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StringTemplate is a java template engine for generating source code, web pages, emails, or any other formatted text output. StringTemplate is particularly good at multi-targeted code generators, multiple site skins, and internationalization/localization. It evolved over years of effort developing jGuru.com. StringTemplate also powers the ANTLR 3 and 4 code generator. Its distinguishing characteristic is that unlike other engines, it strictly enforces model-view separation. Strict separation makes websites and code generators more flexible and maintainable; it also provides an excellent defense against malicious template authors.

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/*
 * [The "BSD license"]
 *  Copyright (c) 2011 Terence Parr
 *  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.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 org.stringtemplate.v4;

import org.stringtemplate.v4.compiler.CompiledST;
import org.stringtemplate.v4.compiler.FormalArgument;
import org.stringtemplate.v4.debug.AddAttributeEvent;
import org.stringtemplate.v4.debug.ConstructionEvent;
import org.stringtemplate.v4.debug.EvalTemplateEvent;
import org.stringtemplate.v4.debug.InterpEvent;
import org.stringtemplate.v4.gui.STViz;
import org.stringtemplate.v4.misc.Aggregate;
import org.stringtemplate.v4.misc.ErrorBuffer;
import org.stringtemplate.v4.misc.ErrorManager;
import org.stringtemplate.v4.misc.MultiMap;

import java.io.*;
import java.lang.reflect.Array;
import java.util.*;

/** An instance of the StringTemplate. It consists primarily of
 *  a {@linkplain ST#impl reference} to its implementation (shared among all
 *  instances) and a hash table of {@linkplain ST#locals attributes}.  Because
 *  of dynamic scoping, we also need a reference to any enclosing instance. For
 *  example, in a deeply nested template for an HTML page body, we could still
 *  reference the title attribute defined in the outermost page template.
 * 

 *  To use templates, you create one (usually via {@link STGroup}) and then inject
 *  attributes using {@link #add}. To render its attacks, use {@link ST#render()}.

 * 

 *  TODO: {@link ST#locals} is not actually a hash table like the documentation
 *  says.

 */
public class ST {
    public final static String VERSION = "4.3.4";

    /** {@code <@r()>}, {@code <@r>...<@end>}, and {@code @t.r() ::= "..."} defined manually by coder */
    public enum RegionType {
        /** {@code <@r()>} */
        IMPLICIT,
        /** {@code <@r>...<@end>} */
        EMBEDDED,
        /** {@code @t.r() ::= "..."} */
        EXPLICIT
    }

    /** Events during template hierarchy construction (not evaluation) */
    public static class DebugState {
        /** Record who made us? {@link ConstructionEvent} creates {@link Exception} to grab stack */
        public ConstructionEvent newSTEvent;

        /** Track construction-time add attribute "events"; used for ST user-level debugging */
        public MultiMap addAttrEvents = new MultiMap();
    }

    public static final String UNKNOWN_NAME = "anonymous";
    public static final Object EMPTY_ATTR = new Object();

    /** When there are no formal args for template t and you map t across
     *  some values, t implicitly gets arg "it".  E.g., "$it$"
     */
    public static final String IMPLICIT_ARG_NAME = "it";

    /** The implementation for this template among all instances of same template . */
    public CompiledST impl;

    /** Safe to simultaneously write via {@link #add}, which is synchronized.
     *  Reading during exec is, however, NOT synchronized.  So, not thread safe
     *  to add attributes while it is being evaluated.  Initialized to
     *  {@link #EMPTY_ATTR} to distinguish {@code null} from empty.
     */
    protected Object[] locals;

    /** Created as instance of which group? We need this to initialize interpreter
     *  via render.  So, we create st and then it needs to know which
     *  group created it for sake of polymorphism:
     *
     *  
     *  st = skin1.getInstanceOf("searchbox");
     *  result = st.render(); // knows skin1 created it
     *  

     *
     *  Say we have a group {@code g1} with template {@code t} that imports
     *  templates {@code t} and {@code u} from another group {@code g2}.
     *  {@code g1.getInstanceOf("u")} finds {@code u} in {@code g2} but remembers
     *  that {@code g1} created it.  If {@code u} includes {@code t}, it should
     *  create {@code g1.t} not {@code g2.t}.
     *
     *  
     *   g1 = {t(), u()}
     *   |
     *   v
     *   g2 = {t()}
     *  

