Java tutorial
/* * 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.commons.text; import java.util.ArrayList; import java.util.Enumeration; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Properties; /** * Substitutes variables within a string by values. * <p> * This class takes a piece of text and substitutes all the variables within it. * The default definition of a variable is <code>${variableName}</code>. * The prefix and suffix can be changed via constructors and set methods. * <p> * Variable values are typically resolved from a map, but could also be resolved * from system properties, or by supplying a custom variable resolver. * <p> * The simplest example is to use this class to replace Java System properties. For example: * <pre> * StrSubstitutor.replaceSystemProperties( * "You are running with java.version = ${java.version} and os.name = ${os.name}."); * </pre> * <p> * Typical usage of this class follows the following pattern: First an instance is created * and initialized with the map that contains the values for the available variables. * If a prefix and/or suffix for variables should be used other than the default ones, * the appropriate settings can be performed. After that the <code>replace()</code> * method can be called passing in the source text for interpolation. In the returned * text all variable references (as long as their values are known) will be resolved. * The following example demonstrates this: * <pre> * Map valuesMap = HashMap(); * valuesMap.put("animal", "quick brown fox"); * valuesMap.put("target", "lazy dog"); * String templateString = "The ${animal} jumped over the ${target}."; * StrSubstitutor sub = new StrSubstitutor(valuesMap); * String resolvedString = sub.replace(templateString); * </pre> * yielding: * <pre> * The quick brown fox jumped over the lazy dog. * </pre> * <p> * Also, this class allows to set a default value for unresolved variables. * The default value for a variable can be appended to the variable name after the variable * default value delimiter. The default value of the variable default value delimiter is ':-', * as in bash and other *nix shells, as those are arguably where the default ${} delimiter set originated. * The variable default value delimiter can be manually set by calling {@link #setValueDelimiterMatcher(StrMatcher)}, * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}. * The following shows an example with variable default value settings: * <pre> * Map valuesMap = HashMap(); * valuesMap.put("animal", "quick brown fox"); * valuesMap.put("target", "lazy dog"); * String templateString = "The ${animal} jumped over the ${target}. ${undefined.number:-1234567890}."; * StrSubstitutor sub = new StrSubstitutor(valuesMap); * String resolvedString = sub.replace(templateString); * </pre> * yielding: * <pre> * The quick brown fox jumped over the lazy dog. 1234567890. * </pre> * <p> * In addition to this usage pattern there are some static convenience methods that * cover the most common use cases. These methods can be used without the need of * manually creating an instance. However if multiple replace operations are to be * performed, creating and reusing an instance of this class will be more efficient. * <p> * Variable replacement works in a recursive way. Thus, if a variable value contains * a variable then that variable will also be replaced. Cyclic replacements are * detected and will cause an exception to be thrown. * <p> * Sometimes the interpolation's result must contain a variable prefix. As an example * take the following source text: * <pre> * The variable ${${name}} must be used. * </pre> * Here only the variable's name referred to in the text should be replaced resulting * in the text (assuming that the value of the <code>name</code> variable is <code>x</code>): * <pre> * The variable ${x} must be used. * </pre> * To achieve this effect there are two possibilities: Either set a different prefix * and suffix for variables which do not conflict with the result text you want to * produce. The other possibility is to use the escape character, by default '$'. * If this character is placed before a variable reference, this reference is ignored * and won't be replaced. For example: * <pre> * The variable $${${name}} must be used. * </pre> * <p> * In some complex scenarios you might even want to perform substitution in the * names of variables, for instance * <pre> * ${jre-${java.specification.version}} * </pre> * <code>StrSubstitutor</code> supports this recursive substitution in variable * names, but it has to be enabled explicitly by setting the * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables} * property to <b>true</b>. * <p>This class is <b>not</b> thread safe.</p> * * @since 1.0 */ public class StrSubstitutor { /** * Constant for the default escape character. */ public static final char DEFAULT_ESCAPE = '$'; /** * Constant for the default variable prefix. */ public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher("${"); /** * Constant for the default variable suffix. */ public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}"); /** * Constant for the default value delimiter of a variable. */ public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-"); /** * Stores the escape character. */ private char escapeChar; /** * Stores the variable prefix. */ private StrMatcher prefixMatcher; /** * Stores the variable suffix. */ private StrMatcher suffixMatcher; /** * Stores the default variable value delimiter */ private StrMatcher valueDelimiterMatcher; /** * Variable resolution is delegated to an implementor of VariableResolver. */ private StrLookup<?