Qute user tags - use defaulted keys if appropriate

- i.e. for params that define no key and contain only single part
- also use Mapper instead of Map for the data passed to a template
- Mapper value resolver has priority 15, i.e. is called before a
generated value resolver
- resolves #21855
- related to #21861

independent-projects/qute/core/src/main/java/io/quarkus/qute/LoopSectionHelper.java

@@ -170,7 +170,7 @@ public ParametersInfo getParameters() {
             return ParametersInfo.builder()
                     .addParameter(ALIAS, EMPTY)
                     .addParameter(IN, EMPTY)
-                    .addParameter(new Parameter(ITERABLE, null, true))
+                    .addParameter(Parameter.builder(ITERABLE).optional())
                     .build();
         }
 

independent-projects/qute/core/src/main/java/io/quarkus/qute/Parameter.java

@@ -1,14 +1,20 @@
 package io.quarkus.qute;
 
 import io.quarkus.qute.SectionHelperFactory.ParametersInfo;
+import java.util.Objects;
+import java.util.function.Predicate;
 
 /**
- * Definition of a section parameter.
+ * Definition of a section factory parameter.
  * 
  * @see ParametersInfo
  * @see SectionHelperFactory#getParameters()
  */
-public class Parameter {
+public final class Parameter {
+
+    public static Builder builder(String name) {
+        return new Builder(name);
+    }
 
     public static final String EMPTY = "$empty$";
 
@@ -18,10 +24,19 @@ public class Parameter {
 
     public final boolean optional;
 
+    public final Predicate<String> valuePredicate;
+
+    private static final Predicate<String> ALWAYS_TRUE = v -> true;
+
     public Parameter(String name, String defaultValue, boolean optional) {
-        this.name = name;
+        this(name, defaultValue, optional, ALWAYS_TRUE);
+    }
+
+    private Parameter(String name, String defaultValue, boolean optional, Predicate<String> valuePredicate) {
+        this.name = Objects.requireNonNull(name);
         this.defaultValue = defaultValue;
         this.optional = optional;
+        this.valuePredicate = valuePredicate != null ? valuePredicate : ALWAYS_TRUE;
     }
 
     public String getName() {
@@ -32,14 +47,24 @@ public String getDefaultValue() {
         return defaultValue;
     }
 
-    public boolean hasDefatulValue() {
+    public boolean hasDefaultValue() {
         return defaultValue != null;
     }
 
     public boolean isOptional() {
         return optional;
     }
 
+    /**
+     * Allows a factory parameter to refuse a value of an unnamed actual parameter.
+     * 
+     * @param value
+     * @return {@code true} if the value is acceptable, {@code false} otherwise
+     */
+    public boolean accepts(String value) {
+        return valuePredicate.test(value);
+    }
+
     @Override
     public String toString() {
         StringBuilder builder = new StringBuilder();
@@ -48,4 +73,37 @@ public String toString() {
         return builder.toString();
     }
 
+    public static class Builder {
+
+        private final String name;
+        private String defaultValue;
+        private boolean optional;
+        private Predicate<String> valuePredicate;
+
+        public Builder(String name) {
+            this.name = name;
+            this.optional = false;
+        }
+
+        public Builder defaultValue(String defaultValue) {
+            this.defaultValue = defaultValue;
+            return this;
+        }
+
+        public Builder optional() {
+            this.optional = true;
+            return this;
+        }
+
+        public Builder valuePredicate(Predicate<String> valuePredicate) {
+            this.valuePredicate = valuePredicate;
+            return this;
+        }
+
+        public Parameter build() {
+            return new Parameter(name, defaultValue, optional, valuePredicate);
+        }
+
+    }
+
 }

independent-projects/qute/core/src/main/java/io/quarkus/qute/Parser.java

@@ -24,6 +24,7 @@
 import java.util.concurrent.CompletionStage;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Function;
+import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 import org.jboss.logging.Logger;
@@ -548,52 +549,34 @@ private void processParams(String tag, String label, Iterator<String> iter, Sect
             }
         }
 
+        Predicate<String> included = params::containsKey;
         // Then process positional params
         if (actualSize < factoryParams.size()) {
             // The number of actual params is less than factory params
             // We need to choose the best fit for positional params
             for (String param : paramValues) {
-                Parameter found = null;
-                for (Parameter factoryParam : factoryParams) {
-                    // Prefer params with no default value
-                    if (factoryParam.defaultValue == null && !params.containsKey(factoryParam.name)) {
-                        found = factoryParam;
-                        params.put(factoryParam.name, param);
-                        break;
-                    }
-                }
-                if (found == null) {
-                    for (Parameter factoryParam : factoryParams) {
-                        if (!params.containsKey(factoryParam.name)) {
-                            found = factoryParam;
-                            params.put(factoryParam.name, param);
-                            break;
-                        }
-                    }
+                Parameter found = findFactoryParameter(param, factoryParams, included, true);
+                if (found != null) {
+                    params.put(found.name, param);
                 }
             }
         } else {
             // The number of actual params is greater or equals to factory params
             int generatedIdx = 0;
             for (String param : paramValues) {
                 // Positional param
-                Parameter found = null;
-                for (Parameter factoryParam : factoryParams) {
-                    if (!params.containsKey(factoryParam.name)) {
-                        found = factoryParam;
-                        params.put(factoryParam.name, param);
-                        break;
-                    }
-                }
-                if (found == null) {
+                Parameter found = findFactoryParameter(param, factoryParams, included, false);
+                if (found != null) {
+                    params.put(found.name, param);
+                } else {
                     params.put("" + generatedIdx++, param);
                 }
             }
         }
 
