Apache CXF example source code file (FiqlParser.java)

This example Apache CXF source code file (FiqlParser.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Apache CXF tags/keywords

arraylist, astnode, astnode, comparison, conditiontype, fiqlparseexception, fiqlparseexception, list, object, object, regex, searchcondition, string, string, subexpression, text, util

The Apache CXF FiqlParser.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.cxf.jaxrs.ext.search;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.xml.datatype.DatatypeConfigurationException;
import javax.xml.datatype.DatatypeFactory;

import org.apache.cxf.jaxrs.utils.InjectionUtils;

/**
 * Parses <a href="http://tools.ietf.org/html/draft-nottingham-atompub-fiql-00">FIQL expression to
 * construct {@link SearchCondition} structure. Since this class operates on Java type T, not on XML
 * structures "selectors" part of specification is not applicable; instead selectors describes getters of type
 * T used as search condition type (see {@link SimpleSearchCondition#isMet(Object)} for details.
 * 
 * @param <T> type of search condition.
 */
public class FiqlParser<T> {

    public static final String OR = ",";
    public static final String AND = ";";

    public static final String GT = "=gt=";
    public static final String GE = "=ge=";
    public static final String LT = "=lt=";
    public static final String LE = "=le=";
    public static final String EQ = "==";
    public static final String NEQ = "!=";

    private static Map<String, ConditionType> operatorsMap;
    static {
        operatorsMap = new HashMap<String, ConditionType>();
        operatorsMap.put(GT, ConditionType.GREATER_THAN);
        operatorsMap.put(GE, ConditionType.GREATER_OR_EQUALS);
        operatorsMap.put(LT, ConditionType.LESS_THAN);
        operatorsMap.put(LE, ConditionType.LESS_OR_EQUALS);
        operatorsMap.put(EQ, ConditionType.EQUALS);
        operatorsMap.put(NEQ, ConditionType.NOT_EQUALS);
    }

    private Beanspector<T> beanspector;

    /**
     * Creates FIQL parser.
     * 
     * @param tclass - class of T used to create condition objects in built syntax tree. Class T must have
     *            accessible no-arg constructor and complementary setters to these used in FIQL expressions.
     */
    public FiqlParser(Class<T> tclass) {
        beanspector = new Beanspector<T>(tclass);
    }

    /**
     * Parses expression and builds search filter. Names used in FIQL expression are names of getters/setters
     * in type T.
     * <p>
     * Example:
     * 
     * <pre>
     * class Condition {
     *   public String getFoo() {...}
     *   public void setFoo(String foo) {...}
     *   public int getBar() {...}
     *   public void setBar(int bar) {...}
     * }
     * 
     * FiqlParser<Condition> parser = new FiqlParser<Condition>(Condition.class);
     * parser.parse("foo==mystery*;bar=ge=10");
     * </pre>
     * 
     * @param fiqlExpression expression of filter.
     * @return tree of {@link SearchCondition} objects representing runtime search structure.
     * @throws FiqlParseException when expression does not follow FIQL grammar
     */
    public SearchCondition<T> parse(String fiqlExpression) throws FiqlParseException {
        ASTNode<T> ast = parseAndsOrsBrackets(fiqlExpression);
        // System.out.println(ast);
        return ast.build();
    }

    private ASTNode<T> parseAndsOrsBrackets(String expr) throws FiqlParseException {
        List<String> subexpressions = new ArrayList();
        List<String> operators = new ArrayList();
        int level = 0;
        int lastIdx = 0;
        int idx = 0;
        for (idx = 0; idx < expr.length(); idx++) {
            char c = expr.charAt(idx);
            if (c == '(') {
                level++;
            } else if (c == ')') {
                level--;
                if (level < 0) {
                    throw new FiqlParseException(String.format("Unexpected closing bracket at position %d",
                                                               idx));
                }
            }
            String cs = Character.toString(c);
            boolean isOperator = AND.equals(cs) || OR.equals(cs);
            if (level == 0 && isOperator) {
                String s1 = expr.substring(lastIdx, idx);
                String s2 = expr.substring(idx, idx + 1);
                subexpressions.add(s1);
                operators.add(s2);
                lastIdx = idx + 1;
            }
            boolean isEnd = idx == expr.length() - 1;
            if (isEnd) {
                String s1 = expr.substring(lastIdx, idx + 1);
                subexpressions.add(s1);
                operators.add(null);
                lastIdx = idx + 1;
            }
        }
        if (level != 0) {
            throw new FiqlParseException(String
                .format("Unmatched opening and closing brackets in expression: %s", expr));
        }
        if (operators.get(operators.size() - 1) != null) {
            String op = operators.get(operators.size() - 1);
            String ex = subexpressions.get(subexpressions.size() - 1);
            throw new FiqlParseException("Dangling operator at the end of expression: ..." + ex + op);
        }
        // looking for adjacent ANDs then group them into ORs
        // Note: in case not ANDs is found (e.g only ORs) every single subexpression is
        // treated as "single item group of ANDs"
        int from = 0;
        int to = 0;
        SubExpression ors = new SubExpression(OR);
        while (to < operators.size()) {
            while (to < operators.size() && AND.equals(operators.get(to))) {
                to++;
            }
            SubExpression ands = new SubExpression(AND);
            for (; from <= to; from++) {
                String subex = subexpressions.get(from);
                ASTNode<T> node = null;
                if (subex.startsWith("(")) {
                    node = parseAndsOrsBrackets(subex.substring(1, subex.length() - 1));
                } else {
                    node = parseComparison(subex);
                }
                ands.add(node);
            }
            to = from;
            if (ands.getSubnodes().size() == 1) {
                ors.add(ands.getSubnodes().get(0));
            } else {
                ors.add(ands);
            }
        }
        if (ors.getSubnodes().size() == 1) {
            return ors.getSubnodes().get(0);
        } else {
            return ors;
        }
    }