> variableResolver; /** * The flag whether substitution in variable names is enabled. */ private boolean enableSubstitutionInVariables; /** * Whether escapes should be preserved. Default is false; */ private boolean preserveEscapes = false; //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables in the given source object with * their matching values from the map. * * @param <V> the type of the values in the map * @param source the source text containing the variables to substitute, null returns null * @param valueMap the map with the values, may be null * @return the result of the replace operation */ public static <V> String replace(final Object source, final Map<String, V> valueMap) { return new StrSubstitutor(valueMap).replace(source); } /** * Replaces all the occurrences of variables in the given source object with * their matching values from the map. This method allows to specifiy a * custom variable prefix and suffix * * @param <V> the type of the values in the map * @param source the source text containing the variables to substitute, null returns null * @param valueMap the map with the values, may be null * @param prefix the prefix of variables, not null * @param suffix the suffix of variables, not null * @return the result of the replace operation * @throws IllegalArgumentException if the prefix or suffix is null */ public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix, final String suffix) { return new StrSubstitutor(valueMap, prefix, suffix).replace(source); } /** * Replaces all the occurrences of variables in the given source object with their matching * values from the properties. * * @param source the source text containing the variables to substitute, null returns null * @param valueProperties the properties with values, may be null * @return the result of the replace operation */ public static String replace(final Object source, final Properties valueProperties) { if (valueProperties == null) { return source.toString(); } final Map<String, String> valueMap = new HashMap<>(); final Enumeration<?> propNames = valueProperties.propertyNames(); while (propNames.hasMoreElements()) { final String propName = (String) propNames.nextElement(); final String propValue = valueProperties.getProperty(propName); valueMap.put(propName, propValue); } return StrSubstitutor.replace(source, valueMap); } /** * Replaces all the occurrences of variables in the given source object with * their matching values from the system properties. * * @param source the source text containing the variables to substitute, null returns null * @return the result of the replace operation */ public static String replaceSystemProperties(final Object source) { return new StrSubstitutor(StrLookup.systemPropertiesLookup()).replace(source); } //----------------------------------------------------------------------- /** * Creates a new instance with defaults for variable prefix and suffix * and the escaping character. */ public StrSubstitutor() { this((StrLookup<?>) null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); } /** * Creates a new instance and initializes it. Uses defaults for variable * prefix and suffix and the escaping character. * * @param <V> the type of the values in the map * @param valueMap the map with the variables' values, may be null */ public <V> StrSubstitutor(final Map<String, V> valueMap) { this(StrLookup.mapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); } /** * Creates a new instance and initializes it. Uses a default escaping character. * * @param <V> the type of the values in the map * @param valueMap the map with the variables' values, may be null * @param prefix the prefix for variables, not null * @param suffix the suffix for variables, not null * @throws IllegalArgumentException if the prefix or suffix is null */ public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) { this(StrLookup.mapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE); } /** * Creates a new instance and initializes it. * * @param <V> the type of the values in the map * @param valueMap the map with the variables' values, may be null * @param prefix the prefix for variables, not null * @param suffix the suffix for variables, not null * @param escape the escape character * @throws IllegalArgumentException if the prefix or suffix is null */ public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix, final char escape) { this(StrLookup.mapLookup(valueMap), prefix, suffix, escape); } /** * Creates a new instance and initializes it. * * @param <V> the type of the values in the map * @param valueMap the map with the variables' values, may be null * @param prefix the prefix for variables, not null * @param suffix the suffix for variables, not null * @param escape the escape character * @param valueDelimiter the variable default value delimiter, may be null * @throws IllegalArgumentException if the prefix or suffix is null */ public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix, final char escape, final String valueDelimiter) { this(StrLookup.mapLookup(valueMap), prefix, suffix, escape, valueDelimiter); } /** * Creates a new instance and initializes it. * * @param variableResolver the variable resolver, may be null */ public StrSubstitutor(final StrLookup<?