Validator


1   /*
2   // $Id: //open/mondrian/src/main/mondrian/olap/Validator.java#7 $
3   // This software is subject to the terms of the Common Public License
4   // Agreement, available at the following URL:
5   // http://www.opensource.org/licenses/cpl.html.
6   // Copyright (C) 2005-2006 Julian Hyde
7   // All Rights Reserved.
8   // You must accept the terms of that agreement to use this software.
9   */
10  package mondrian.olap;
11  
12  import mondrian.olap.fun.ParameterFunDef;
13  import mondrian.olap.type.Type;
14  import mondrian.mdx.ParameterExpr;
15  
16  /**
17   * Provides context necessary to resolve identifiers to objects, function
18   * calls to specific functions.
19   *
20   * <p>An expression calls {@link #validate} on each of its children,
21   * which in turn calls {@link Exp#accept}.
22   *
23   * @author jhyde
24   * @version $Id: //open/mondrian/src/main/mondrian/olap/Validator.java#7 $
25   */
26  public interface Validator {
27      /**
28       * Returns the {@link Query} which is being validated.
29       */
30      Query getQuery();
31  
32      /**
33       * Validates an expression, and returns the expression it resolves to.
34       *
35       * @param exp Expression to validate
36       * @param scalar Whether the context requires that the expression is
37       *   evaluated to a value, as opposed to a tuple
38       */
39      Exp validate(Exp exp, boolean scalar);
40  
41      /**
42       * Validates a usage of a parameter.
43       *
44       * <p>It must resolve to the same object (although sub-objects may change).
45       */
46      void validate(ParameterExpr parameterExpr);
47  
48      /**
49       * Validates a child member property.
50       *
51       * <p>It must resolve to the same object (although sub-objects may change).
52       */
53      void validate(MemberProperty memberProperty);
54  
55      /**
56       * Validates an axis.
57       *
58       * It must resolve to the same object (although sub-objects may change).
59       */
60      void validate(QueryAxis axis);
61  
62      /**
63       * Validates a formula.
64       *
65       * It must resolve to the same object (although sub-objects may change).
66       */
67      void validate(Formula formula);
68  
69      /**
70       * Returns whether the current context requires an expression.
71       */
72      boolean requiresExpression();
73  
74      /**
75       * Returns whether we can convert an argument to a parameter type.
76       *
77       * @param fromExp argument type
78       * @param to   parameter type
79       * @param conversionCount in/out count of number of conversions performed;
80       *             is incremented if the conversion is non-trivial (for
81       *             example, converting a member to a level).
82       */
83      boolean canConvert(Exp fromExp, int to, int[] conversionCount);
84  
85      /**
86       * Returns the table of function and operator definitions.
87       */
88      FunTable getFunTable();
89  
90      /**
91       * Creates or retrieves the parameter corresponding to a "Parameter" or
92       * "ParamRef" function call.
93       */
94      Parameter createOrLookupParam(
95          boolean definition,
96          String   name,
97          Type type,
98          Exp defaultExp,
99          String   description);
100 }
101 
102 // End Validator.java
103
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