Added a "standards mode" based on patches from mrdon. In standards mode, we do

not search parent contexts for name bindings, nor do we support compound keys.
Also added support for {{.}} which has the same semantics as {{this}}. I must
have missed this when reading the Mustache spec.

src/main/java/com/samskivert/mustache/Mustache.java

@@ -34,6 +34,9 @@ public class Mustache
         /** Whether or not HTML entities are escaped by default. */
         public final boolean escapeHTML;
 
+        /** Whether or not standards mode is enabled. */
+        public final boolean standardsMode;
+
         /** Compiles the supplied template into a repeatedly executable intermediate form. */
         public Template compile (String template)
         {
@@ -48,20 +51,28 @@ public class Mustache
 
         /** Returns a compiler that either does or does not escape HTML by default. */
         public Compiler escapeHTML (boolean escapeHTML) {
-            return new Compiler(escapeHTML);
+            return new Compiler(escapeHTML, this.standardsMode);
         }
 
-        protected Compiler (boolean escapeHTML) {
+        /** Returns a compiler that either does or does not use standards mode. Standards mode
+         * disables the non-standard JMustache extensions like looking up missing names in a parent
+         * context. */
+        public Compiler standardsMode (boolean standardsMode) {
+            return new Compiler(this.escapeHTML, standardsMode);
+        }
+
+        protected Compiler (boolean escapeHTML, boolean standardsMode) {
             this.escapeHTML = escapeHTML;
+            this.standardsMode = standardsMode;
         }
     }
 
     /**
-     * Returns a compiler that escapes HTML by default.
+     * Returns a compiler that escapes HTML by default and does not use standards mode.
      */
     public static Compiler compiler ()
     {
-        return new Compiler(true);
+        return new Compiler(true, false);
     }
 
     /**
@@ -185,7 +196,7 @@ public class Mustache
             throw new MustacheException("Template ended while parsing a tag TODO");
         }
 
-        return new Template(accum.finish());
+        return new Template(accum.finish(), compiler);
     }
 
     private Mustache () {} // no instantiateski
@@ -356,10 +367,12 @@ public class Mustache
         @Override public void execute (Template tmpl, Template.Context ctx, Writer out)  {
             Object value = tmpl.getValue(ctx, _name, _line);
             // TODO: configurable behavior on missing values
-            if (value != null) {
+            if (value == null) {
-                String text = String.valueOf(value);
+                throw new MustacheException(
-                write(out, _escapeHTML ? escapeHTML(text) : text);
+                    "No key, method or field with name '" + _name + "' on line " + _line);
             }
+            String text = String.valueOf(value);
+            write(out, _escapeHTML ? escapeHTML(text) : text);
         }
         protected boolean _escapeHTML;
     }
@@ -425,8 +438,7 @@ public class Mustache
             Object value = tmpl.getValue(ctx, _name, _line);
             if (value == null) {
                 executeSegs(tmpl, ctx, out); // TODO: configurable behavior on missing values
-            }
+            } else if (value instanceof Iterable<?>) {
-            if (value instanceof Iterable<?>) {
                 Iterable<?> iable = (Iterable<?>)value;
                 if (!iable.iterator().hasNext()) {
                     executeSegs(tmpl, ctx, out);
@@ -444,7 +456,7 @@ public class Mustache
                 if (!iter.hasNext()) {
                     executeSegs(tmpl, ctx, out);
                 }
-            }
+            } // TODO: fail?
         }
     }
 

src/main/java/com/samskivert/mustache/Template.java

@@ -60,9 +60,10 @@ public class Template
         return out.toString();
     }
 
-    protected Template (Segment[] segs)
+    protected Template (Segment[] segs, Mustache.Compiler compiler)
     {
         _segs = segs;
+        _compiler = compiler;
     }
 