> variableResolver) { this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); } /** * Creates a new instance and initializes it. * * @param variableResolver the variable resolver, may be null * @param prefix the prefix for variables, not null * @param suffix the suffix for variables, not null * @param escape the escape character * @throws IllegalArgumentException if the prefix or suffix is null */ public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix, final char escape) { this.setVariableResolver(variableResolver); this.setVariablePrefix(prefix); this.setVariableSuffix(suffix); this.setEscapeChar(escape); this.setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER); } /** * Creates a new instance and initializes it. * * @param variableResolver the variable resolver, may be null * @param prefix the prefix for variables, not null * @param suffix the suffix for variables, not null * @param escape the escape character * @param valueDelimiter the variable default value delimiter string, may be null * @throws IllegalArgumentException if the prefix or suffix is null */ public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix, final char escape, final String valueDelimiter) { this.setVariableResolver(variableResolver); this.setVariablePrefix(prefix); this.setVariableSuffix(suffix); this.setEscapeChar(escape); this.setValueDelimiter(valueDelimiter); } /** * Creates a new instance and initializes it. * * @param variableResolver the variable resolver, may be null * @param prefixMatcher the prefix for variables, not null * @param suffixMatcher the suffix for variables, not null * @param escape the escape character * @throws IllegalArgumentException if the prefix or suffix is null */ public StrSubstitutor(final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher, final char escape) { this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER); } /** * Creates a new instance and initializes it. * * @param variableResolver the variable resolver, may be null * @param prefixMatcher the prefix for variables, not null * @param suffixMatcher the suffix for variables, not null * @param escape the escape character * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null * @throws IllegalArgumentException if the prefix or suffix is null */ public StrSubstitutor(final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher, final char escape, final StrMatcher valueDelimiterMatcher) { this.setVariableResolver(variableResolver); this.setVariablePrefixMatcher(prefixMatcher); this.setVariableSuffixMatcher(suffixMatcher); this.setEscapeChar(escape); this.setValueDelimiterMatcher(valueDelimiterMatcher); } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source string as a template. * * @param source the string to replace in, null returns null * @return the result of the replace operation */ public String replace(final String source) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(source); if (substitute(buf, 0, source.length()) == false) { return source; } return buf.toString(); } /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source string as a template. * <p> * Only the specified portion of the string will be processed. * The rest of the string is not processed, and is not returned. * * @param source the string to replace in, null returns null * @param offset the start offset within the array, must be valid * @param length the length within the array to be processed, must be valid * @return the result of the replace operation */ public String replace(final String source, final int offset, final int length) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(length).append(source, offset, length); if (substitute(buf, 0, length) == false) { return source.substring(offset, offset + length); } return buf.toString(); } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source array as a template. * The array is not altered by this method. * * @param source the character array to replace in, not altered, null returns null * @return the result of the replace operation */ public String replace(final char[] source) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(source.length).append(source); substitute(buf, 0, source.length); return buf.toString(); } /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source array as a template. * The array is not altered by this method. * <p> * Only the specified portion of the array will be processed. * The rest of the array is not processed, and is not returned. * * @param source the character array to replace in, not altered, null returns null * @param offset the start offset within the array, must be valid * @param length the length within the array to be processed, must be valid * @return the result of the replace operation */ public String replace(final char[] source, final int offset, final int length) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(length).append(source, offset, length); substitute(buf, 0, length); return buf.toString(); } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source buffer as a template. * The buffer is not altered by this method. * * @param source the buffer to use as a template, not changed, null returns null * @return the result of the replace operation */ public String replace(final StringBuffer source) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(source.length()).append(source); substitute(buf, 0, buf.length()); return buf.toString(); } /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source buffer as a template. * The buffer is not altered by this method. * <p> * Only the specified portion of the buffer will be processed. * The rest of the buffer is not processed, and is not returned. * * @param source the buffer to use as a template, not changed, null returns null * @param offset the start offset within the array, must be valid * @param length the length within the array to be processed, must be valid * @return the result of the replace operation */ public String replace(final StringBuffer source, final int offset, final int length) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(length).append(source, offset, length); substitute(buf, 0, length); return buf.toString(); } /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source as a template. * The source is not altered by this method. * * @param source the buffer to use as a template, not changed, null returns null * @return the result of the replace operation */ public String replace(final CharSequence source) { if (source == null) { return null; } return replace(source, 0, source.length()); } /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source as a template. * The source is not altered by this method. * <p> * Only the specified portion of the buffer will be processed. * The rest of the buffer is not processed, and is not returned. * * @param source the buffer to use as a template, not changed, null returns null * @param offset the start offset within the array, must be valid * @param length the length within the array to be processed, must be valid * @return the result of the replace operation */ public String replace(final CharSequence source, final int offset, final int length) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(length).append(source, offset, length); substitute(buf, 0, length); return buf.toString(); } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source builder as a template. * The builder is not altered by this method. * * @param source the builder to use as a template, not changed, null returns null * @return the result of the replace operation */ public String replace(final StrBuilder source) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(source.length()).append(source); substitute(buf, 0, buf.length()); return buf.toString(); } /** * Replaces all the occurrences of variables with their matching values * from the resolver using the given source builder as a template. * The builder is not altered by this method. * <p> * Only the specified portion of the builder will be processed. * The rest of the builder is not processed, and is not returned. * * @param source the builder to use as a template, not changed, null returns null * @param offset the start offset within the array, must be valid * @param length the length within the array to be processed, must be valid * @return the result of the replace operation */ public String replace(final StrBuilder source, final int offset, final int length) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder(length).append(source, offset, length); substitute(buf, 0, length); return buf.toString(); } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables in the given source object with * their matching values from the resolver. The input source object is * converted to a string using <code>toString</code> and is not altered. * * @param source the source to replace in, null returns null * @return the result of the replace operation */ public String replace(final Object source) { if (source == null) { return null; } final StrBuilder buf = new StrBuilder().append(source); substitute(buf, 0, buf.length()); return buf.toString(); } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables within the given source buffer * with their matching values from the resolver. * The buffer is updated with the result. * * @param source the buffer to replace in, updated, null returns zero * @return true if altered */ public boolean replaceIn(final StringBuffer source) { if (source == null) { return false; } return replaceIn(source, 0, source.length()); } /** * Replaces all the occurrences of variables within the given source buffer * with their matching values from the resolver. * The buffer is updated with the result. * <p> * Only the specified portion of the buffer will be processed. * The rest of the buffer is not processed, but it is not deleted. * * @param source the buffer to replace in, updated, null returns zero * @param offset the start offset within the array, must be valid * @param length the length within the buffer to be processed, must be valid * @return true if altered */ public boolean replaceIn(final StringBuffer source, final int offset, final int length) { if (source == null) { return false; } final StrBuilder buf = new StrBuilder(length).append(source, offset, length); if (substitute(buf, 0, length) == false) { return false; } source.replace(offset, offset + length, buf.toString()); return true; } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables within the given source buffer * with their matching values from the resolver. * The buffer is updated with the result. * * @param source the buffer to replace in, updated, null returns zero * @return true if altered */ public boolean replaceIn(final StringBuilder source) { if (source == null) { return false; } return replaceIn(source, 0, source.length()); } /** * Replaces all the occurrences of variables within the given source builder * with their matching values from the resolver. * The builder is updated with the result. * <p> * Only the specified portion of the buffer will be processed. * The rest of the buffer is not processed, but it is not deleted. * * @param source the buffer to replace in, updated, null returns zero * @param offset the start offset within the array, must be valid * @param length the length within the buffer to be processed, must be valid * @return true if altered */ public boolean replaceIn(final StringBuilder source, final int offset, final int length) { if (source == null) { return false; } final StrBuilder buf = new StrBuilder(length).append(source, offset, length); if (substitute(buf, 0, length) == false) { return false; } source.replace(offset, offset + length, buf.toString()); return