len, len] = void_array
# tstack must be updated AFTER method call
if use_result
vstack.push __send__(method_id, tmp_v, vstack, tmp_v[0])
else
vstack.push __send__(method_id, tmp_v, vstack)
end
tstack.push reduce_to
racc_reduce(tmp_t, reduce_to, tstack, vstack) if @yydebug
k1 = reduce_to - nt_base
if i = goto_pointer[k1]
i += state[-1]
if i >= 0 and (curstate = goto_table[i]) and goto_check[i] == k1
return curstate
end
end
goto_default[k1]
end
# This method is called when a parse error is found.
#
# ERROR_TOKEN_ID is an internal ID of token which caused error.
# You can get string representation of this ID by calling
# #token_to_str.
#
# ERROR_VALUE is a value of error token.
#
# value_stack is a stack of symbol values.
# DO NOT MODIFY this object.
#
# This method raises ParseError by default.
#
# If this method returns, parsers enter "error recovering mode".
def on_error(t, val, vstack)
raise ParseError, sprintf("\nparse error on value %s (%s)",
val.inspect, token_to_str(t) || '?')
end
# Enter error recovering mode.
# This method does not call #on_error.
def yyerror
throw :racc_jump, 1
end
# Exit parser.
# Return value is Symbol_Value_Stack[0].
def yyaccept
throw :racc_jump, 2
end
# Leave error recovering mode.
def yyerrok
@racc_error_status = 0
end
# For debugging output
def racc_read_token(t, tok, val)
@racc_debug_out.print 'read '
@racc_debug_out.print tok.inspect, '(', racc_token2str(t), ') '
@racc_debug_out.puts val.inspect
@racc_debug_out.puts
end
def racc_shift(tok, tstack, vstack)
@racc_debug_out.puts "shift #{racc_token2str tok}"
racc_print_stacks tstack, vstack
@racc_debug_out.puts
end
def racc_reduce(toks, sim, tstack, vstack)
out = @racc_debug_out
out.print 'reduce '
if toks.empty?
out.print ' <none>'
else
toks.each {|t| out.print ' ', racc_token2str(t) }
end
out.puts " --> #{racc_token2str(sim)}"
racc_print_stacks tstack, vstack
@racc_debug_out.puts
end
def racc_accept
@racc_debug_out.puts 'accept'
@racc_debug_out.puts
end
def racc_e_pop(state, tstack, vstack)
@racc_debug_out.puts 'error recovering mode: pop token'
racc_print_states state
racc_print_stacks tstack, vstack
@racc_debug_out.puts
end
def racc_next_state(curstate, state)
@racc_debug_out.puts "goto #{curstate}"
racc_print_states state
@racc_debug_out.puts
end
def racc_print_stacks(t, v)
out = @racc_debug_out
out.print ' ['
t.each_index do |i|
out.print ' (', racc_token2str(t[i]), ' ', v[i].inspect, ')'
end
out.puts ' ]'
end
def racc_print_states(s)
out = @racc_debug_out
out.print ' ['
s.each {|st| out.print ' ', st }
out.puts ' ]'
end
def racc_token2str(tok)
self.class::Racc_token_to_s_table[tok] or
raise "[Racc Bug] can't convert token #{tok} to string"
end
# Convert internal ID of token symbol to the string.
def token_to_str(t)
self.class::Racc_token_to_s_table[t]
end
end
end