ISSUE-201: added a new operator for use with template inheritance. {{?name}}{{/name}} will only be included in the template if the "name" section is overridden.

Author: spullara

compiler/src/main/java/com/github/mustachejava/DefaultMustacheVisitor.java

@@ -58,6 +58,11 @@ public void name(TemplateContext templateContext, String variable, Mustache must
     list.add(new ExtendNameCode(templateContext, df, mustache, variable));
   }
 
+  @Override
+  public void checkName(TemplateContext templateContext, String variable, Mustache mustache) {
+      list.add(new ExtendCheckNameCode(templateContext, df, mustache, variable));
+  }
+
   @Override
   public void partial(TemplateContext tc, final String variable) {
     TemplateContext partialTC = new TemplateContext("{{", "}}", tc.file(), tc.line(), tc.startOfLine());

compiler/src/main/java/com/github/mustachejava/MustacheParser.java

@@ -136,6 +136,7 @@ protected Mustache compile(final Reader reader, String tag, final AtomicInteger
                 case '#':
                 case '^':
                 case '<':
+                case '?':
                 case '$': {
                   boolean oldStartOfLine = startOfLine;
                   startOfLine = startOfLine & onlywhitespace;
@@ -159,6 +160,9 @@ protected Mustache compile(final Reader reader, String tag, final AtomicInteger
                     case '$':
                       mv.name(new TemplateContext(sm, em, file, line, startOfLine), variable, mustache);
                       break;
+                    case '?':
+                      mv.checkName(new TemplateContext(sm, em, file, line, startOfLine), variable, mustache);
+                      break;
                   }
                   iterable = lines != 0;
                   break;

compiler/src/main/java/com/github/mustachejava/MustacheVisitor.java

@@ -28,5 +28,7 @@ public interface MustacheVisitor {
 
   void name(TemplateContext templateContext, String variable, Mustache mustache);
 
+  void checkName(TemplateContext templateContext, String variable, Mustache mustache);
+
   void comment(TemplateContext templateContext, String comment);
 }

compiler/src/main/java/com/github/mustachejava/codes/ExtendCheckNameCode.java

@@ -0,0 +1,23 @@
+package com.github.mustachejava.codes;
+
+import com.github.mustachejava.DefaultMustacheFactory;
+import com.github.mustachejava.Mustache;
+import com.github.mustachejava.TemplateContext;
+
+import java.io.Writer;
+import java.util.List;
+
+/**
+ * Name a section: {{$name}}...{{/name}}
+ */
+public class ExtendCheckNameCode extends DefaultCode {
+  private boolean suppressed;
+
+  public ExtendCheckNameCode(TemplateContext templateContext, DefaultMustacheFactory df, Mustache mustache, String variable) {
+    super(templateContext, df, mustache, variable, "$");
+  }
+
+  public String getName() {
+    return name;
+  }
+}

compiler/src/main/java/com/github/mustachejava/codes/ExtendCode.java

@@ -43,6 +43,12 @@ private Code[] replaceCodes(Code[] supercodes, Map<String, ExtendNameCode> repla
             enc.setCodes(replaceCodes(enc.getCodes(), replaceMap, seen));
           }
         } else {
+          if (code instanceof ExtendCheckNameCode) {
+            ExtendCheckNameCode ecnc = (ExtendCheckNameCode) code;
+            if (!replaceMap.containsKey(ecnc.getName())) {
+              code.setCodes(new Code[0]);
+            }
+          }
           Code[] codes = code.getCodes();
           if (codes != null) {
             code.setCodes(replaceCodes(codes, replaceMap, seen));

compiler/src/test/java/com/github/mustachejava/InterpreterTest.java

@@ -926,61 +926,7 @@ public void testRelativePathFail() throws IOException {
   }
 
   public void testVariableInhertiance() throws IOException {
-    DefaultMustacheFactory mf = new DefaultMustacheFactory(root) {
-      @Override
-      public MustacheVisitor createMustacheVisitor() {
-        DefaultMustacheVisitor visitor = new DefaultMustacheVisitor(this) {
-          @Override
-          public void extend(TemplateContext templateContext, String variable, Mustache mustache) {
-            list.add(new ExtendCode(templateContext, df, mustache, variable) {
-              @Override
-              public synchronized void init() {
-                // Find the comments that the pragma generates
-                List<Code> comments = new ArrayList<>();
-                for (Code code : mustache.getCodes()) {
-                  if (code instanceof CommentCode) {
-                    comments.add(code);
-                  }
-                }
-                super.init();
-                // Put the comments at the start of the base codes
-                Code[] codes = partial.getCodes();
-                if (!comments.isEmpty()) {
-                  Code[] newcodes = new Code[comments.size() + codes.length];
-                  for (int i = 0; i < comments.size(); i++) {
-                    newcodes[i] = comments.get(i);
-                  }
-                  System.arraycopy(codes, 0, newcodes, comments.size(), codes.length);
-                  partial.setCodes(newcodes);
-                }
-
-              }
-            });
-          }
-        };
-        visitor.addPragmaHandler("set", (tc, pragma, args) -> {
-          // Create a comment code that sets variables
-          int index = args.indexOf("=");
-          if (index == -1) {
-            throw new MustacheException("Pragme 'set' must have varname=value as an argument");
-          }
-          String name = args.substring(0, index);
-          String value = args.substring(index + 1);
-          Map<String, String> variable = new HashMap<String, String>() {{
-            put(name, value);
-          }};
-          return new CommentCode(tc, null, "") {
-            @Override
-            public Writer execute(Writer writer, List<Object> scopes) {
-              scopes.add(variable);
-              return writer;
-            }
-          };
-        });
-        return visitor;
-      }
-    };
-
+    DefaultMustacheFactory mf = createMustacheFactory();
     Mustache m = mf.compile("issue_201/chat.html");
     StringWriter sw = new StringWriter();
     m.execute(sw, new Object()).close();

compiler/src/test/resources/issue_201/base.html

@@ -1 +1 @@
-{{#jsUrl}}<script src="{{jsUrl}}"></script>{{/jsUrl}}
+{{?jsUrl}}<script src="{{$jsUrl}}default{{/jsUrl}}"></script>{{/jsUrl}}{{?jsUrl2}}<script src="{{$jsUrl}}default{{/jsUrl}}"></script>{{/jsUrl2}}

compiler/src/test/resources/issue_201/chat.html

@@ -1,3 +1,3 @@
 {{<base.html}}
-{{%set jsUrl=test}}
+{{$jsUrl}}test{{/jsUrl}}
 {{/base.html}}