true; } //----------------------------------------------------------------------- /** * Replaces all the occurrences of variables within the given source * builder with their matching values from the resolver. * * @param source the builder to replace in, updated, null returns zero * @return true if altered */ public boolean replaceIn(final StrBuilder source) { if (source == null) { return false; } return substitute(source, 0, source.length()); } /** * Replaces all the occurrences of variables within the given source * builder with their matching values from the resolver. * <p> * Only the specified portion of the builder will be processed. * The rest of the builder is not processed, but it is not deleted. * * @param source the builder to replace in, null returns zero * @param offset the start offset within the array, must be valid * @param length the length within the builder to be processed, must be valid * @return true if altered */ public boolean replaceIn(final StrBuilder source, final int offset, final int length) { if (source == null) { return false; } return substitute(source, offset, length); } //----------------------------------------------------------------------- /** * Internal method that substitutes the variables. * <p> * Most users of this class do not need to call this method. This method will * be called automatically by another (public) method. * <p> * Writers of subclasses can override this method if they need access to * the substitution process at the start or end. * * @param buf the string builder to substitute into, not null * @param offset the start offset within the builder, must be valid * @param length the length within the builder to be processed, must be valid * @return true if altered */ protected boolean substitute(final StrBuilder buf, final int offset, final int length) { return substitute(buf, offset, length, null) > 0; } /** * Recursive handler for multiple levels of interpolation. This is the main * interpolation method, which resolves the values of all variable references * contained in the passed in text. * * @param buf the string builder to substitute into, not null * @param offset the start offset within the builder, must be valid * @param length the length within the builder to be processed, must be valid * @param priorVariables the stack keeping track of the replaced variables, may be null * @return the length change that occurs, unless priorVariables is null when the int * represents a boolean flag as to whether any change occurred. */ private int substitute(final StrBuilder buf, final int offset, final int length, List<String> priorVariables) { final StrMatcher pfxMatcher = getVariablePrefixMatcher(); final StrMatcher suffMatcher = getVariableSuffixMatcher(); final char escape = getEscapeChar(); final StrMatcher valueDelimMatcher = getValueDelimiterMatcher(); final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables(); final boolean top = priorVariables == null; boolean altered = false; int lengthChange = 0; char[] chars = buf.buffer; int bufEnd = offset + length; int pos = offset; while (pos < bufEnd) { final int startMatchLen = pfxMatcher.isMatch(chars, pos, offset, bufEnd); if (startMatchLen == 0) { pos++; } else { // found variable start marker if (pos > offset && chars[pos - 1] == escape) { // escaped if (preserveEscapes) { pos++; continue; } buf.deleteCharAt(pos - 1); chars = buf.buffer; // in case buffer was altered lengthChange--; altered = true; bufEnd--; } else { // find suffix final int startPos = pos; pos += startMatchLen; int endMatchLen = 0; int nestedVarCount = 0; while (pos < bufEnd) { if (substitutionInVariablesEnabled && (endMatchLen = pfxMatcher.isMatch(chars, pos, offset, bufEnd)) != 0) { // found a nested variable start nestedVarCount++; pos += endMatchLen; continue; } endMatchLen = suffMatcher.isMatch(chars, pos, offset, bufEnd); if (endMatchLen == 0) { pos++; } else { // found variable end marker if (nestedVarCount == 0) { String varNameExpr = new String(chars, startPos + startMatchLen, pos - startPos - startMatchLen); if (substitutionInVariablesEnabled) { final StrBuilder bufName = new StrBuilder(varNameExpr); substitute(bufName, 0, bufName.length()); varNameExpr = bufName.toString(); } pos += endMatchLen; final int endPos = pos; String varName = varNameExpr; String varDefaultValue = null; if (valueDelimMatcher != null) { final char[] varNameExprChars = varNameExpr.toCharArray(); int valueDelimiterMatchLen = 0; for (int i = 0; i < varNameExprChars.length; i++) { // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value. if (!substitutionInVariablesEnabled && pfxMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) { break; } if ((valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i)) != 0) { varName = varNameExpr.substring(0, i); varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen); break; } } } // on the first call initialize priorVariables if (priorVariables == null) { priorVariables = new ArrayList<>(); priorVariables.add(new String(chars, offset, length)); } // handle cyclic substitution checkCyclicSubstitution(varName, priorVariables); priorVariables.add(varName); // resolve the variable String varValue = resolveVariable(varName, buf, startPos, endPos); if (varValue == null) { varValue = varDefaultValue; } if (varValue != null) { // recursive replace final int varLen = varValue.length(); buf.replace(startPos, endPos, varValue); altered = true; int change = substitute(buf, startPos, varLen, priorVariables); change = change + varLen - (endPos - startPos); pos += change; bufEnd += change; lengthChange += change; chars = buf.buffer; // in case buffer was // altered } // remove variable from the cyclic stack priorVariables.remove(priorVariables.size() - 1); break; } nestedVarCount--; pos += endMatchLen; } } } } } if (top) { return altered ? 