     */
    public STGroup groupThatCreatedThisInstance;

    /** If {@link STGroup#trackCreationEvents}, track creation and add
     *  attribute events for each object. Create this object on first use.
     */
    public DebugState debugState;

    /** Just an alias for {@link ArrayList}, but this way I can track whether a
     *  list is something ST created or it's an incoming list.
     */
    public static final class AttributeList extends ArrayList {
        public AttributeList(int size) { super(size); }
        public AttributeList() { super(); }
    }

    /** Used by group creation routine, not by users */
    protected ST() {
        if ( STGroup.trackCreationEvents ) {
            if ( debugState==null ) debugState = new ST.DebugState();
            debugState.newSTEvent = new ConstructionEvent();
        }
    }

    /** Used to make templates inline in code for simple things like SQL or log records.
     *  No formal arguments are set and there is no enclosing instance.
     */
    public ST(String template) {
        this(STGroup.defaultGroup, template);
    }

    /** Create ST using non-default delimiters; each one of these will live
     *  in it's own group since you're overriding a default; don't want to
     *  alter {@link STGroup#defaultGroup}.
     */
    public ST(String template, char delimiterStartChar, char delimiterStopChar) {
        this(new STGroup(delimiterStartChar, delimiterStopChar), template);
    }

    public ST(STGroup group, String template) {
        this();
        groupThatCreatedThisInstance = group;
        impl = groupThatCreatedThisInstance.compile(group.getFileName(), null,
                                                    null, template, null);
        impl.hasFormalArgs = false;
        impl.name = UNKNOWN_NAME;
        impl.defineImplicitlyDefinedTemplates(groupThatCreatedThisInstance);
    }

    /** Clone a prototype template.
     *  Copy all fields minus {@link #debugState}; don't delegate to {@link #ST()},
     *  which creates {@link ConstructionEvent}.
     */
    public ST(ST proto) {
        try {
            // Because add() can fake a formal arg def, make sure to clone impl
            // entire impl so formalArguments list is cloned as well. Don't want
            // further derivations altering previous arg defs. See
            // testRedefOfKeyInCloneAfterAddingAttribute().
            this.impl = proto.impl.clone();
        }
        catch (CloneNotSupportedException e) {
            throw new RuntimeException(e);
        }
        if ( proto.locals!=null ) {
            this.locals = new Object[proto.locals.length];
            System.arraycopy(proto.locals, 0, this.locals, 0, proto.locals.length);
        }
        else if (impl.formalArguments != null && !impl.formalArguments.isEmpty()) {
            this.locals = new Object[impl.formalArguments.size()];
            Arrays.fill(this.locals, EMPTY_ATTR);
        }
        this.groupThatCreatedThisInstance = proto.groupThatCreatedThisInstance;
    }

    /** Inject an attribute (name/value pair). If there is already an attribute
     *  with that name, this method turns the attribute into an
     *  {@link AttributeList} with both the previous and the new attribute as
     *  elements. This method will never alter a {@link List} that you inject.
     *  If you send in a {@link List} and then inject a single value element,
     *  {@code add} copies original list and adds the new value. The
     *  attribute name cannot be null or contain '.'.
     *  

     *  Return {@code this} so we can chain:

     *  

     *  {@code t.add("x", 1).add("y", "hi")}

     */
    public synchronized ST add(String name, Object value) {
        if ( name==null ) {
            throw new NullPointerException("null attribute name");
        }
        if ( name.indexOf('.')>=0 ) {
            throw new IllegalArgumentException("cannot have '.' in attribute names");
        }

        if ( STGroup.trackCreationEvents ) {
            if ( debugState==null ) debugState = new ST.DebugState();
            debugState.addAttrEvents.map(name, new AddAttributeEvent(name, value));
        }

