compiler.cpp

来自「FastDb是高效的内存数据库系统」· C++ 代码 · 共 1,688 行 · 第 1/5 页

        } else if (fd->type == dbField::tpRectangle) {
            expr = new dbExprNode(expr != NULL ? dbvmLoadRectangle: dbvmLoadSelfRectangle, 
                                  fd, expr);
        } else if (fd->type != dbField::tpStructure) { 
            expr = new dbExprNode((expr != NULL 
                                   ? dbvmLoadBool : dbvmLoadSelfBool) 
                                  + fd->type, fd, expr);
        }
        lex = scan();
    }
}



dbExprNode* dbCompiler::buildList() { 
    dbExprNode* expr = disjunction(); 
    return new dbExprNode(dbvmList, expr, lex == tkn_comma ? buildList() : NULL);
}

dbExprNode* dbCompiler::term() 
{
    dbFieldDescriptor* fd;
    dbTableDescriptor* refTable;
    int cop;
    int pos = currPos;
    int prevLex = lex;
    dbBinding* bp;
    dbExprNode* expr = NULL;
    dbUserFunction* func;

    if ((cop = scan()) == tkn_where) { 
        if (firstPos == 0) { 
            firstPos = currPos;
        }
        cop = scan(); // just ignore 'where' keyword
    }
    lex = cop;

    switch (cop) { 
      case tkn_eof:
      case tkn_order:
      case tkn_start:
      case tkn_limit:
        return new dbExprNode(dbvmVoid);
      case tkn_current:
        lex = scan();
        return field(new dbExprNode(dbvmCurrent), table, NULL);
      case tkn_ident:
        for (bp = bindings; bp != NULL; bp = bp->next) { 
            if (name == bp->name) { 
                bp->used = true;
                lex = scan();
                return new dbExprNode(dbvmVariable, (dbExprNode*)0, bp->index);
            }
        }
        if ((fd = table->findSymbol(name)) == NULL) { 
            if ((func = dbUserFunction::find(name)) != NULL) { 
                pos = currPos;
                expr = term();
                int argType = func->getParameterType();
                int nParams =  func->getNumberOfParameters();
                if (nParams > 1) { 
                    if (expr->type != tpList) {
                        error("Too few paramters for user defined function");
                    }
                    dbExprNode* params[3];
                    int n = 0;
                    do { 
                        if (n == nParams) { 
                            error("Too many parameters for user defined function");
                        }       
                        dbExprNode* param = expr->operand[0];
                        if (param->type != tpInteger && param->type != tpReal && param->type != tpString
                            && param->type != tpReference && param->type != tpRawBinary && param->type != tpBoolean)
                        {
                            error("User function should receive parameters of boolean, integer, real, string, reference or user defined type", pos);
                        } 
                        params[n++] = param;
                        expr = expr->operand[1];
                    } while (expr != NULL);