    private Comparison parseComparison(String expr) throws FiqlParseException {
        String comparators = GT + "|" + GE + "|" + LT + "|" + LE + "|" + EQ + "|" + NEQ;
        String s1 = "[\\p{ASCII}]+(" + comparators + ")";
        Pattern p = Pattern.compile(s1);
        Matcher m = p.matcher(expr);
        if (m.find()) {
            String name = expr.substring(0, m.start(1));
            String operator = m.group(1);
            String value = expr.substring(m.end(1));
            if ("".equals(value)) {
                throw new FiqlParseException("Not a comparison expression: " + expr);
            }
            Object castedValue = parseDatatype(name, value);
            return new Comparison(name, operator, castedValue);
        } else {
            throw new FiqlParseException("Not a comparison expression: " + expr);
        }
    }

    private Object parseDatatype(String setter, String value) throws FiqlParseException {
        Object castedValue = value;
        Class<?> valueType;
        try {
            valueType = beanspector.getAccessorType(setter);
        } catch (Exception e) {
            throw new FiqlParseException(e);
        }
        if (Date.class.isAssignableFrom(valueType)) {
            DateFormat df;
            try {
                df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
                // zone in XML is "+01:00" in Java is "+0100"; stripping semicolon
                int idx = value.lastIndexOf(':');
                if (idx != -1) {
                    String v = value.substring(0, idx) + value.substring(idx + 1);
                    castedValue = df.parse(v);
                } else {
                    castedValue = df.parse(value);
                }
            } catch (ParseException e) {
                // is that duration?
                try {
                    Date now = new Date();
                    DatatypeFactory.newInstance().newDuration(value).addTo(now);
                    castedValue = now;
                } catch (DatatypeConfigurationException e1) {
                    throw new FiqlParseException(e1);
                } catch (IllegalArgumentException e1) {
                    throw new FiqlParseException("Can parse " + value + " neither as date nor duration", e);
                }
            }
        } else {
            try {
                castedValue = InjectionUtils.convertStringToPrimitive(value, valueType);
            } catch (Exception e) {
                throw new FiqlParseException("Cannot convert String value \"" + value
                                             + "\" to a value of class " + valueType.getName(), e);
            }
        }
        return castedValue;
    }

    // node of abstract syntax tree
    private interface ASTNode<T> {
        SearchCondition<T> build() throws FiqlParseException;
    }

    private class SubExpression implements ASTNode<T> {
        private String operator;
        private List<ASTNode subnodes = new ArrayList>();

        public SubExpression(String operator) {
            this.operator = operator;
        }

        public void add(ASTNode<T> node) {
            subnodes.add(node);
        }

        public List<ASTNode getSubnodes() {
            return Collections.unmodifiableList(subnodes);
        }

        @Override
        public String toString() {
            String s = operator.equals(AND) ? "AND" : "OR";
            s += ":[";
            for (int i = 0; i < subnodes.size(); i++) {
                s += subnodes.get(i);
                if (i < subnodes.size() - 1) {
                    s += ", ";
                }
            }
            s += "]";
            return s;
        }

        public SearchCondition<T> build() throws FiqlParseException {
            boolean hasSubtree = false;
            for (ASTNode<T> node : subnodes) {
                if (node instanceof FiqlParser.SubExpression) {
                    hasSubtree = true;
                    break;
                }
            }
            if (!hasSubtree && AND.equals(operator)) {
                try {
                    // Optimization: single SimpleSearchCondition for 'AND' conditions
                    Map<String, ConditionType> map = new HashMap();
                    beanspector.instantiate();
                    for (ASTNode<T> node : subnodes) {
                        FiqlParser<T>.Comparison comp = (Comparison)node;
                        map.put(comp.getName(), operatorsMap.get(comp.getOperator()));
                        beanspector.setValue(comp.getName(), comp.getValue());
                    }
                    return new SimpleSearchCondition<T>(map, beanspector.getBean());
                } catch (Throwable e) {
                    throw new RuntimeException(e);
                }
            } else {
                List<SearchCondition scNodes = new ArrayList>();
                for (ASTNode<T> node : subnodes) {
                    scNodes.add(node.build());
                }
                if (OR.equals(operator)) {
                    return new OrSearchCondition<T>(scNodes);
                } else {
                    return new AndSearchCondition<T>(scNodes);
                }
            }
        }
    }

    private class Comparison implements ASTNode<T> {
        private String name;
        private String operator;
        private Object value;

        public Comparison(String name, String operator, Object value) {
            this.name = name;
            this.operator = operator;
            this.value = value;
        }

        public String getName() {
            return name;
        }

        public String getOperator() {
            return operator;
        }

        public Object getValue() {
            return value;
        }

        @Override
        public String toString() {
            return name + " " + operator + " " + value + " (" + value.getClass().getSimpleName() + ")";
        }

        public SearchCondition<T> build() throws FiqlParseException {
            T cond = createTemplate(name, value);
            ConditionType ct = operatorsMap.get(operator);
            return new SimpleSearchCondition<T>(ct, cond);
        }

        private T createTemplate(String setter, Object val) throws FiqlParseException {
            try {
                beanspector.instantiate().setValue(setter, val);
                return beanspector.getBean();
            } catch (Throwable e) {
                throw new FiqlParseException(e);
            }
        }
    }
}