        FormalArgument arg = null;
        if ( impl.hasFormalArgs ) {
            if ( impl.formalArguments!=null ) arg = impl.formalArguments.get(name);
            if ( arg==null ) {
                throw new IllegalArgumentException("no such attribute: "+name);
            }
        }
        else {
            // define and make room in locals (a hack to make new ST("simple template") work.)
            if ( impl.formalArguments!=null ) {
                arg = impl.formalArguments.get(name);
            }
            if ( arg==null ) { // not defined
                arg = new FormalArgument(name);
                impl.addArg(arg);
                if ( locals==null ) locals = new Object[1];
                else {
                    Object[] copy = new Object[impl.formalArguments.size()];
                    System.arraycopy(locals, 0, copy, 0,
                                     Math.min(locals.length, impl.formalArguments.size()));
                    locals = copy;
                }
                locals[arg.index] = EMPTY_ATTR;
            }
        }

        Object curvalue = locals[arg.index];
        if ( curvalue==EMPTY_ATTR ) { // new attribute
            locals[arg.index] = value;
            return this;
        }

        // attribute will be multi-valued for sure now
        // convert current attribute to list if not already
        // copy-on-write semantics; copy a list injected by user to add new value
        AttributeList multi = convertToAttributeList(curvalue);
        locals[arg.index] = multi; // replace with list

        // now, add incoming value to multi-valued attribute
        if ( value instanceof List ) {
            // flatten incoming list into existing list
            multi.addAll((List)value);
        }
        else if ( value!=null && value.getClass().isArray() ) {
            if (value instanceof Object[]) {
                multi.addAll(Arrays.asList((Object[])value));
            }
            else {
                multi.addAll(convertToAttributeList(value));
            }
        }
        else {
            multi.add(value);
        }
        return this;
    }

    /** Split {@code aggrName.{propName1,propName2}} into list
     *  {@code [propName1, propName2]} and the {@code aggrName}. Spaces are
     *  allowed around {@code ','}.
     */
    public synchronized ST addAggr(String aggrSpec, Object... values) {
        int dot = aggrSpec.indexOf(".{");
        if ( values==null || values.length==0 ) {
            throw new IllegalArgumentException("missing values for aggregate attribute format: "+
                                               aggrSpec);
        }
        int finalCurly = aggrSpec.indexOf('}');
        if ( dot<0 || finalCurly < 0 ) {
            throw new IllegalArgumentException("invalid aggregate attribute format: "+
                                               aggrSpec);
        }
        String aggrName = aggrSpec.substring(0, dot);
        String propString = aggrSpec.substring(dot+2, aggrSpec.length()-1);
        propString = propString.trim();
        String[] propNames = propString.split("\\ *,\\ *");
        if ( propNames==null || propNames.length==0 ) {
            throw new IllegalArgumentException("invalid aggregate attribute format: "+
                                               aggrSpec);
        }
        if ( values.length != propNames.length ) {
            throw new IllegalArgumentException(
                "number of properties and values mismatch for aggregate attribute format: "+
                aggrSpec);
        }
        int i=0;
        Aggregate aggr = new Aggregate();
        for (String p : propNames) {
            Object v = values[i++];
            aggr.properties.put(p, v);
        }

        add(aggrName, aggr); // now add as usual
        return this;
    }

    /** Remove an attribute value entirely (can't remove attribute definitions). */
    public void remove(String name) {
        if ( impl.formalArguments==null ) {
            if ( impl.hasFormalArgs ) {
                throw new IllegalArgumentException("no such attribute: "+name);
            }
            return;
        }
        FormalArgument arg = impl.formalArguments.get(name);
        if ( arg==null ) {
            throw new IllegalArgumentException("no such attribute: "+name);
        }
        locals[arg.index] = EMPTY_ATTR; // reset value
    }

    /** Set {@code locals} attribute value when you only know the name, not the
     *  index. This is ultimately invoked by calling {@code ST#add} from
     *  outside so toss an exception to notify them.
     */
    protected void rawSetAttribute(String name, Object value) {
        if ( impl.formalArguments==null ) {
            throw new IllegalArgumentException("no such attribute: "+name);
        }
        FormalArgument arg = impl.formalArguments.get(name);
        if ( arg==null ) {
            throw new IllegalArgumentException("no such attribute: "+name);
        }
        locals[arg.index] = value;
    }

