compile.java

基于c0文法写的生成p-code的编译器

        error = 0;
        return 0;
    }
    //函数定义递归子程序
    private int FuncD() {
        if (flag.type == Lex.IDSY) {
            if (checkfname(flag.word) != 0) {
                return error;
            }
            func = new Function(flag.word, Function.R_INT);
            lev++;
        } else {
            if (checkfname(flag.word) != 0) {
                return error;
            }
            func = new Function(lop.word, Function.R_VOID);
            lev++;
            next();
        }
        funclist.add(func);
        if (Para() != 0) {
            error = ERR_PARALACK;
            return error;
        }
        //有参数时填map
        int i = 0;
        for (String a : func.para) {
            func.pmap.put(a, (i + 2) * 4);
            i++;
        }
        if (Complex() != 0) {
            return error;
        }
        //四元式成功生成后填map
        i = 1;
        for (String v : func.var) {
            func.vmap.put(v, i * 4);
            i++;
        }
        for (Four f : func.fourlist) {
            if (f.result != null && f.result.startsWith("@")) {
                func.vmap.put(f.result, i * 4);
                i++;
            }
        }
        checkret = 0;
        flab = 0;
        error = 0;
        return 0;
    }
    //主函数递归子程序
    private int Main() {
        func = new Function("main", Function.R_VOID);
        lev++;
        funclist.add(func);
        if (lop.type != Lex.Lpar) {
            error = ERR_PARALACK;
            return error;
        }
        if (next() == ERR_OVERFLOW || lop.type != Lex.Rpar) {
            error = ERR_ABNORMAL;
            return error;
        }
        if (next() == ERR_OVERFLOW || Complex() != 0) {
            return error;
        }
        //四元式成功生成后填map
        int i = 1;
        for (String v : func.var) {
            func.vmap.put(v, i * 4);
            i++;
        }
        for (Four f : func.fourlist) {
            if (f.result != null && f.result.startsWith("@")) {
                func.vmap.put(f.result, i * 4);
                i++;
            }
        }
        flab = 0;
        error = 0;
        return 0;
    }
    //复合语句递归子程序
    private int Complex() {
        if (lop.type != Lex.Lbra) {
            error = ERR_NOTBE;
            return error;
        }
        if (next() == ERR_OVERFLOW) {
            error = ERR_ABNORMAL;
            return error;
        }
        if (lop.type == Lex.CONST && ConstI() != 0) {
            return error;
        }
        if (VarI() == ERR_SAMECVP) {
            return error;
        }
        if (SentenceQ() != 0) {
            return error;
        }
        if (lop.type != Lex.Rbra) {
            error = ERR_RBRALACK;
            return error;
        }
        next();
        error = 0;
        return 0;
    }
    //参数递归子程序
    private int Para() {
        if (lop.type != Lex.Lpar) {
            error = ERR_NOTBE;
            return error;
        }
        if (next() == ERR_OVERFLOW || ParaT() != 0) {
            error = ERR_ABNORMAL;
            return error;
        }
        if (lop.type != Lex.Rpar) {
            error = ERR_ABNORMAL;
            return error;
        }
        next();
        error = 0;
        return 0;
    }
    //参数表递归子程序
    private int ParaT() {
        if (lop.type != Lex.INT) {
            error = 0;
            return 0;
        }
        do {
            if (next() == ERR_OVERFLOW || lop.type != Lex.IDSY) {
                error = ERR_ABNORMAL;
                return error;
            }
            func.para.add(lop.word);
            if (next() == ERR_OVERFLOW || lop.type != Lex.COMMA) {
                error = 0;
                return 0;
            }
            if (next() == ERR_OVERFLOW || lop.type != Lex.INT) {
                error = ERR_ABNORMAL;
                return error;
            }
            continue;
        } while (true);
    }
    //语句序列递归子程序
    private int SentenceQ() {
        int f = 0;
        while (Sentence() == 0) {
            f++;
        }
        if (f == 0) {
            if (error == ERR_NOTBE) {
                error = ERR_SENTLACK;
                return error;
            } else {
                return error;
            }
        }
        if (error == ERR_NOTBE) {
            error = 0;
            return 0;
        } else {
            return error;
        }
    }
    //语句递归子程序
    private int Sentence() {
        if (ConditionS() == 0) {
            error = 0;
            return 0;
        }
        if (error != ERR_NOTBE) {
            return error;
        }
        if (LoopS() == 0) {
            error = 0;
            return 0;
        }
        if (error != ERR_NOTBE) {
            return error;
        }
        if (lop.type == Lex.Lbra) {
            if (next() == ERR_OVERFLOW || SentenceQ() != 0) {
                return error;
            }
            if (lop.type != Lex.Rbra) {
                error = ERR_RBRALACK;
                return error;
            }
            next();
            error = 0;
            return 0;
        }
        if (lop.type == Lex.IDSY) {  //当以标识符开头时，可能是赋值语句也可能是函数调用，需要把标识符存入intime，再预读一个来判断
            intime = lop.word;
            if (next() == ERR_OVERFLOW) {
                error = ERR_ABNORMAL;
                return error;
            }
            if (lop.type == Lex.EQUAL) {
                if (next() == ERR_OVERFLOW || EvaluateS() != 0) {
                    return error;
                }
                if (lop.type != Lex.SEMICOLON) {
                    error = ERR_SEMILACK;
                    return error;
                }
                next();
                error = 0;
                return 0;
            }
            if (lop.type == Lex.Lpar) {
                if (next() == ERR_OVERFLOW || Call() != 0) {
                    return error;
                }
                if (lop.type != Lex.SEMICOLON) {
                    error = ERR_SEMILACK;
                    return error;
                }
                next();
                error = 0;
                return 0;
            }
            error = ERR_ABNORMAL;
            return error;
        }
        if (ReturnS() == 0) {
            checkret++;
            if (lop.type != Lex.SEMICOLON) {
                error = ERR_SEMILACK;
                return error;
            }
            next();
            error = 0;
            return 0;
        }