     /**
@@ -71,29 +72,33 @@ public class Template
      *
      * @param ctx the context in which to look up the variable.
      * @param name the name of the variable to be resolved, which must be an interned string.
+     *
+     * @return the value associated with the supplied name or null if no value could be resolved.
      */
     protected Object getValue (Context ctx, String name, int line)
     {
-        // if we're dealing with a compound key, resolve each component and use the result to
+        if (!_compiler.standardsMode) {
-        // resolve the subsequent component and so forth
+            // if we're dealing with a compound key, resolve each component and use the result to
-        if (name.indexOf(".") != -1) {
+            // resolve the subsequent component and so forth
-            String[] comps = name.split("\\.");
+            if (name.indexOf(".") != -1) {
-            // we want to allow the first component of a compound key to be located in a parent
+                String[] comps = name.split("\\.");
-            // context, but once we're selecting sub-components, they must only be resolved in the
+                // we want to allow the first component of a compound key to be located in a parent
-            // object that represents that component
+                // context, but once we're selecting sub-components, they must only be resolved in the
-            Object data = getValue(ctx, comps[0].intern(), line);
+                // object that represents that component
-            for (int ii = 1; ii < comps.length; ii++) {
+                Object data = getValue(ctx, comps[0].intern(), line);
-                // generate more helpful error message
+                for (int ii = 1; ii < comps.length; ii++) {
-                if (data == null) {
+                    // generate more helpful error message
-                    throw new NullPointerException(
+                    if (data == null) {
-                        "Null context for compound variable '" + name + "' on line " + line +
+                        throw new NullPointerException(
-                        ". '" + comps[ii - 1] + "' resolved to null.");
+                            "Null context for compound variable '" + name + "' on line " + line +
+                            ". '" + comps[ii - 1] + "' resolved to null.");
+                    }
+                    // once we step into a composite key, we drop the ability to query our parent
+                    // contexts; that would be weird and confusing
+                    data = getValueIn(data, comps[ii].intern(), line);
                 }
-                // once we step into a composite key, we drop the ability to query our parent
+                return data;
-                // contexts; that would be weird and confusing
-                data = getValueIn(data, comps[ii].intern(), line);
             }
-            return data;
         }
 
         // handle our special variables
@@ -105,6 +110,11 @@ public class Template
             return ctx.index;
         }
 
+        // if we're in standards mode, we don't search our parent contexts
+        if (_compiler.standardsMode) {
+            return getValueIn(ctx.data, name, line);
+        }
+
         while (ctx != null) {
             Object value = getValueIn(ctx.data, name, line);
             if (value != null) {
@@ -112,9 +122,8 @@ public class Template
             }
             ctx = ctx.parent;
         }
-        // we've popped all the way off the top of our stack of contexts, so fail
+        // we've popped off the top of our stack of contexts, so return null
-        throw new MustacheException(
+        return null;
-            "No key, method or field with name '" + name + "' on line " + line);
     }
 
     protected Object getValueIn (Object data, String name, int line)
@@ -154,12 +163,14 @@ public class Template
     }
 
     protected final Segment[] _segs;
+    protected final Mustache.Compiler _compiler;
     protected final Map<Key, VariableFetcher> _fcache =
         new ConcurrentHashMap<Key, VariableFetcher>();
 
     protected static VariableFetcher createFetcher (Key key)
     {
-        if (key.name == THIS_NAME) {
+        // support both .name and this.name to fetch members
+        if (key.name == DOT_NAME || key.name == THIS_NAME) {
             return THIS_FETCHER;
         }
 
@@ -314,6 +325,7 @@ public class Template
         }
     };
 
+    protected static final String DOT_NAME = ".".intern();
     protected static final String THIS_NAME = "this".intern();
     protected static final String FIRST_NAME = "-first".intern();
     protected static final String LAST_NAME = "-last".intern();

src/test/java/com/samskivert/mustache/MustacheTest.java

@@ -203,6 +203,33 @@ public class MustacheTest
         }
     }
 
+    @Test public void testStandardsModeWithNullValuesInLoop () {
+        String tmpl = "first line\n{{#nonexistent}}foo{{/nonexistent}}\nsecond line";
+        String result = Mustache.compiler().standardsMode(true).compile(tmpl).execute(new Object());
+        assertEquals("first line\nsecond line", result);
+    }
+
+    @Test public void testStandardsModeWithNullValuesInInverseLoop () {
+        String tmpl = "first line\n{{^nonexistent}}foo{{/nonexistent}} \nsecond line";
+        String result = Mustache.compiler().standardsMode(true).compile(tmpl).execute(new Object());
+        assertEquals("first line\nfoo \nsecond line", result);
+    }
+
+    @Test public void testStandardsModeWithDotValue () {
+        String tmpl = "{{#foo}}:{{.}}:{{/foo}}";
+        String result = Mustache.compiler().standardsMode(true).compile(tmpl).
+            execute(Collections.singletonMap("foo", "bar"));
+        assertEquals(":bar:", result);
+    }
+
+    @Test(expected = MustacheException.class)
+    public void testStandardsModeWithNoParentContextSearching () {
+        String tmpl = "{{#parent}}foo{{parentProperty}}bar{{/parent}}";
+        String result = Mustache.compiler().standardsMode(true).compile(tmpl).
+            execute(context("parent", new Object(),
+                            "parentProperty", "bar"));
+    }
+
     protected void test (String expected, String template, Object ctx)
     {
         assertEquals(expected, Mustache.compiler().compile(template).execute(ctx));