    /** Find an attribute in this template only. */
    public Object getAttribute(String name) {
        FormalArgument localArg = null;
        if ( impl.formalArguments!=null ) localArg = impl.formalArguments.get(name);
        if ( localArg!=null ) {
            Object o = locals[localArg.index];
            if ( o==ST.EMPTY_ATTR ) o = null;
            return o;
        }
        return null;
    }

    public Map getAttributes() {
        if ( impl.formalArguments==null ) return null;
        Map attributes = new HashMap();
        for (FormalArgument a : impl.formalArguments.values()) {
            Object o = locals[a.index];
            if ( o==ST.EMPTY_ATTR ) o = null;
            attributes.put(a.name, o);
        }
        return attributes;
    }

    protected static AttributeList convertToAttributeList(Object curvalue) {
        AttributeList multi;
        if ( curvalue == null ) {
            multi = new AttributeList(); // make list to hold multiple values
            multi.add(curvalue);                 // add previous single-valued attribute
        }
        else if ( curvalue instanceof AttributeList ) { // already a list made by ST
            multi = (AttributeList)curvalue;
        }
        else if ( curvalue instanceof List) { // existing attribute is non-ST List
            // must copy to an ST-managed list before adding new attribute
            // (can't alter incoming attributes)
            List listAttr = (List)curvalue;
            multi = new AttributeList(listAttr.size());
            multi.addAll(listAttr);
        }
        else if ( curvalue instanceof Object[] ) { // copy array to list
            Object[] a = (Object[])curvalue;
            multi = new AttributeList(a.length);
            multi.addAll(Arrays.asList(a)); // asList doesn't copy as far as I can tell
        }
        else if ( curvalue.getClass().isArray() ) { // copy primitive array to list
            int length = Array.getLength(curvalue);
            multi = new AttributeList(length);
            for (int i = 0; i < length; i++) {
                multi.add(Array.get(curvalue, i));
            }
        }
        else {
            // curvalue nonlist and we want to add an attribute
            // must convert curvalue existing to list
            multi = new AttributeList(); // make list to hold multiple values
            multi.add(curvalue);                 // add previous single-valued attribute
        }
        return multi;
    }

    public String getName() { return impl.name; }

    public boolean isAnonSubtemplate() { return impl.isAnonSubtemplate; }

    public int write(STWriter out) throws IOException {
        Interpreter interp = new Interpreter(groupThatCreatedThisInstance,
                                             impl.nativeGroup.errMgr,
                                             false);
        InstanceScope scope = new InstanceScope(null, this);
        return interp.exec(out, scope);
    }

    public int write(STWriter out, Locale locale) {
        Interpreter interp = new Interpreter(groupThatCreatedThisInstance,
                                             locale,
                                             impl.nativeGroup.errMgr,
                                             false);
        InstanceScope scope = new InstanceScope(null, this);
        return interp.exec(out, scope);
    }

    public int write(STWriter out, STErrorListener listener) {
        Interpreter interp = new Interpreter(groupThatCreatedThisInstance,
                                             new ErrorManager(listener),
                                             false);
        InstanceScope scope = new InstanceScope(null, this);
        return interp.exec(out, scope);
    }

    public int write(STWriter out, Locale locale, STErrorListener listener) {
        Interpreter interp = new Interpreter(groupThatCreatedThisInstance,
                                             locale,
                                             new ErrorManager(listener),
                                             false);
        InstanceScope scope = new InstanceScope(null, this);
        return interp.exec(out, scope);
    }

    public int write(File outputFile, STErrorListener listener) throws IOException {
        return write(outputFile, listener, "UTF-8", Locale.getDefault(), STWriter.NO_WRAP);
    }

    public int write(File outputFile, STErrorListener listener, String encoding)
        throws IOException
    {
        return write(outputFile, listener, encoding, Locale.getDefault(), STWriter.NO_WRAP);
    }

