190 lines
3.9 KiB
Ruby
190 lines
3.9 KiB
Ruby
require_relative "lexer.rb"
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require_relative "token.rb"
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require "pry"
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class Parser
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@@tag_to_op={:ADD=>"+",:SUB=>"-",:MUL=>"*",:DIV=>"/"}
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attr_reader :output
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def initialize(string)
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@debug=false
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@tokens=Lexer.new(string).tokenize
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p @tokens if @debug
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@token=@tokens.shift
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@tmpid=1
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@output=[]
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end
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def parse()
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block()
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expected("EOF") if @token != nil
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end
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private
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def expected(str)
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puts "Error: #{str} Expected"
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begin
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raise StandardError
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rescue StandardError => e
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e.backtrace.shift
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puts e.backtrace
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end
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exit
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end
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def get_numb()
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expected("Number") if @token.class!=Number
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tok=@token
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@token=@tokens.shift
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p tok if @debug
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p [@token,@tokens].flatten if @debug
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return tok.val
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end
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def get_name()
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expected("Name") if @token.class!=Ident
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tok=@token
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@token=@tokens.shift
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p tok if @debug
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p [@token,@tokens].flatten if @debug
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return tok.val
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end
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def get_str()
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expected("String") if @token.class!=StrTok
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tok=@token
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@token=@tokens.shift
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p tok if @debug
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p [@token,@tokens].flatten if @debug
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return tok.strval
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end
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def match(tag)
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expected(tag) if @token==nil
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expected(tag) if @token.tag!=tag
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@token=@tokens.shift
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p tok if @debug
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p [@token,@tokens].flatten if @debug
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end
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def make_tmp()
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tmp="t#{@tmpid}"
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@tmpid+=1
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return tmp
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end
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def factor()
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case @token.tag
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when :IDENT
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name=get_name()
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tmp=make_tmp()
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if @token.tag==:OPEN_PAREN
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params=[]
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match(:OPEN_PAREN)
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while true
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break if @token.tag==:CLOSE_PAREN
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params.push expression()
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break if @token.tag!=:COMMA
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match(:COMMA)
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end
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match(:CLOSE_PAREN)
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params.each do |tmpvar|
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@output.push [nil,"param",tmpvar,nil]
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end
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@output.push [tmp,"call",name,nil]
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else
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@output.push [tmp,"=",name,nil]
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end
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when :OPEN_PAREN
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match(:OPEN_PAREN)
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tmp=expression()
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match(:CLOSE_PAREN)
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when :SUB
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match(:SUB)
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tmp=make_tmp()
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num=get_numb()
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@output.push [tmp,"=","-#{num}",nil]
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else
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tmp=make_tmp()
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if @token.class==StrTok
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val=get_str()
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else
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val=get_numb()
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end
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@output.push [tmp,"=",val,nil]
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end
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return tmp
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end
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def term()
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ops=[:MUL,:DIV]
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tmp=factor()
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oldtmp=tmp
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return tmp if @token==nil
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while ops.include? @token.tag
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tmp=make_tmp()
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op=@token.tag
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match(op)
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op=@@tag_to_op[op]
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fact=factor()
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@output.push [tmp,op,oldtmp,fact]
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oldtmp=tmp
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break if @token==nil
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end
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return tmp
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end
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def expression()
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ops=[:ADD,:SUB]
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tmp=term()
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oldtmp=tmp
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return tmp if @token==nil
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while ops.include? @token.tag
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tmp=make_tmp()
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op=@token.tag
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match(op)
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op=@@tag_to_op[op]
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trm=term()
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@output.push [tmp,op,oldtmp,trm]
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oldtmp=tmp
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break if @token==nil
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end
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return tmp
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end
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def assingment()
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name=get_name()
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match(:EQUALS)
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tmpvar=expression()
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@output.push [name,"=",tmpvar,nil]
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end
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def func()
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match(:DEF)
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name=@token.val
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match(:IDENT)
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match(:OPEN_CURL)
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@output.push [nil,"func",name,nil]
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block(:CLOSE_CURL)
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@output.push [nil,"return",nil,nil]
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@output.push [nil,"funcend",nil,nil]
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end
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def ret()
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match(:RETURN)
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tmpvar=expression()
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@output.push [nil,"return",tmpvar,nil]
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end
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def statement()
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if @token.tag==:IDENT and @tokens[0].tag==:EQUALS
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assingment()
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match(:SEMICOLON)
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elsif @token.tag==:DEF
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func()
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elsif @token.tag==:RETURN
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ret()
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match(:SEMICOLON)
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else
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expression()
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match(:SEMICOLON)
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end
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end
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def block(end_tok=nil)
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if end_tok
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while @token.tag!=end_tok
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statement()
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end
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match(end_tok)
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else
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while @token!=nil
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statement()
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end
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end
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end
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end
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