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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.yql;
import com.google.common.base.Predicate;
import com.google.inject.TypeLiteral;
import java.util.List;
/**
* Logical sequence operators represent a logical description of a "source" (query against data stores + pipes), representing
* a source_expression in the grammar.
*/
enum SequenceOperator implements Operator {
SCAN(TypeCheckers.LIST_OF_STRING, TypeCheckers.EXPRS), // scan a named data source (with optional arguments)
/**
* INSERT(target-sequence, input-records)
*/
INSERT(SequenceOperator.class, SequenceOperator.class),
UPDATE(SequenceOperator.class, ExpressionOperator.MAP, ExpressionOperator.class),
UPDATE_ALL(SequenceOperator.class, ExpressionOperator.MAP),
DELETE(SequenceOperator.class, ExpressionOperator.class),
DELETE_ALL(SequenceOperator.class),
EMPTY(), // emits a single, empty row
// evaluate the given expression and use the result as a sequence
EVALUATE(ExpressionOperator.class),
NEXT(String.class),
PROJECT(SequenceOperator.class, new TypeLiteral<List<OperatorNode<ProjectOperator>>>() {
}), // transform a sequence into a new schema
FILTER(SequenceOperator.class, ExpressionOperator.class), // filter a sequence by an expression
SORT(SequenceOperator.class, new TypeLiteral<List<OperatorNode<SortOperator>>>() {
}), // sort a sequence
PIPE(SequenceOperator.class, TypeCheckers.LIST_OF_STRING, TypeCheckers.EXPRS), // pipe from one source through a named transformation
LIMIT(SequenceOperator.class, ExpressionOperator.class),
OFFSET(SequenceOperator.class, ExpressionOperator.class),
SLICE(SequenceOperator.class, ExpressionOperator.class, ExpressionOperator.class),
MERGE(TypeCheckers.SEQUENCES),
JOIN(SequenceOperator.class, SequenceOperator.class, ExpressionOperator.class), // combine two (or more, in the case of MERGE) sequences to produce a new sequence
LEFT_JOIN(SequenceOperator.class, SequenceOperator.class, ExpressionOperator.class),
FALLBACK(SequenceOperator.class, SequenceOperator.class),
TIMEOUT(SequenceOperator.class, ExpressionOperator.class),
PAGE(SequenceOperator.class, ExpressionOperator.class),
ALL(),
MULTISOURCE(TypeCheckers.LIST_OF_LIST_OF_STRING);
private final ArgumentsTypeChecker checker;
public static Predicate<OperatorNode<? extends Operator>> IS = new Predicate<OperatorNode<? extends Operator>>() {
@Override
public boolean apply(OperatorNode<? extends Operator> input) {
return input.getOperator() instanceof SequenceOperator;
}
};
private SequenceOperator(Object... types) {
checker = TypeCheckers.make(this, types);
}
@Override
public void checkArguments(Object... args) {
checker.check(args);
}
}
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