main.c

参照清华大学《编译原理》写的cmm语言词法分析程序

            case ifsym:
                  printf("ConditionStatement-->\n");
                  printspace(lev+iden);
                  printf("keyword:if\n");
                  getsymdo;
                  if (sym == lparen) {
                        printspace(lev+iden);
                        printf("lparen:(\n");
                        getsymdo;
                        condition(lev+iden);
                        if (sym == rparen) {
                              printspace(lev+iden);
                              printf("rparen:)\n");
                              getsymdo;
                              statement(lev+iden);
                              while (sym == elsesym) {
                                    printspace(lev+iden);
                                    printf("keyword:else\n");
                                    getsymdo;
                                    if (sym == ifsym) {
                                          printspace(lev+iden);
                                          printf("keyword:if\n");
                                          getsymdo;
                                          if (sym == lparen) {
                                                printspace(lev+iden);
                                                printf("lparen:(\n");
                                                getsymdo;
                                                condition(lev+iden);
                                                if (sym == rparen) {
                                                      printspace(lev+iden);
                                                      printf("rparen:)\n");
                                                      getsymdo;
                                                      statement(lev+iden);
                                                }
                                          }
                                    }
                                    else {
                                          statement(lev+iden);
                                    }
                              }
                        }
                  }
                  break;
            case whilesym:
                  printf("WhileStatement-->\n");
                  printspace(lev+iden);
                  printf("keyword:while\n");
                  getsymdo;
                  if (sym == lparen) {
                        printspace(lev+iden);
                        printf("lparen:(\n");
                        getsymdo;
                        condition(lev+iden);
                        if (sym == rparen) {
                              printspace(lev+iden);
                              printf("rparen:)\n");
                              getsymdo;
                              statement(lev+iden);
                        }
                  }
                  break;
            case readsym:
                  printf("ReadStatement-->\n");
                  printspace(lev+iden);
                  printf("keyword:read\n");
                  getsymdo;
                  if (sym == lparen) {
                        printspace(lev+iden);
                        printf("lparen:(\n");
                        getsymdo;
                        if (sym == ident) {
                              printspace(lev+iden);
                              printf("identifier:%s\n",id);
                              getsymdo;
                        }
                        while (sym == comma) {
                              printspace(lev+iden);
                              printf("comma:,\n");
                              getsymdo;
                              if (sym == ident) {
                                    printspace(lev+iden);
                                    printf("identifier:%s\n",id);
                                    getsymdo;
                              }
                        } 
                        if (sym == rparen) {
                              printspace(lev+iden);
                              printf("rparen:)\n");
                              getsymdo;
                              if (sym == semicolon) {
                                    printspace(lev+iden);
                                    printf("semicolon:;\n");
                                    getsymdo;
                              }
                        }
                  }
                  break;
            case lbrace:
                  printf("CompoundStatement-->\n");
                  printspace(lev+iden);
                  printf("lbrace:{\n");
                  getsymdo;
                  while (sym != rbrace) {
                        statement(lev+iden);
                  }
                  if (sym == rbrace) {
                        printspace(lev+iden);
                        printf("rbrace:}\n");
                        getsymdo;
                  }
                  break;
            case writesym:
                  printf("WriteStatement-->\n");
                  printspace(lev+iden);
                  printf("keyword:write\n");
                  getsymdo;
                  if (sym == lparen) {
                        printspace(lev+iden);
                        printf("lparen:(\n");
                        getsymdo;
                        expression(lev+iden);
                        while(sym == comma) {
                              printspace(lev+iden);
                              printf("comma:,\n");
                              getsymdo;
                              expression(lev+iden);
                        }
                        if (sym == rparen) {
                              printspace(lev+iden);
                              printf("rparen:)\n");
                              getsymdo;
                              if (sym == semicolon) {
                                    printspace(lev+iden);
                                    printf("semicolon:;\n");
                                    getsymdo;
                              }
                        }
                  }
            default:
                  break;
      }
}

int condition(int lev){
      printspace(lev);
      printf("Condition-->\n");
      expression(lev+iden);
      switch (sym) {
            case eql:
                  printspace(lev+iden);
                  printf("equall: ==\n"); getsymdo; break;
            case neq:
                  printspace(lev+iden);
                  printf("not equal: !=\n"); getsymdo; ;break;
            case gtr:
                  printspace(lev+iden);
                  printf("greater than:>\n"); getsymdo; ;break;
            case geq:
                  printspace(lev+iden);
                  printf("greater or equal:>=\n"); getsymdo; ;break;
            case lss:
                  printspace(lev+iden);
                  printf("less than:<\n"); getsymdo; ;break;
            case leq:
                  printspace(lev+iden);
                  printf("less or equal:<=\n"); getsymdo; ;break;
            default:
                  break;
      }
      expression(lev+iden);
}
int vardeclaration(int lev) {
      printspace(lev);
      printf("VarDeclaration-->\n");
      printspace(lev+iden);
      if (sym == intsym) printf("keyword:int\n");
      else printf("keyword:real\n");
      getsymdo;
      while (sym != semicolon) {
            vardeclarationid(lev+iden);
            if (sym == assign) {
                  printspace(lev+iden);
                  printf("assign operator:=\n");
                  getsymdo;
                  varinitializer(lev+iden);
                  if(sym == comma) {
                        printspace(lev+iden);
                        printf("comma:,\n");
                        getsymdo;
                  }
            }
      }
      if (sym == semicolon) {
            printspace(lev+iden);
            printf("semicolon:;\n");
            getsymdo;
      }
} 

