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1、编译原理与实践CompilerPrincipleand Implementation中英双语版张菁著/黄维通Baikunthnath审1zhangjing@hrbeu.edu.cnChapter6SymbolTableManager andTypeCheckingZhangJing,WangHaiLingCollegeofComputerScience&TechnologyHarbinEngineeringUniversitysomesymbolsmustbecollectedandbeputtogetherintotables—
2、SymbolTable.Therearetwofunctionsinsymboltable,thefirstoneistohelpcheckifthesemanticiscorrect,thesecondoneistoassistgeneratingthecode.Tosumup,thischapterwouldintroducethefunctions,content,structureandoperationofsymboltable.3zhangjing@hrbeu.edu.cn6.1TheFunctionsofSymbol
3、TablesThefunctionsofsymboltableare:（1）Storeinformation（2）TypesChecking（3）DataAddress4zhangjing@hrbeu.edu.cnStoreinformation:Beforestoreinformation,wefirstlyshoulddividedthedataintodifferenttypes,thenputthemintothecorrespondedtables.Sometimesinformationisstoredintabled
4、uringlexicalanalysis,sometimesitisdoneinsemanticanalysis..Ifthedataisanidentifier,itwouldbestoredinanidentifiertable，elseifthedataisaconstant,itwillbeputintoaconstanttable.5zhangjing@hrbeu.edu.cnTypesCheckingAcompilerusesasymboltabletokeeptrackofthetypeandbindinginfor
5、mationaboutnames.Thesymboltableissearchedeverytimebyanamethatisencounteredinthesourcetext.Ifanewnameornewinformationaboutanexistingnameisdiscovered,thetableischanged.6zhangjing@hrbeu.edu.cnDataAddress:Whenadatawasstored,thedata’saddressinthetablewasalsorecordedasanatt
6、ributeofthetable.Intheperiodofcodegenerationincompiler,thedataaddresscanbeobtainedfromthesymboltableandcanbeuseddirectly..7zhangjing@hrbeu.edu.cn6.2TheAttributeofSymbolTableSymboltableiscreatedaccordingtosymbol’sname,sothekeywordofthesymboltableissymbol’sname.Exceptna
7、meattribute,therearealsosixattributesofasymbolinsymboltableusingforsemanticchecking..8zhangjing@hrbeu.edu.cnThesixattributesofasymbolasfollow:AttributeofkindAttributeofdimensionorsizeAttributeofparameterAttributeofaddressAttributeoflevelinprogramAttributeoflinepositio
8、ninsourceprogram9zhangjing@hrbeu.edu.cnAttributeofkindKindcandescribethecharacteristicsofasymbol.Everysymbolhasitsowntype,su
