hunt.sql.visitor.functions.Length 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.Length;
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.Integer;
25 import hunt.String;
26 import hunt.String;
27 import hunt.collection;
28 import std.conv;
29 import std.uni;
30 
31 import std.concurrency : initOnce;
32 
33 public class Length : Function {
34     
35     static Length instance() {
36         __gshared Length inst;
37         return initOnce!inst(new Length());
38     }    
39         
40     // public  static Length instance;
41 
42     // static this()
43     // {
44     //     instance = new Length();
45     // }
46     
47     public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
48         if (x.getParameters().size() != 1) {
49             return cast(Object)(SQLEvalVisitor.EVAL_ERROR);
50         }
51 
52         SQLExpr param0 = x.getParameters().get(0);
53         param0.accept(visitor);
54 
55         Object param0Value = param0.getAttributes().get(SQLEvalVisitor.EVAL_VALUE);
56         if (param0Value is null) {
57             return cast(Object)(SQLEvalVisitor.EVAL_ERROR);
58         }
59 
60         string strValue = param0Value.toString();
61 
62         int result = cast(int)(strValue.length);
63         return new Integer(result);
64     }
65 }