1 : 0; } return lengthChange; } /** * Checks if the specified variable is already in the stack (list) of variables. * * @param varName the variable name to check * @param priorVariables the list of prior variables */ private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) { if (priorVariables.contains(varName) == false) { return; } final StrBuilder buf = new StrBuilder(256); buf.append("Infinite loop in property interpolation of "); buf.append(priorVariables.remove(0)); buf.append(": "); buf.appendWithSeparators(priorVariables, "->"); throw new IllegalStateException(buf.toString()); } /** * Internal method that resolves the value of a variable. * <p> * Most users of this class do not need to call this method. This method is * called automatically by the substitution process. * <p> * Writers of subclasses can override this method if they need to alter * how each substitution occurs. The method is passed the variable's name * and must return the corresponding value. This implementation uses the * {@link #getVariableResolver()} with the variable's name as the key. * * @param variableName the name of the variable, not null * @param buf the buffer where the substitution is occurring, not null * @param startPos the start position of the variable including the prefix, valid * @param endPos the end position of the variable including the suffix, valid * @return the variable's value or <b>null</b> if the variable is unknown */ protected String resolveVariable(final String variableName, final StrBuilder buf, final int startPos, final int endPos) { final StrLookup<?> resolver = getVariableResolver(); if (resolver == null) { return null; } return resolver.lookup(variableName); } // Escape //----------------------------------------------------------------------- /** * Returns the escape character. * * @return the character used for escaping variable references */ public char getEscapeChar() { return this.escapeChar; } /** * Sets the escape character. * If this character is placed before a variable reference in the source * text, this variable will be ignored. * * @param escapeCharacter the escape character (0 for disabling escaping) */ public void setEscapeChar(final char escapeCharacter) { this.escapeChar = escapeCharacter; } // Prefix //----------------------------------------------------------------------- /** * Gets the variable prefix matcher currently in use. * <p> * The variable prefix is the characer or characters that identify the * start of a variable. This prefix is expressed in terms of a matcher * allowing advanced prefix matches. * * @return the prefix matcher in use */ public StrMatcher getVariablePrefixMatcher() { return prefixMatcher; } /** * Sets the variable prefix matcher currently in use. * <p> * The variable prefix is the characer or characters that identify the * start of a variable. This prefix is expressed in terms of a matcher * allowing advanced prefix matches. * * @param prefixMatcher the prefix matcher to use, null ignored * @return this, to enable chaining * @throws IllegalArgumentException if the prefix matcher is null */ public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) { if (prefixMatcher == null) { throw new IllegalArgumentException("Variable prefix matcher must not be null!"); } this.prefixMatcher = prefixMatcher; return this; } /** * Sets the variable prefix to use. * <p> * The variable prefix is the character or characters that identify the * start of a variable. This method allows a single character prefix to * be easily set. * * @param prefix the prefix character to use * @return this, to enable chaining */ public StrSubstitutor setVariablePrefix(final char prefix) { return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix)); } /** * Sets the variable prefix to use. * <p> * The variable prefix is the characer or characters that identify the * start of a variable. This method allows a string prefix to be easily set. * * @param prefix the prefix for variables, not null * @return this, to enable chaining * @throws IllegalArgumentException if the prefix is null */ public StrSubstitutor setVariablePrefix(final String prefix) { if (prefix == null) { throw new IllegalArgumentException("Variable prefix must not be null!"); } return setVariablePrefixMatcher(StrMatcher.stringMatcher(prefix)); } // Suffix //----------------------------------------------------------------------- /** * Gets the variable suffix matcher currently in use. * <p> * The variable suffix is the characer or characters that identify the * end of a variable. This suffix is expressed in terms of a matcher * allowing advanced suffix matches. * * @return the suffix matcher in use */ public StrMatcher getVariableSuffixMatcher() { return suffixMatcher; } /** * Sets the variable suffix matcher currently in use. * <p> * The variable suffix is the characer or characters that identify the * end of a variable. This suffix is expressed in terms of a matcher * allowing advanced suffix matches. * * @param suffixMatcher the suffix matcher to use, null ignored * @return this, to enable chaining * @throws IllegalArgumentException if the suffix matcher is null */ public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) { if (suffixMatcher == null) { throw new IllegalArgumentException("Variable suffix matcher must not be null!"); } this.suffixMatcher = suffixMatcher; return this; } /** * Sets the variable suffix to use. * <p> * The variable suffix is the characer or characters that identify the * end of a