《编译原理概述》ppt课件

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1、Chapter1IntroductionInstructorJianhuiYueSoftwareCollege@SCUOffice:JC-B321Outline1Conceptions2CompilerProcessesOverview3SuggestionsonhowtostudythiscourseCompilersCompilersarecomputerprogramsthattranslateonelanguagetoanother.Verycomplexprogramfrom10,000to1,000,000linesofc

2、ode.Itsinputisaprogramwritteninitssourcelanguage.Usually,thesourcelanguageisahigh-levellanguage(C,C++,etc).Itproducesanequivalentprogramwritteninitstargetlanguage.Thetargetlanguageisobjectcode(machinecode)forthetargetmachine.MachineLanguageInitially,theprogramswerewritt

3、eninmachinelanguage–numericcodesthatrepresentedtheactualmachineoperationstobeperformed.C70600000002movesnumber2tothelocation0000.Writingsuchcodesistimeconsumingandtedious.AssemblyLanguageInassemblylanguageinstructionsandmemorylocationsaregivensymbolicforms.MOVX,2Anassem

4、blertranslatesthesymboliccodesandmemorylocationsintocorrespondingnumericcodes.Advantages:Greatimprovementinspeedandaccuracyofwritingprograms.stillusedtoday.Disadvantages:Stillnoteasytowriteanddifficulttoreadandunderstand.Machinedependent.High-levelLanguagesNearlyresembl

5、esmathematicalnotationornaturallanguage.Independentonanyparticularmachine.CapableofbeingtranslatedintoexecutablecodeX=2Needaprogramthatperformstranslation.Isitpossible?Isgeneratedobjectcodeefficient?TheoreticalFoundationsNoamChomsky’sstudyofthestructureofnaturallanguage

6、s.Classificationoflanguagesaccordingtothecomplexityoftheirgrammarsandthealgorithmstorecognizethem.Context-freegrammarsarethemostusefulforprogramminglanguagesStudyoftheparsingproblem,whichbecomeastandardpartofcompilertheory.Studyoffiniteautomataandregularexpressions.Ledt

7、osymbolicmethodsforexpressingthestructureofwordsofaprogramminglanguageOptimizationtechniques(codeimprovementtechniques).InterpretersAninterpreterisalanguagetranslatorlikeacompiler.Thedifference:thesourceprograminexecutedimmediately,notaftertranslationiscomplete.Programm

8、inglanguagecanbeeitherinterpretedorcompiled.Interpretedlanguages:BASIC,LISP,JavaCompiledlanguages:FORTRAN,C,C+