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ericbnericbn
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#210 First implementation of TemplateParser
using recursive descent parser. Pending: parse IfTag and ListTag.
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‎javalite-templator/src/main/java/org/javalite/templator/ConstNode.java

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package org.javalite.templator;
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import java.util.Map;
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/**
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* This terminal node represents a static chunk of text in template.
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*
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* @author Igor Polevoy
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* @author Eric Nielsen
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*/
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class ConstNode extends TemplateNode {
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private final String value;
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public ConstNode(String value) {
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this.value = value;
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}
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@Override
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public void process(Map values, Appendable appendable) throws Exception {
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appendable.append(value);
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}
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@Override
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public String toString(){
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return value;
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}
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}

‎javalite-templator/src/main/java/org/javalite/templator/TemplateNode.java

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package org.javalite.templator;
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import java.util.Map;
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/**
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* @author Igor Polevoy
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* @author Eric Nielsen
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*/
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abstract class TemplateNode {
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abstract void process(Map values, Appendable appendable) throws Exception;
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}

‎javalite-templator/src/main/java/org/javalite/templator/TemplateParser.java

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package org.javalite.templator;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* BNF rules:
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*
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* <pre>
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* WHITESPACE = Character.isWhitespace()+
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* IDENTIFIER = (Character.isJavaIdentifierStart() excluding '$') Character.isJavaIdentifierPart()*
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* IDENTIFIER_OR_FUNCTION = IDENTIFIER ('(' ')')?
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* CHAINED_IDENTIFIERS = IDENTIFIER ('.' IDENTIFIER_OR_FUNCTION)*
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* VAR = '$' '{' CHAINED_IDENTIFIER (WHITESPACE IDENTIFIER)? '}'
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* CONST = .*
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*
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* TAG_START = '&lt;' '#'
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* TAG_END = '&lt;' '/' '#'
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* LIST_TAG = TAG_START "list" WHITESPACE IDENTIFIER WHITESPACE "as" WHITESPACE IDENTIFIER '&gt;' LIST_TAG_BODY TAG_END "list" '>'
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* </pre>
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*
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* @author Eric Nielsen
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*/
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final class TemplateParser {
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private final List<TemplateNode> nodes = new ArrayList<TemplateNode>();
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private final String source;
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private int index = -1;
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private int currentCodePoint = 0;
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private int constStartIndex;
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TemplateParser(String source) {
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this.source = source;
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}
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private boolean next() {
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if (++index < source.length()) {
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currentCodePoint = source.codePointAt(index);
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return true;
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} else {
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return false;
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}
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}
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@SuppressWarnings("empty-statement")
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private boolean _whitespace() {
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if (!Character.isWhitespace(currentCodePoint)) { return false; }
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while (next() && Character.isWhitespace(currentCodePoint));
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return true;
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}
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@SuppressWarnings("empty-statement")
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private boolean _identifier() {
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// Do not accept $ at identifier start. Will someone ever complain about this?
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if (currentCodePoint == '$' || !Character.isJavaIdentifierStart(currentCodePoint)) { return false; }
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while (next() && Character.isJavaIdentifierPart(currentCodePoint));
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return true;
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}
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private boolean _identifierOrFunction() {
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if (!_identifier()) { return false; }
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if (currentCodePoint == '(') {
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if (!(next() && currentCodePoint == ')')) { return false; }
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next();
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}
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return true;
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}
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private boolean _chainedIdentifiers(List<String> identifiers) {
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int startIndex = index;
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if (!_identifier()) { return false; }
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identifiers.add(source.substring(startIndex, index));
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while (currentCodePoint == '.') {
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if (!next()) { return false; }
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startIndex = index;
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if (!_identifierOrFunction()) { return false; }
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identifiers.add(source.substring(startIndex, index));
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}
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return true;
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}
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private boolean _var() {
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int startIndex = index;
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if (currentCodePoint != '$') { return false; }
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if (!(next() && currentCodePoint == '{')) { return false; }
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List<String> identifiers = new ArrayList<String>();
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if (!(next() && _chainedIdentifiers(identifiers))) { return false; }
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BuiltIn builtIn = null;
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if (_whitespace()) {
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int builtInStartIndex = index;
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if (!_identifier()) { return false; }
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builtIn = TemplatorConfig.instance().getBuiltIn(source.substring(builtInStartIndex, index));
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}
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if (currentCodePoint != '}') { return false; }
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next();
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//TODO: refator this
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addConstEndingAt(startIndex);
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constStartIndex = index;
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nodes.add(new VarNode(identifiers, builtIn));
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return true;
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}
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@SuppressWarnings("empty-statement")
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List<TemplateNode> parse() {
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//TODO: refactor this
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if (next()) {
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for (;;) {
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int startIndex = index;
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if (!_var()) {
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if (startIndex == index) {
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if (!next()) { break; }
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}
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}
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}
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}
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addConstEndingAt(source.length());
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return nodes;
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}
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private void addConstEndingAt(int endIndex) {
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if (endIndex - 1 > constStartIndex) {
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nodes.add(new ConstNode(source.substring(constStartIndex, endIndex)));
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}
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}
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}

