Examples with Evaluator org.apache.nifi.attribute.expression.language.evaluation.Evaluator used on opensource projects

Example 1 with Evaluator

use of org.apache.nifi.attribute.expression.language.evaluation.Evaluator in project nifi by apache.

the class ExpressionCompiler method newStringLiteralEvaluator.

private Evaluator<String> newStringLiteralEvaluator(final String literalValue) {
    if (literalValue == null || literalValue.length() < 2) {
        return addToken(new StringLiteralEvaluator(literalValue), literalValue);
    }
    final List<Range> ranges = Query.extractExpressionRanges(literalValue);
    if (ranges.isEmpty()) {
        return addToken(new StringLiteralEvaluator(literalValue), literalValue);
    }
    final List<Evaluator<?>> evaluators = new ArrayList<>();
    int lastIndex = 0;
    for (final Range range : ranges) {
        if (range.getStart() > lastIndex) {
            evaluators.add(newStringLiteralEvaluator(literalValue.substring(lastIndex, range.getStart())));
        }
        final String treeText = literalValue.substring(range.getStart(), range.getEnd() + 1);
        evaluators.add(buildEvaluator(compileTree(treeText)));
        lastIndex = range.getEnd() + 1;
    }
    final Range lastRange = ranges.get(ranges.size() - 1);
    if (lastRange.getEnd() + 1 < literalValue.length()) {
        final String treeText = literalValue.substring(lastRange.getEnd() + 1);
        evaluators.add(newStringLiteralEvaluator(treeText));
    }
    if (evaluators.size() == 1) {
        return toStringEvaluator(evaluators.get(0));
    }
    Evaluator<String> lastEvaluator = toStringEvaluator(evaluators.get(0));
    for (int i = 1; i < evaluators.size(); i++) {
        lastEvaluator = new AppendEvaluator(lastEvaluator, toStringEvaluator(evaluators.get(i)));
    }
    this.evaluators.addAll(evaluators);
    return lastEvaluator;
}

Example 2 with Evaluator

use of org.apache.nifi.attribute.expression.language.evaluation.Evaluator in project nifi by apache.

the class ExpressionCompiler method buildFunctionExpressionEvaluator.

private Evaluator<?> buildFunctionExpressionEvaluator(final Tree tree, final int offset) {
    if (tree.getChildCount() == 0) {
        throw new AttributeExpressionLanguageParsingException("EXPRESSION tree node has no children");
    }
    final int firstChildIndex = tree.getChildCount() - offset - 1;
    if (firstChildIndex == 0) {
        return buildEvaluator(tree.getChild(0));
    }
    final Tree functionTree = tree.getChild(firstChildIndex);
    final Evaluator<?> subjectEvaluator = buildFunctionExpressionEvaluator(tree, offset + 1);
    final Tree functionNameTree = functionTree.getChild(0);
    final List<Evaluator<?>> argEvaluators = new ArrayList<>();
    for (int i = 1; i < functionTree.getChildCount(); i++) {
        argEvaluators.add(buildEvaluator(functionTree.getChild(i)));
    }
    return buildFunctionEvaluator(functionNameTree, subjectEvaluator, argEvaluators);
}

Example 3 with Evaluator

use of org.apache.nifi.attribute.expression.language.evaluation.Evaluator in project nifi by apache.

the class ExpressionCompiler method compile.

public CompiledExpression compile(final String expression) {
    try {
        final CharStream input = new ANTLRStringStream(expression);
        final AttributeExpressionLexer lexer = new AttributeExpressionLexer(input);
        final CommonTokenStream lexerTokenStream = new CommonTokenStream(lexer);
        final AttributeExpressionParser parser = new AttributeExpressionParser(lexerTokenStream);
        final Tree ast = (Tree) parser.query().getTree();
        final Tree tree = ast.getChild(0);
        final Evaluator<?> evaluator = buildEvaluator(tree);
        verifyMappingEvaluatorReduced(evaluator);
        final Set<Evaluator<?>> allEvaluators = new HashSet<>(evaluators);
        this.evaluators.clear();
        return new CompiledExpression(expression, evaluator, tree, allEvaluators);
    } catch (final AttributeExpressionLanguageParsingException e) {
        throw e;
    } catch (final Exception e) {
        throw new AttributeExpressionLanguageParsingException(e);
    }
}