// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
package jodd.util;
import java.util.Map;
/**
* Parser for string macro templates. On parsing, macro values
* in provided string are resolved and replaced with real values.
* Once set, one string template parser can be reused for parsing,
* even using different macro resolvers.
*/
public class StringTemplateParser {
/**
* Static ctor.
*/
public static StringTemplateParser create() {
return new StringTemplateParser();
}
public static final String DEFAULT_MACRO_PREFIX = "$";
public static final String DEFAULT_MACRO_START = "${";
public static final String DEFAULT_MACRO_END = "}";
// ---------------------------------------------------------------- properties
protected boolean replaceMissingKey = true;
protected String missingKeyReplacement;
protected boolean resolveEscapes = true;
protected String macroPrefix = DEFAULT_MACRO_PREFIX;
protected String macroStart = DEFAULT_MACRO_START;
protected String macroEnd = DEFAULT_MACRO_END;
protected char escapeChar = '\\';
protected boolean parseValues;
public boolean isReplaceMissingKey() {
return replaceMissingKey;
}
/**
* Specifies if missing keys should be resolved at all,
* <code>true</code> by default.
* If <code>false</code> missing keys will be left as it were, i.e.
* they will not be replaced.
*/
public void setReplaceMissingKey(boolean replaceMissingKey) {
this.replaceMissingKey = replaceMissingKey;
}
public String getMissingKeyReplacement() {
return missingKeyReplacement;
}
/**
* Specifies replacement for missing keys. If <code>null</code>
* exception will be thrown.
*/
public StringTemplateParser setMissingKeyReplacement(String missingKeyReplacement) {
this.missingKeyReplacement = missingKeyReplacement;
return this;
}
public boolean isResolveEscapes() {
return resolveEscapes;
}
/**
* Specifies if escaped values should be resolved. In special usecases,
* when the same string has to be processed more then once,
* this may be set to <code>false</code> so escaped values
* remains.
*/
public StringTemplateParser setResolveEscapes(boolean resolveEscapes) {
this.resolveEscapes = resolveEscapes;
return this;
}
public String getMacroStart() {
return macroStart;
}
/**
* Defines macro start string.
*/
public StringTemplateParser setMacroStart(String macroStart) {
this.macroStart = macroStart;
return this;
}
public String getMacroPrefix() {
return macroPrefix;
}
public StringTemplateParser setMacroPrefix(String macroPrefix) {
this.macroPrefix = macroPrefix;
return this;
}
public String getMacroEnd() {
return macroEnd;
}
/**
* Defines macro end string.
*/
public StringTemplateParser setMacroEnd(String macroEnd) {
this.macroEnd = macroEnd;
return this;
}
/**
* Sets the strict format by setting the macro prefix to <code>null</code>.
*/
public StringTemplateParser setStrictFormat() {
macroPrefix = null;
return this;
}
public char getEscapeChar() {
return escapeChar;
}
/**
* Defines escape character.
*/
public StringTemplateParser setEscapeChar(char escapeChar) {
this.escapeChar = escapeChar;
return this;
}
public boolean isParseValues() {
return parseValues;
}
/**
* Defines if macro values has to be parsed, too.
* By default, macro values are returned as they are.
*/
public StringTemplateParser setParseValues(boolean parseValues) {
this.parseValues = parseValues;
return this;
}
// ---------------------------------------------------------------- parse
/**
* Parses string template and replaces macros with resolved values.
*/
public String parse(String template, MacroResolver macroResolver) {
StringBuilder result = new StringBuilder(template.length());
int i = 0;
int len = template.length();
// strict flag means that start and end tag are not necessary
boolean strict;
if (macroPrefix == null) {
// when prefix is not specified, make it equals to macro start
// so we can use the same code
macroPrefix = macroStart;
strict = true;
}
else {
strict = false;
}
int prefixLen = macroPrefix.length();
int startLen = macroStart.length();
int endLen = macroEnd.length();
while (i < len) {
int ndx = template.indexOf(macroPrefix, i);
if (ndx == -1) {
result.append(i == 0 ? template : template.substring(i));
break;
}
// check escaped
int j = ndx - 1;
boolean escape = false;
int count = 0;
while ((j >= 0) && (template.charAt(j) == escapeChar)) {
escape = !escape;
if (escape) {
count++;
}
j--;
}
if (resolveEscapes) {
result.append(template.substring(i, ndx - count));
} else {
result.append(template.substring(i, ndx));
}
if (escape) {
result.append(macroPrefix);
i = ndx + prefixLen;
continue;
}
// macro started, detect strict format
boolean strictFormat = strict;
if (!strictFormat) {
if (StringUtil.isSubstringAt(template, macroStart, ndx)) {
strictFormat = true;
}
}
int ndx1;
int ndx2;
if (!strictFormat) {
// not strict format: $foo
ndx += prefixLen;
ndx1 = ndx;
ndx2 = ndx;
while ((ndx2 < len) && CharUtil.isPropertyNameChar(template.charAt(ndx2))) {
ndx2++;
}
if (ndx2 == len) {
ndx2--;
}
while ((ndx2 > ndx) && !CharUtil.isAlphaOrDigit(template.charAt(ndx2))) {
ndx2--;
}
ndx2++;
if (ndx2 == ndx1 + 1) {
// no value, hence no macro
result.append(macroPrefix);
i = ndx1;
continue;
}
}
else {
// strict format: ${foo}
// find macros end
ndx += startLen;
ndx2 = template.indexOf(macroEnd, ndx);
if (ndx2 == -1) {
throw new IllegalArgumentException("Invalid template, unclosed macro at: " + (ndx - startLen));
}
// detect inner macros, there is no escaping
ndx1 = ndx;
while (ndx1 < ndx2) {
int n = StringUtil.indexOf(template, macroStart, ndx1, ndx2);
if (n == -1) {
break;
}
ndx1 = n + startLen;
}
}
final String name = template.substring(ndx1, ndx2);
// find value and append
Object value;
if (missingKeyReplacement != null || !replaceMissingKey) {
try {
value = macroResolver.resolve(name);
} catch (Exception ignore) {
value = null;
}
if (value == null) {
if (replaceMissingKey) {
value = missingKeyReplacement;
} else {
value = template.substring(ndx1 - startLen, ndx2 + 1);
}
}
} else {
value = macroResolver.resolve(name);
if (value == null) {
value = StringPool.EMPTY;
}
}
if (ndx == ndx1) {
String stringValue = value.toString();
if (parseValues) {
if (stringValue.contains(macroStart)) {
stringValue = parse(stringValue, macroResolver);
}
}
result.append(stringValue);
i = ndx2;
if (strictFormat) {
i += endLen;
}
} else {
// inner macro
template = template.substring(0, ndx1 - startLen) + value.toString() + template.substring(ndx2 + endLen);
len = template.length();
i = ndx - startLen;
}
}
return result.toString();
}
// ---------------------------------------------------------------- resolver
/**
* Macro value resolver.
*/
public interface MacroResolver {
/**
* Resolves macro value for macro name founded in
* string template. <code>null</code> values will
* be replaced with empty strings.
*/
String resolve(String macroName);
}
/**
* Creates commonly used {@link MacroResolver} that resolved
* macros in the provided map.
*/
public static MacroResolver createMapMacroResolver(final Map map) {
return macroName -> {
Object value = map.get(macroName);
if (value == null) {
return null;
}
return value.toString();
};
}
}