    public int write(File outputFile, STErrorListener listener, String encoding, int lineWidth)
        throws IOException
    {
        return write(outputFile, listener, encoding, Locale.getDefault(), lineWidth);
    }

    public int write(File outputFile,
                     STErrorListener listener,
                     String encoding,
                     Locale locale,
                     int lineWidth)
        throws IOException
    {
        Writer bw = null;
        try {
            FileOutputStream fos = new FileOutputStream(outputFile);
            OutputStreamWriter osw = new OutputStreamWriter(fos, encoding);
            bw = new BufferedWriter(osw);
            AutoIndentWriter w = new AutoIndentWriter(bw);
            w.setLineWidth(lineWidth);
            int n = write(w, locale, listener);
            bw.close();
            bw = null;
            return n;
        }
        finally {
            if (bw != null) bw.close();
        }
    }

    public String render() { return render(Locale.getDefault()); }

    public String render(int lineWidth) { return render(Locale.getDefault(), lineWidth); }

    public String render(Locale locale) { return render(locale, STWriter.NO_WRAP); }

    public String render(Locale locale, int lineWidth) {
        StringWriter out = new StringWriter();
        STWriter wr = new AutoIndentWriter(out);
        wr.setLineWidth(lineWidth);
        write(wr, locale);
        return out.toString();
    }

    // LAUNCH A WINDOW TO INSPECT TEMPLATE HIERARCHY

    public STViz inspect() { return inspect(Locale.getDefault()); }

    public STViz inspect(int lineWidth) {
        return inspect(impl.nativeGroup.errMgr, Locale.getDefault(), lineWidth);
    }

    public STViz inspect(Locale locale) {
        return inspect(impl.nativeGroup.errMgr, locale, STWriter.NO_WRAP);
    }

    public STViz inspect(ErrorManager errMgr, Locale locale, int lineWidth) {
        ErrorBuffer errors = new ErrorBuffer();
        impl.nativeGroup.setListener(errors);
        StringWriter out = new StringWriter();
        STWriter wr = new AutoIndentWriter(out);
        wr.setLineWidth(lineWidth);
        Interpreter interp =
            new Interpreter(groupThatCreatedThisInstance, locale, true);
        InstanceScope scope = new InstanceScope(null, this);
        interp.exec(wr, scope); // render and track events
        List events = interp.getEvents();
        EvalTemplateEvent overallTemplateEval =
            (EvalTemplateEvent)events.get(events.size()-1);
        STViz viz = new STViz(errMgr, overallTemplateEval, out.toString(), interp,
                              interp.getExecutionTrace(), errors.errors);
        viz.open();
        return viz;
    }

    // TESTING SUPPORT

    public List getEvents() { return getEvents(Locale.getDefault()); }

    public List getEvents(int lineWidth) { return getEvents(Locale.getDefault(), lineWidth); }

    public List getEvents(Locale locale) { return getEvents(locale, STWriter.NO_WRAP); }

    public List getEvents(Locale locale, int lineWidth) {
        StringWriter out = new StringWriter();
        STWriter wr = new AutoIndentWriter(out);
        wr.setLineWidth(lineWidth);
        Interpreter interp =
            new Interpreter(groupThatCreatedThisInstance, locale, true);
        InstanceScope scope = new InstanceScope(null, this);
        interp.exec(wr, scope); // render and track events
        return interp.getEvents();
    }

    @Override
    public String toString() {
        if ( impl==null ) return "bad-template()";
        String name = impl.name+"()";
        if (this.impl.isRegion) {
            name = "@" + STGroup.getUnMangledTemplateName(name);
        }

        return name;
    }

    /**
     * 
     * ST.format("<%1>:<%2>", n, p);
     * 

     */
    public static String format(String template, Object... attributes) {
        return format(STWriter.NO_WRAP, template, attributes);
    }

    public static String format(int lineWidth, String template, Object... attributes) {
        template = template.replaceAll("%([0-9]+)", "arg$1");
        ST st = new ST(template);
        int i = 1;
        for (Object a : attributes) {
            st.add("arg"+i, a);
            i++;
        }
        return st.render(lineWidth);
    }
}
    

    

    

            

    

            



    
    






    
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