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panda.el.ELTemplate Maven / Gradle / Ivy
Panda Core is the core module of Panda Framework, it contains commonly used utility classes similar to apache-commons.
package panda.el;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;
import panda.lang.Arrays;
import panda.lang.Asserts;
import panda.lang.Chars;
import panda.tpl.AbstractTemplate;
import panda.tpl.TemplateException;
public class ELTemplate extends AbstractTemplate {
private static Map cache = new WeakHashMap();
public static final char[] PREFIXS = { Chars.DOLLAR, Chars.PERCENT };
private List segments;
public ELTemplate(String expr) throws TemplateException {
this(expr, PREFIXS);
}
public ELTemplate(String expr, char prefix) throws TemplateException {
this(expr, prefix, Chars.BRACES_LEFT, Chars.BRACES_RIGHT);
}
public ELTemplate(String expr, char[] prefixs) throws TemplateException {
this(expr, prefixs, Chars.BRACES_LEFT, Chars.BRACES_RIGHT);
}
public ELTemplate(String expr, char prefix, char open, char close) throws TemplateException {
this(expr, new char[] { prefix }, open, close);
}
public ELTemplate(String expr, char[] prefixs, char open, char close) throws TemplateException {
Asserts.notNull(expr);
segments = new ArrayList();
if (Arrays.isEmpty(prefixs)) {
initWithoutPrefix(expr, open, close);
}
else if (prefixs.length == 1) {
initWithPrefix(expr, prefixs[0], open, close);
}
else {
initWithPrefixs(expr, prefixs, open, close);
}
}
private void initWithoutPrefix(String expr, char open, char close) throws TemplateException {
int x = 0, len = expr.length();
for (int i = 0; i < len; i++) {
char c = expr.charAt(i);
if (c != open) {
continue;
}
i = findSegment(expr, x, i, i + 1, close);
x = i + 1;
}
if (x < len) {
segments.add(expr.substring(x, len));
}
}
private void initWithPrefix(String expr, char prefix, char open, char close) throws TemplateException {
int x = 0, len = expr.length();
for (int i = 0; i < len; i++) {
char c = expr.charAt(i);
if (c != prefix) {
continue;
}
if (i < len - 1 && expr.charAt(i + 1) == open) {
i = findSegment(expr, x, i, i + 2, close);
x = i + 1;
}
}
if (x < len) {
segments.add(expr.substring(x, len));
}
}
private void initWithPrefixs(String expr, char[] prefixs, char open, char close) throws TemplateException {
int x = 0, len = expr.length();
for (int i = 0; i < len; i++) {
char c = expr.charAt(i);
if (!Arrays.contains(prefixs, c)) {
continue;
}
if (i < len - 1 && expr.charAt(i + 1) == open) {
i = findSegment(expr, x, i, i + 2, close);
x = i + 1;
}
}
if (x < len) {
segments.add(expr.substring(x, len));
}
}
private int findSegment(String expr, int x, int i, int s, char close) {
String el = null;
int len = expr.length();
int j = s;
for (; j < len; j++) {
if (expr.charAt(j) == close) {
el = expr.substring(s, j);
break;
}
}
// close char not found
if (el == null) {
segments.add(expr.substring(x));
return len;
}
// empty expression
if (el.length() < 1) {
throw new TemplateException("Illegal statement (" + i + "): the el expression can not be empty.");
}
if (i > x) {
segments.add(expr.substring(x, i));
}
segments.add(EL.get(el));
return j;
}
public void evaluate(Appendable out, Object context, boolean strict) throws TemplateException {
try {
for (Object o : segments) {
if (o instanceof EL) {
Object r = ((EL)o).eval(new ELContext(context, strict));
if (r != null) {
out.append(r.toString());
}
}
else {
out.append((String)o);
}
}
}
catch (IOException e) {
throw new RuntimeException(e);
}
}
public String evaluate(Object context, boolean strict) throws TemplateException {
StringBuilder sb = new StringBuilder();
evaluate(sb, context, strict);
return sb.toString();
}
@Override
public void evaluate(Appendable out, Object context) throws TemplateException {
evaluate(out, context, false);
}
//-----------------------------------------------------------------------
// static methods
//
private static ELTemplate get(String expression) throws TemplateException {
ELTemplate elt = cache.get(expression);
if (elt != null) {
return elt;
}
synchronized(cache) {
elt = cache.get(expression);
if (elt != null) {
return elt;
}
elt = new ELTemplate(expression);
cache.put(expression, elt);
return elt;
}
}
public static String evaluate(String expression) throws TemplateException {
try {
return get(expression).evaluate();
}
catch (Exception e) {
throw new TemplateException("Failed to evaluate(" + expression + ")", e);
}
}
public static String evaluate(String expression, Object context) throws TemplateException {
try {
return get(expression).evaluate(context);
}
catch (Exception e) {
throw new TemplateException("Failed to evaluate(" + expression + ")", e);
}
}
public static String evaluate(String expression, Object context, boolean strict) throws TemplateException {
try {
return get(expression).evaluate(context, strict);
}
catch (Exception e) {
throw new TemplateException("Failed to evaluate(" + expression + ")", e);
}
}
public static void evaluate(String expression, Appendable out) throws TemplateException {
try {
get(expression).evaluate(out);
}
catch (Exception e) {
throw new TemplateException("Failed to evaluate(" + expression + ")", e);
}
}
public static void evaluate(String expression, Appendable out, Object context) throws TemplateException {
try {
get(expression).evaluate(out, context);
}
catch (Exception e) {
throw new TemplateException("Failed to evaluate(" + expression + ")", e);
}
}
}