        if (error != ERR_NOTBE) {
            return error;
        }

        if (ReadS() == 0) {
            if (lop.type != Lex.SEMICOLON) {
                error = ERR_SEMILACK;
                return error;
            }
            next();
            error = 0;
            return 0;
        }

        if (error != ERR_NOTBE) {
            return error;
        }

        if (WriteS() == 0) {
            if (lop.type != Lex.SEMICOLON) {
                error = ERR_SEMILACK;
                return error;
            }
            next();
            error = 0;
            return 0;
        }

        if (error != ERR_NOTBE) {
            return error;
        }

        error = ERR_NOTBE;
        return error;
    }
    //条件语句递归子程序
    private int ConditionS() {
        if (lop.type != Lex.IF) {
            error = ERR_NOTBE;
            return error;
        }
        if (next() == ERR_OVERFLOW || lop.type != Lex.Lpar) {
            error = ERR_ABNORMAL;
            return error;
        }
        if (next() == ERR_OVERFLOW || Condition() != 0) {
            return error;
        }

        addfour(JFALSE, func.name + "label" + flab, null, null);  //不满足条件时跳转至本函数的第flab个标签处
        String elsestart = func.name + "label" + flab;
        flab++;

        if (lop.type != Lex.Rpar) {
            error = ERR_ABNORMAL;
            return error;
        }
        if (next() == ERR_OVERFLOW || Sentence() != 0) {
            return error;
        }
        addfour(J, func.name + "label" + flab, null, null);
        String end = func.name + "label" + flab;
        flab++;
        addfour(STAMP, elsestart, null, null);                 //给函数fanc.name加第flab个标签
        flab++;
        if (lop.type == Lex.ELSE) {

            if (next() == ERR_OVERFLOW || Sentence() != 0) {
                return error;
            }
        }
        addfour(STAMP, end, null, null);
        error = 0;
        return 0;
    }
    //循环语句递归子程序
    private int LoopS() {
        if (lop.type != Lex.WHILE) {
            error = ERR_NOTBE;
            return error;
        }
        String start = func.name + "label" + flab;
        flab++;
        addfour(STAMP, start, null, null);                        //加标签（循环起始处）

        if (next() == ERR_OVERFLOW || lop.type != Lex.Lpar) {
            error = ERR_ABNORMAL;
            return error;
        }
        if (next() == ERR_OVERFLOW || Condition() != 0) {
            return error;
        }
        if (lop.type != Lex.Rpar) {
            error = ERR_ABNORMAL;
            return error;
        }

        addfour(JFALSE, func.name + "label" + flab, null, null);                   //当不满足条件是越过后面的语句到标签处
        String end = func.name + "label" + flab;
        flab++;