io.wcm.devops.conga.generator.util.VariableStringResolver.java Source code

Introduction

Here is the source code for io.wcm.devops.conga.generator.util.VariableStringResolver.java

Source

/*
 * #%L
 * wcm.io
 * %%
 * Copyright (C) 2015 wcm.io
 * %%
 * Licensed 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.
 * #L%
 */
package io.wcm.devops.conga.generator.util;

import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang3.StringUtils;

import io.wcm.devops.conga.model.util.MapExpander;

/**
 * Resolve variables in a string referencing entries from a map.
 */
public final class VariableStringResolver {

    private static final Pattern VARIABLE_PATTERN = Pattern.compile("(\\\\?\\$)\\{([^\\}\\{\\$]+)\\}");
    private static final int REPLACEMENT_MAX_ITERATIONS = 20;

    private VariableStringResolver() {
        // static methods only
    }

    /**
     * Replace variable placeholders in a string with syntax ${key} with values from a map.
     * The variables can recursively reference each other.
     * All escaped variables are deescaped.
     * @param value Value with variable placeholders
     * @param variables Variable map
     * @return Value with variable placeholders resolved.
     * @throws IllegalArgumentException when a variable name could not be resolve.d
     */
    public static String resolve(String value, Map<String, Object> variables) {
        return resolve(value, variables, true);
    }

    /**
     * Replace variable placeholders in a string with syntax ${key} with values from a map.
     * The variables can recursively reference each other.
     * @param value Value with variable placeholders
     * @param variables Variable map
     * @param deescapeVariables If true, {@link #deescape(String)} is applied to the result string
     * @return Value with variable placeholders resolved.
     * @throws IllegalArgumentException when a variable name could not be resolve.d
     */
    public static String resolve(String value, Map<String, Object> variables, boolean deescapeVariables) {
        if (value == null) {
            return null;
        }

        String resolvedString = resolve(value, variables, 0);

        if (deescapeVariables) {
            resolvedString = deescape(resolvedString);
        }

        return resolvedString;
    }

    /**
     * De-escapes all escaped variables in the given string.
     * @param value String that may contain escaped variable references (starting with \$)
     * @return String with de-escaped variable references.
     */
    public static String deescape(String value) {
        return VARIABLE_PATTERN.matcher(value).replaceAll("\\$\\{$2\\}");
    }

    private static String resolve(String value, Map<String, Object> variables, int iterationCount) {
        if (iterationCount >= REPLACEMENT_MAX_ITERATIONS) {
            throw new IllegalArgumentException("Cyclic dependencies in variable string detected: " + value);
        }

        Matcher matcher = VARIABLE_PATTERN.matcher(value);
        StringBuffer sb = new StringBuffer();
        boolean replacedAny = false;
        while (matcher.find()) {
            boolean escapedVariable = StringUtils.equals(matcher.group(1), "\\$");
            String variable = matcher.group(2);
            if (escapedVariable) {
                // keep escaped variables intact
                matcher.appendReplacement(sb, Matcher.quoteReplacement("\\${" + variable + "}"));
            } else {
                Object valueObject = MapExpander.getDeep(variables, variable);
                if (valueObject != null) {
                    String variableValue = valueToString(valueObject);
                    matcher.appendReplacement(sb, Matcher.quoteReplacement(variableValue.toString()));
                    replacedAny = true;
                } else {
                    throw new IllegalArgumentException("Unknown variable: " + variable);
                }
            }
        }
        matcher.appendTail(sb);
        if (replacedAny) {
            // try again until all nested references are resolved
            return resolve(sb.toString(), variables, iterationCount + 1);
        } else {
            return sb.toString();
        }
    }

    @SuppressWarnings("unchecked")
    private static String valueToString(Object value) {
        if (value == null) {
            return "";
        } else if (value instanceof List) {
            StringBuilder sb = new StringBuilder();
            for (Object item : ((List) value)) {
                if (sb.length() > 0) {
                    sb.append(",");
                }
                sb.append(valueToString(item));
            }
            return sb.toString();
        } else if (value instanceof Map) {
            StringBuilder sb = new StringBuilder();
            // use sorted map to ensure consistent order of keys
            SortedMap<Object, Object> sortedMap = new TreeMap<>((Map<Object, Object>) value);
            for (Map.Entry<Object, Object> entry : sortedMap.entrySet()) {
                if (sb.length() > 0) {
                    sb.append(",");
                }
                sb.append(valueToString(entry.getKey()));
                sb.append("=");
                sb.append(valueToString(entry.getValue()));
            }
            return sb.toString();
        } else {
            return value.toString();
        }
    }

}