int vardeclarationid(int lev){
      printspace(lev);
      printf("VarDeclarationid-->\n");
      if (sym == ident) {
            printspace(lev+iden);
            printf("identifier:%s\n",id);
            getsymdo;
            while (sym == lbracket) {
                  printspace(lev+iden);
                  printf("lbracket:[\n");
                  getsymdo;
                  if (sym == rbracket) {
                        printspace(lev+iden);
                        printf("rbracket:]\n");
                        getsymdo;
                  }
            }
      }
}

int varinitializer(int lev){
      printspace(lev);
      printf("VarInitializer-->\n");
      if (sym == lbrace) {
            arrayinitializer(lev+iden);
      }
      else{
            expression(lev+iden);
      }
}

int arrayinitializer(int lev) {
      printspace(lev);
      printf("ArrayInitializer-->\n");
      printspace(lev+iden);
      printf("lbrace:{\n");
      getsymdo;
      while(sym != rbrace) {
            varinitializer(lev+iden);
            if (sym == comma) {
                  printspace(lev+iden);
                  printf("comma:,\n");
                  getsymdo;
            }
      }
      if (sym == rbrace) {
            printspace(lev+iden);
            printf("rbrace:}\n");
            getsymdo;
      }
}

int expression(int lev) {
      printspace(lev);
      printf("Expression-->\n");
      item(lev+iden);
      while (sym == plus || sym == minus) {
            printspace(lev+iden);
            if (sym == plus) printf("plus:+\n");
            else printf("minus:-\n");
            getsymdo;
            item(lev+iden);
      }
}

int item(int lev) {
      printspace(lev);
      printf("Item-->\n");
      factor(lev+iden);
      while (sym == times || sym == slash) {
            printspace(lev+iden);
            if (sym == times)  printf("times:*\n");
            else printf("slash:/\n");
            getsymdo;
            factor(iden+lev);
      }
}

int factor(int lev) {
      printspace(lev);
      printf("Factor-->\n");
      printspace(lev+iden);
      switch(sym) {
            case ident:
                  printf("identifier:%s\n",id); getsymdo; break;
            case number:
                  printf("number:%d\n",num); getsymdo; break;
            case real:
                  printf("real:%f\n",realvalue); getsymdo; break;
            case minus:
                  printf("minus:-\n");
                  getsymdo;
                  factor(lev+iden);
                  break;
            case lparen:
                  printf("lparen:(\n");
                  getsymdo;
                  expression(lev+iden);
                  if (sym == rparen) {
                        printspace(lev+iden);
                        printf("rparen:)\n");
                        getsymdo;
                  }
                  break;
            default:break;
      }
}
int constdeclaration(int lev) {
      printspace(lev);
      printf("ConstDeclaration\n");
      printspace(lev+iden);
      printf("keyword:const\n");
      getsymdo;
      if (sym == intsym || sym == realsym) {
            printspace(lev+iden);
            if (sym == intsym) printf("keyword:int\n");
            else printf("keyword:real\n");
            getsymdo;
            while (sym != semicolon) {
                  if (sym == ident) {
                        printspace(lev+iden);
                        printf("identifier:%s\n",id);
                        getsymdo;
                        if (sym == assign) {
                              printspace(lev+iden);
                              printf("assign operator:=\n");
                              getsymdo;
                              printspace(lev+iden);
                              if (sym == number) {
                                    printf("number:%d\n",num);
                              }
                              else if (sym == real) {
                                    printf("real:%f\n",realvalue);
                              }
                              getsymdo;
                              if (sym == comma) {
                                    printspace(lev+iden);
                                    printf("comma:,\n");
                                    getsymdo;
                              }
                        }
                  }
            }
            if (sym == semicolon) {
                  printspace(lev+iden);
                  printf("semicolon:;\n");
                  getsymdo;
            }
      }
}

int error(int eid){
      switch(eid){
      }
}

void printspace(int n) {
      int i = n;
      for (i = 0; i < n; i++) {
            printf(" ");
      }
}