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require "strscan"
require "lrama/report"
module Lrama
# Lexer for parse.y
class Lexer
include Lrama::Report::Duration
# s_value is semantic value
Token = Struct.new(:type, :s_value, keyword_init: true) do
Type = Struct.new(:id, :name, keyword_init: true)
attr_accessor :line, :column, :referred
# For User_code
attr_accessor :references
def to_s
"#{super} line: #{line}, column: #{column}"
end
@i = 0
@types = []
def self.define_type(name)
type = Type.new(id: @i, name: name.to_s)
const_set(name, type)
@types << type
@i += 1
end
# Token types
define_type(:P_expect) # %expect
define_type(:P_define) # %define
define_type(:P_printer) # %printer
define_type(:P_lex_param) # %lex-param
define_type(:P_parse_param) # %parse-param
define_type(:P_initial_action) # %initial-action
define_type(:P_union) # %union
define_type(:P_token) # %token
define_type(:P_type) # %type
define_type(:P_nonassoc) # %nonassoc
define_type(:P_left) # %left
define_type(:P_right) # %right
define_type(:P_prec) # %prec
define_type(:User_code) # { ... }
define_type(:Tag) # <int>
define_type(:Number) # 0
define_type(:Ident_Colon) # k_if:, k_if : (spaces can be there)
define_type(:Ident) # api.pure, tNUMBER
define_type(:Semicolon) # ;
define_type(:Bar) # |
define_type(:String) # "str"
define_type(:Char) # '+'
end
# States
#
# See: https://www.gnu.org/software/bison/manual/html_node/Grammar-Outline.html
Initial = 0
Prologue = 1
BisonDeclarations = 2
GrammarRules = 3
Epilogue = 4
# Token types
attr_reader :prologue, :bison_declarations, :grammar_rules, :epilogue,
:bison_declarations_tokens, :grammar_rules_tokens
def initialize(text)
@text = text
@state = Initial
# Array of texts
@prologue = []
@bison_declarations = []
@grammar_rules = []
@epilogue = []
#
@bison_declarations_tokens = []
@grammar_rules_tokens = []
@debug = false
report_duration(:lex) do
lex_text
lex_bison_declarations_tokens
lex_grammar_rules_tokens
end
end
private
def create_token(type, s_value, line, column)
t = Token.new(type: type, s_value: s_value)
t.line = line
t.column = column
return t
end
# TODO: Remove this
def lex_text
@text.each_line.with_index(1) do |string, lineno|
case @state
when Initial
# Skip until "%{"
if string == "%{\n"
@state = Prologue
@prologue << ["", lineno]
next
end
when Prologue
# Between "%{" and "%}"
if string == "%}\n"
@state = BisonDeclarations
@prologue << ["", lineno]
next
end
@prologue << [string, lineno]
when BisonDeclarations
if string == "%%\n"
@state = GrammarRules
next
end
@bison_declarations << [string, lineno]
when GrammarRules
# Between "%%" and "%%"
if string == "%%\n"
@state = Epilogue
next
end
@grammar_rules << [string, lineno]
when Epilogue
@epilogue << [string, lineno]
else
raise "Unknown state: #{@state}"
end
end
end
# See:
# * https://www.gnu.org/software/bison/manual/html_node/Decl-Summary.html
# * https://www.gnu.org/software/bison/manual/html_node/Symbol-Decls.html
# * https://www.gnu.org/software/bison/manual/html_node/Empty-Rules.html
def lex_common(lines, tokens)
line = lines.first[1]
column = 0
ss = StringScanner.new(lines.map(&:first).join)
while !ss.eos? do
case
when ss.scan(/\n/)
line += 1
column = ss.pos
when ss.scan(/\s+/)
# skip
when ss.scan(/;/)
tokens << create_token(Token::Semicolon, ss[0], line, ss.pos - column)
when ss.scan(/\|/)
tokens << create_token(Token::Bar, ss[0], line, ss.pos - column)
when ss.scan(/(\d+)/)
tokens << create_token(Token::Number, Integer(ss[0]), line, ss.pos - column)
when ss.scan(/(<[a-zA-Z0-9_]+>)/)
tokens << create_token(Token::Tag, ss[0], line, ss.pos - column)
when ss.scan(/([a-zA-Z_.][-a-zA-Z0-9_.]*)\s*:/)
tokens << create_token(Token::Ident_Colon, ss[1], line, ss.pos - column)
when ss.scan(/([a-zA-Z_.][-a-zA-Z0-9_.]*)/)
tokens << create_token(Token::Ident, ss[0], line, ss.pos - column)
when ss.scan(/%expect/)
tokens << create_token(Token::P_expect, ss[0], line, ss.pos - column)
when ss.scan(/%define/)
tokens << create_token(Token::P_define, ss[0], line, ss.pos - column)
when ss.scan(/%printer/)
tokens << create_token(Token::P_printer, ss[0], line, ss.pos - column)
when ss.scan(/%lex-param/)
tokens << create_token(Token::P_lex_param, ss[0], line, ss.pos - column)
when ss.scan(/%parse-param/)
tokens << create_token(Token::P_parse_param, ss[0], line, ss.pos - column)
when ss.scan(/%initial-action/)
tokens << create_token(Token::P_initial_action, ss[0], line, ss.pos - column)
when ss.scan(/%union/)
tokens << create_token(Token::P_union, ss[0], line, ss.pos - column)
when ss.scan(/%token/)
tokens << create_token(Token::P_token, ss[0], line, ss.pos - column)
when ss.scan(/%type/)
tokens << create_token(Token::P_type, ss[0], line, ss.pos - column)
when ss.scan(/%nonassoc/)
tokens << create_token(Token::P_nonassoc, ss[0], line, ss.pos - column)
when ss.scan(/%left/)
tokens << create_token(Token::P_left, ss[0], line, ss.pos - column)
when ss.scan(/%right/)
tokens << create_token(Token::P_right, ss[0], line, ss.pos - column)
when ss.scan(/%prec/)
tokens << create_token(Token::P_prec, ss[0], line, ss.pos - column)
when ss.scan(/{/)
token, line = lex_user_code(ss, line, ss.pos - column, lines)
tokens << token
when ss.scan(/"/)
string, line = lex_string(ss, "\"", line, lines)
token = create_token(Token::String, string, line, ss.pos - column)
tokens << token
when ss.scan(/\/\*/)