variable. This method allows a single character suffix to * be easily set. * * @param suffix the suffix character to use * @return this, to enable chaining */ public StrSubstitutor setVariableSuffix(final char suffix) { return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix)); } /** * Sets the variable suffix to use. * <p> * The variable suffix is the character or characters that identify the * end of a variable. This method allows a string suffix to be easily set. * * @param suffix the suffix for variables, not null * @return this, to enable chaining * @throws IllegalArgumentException if the suffix is null */ public StrSubstitutor setVariableSuffix(final String suffix) { if (suffix == null) { throw new IllegalArgumentException("Variable suffix must not be null!"); } return setVariableSuffixMatcher(StrMatcher.stringMatcher(suffix)); } // Variable Default Value Delimiter //----------------------------------------------------------------------- /** * Gets the variable default value delimiter matcher currently in use. * <p> * The variable default value delimiter is the characer or characters that delimite the * variable name and the variable default value. This delimiter is expressed in terms of a matcher * allowing advanced variable default value delimiter matches. * <p> * If it returns null, then the variable default value resolution is disabled. * * @return the variable default value delimiter matcher in use, may be null */ public StrMatcher getValueDelimiterMatcher() { return valueDelimiterMatcher; } /** * Sets the variable default value delimiter matcher to use. * <p> * The variable default value delimiter is the characer or characters that delimite the * variable name and the variable default value. This delimiter is expressed in terms of a matcher * allowing advanced variable default value delimiter matches. * <p> * If the <code>valueDelimiterMatcher</code> is null, then the variable default value resolution * becomes disabled. * * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null * @return this, to enable chaining */ public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) { this.valueDelimiterMatcher = valueDelimiterMatcher; return this; } /** * Sets the variable default value delimiter to use. * <p> * The variable default value delimiter is the characer or characters that delimite the * variable name and the variable default value. This method allows a single character * variable default value delimiter to be easily set. * * @param valueDelimiter the variable default value delimiter character to use * @return this, to enable chaining */ public StrSubstitutor setValueDelimiter(final char valueDelimiter) { return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter)); } /** * Sets the variable default value delimiter to use. * <p> * The variable default value delimiter is the characer or characters that delimite the * variable name and the variable default value. This method allows a string * variable default value delimiter to be easily set. * <p> * If the <code>valueDelimiter</code> is null or empty string, then the variable default * value resolution becomes disabled. * * @param valueDelimiter the variable default value delimiter string to use, may be null or empty * @return this, to enable chaining */ public StrSubstitutor setValueDelimiter(final String valueDelimiter) { if (valueDelimiter == null || valueDelimiter.length() == 0) { setValueDelimiterMatcher(null); return this; } return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter)); } // Resolver //----------------------------------------------------------------------- /** * Gets the VariableResolver that is used to lookup variables. * * @return the VariableResolver */ public StrLookup<?> getVariableResolver() { return this.variableResolver; } /** * Sets the VariableResolver that is used to lookup variables. * * @param variableResolver the VariableResolver */ public void setVariableResolver(final StrLookup<?> variableResolver) { this.variableResolver = variableResolver; } // Substitution support in variable names //----------------------------------------------------------------------- /** * Returns a flag whether substitution is done in variable names. * * @return the substitution in variable names flag */ public boolean isEnableSubstitutionInVariables() { return enableSubstitutionInVariables; } /** * Sets a flag whether substitution is done in variable names. If set to * <b>true</b>, the names of variables can contain other variables which are * processed first before the original variable is evaluated, e.g. * <code>${jre-${java.version}}</code>. The default value is <b>false</b>. * * @param enableSubstitutionInVariables the new value of the flag */ public void setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) { this.enableSubstitutionInVariables = enableSubstitutionInVariables; } /** * Returns the flag controlling whether escapes are preserved during * substitution. * * @return the preserve escape flag */ public boolean isPreserveEscapes() { return preserveEscapes; } /** * Sets a flag controlling whether escapes are preserved during * substitution. If set to <b>true</b>, the escape character is retained * during substitution (e.g. <code>$${this-is-escaped}</code> remains * <code>$${this-is-escaped}</code>). If set to <b>false</b>, the escape * character is removed during substitution (e.g. * <code>$${this-is-escaped}</code> becomes * <code>${this-is-escaped}</code>). The default value is <b>false</b> * * @param preserveEscapes true if escapes are to be preserved */ public void setPreserveEscapes(final boolean preserveEscapes) { this.preserveEscapes = preserveEscapes; } }