[Properties (by Name)] [Methods (by Name)] [Events (by Name)]
Internally used Base class for aggregate expressions
Source position: fpexprpars.pp line 646
type TAggregateExpr = class(TFPExprFunction) |
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public |
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class function IsAggregate; override; |
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Check if expression is an aggregate |
procedure GetNodeValue(); override; |
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Get the aggregate expression value |
end; |
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Internally used Base class for aggregate expressions |
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Internally used class for representing function calls in expression trees |
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Internally used class for identifier nodes in expression trees |
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Class for representing nodes in expression trees |
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This abstract base class provides the foundation for all aggregate expression classes in the expression parser. Aggregate expressions perform calculations over multiple values, such as sums, averages, counts, minimums, and maximums.
The class extends TFPExprNode to provide aggregate-specific functionality including initialization and update methods that are called as values are processed. Derived classes must implement the specific aggregation logic for their particular operation.
Aggregate expressions typically maintain internal state that accumulates as values are processed, making them stateful unlike regular expression nodes. The aggregation process involves initialization, iterative updates, and final value calculation.
This class is used internally by the TFPExpressionParser class to construct an AST (Abstract Syntax Tree). There is normally no need for you to use or instantiate this class directly.
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Class for representing nodes in expression trees |