code: public void parse(final InsertStatement insertStatement) {
          if (!lexerEngine.skipIfEqual(getCustomizedInsertKeywords())) {
              return;
          }
          removeUnnecessaryToken(insertStatement);
          Optional<InsertValuesToken> insertValuesToken = insertStatement.findSQLToken(InsertValuesToken.class);
          Preconditions.checkState(insertValuesToken.isPresent());
          insertStatement.getSQLTokens().remove(insertValuesToken.get());
          insertStatement.addSQLToken(new InsertSetToken(insertValuesToken.get().getStartIndex()));
          do {
              SQLExpression left = basicExpressionParser.parse(insertStatement);
              Column column = null;
              if (left instanceof SQLPropertyExpression) {
                  column = new Column(SQLUtil.getExactlyValue(((SQLPropertyExpression) left).getName()), insertStatement.getTables().getSingleTableName());
              }
              if (left instanceof SQLIdentifierExpression) {
                  column = new Column(SQLUtil.getExactlyValue(((SQLIdentifierExpression) left).getName()), insertStatement.getTables().getSingleTableName());
              }
              if (left instanceof SQLIgnoreExpression) {
                  column = new Column(SQLUtil.getExactlyValue(((SQLIgnoreExpression) left).getExpression()), insertStatement.getTables().getSingleTableName());
              }
              Preconditions.checkNotNull(column);
              lexerEngine.accept(Symbol.EQ);
              SQLExpression right = basicExpressionParser.parse(insertStatement);
              if (shardingRule.isShardingColumn(column.getName(), column.getTableName()) 
                      && (right instanceof SQLNumberExpression || right instanceof SQLTextExpression || right instanceof SQLParameterMarkerExpression)) {
                  insertStatement.getRouteConditions().add(new Condition(column, right));
              }
          } while (lexerEngine.skipIfEqual(Symbol.COMMA));
          InsertValue insertValue = new InsertValue(new LinkedList<SQLExpression>());
          insertStatement.getValues().add(insertValue);
      }
docs: Parse insert set.
  
  @param insertStatement insert statement