hunt.sql.visitor.functions.BitLength source code

1 /*
2  * Copyright 2015-2018 HuntLabs.cn
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 module hunt.sql.visitor.functions.BitLength;
17 
18 // import hunt.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
19 
20 import hunt.sql.ast.SQLExpr;
21 import hunt.sql.ast.expr.SQLMethodInvokeExpr;
22 import hunt.sql.visitor.SQLEvalVisitor;
23 import hunt.sql.visitor.functions.Function;
24 import hunt.Long;
25 import hunt.String;
26 
27 import std.concurrency : initOnce;
28 
29 public class BitLength : Function {
30 
31     static BitLength instance() {
32         __gshared BitLength inst;
33         return initOnce!inst(new BitLength());
34     }    
35 
36     // public  static BitLength instance;
37 
38     // static this()
39     // {
40     //     instance = new BitLength();
41     // }
42 
43     public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
44         if (x.getParameters().size() != 1) {
45             return cast(Object)(SQLEvalVisitor.EVAL_ERROR);
46         }
47 
48         SQLExpr param0 = x.getParameters().get(0);
49         param0.accept(visitor);
50 
51         Object param0Value = param0.getAttributes().get(SQLEvalVisitor.EVAL_VALUE);
52         if (param0Value is null) {
53             return cast(Object)(SQLEvalVisitor.EVAL_ERROR);
54         }
55 
56         if (cast(String)(param0Value) !is null) {
57             return new Long((cast(String) param0Value).value().length * 8);
58         }
59         return cast(Object)(SQLEvalVisitor.EVAL_ERROR);
60     }
61 }