# TODO: Need to keep comment?
line = lex_comment(ss, line, lines, "")
when ss.scan(/'(.)'/)
tokens << create_token(Token::Char, ss[0], line, ss.pos - column)
when ss.scan(/'\\(.)'/) # '\\', '\t'
tokens << create_token(Token::Char, ss[0], line, ss.pos - column)
when ss.scan(/'\\(\d+)'/) # '\13'
tokens << create_token(Token::Char, ss[0], line, ss.pos - column)
when ss.scan(/%empty/)
# skip
else
l = line - lines.first[1]
split = ss.string.split("\n")
col = ss.pos - split[0...l].join("\n").length
raise "Parse error (unknow token): #{split[l]} \"#{ss.string[ss.pos]}\" (#{line}: #{col})"
end
end
end
def lex_bison_declarations_tokens
lex_common(@bison_declarations, @bison_declarations_tokens)
end
def lex_user_code(ss, line, column, lines)
first_line = line
first_column = column
debug("Enter lex_user_code: #{line}")
brace_count = 1
str = "{"
# Array of [type, $n, tag, first column, last column]
# TODO: Is it better to keep string, like "$$", and use gsub?
references = []
while !ss.eos? do
case
when ss.scan(/\n/)
line += 1
when ss.scan(/"/)
string, line = lex_string(ss, "\"", line, lines)
str << string
next
when ss.scan(/'/)
string, line = lex_string(ss, "'", line, lines)
str << string
next
when ss.scan(/\$(<[a-zA-Z0-9_]+>)?\$/) # $$, $<long>$
tag = ss[1] ? create_token(Token::Tag, ss[1], line, str.length) : nil
references << [:dollar, "$", tag, str.length, str.length + ss[0].length - 1]
when ss.scan(/\$(<[a-zA-Z0-9_]+>)?(\d+)/) # $1, $2, $<long>1
tag = ss[1] ? create_token(Token::Tag, ss[1], line, str.length) : nil
references << [:dollar, Integer(ss[2]), tag, str.length, str.length + ss[0].length - 1]
when ss.scan(/@\$/) # @$
references << [:at, "$", nil, str.length, str.length + ss[0].length - 1]
when ss.scan(/@(\d)+/) # @1
references << [:at, Integer(ss[1]), nil, str.length, str.length + ss[0].length - 1]
when ss.scan(/{/)
brace_count += 1
when ss.scan(/}/)
brace_count -= 1
debug("Return lex_user_code: #{line}")
if brace_count == 0
str << ss[0]
user_code = Token.new(type: Token::User_code, s_value: str.freeze)
user_code.line = first_line
user_code.column = first_column
user_code.references = references
return [user_code, line]
end
when ss.scan(/\/\*/)
str << ss[0]
line = lex_comment(ss, line, lines, str)
else
# noop, just consume char
str << ss.getch
next
end
str << ss[0]
end
# Reach to end of input but brace does not match
l = line - lines.first[1]
raise "Parse error (brace mismatch): #{ss.string.split("\n")[l]} \"#{ss.string[ss.pos]}\" (#{line}: #{ss.pos})"
end
def lex_string(ss, terminator, line, lines)
debug("Enter lex_string: #{line}")
str = terminator.dup
while (c = ss.getch) do
str << c
case c
when "\n"
line += 1
when terminator
debug("Return lex_string: #{line}")
return [str, line]
else
# noop
end
end
# Reach to end of input but quote does not match
l = line - lines.first[1]
raise "Parse error (quote mismatch): #{ss.string.split("\n")[l]} \"#{ss.string[ss.pos]}\" (#{line}: #{ss.pos})"
end
# TODO: Need to handle // style comment
#
# /* */ style comment
def lex_comment(ss, line, lines, str)
while !ss.eos? do
case
when ss.scan(/\n/)
line += 1
when ss.scan(/\*\//)
return line
else
str << ss.getch
next
end
str << ss[0]
end
# Reach to end of input but quote does not match
l = line - lines.first[1]
raise "Parse error (comment mismatch): #{ss.string.split("\n")[l]} \"#{ss.string[ss.pos]}\" (#{line}: #{ss.pos})"
end
def lex_grammar_rules_tokens
lex_common(@grammar_rules, @grammar_rules_tokens)
end
def debug(msg)
return unless @debug
puts "#{msg}\n"
end
end
end
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