                    if (n != nParams) { 
                        error("Too few parameters for user defined function");
                    }   
                    expr = new dbExprNode(dbvmFuncInt2Bool + func->type, func->fptr, params[0], params[1], params[2]);
                } else { 
                    if (argType == tpReal && expr->type == tpInteger) { 
                        expr = int2real(expr);
                    } else if (argType == tpList) {
                        if (expr->type != tpInteger && expr->type != tpReal && expr->type != tpString
                            && expr->type != tpReference && expr->type != tpRawBinary && expr->type != tpBoolean)
                        {
                            error("User function should receive parameter of boolean, integer, real, string, reference or user defined type", pos);
                        } 
                    } else if (argType != expr->type) { 
                        error("Incompatible function argument", pos);
                    }
                    expr = new dbExprNode(dbvmFuncInt2Bool + func->type, func->fptr, expr);
                }
                return field(expr, NULL, NULL);
            }
            error("Field not found", pos);
        }
        if (fd->type == dbField::tpRawBinary) { 
            expr = new dbExprNode(dbvmLoadSelfRawBinary, fd);
        } else if (fd->type == dbField::tpRectangle) { 
            expr = new dbExprNode(dbvmLoadSelfRectangle, fd);
        } else if (fd->type != dbField::tpStructure) {
            expr = new dbExprNode(dbvmLoadSelfBool + fd->type, fd);
        } 
        lex = scan();
        return field(expr, NULL, fd);
      case tkn_exists:
        if (scan() == tkn_ident) { 
            dbBinding var;
            var.next = bindings;
            var.name = name;
            var.used = false;
            var.index = nFreeVars++;
            bindings = &var;
            if (nFreeVars >= maxFreeVars) { 
                error("Too many nested EXISTS clauses\n");
            }
            pos = currPos;
            if (scan() != tkn_col) { 
                error("':' expected", pos);
            }
            expr = term();
            if (expr->type != tpBoolean) { 
                error("Expresion in EXISTS clause should be of boolean type");
            }
            if (var.used) { 
                expr = new dbExprNode(dbvmExists, expr, nFreeVars-1);
            }
            nFreeVars -= 1;         
            assert(bindings == &var);
            bindings = var.next;
            return expr;
        } else { 
            error("Free variable name expected");
        }       
        break;
      case tkn_first:
        lex = scan();
        return field(new dbExprNode(dbvmFirst), table, NULL);
      case tkn_last:
        lex = scan();
        return field(new dbExprNode(dbvmLast), table, NULL);
      case tkn_false:
        expr = new dbExprNode(dbvmLoadFalse);
        break;
      case tkn_true:
        expr = new dbExprNode(dbvmLoadTrue);
        break;
      case tkn_null:
        expr = new dbExprNode(dbvmLoadNull);
        break;
      case tkn_iconst:
        expr = new dbExprNode(dbvmLoadIntConstant, ivalue);
        break;
      case tkn_fconst:
        expr = new dbExprNode(dbvmLoadRealConstant, fvalue);
        break;
      case tkn_sconst:
        expr = new dbExprNode(dbvmLoadStringConstant, svalue); 
        lex = scan();
        return field(expr, NULL, NULL);
      case tkn_var:
        expr = new dbExprNode(dbvmLoadVarBool + varType - 
                              dbQueryElement::qVarBool, varPtr);
        refTable = varRefTable;
        lex = scan();
        return field(expr, refTable, NULL);
      case tkn_abs:
      case tkn_area:
      case tkn_length:
      case tkn_lower:
      case tkn_upper:
      case tkn_integer:
      case tkn_real:
      case tkn_string:
        pos = currPos;
        expr = term();
        switch (cop) {
          case tkn_abs:
            if (expr->type == tpInteger) { 
                cop = dbvmAbsInt;
            } else if (expr->type == tpReal) { 
                cop = dbvmAbsReal;
            } else { 
                error("ABS function can be applied only "
                      "to integer or real expression", pos);
            }
            break;
          case tkn_area:
            if (expr->type == tpRectangle) {
                cop = dbvmRectangleArea;
            } else if (expr->type == tpList) { 
                expr = rectangleConstant(expr);
                cop = dbvmRectangleArea;                
            } else {
                error("AREA function can be applied only to rectangles", pos);
            }
            break;
          case tkn_length:
            if (expr->type == tpArray) { 
                cop = dbvmLength;
            } else if (expr->type == tpString) { 
                cop = dbvmStringLength;
            } else { 
                error("LENGTH function is defined only for arrays and strings",
                      pos);
            } 
            break;
          case tkn_integer:
            if (expr->type == tpReal) { 
                cop = dbvmRealToInt;
            } else { 
                error("INTEGER function can be applied only to "
                      "expression of real type", pos);
            }
            break;
          case tkn_real:
            if (expr->type == tpInteger) { 
                cop = dbvmIntToReal;
            } else { 
                error("REAL function can be applied only to "
                      "expression of integer type", pos);
            }
            break;
          case tkn_string:
            if (expr->type == tpInteger) { 
                cop = dbvmIntToString;
            } else if (expr->type == tpReal) { 
                cop = dbvmRealToString;
            } else { 
                error("STRING function can be applied only "
                      "to integer or real expression", pos);
            }
            break;
          case tkn_lower:
            if (expr->type != tpString) { 
                error("LOWER function can be applied only to string argument",
                      pos);
            } else { 
                cop = dbvmLowerString;
            }
            break;
          case tkn_upper:
            if (expr->type != tpString) { 
                error("UPPER function can be applied only to string argument",
                      pos);
            } else { 
                cop = dbvmUpperString;
            }
            break;
          default:
            assert(false);
        }
        return field(new dbExprNode(cop, expr), NULL, NULL);
      case tkn_lpar:
        {
            expr = disjunction();            
            if (lex == tkn_comma) { 
                expr = new dbExprNode(dbvmList, expr, buildList());
            } else if (prevLex == tkn_in) { 
                expr = new dbExprNode(dbvmList, expr);
            }
            if (lex != tkn_rpar) { 
                error("')' expected");
            }
        }
        break;
      case tkn_not:
        pos = currPos;
        expr = comparison();
        if (expr->type == tpInteger) { 
            if (expr->cop == dbvmLoadIntConstant) { 
                expr->ivalue = ~expr->ivalue;
            } else {
                expr = new dbExprNode(dbvmNotInt, expr);
            } 
            return expr;
        } else if (expr->type == tpBoolean) { 
            return new dbExprNode(dbvmNotBool, expr);
        } else { 
            error("NOT operator can be applied only to "
                  "integer or boolean expressions", pos);
        }
        break;
      case tkn_add:
        error("Using of unary plus operator has no sence");
        break;
      case tkn_sub:
        pos = currPos;
        expr = term();
        if (expr->type == tpInteger) { 
            if (expr->cop == dbvmLoadIntConstant) { 
                expr->ivalue = -expr->ivalue;
            } else { 
                expr = new dbExprNode(dbvmNegInt, expr);
            }
            return expr;
        } else if (expr->type == tpReal) { 
            if (expr->cop == dbvmLoadRealConstant) { 
                expr->fvalue = -expr->fvalue;
            } else { 
                expr = new dbExprNode(dbvmNegReal, expr);
            }
            return expr;
        } else { 
            error("Unary minus can be applied only to "
                  "integer or real expressions", pos);
        }
      default:
        error("operand expected");
    }
    lex = scan();
    return expr;
}

void dbCompiler::error(const char* msg, int pos) 
{ 
    if (pos < 0) { 
        if ((pos = currPos-1) < 0) { 
            pos = 0;
        }
    } else if (pos < firstPos) { 
        pos = firstPos;
    }
    if (pos + offsetWithinStatement >= 0) { 
        pos += offsetWithinStatement;
    }
    table->db->handleError(dbDatabase::QueryError, msg, pos);
    longjmp(abortCompilation, dbDatabase::QueryError);
}

void dbCompiler::compileStartFollowPart(dbQuery& query)