‎javalite-templator/src/main/java/org/javalite/templator/VarNode.java

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package org.javalite.templator;
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import java.util.List;
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import java.util.Map;
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import static org.javalite.common.Inflector.capitalize;
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/**
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* This terminal node represents a variable chunk of text in template.
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*
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* @author Igor Polevoy
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* @author Eric Nielsen
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*/
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class VarNode extends TemplateNode {
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private final List<String> identifiers;
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private final BuiltIn builtIn;
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VarNode(List<String> identifiers, BuiltIn builtIn) {
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this.identifiers = identifiers;
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this.builtIn = builtIn;
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}
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private Object valueOf(Object obj, String propertyName) throws Exception {
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if (propertyName.endsWith("()")) {
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return obj.getClass().getMethod(propertyName.substring(0, propertyName.length() - 2)).invoke(obj);
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}
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if (obj instanceof Map) {
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return ((Map) obj).get(propertyName);
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}
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try {
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// try generic get method
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return obj.getClass().getMethod("get", String.class).invoke(obj, propertyName);
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} catch (Exception e) {
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try {
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// try javabean property
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return obj.getClass().getMethod("get" + capitalize(propertyName)).invoke(obj);
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} catch (Exception e1) {
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// try public field
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try {
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return obj.getClass().getDeclaredField(propertyName).get(obj);
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} catch (Exception e2) {
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}
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}
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}
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return null;
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}
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@Override
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void process(Map values, Appendable appendable) throws Exception {
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Object obj = values.get(identifiers.get(0));
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for (int i = 1 ; i < identifiers.size(); i++) {
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obj = valueOf(obj, identifiers.get(i));
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}
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if (obj != null) {
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if (builtIn != null) {
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obj = builtIn.process(obj.toString());
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}
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appendable.append(obj.toString());
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}
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}
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}

‎javalite-templator/src/test/java/org/javalite/templator/TemplateParserSpec.java

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package org.javalite.templator;
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import java.io.StringWriter;
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import org.junit.Test;
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import java.util.List;
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import java.util.Map;
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import static org.javalite.common.Collections.*;
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import static org.javalite.test.jspec.JSpec.*;
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/**
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* @author Eric Nielsen
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*/
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public class TemplateParserSpec {
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@Test
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public void shouldParseTextTemplate() throws Exception {
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String source = "this is just plain text, no strings attached";
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List<TemplateNode> tokens = new TemplateParser(source).parse();
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the(tokens.size()).shouldBeEqual(1);
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StringWriter sw = new StringWriter();
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tokens.get(0).process(map(), sw);
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the(sw.toString()).shouldBeEqual(source);
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}
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@Test
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public void shouldTokenizeTemplate() throws Exception {
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List<TemplateNode> tokens = new TemplateParser(
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"Hello ${first_name}, your code is <b>${${foo.size()}${invalid()}}</b> ${one.two.three.four}")
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.parse();
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a(tokens.size()).shouldBeEqual(6);
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Map values = map(
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"first_name", "John",
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"foo", map(),
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"one", map("two", map("three", map("four", "five"))));
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StringWriter sw = new StringWriter();
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tokens.get(0).process(values, sw);
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tokens.get(1).process(values, sw);
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tokens.get(2).process(values, sw);
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tokens.get(3).process(values, sw);
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tokens.get(4).process(values, sw);
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tokens.get(5).process(values, sw);
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the(sw.toString()).shouldBeEqual("Hello John, your code is <b>${0${invalid()}}</b> five");
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}
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@Test
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public void shouldParseBuiltIn() throws Exception {
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List<TemplateNode> tokens = new TemplateParser("<b>${article.content esc}</b>").parse();
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a(tokens.size()).shouldBeEqual(3);
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Map values = map("article", map("content", "R&B"));
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StringWriter sw = new StringWriter();
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tokens.get(0).process(values, sw);
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tokens.get(1).process(values, sw);
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tokens.get(2).process(values, sw);
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the(sw.toString()).shouldBeEqual("<b>R&amp;B</b>");
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}
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}

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