         // Use the default values if needed
         factoryParams.stream()
-                .filter(Parameter::hasDefatulValue)
+                .filter(Parameter::hasDefaultValue)
                 .forEach(p -> params.putIfAbsent(p.name, p.defaultValue));
 
         // Find undeclared mandatory params
@@ -609,6 +592,24 @@ private void processParams(String tag, String label, Iterator<String> iter, Sect
         params.forEach(block::addParameter);
     }
 
+    private Parameter findFactoryParameter(String paramValue, List<Parameter> factoryParams, Predicate<String> included,
+            boolean noDefaultValueTakesPrecedence) {
+        if (noDefaultValueTakesPrecedence) {
+            for (Parameter param : factoryParams) {
+                // Params with no default value take precedence
+                if (param.accepts(paramValue) && !param.hasDefaultValue() && !included.test(param.name)) {
+                    return param;
+                }
+            }
+        }
+        for (Parameter param : factoryParams) {
+            if (param.accepts(paramValue) && !included.test(param.name)) {
+                return param;
+            }
+        }
+        return null;
+    }
+
     /**
      *
      * @param part

independent-projects/qute/core/src/main/java/io/quarkus/qute/ResolutionContextImpl.java

@@ -2,20 +2,21 @@
 
 import java.util.Map;
 import java.util.concurrent.CompletionStage;
+import java.util.function.Function;
 
 class ResolutionContextImpl implements ResolutionContext {
 
     private final Object data;
     private final Evaluator evaluator;
     private final Map<String, SectionBlock> extendingBlocks;
-    private final TemplateInstance templateInstance;
+    private final Function<String, Object> attributeFun;
 
     ResolutionContextImpl(Object data,
-            Evaluator evaluator, Map<String, SectionBlock> extendingBlocks, TemplateInstance templateInstance) {
+            Evaluator evaluator, Map<String, SectionBlock> extendingBlocks, Function<String, Object> attributeFun) {
         this.data = data;
         this.evaluator = evaluator;
         this.extendingBlocks = extendingBlocks;
-        this.templateInstance = templateInstance;
+        this.attributeFun = attributeFun;
     }
 
     @Override
@@ -53,7 +54,7 @@ public SectionBlock getExtendingBlock(String name) {
 
     @Override
     public Object getAttribute(String key) {
-        return templateInstance.getAttribute(key);
+        return attributeFun.apply(key);
     }
 
     @Override

independent-projects/qute/core/src/main/java/io/quarkus/qute/Results.java

@@ -159,7 +159,7 @@ public String asMessage() {
             if (name != null) {
                 Object base = getBase().orElse(null);
                 List<Expression> params = getParams();
-                boolean isDataMap = (base instanceof Map) && ((Map<?, ?>) base).containsKey(TemplateInstanceBase.DATA_MAP_KEY);
+                boolean isDataMap = isDataMap(base);
                 // Entry "foo" not found in the data map
                 // Property "foo" not found on base object "org.acme.Bar"
                 // Method "getDiscount(value)" not found on base object "org.acme.Item"
@@ -190,6 +190,15 @@ public String asMessage() {
             }
         }
 
+        private boolean isDataMap(Object base) {
+            if (base instanceof Map) {
+                return ((Map<?, ?>) base).containsKey(TemplateInstanceBase.DATA_MAP_KEY);
+            } else if (base instanceof Mapper) {
+                return ((Mapper) base).get(TemplateInstanceBase.DATA_MAP_KEY) != null;
+            }
+            return false;
+        }
+
         @Override
         public String toString() {
             return "NOT_FOUND";

independent-projects/qute/core/src/main/java/io/quarkus/qute/SectionHelper.java

@@ -1,5 +1,6 @@
 package io.quarkus.qute;
 
+import java.util.Map;
 import java.util.concurrent.CompletionStage;
 
 /**
@@ -28,6 +29,14 @@ public interface SectionResolutionContext {
          */
         ResolutionContext resolutionContext();
 
+        /**
+         *
+         * @param data
+         * @param extendingBlocks
+         * @return a new resolution context
+         */
+        ResolutionContext newResolutionContext(Object data, Map<String, SectionBlock> extendingBlocks);
+
         /**
          * Execute the main block with the current resolution context.
          * 

independent-projects/qute/core/src/main/java/io/quarkus/qute/SectionHelperFactory.java

@@ -26,9 +26,34 @@ default List<String> getDefaultAliases() {
     }
 
     /**
+     * A factory may define {@code factory parameters} for the start tag of any section block. A factory {@link Parameter} has a
+     * name and optional default value. The default value is automatically assigned if no other value is set by a parser. A
+     * parameter may be optional. A non-optional parameter that has no value assigned results in a parser error.
+     * <p>
+     * A section block in a template defines the {@code actual parameters}:
      * 
-     * @return the info about the expected parameters
+     * <pre>
+     * {! The value is "item.isActive". The name is not defined. !}
+     * {#if item.isActive}{/}
+     * 
+     * {! The name is "age" and the value is "10". !}
+     * {#let age=10}{/}
+     * </pre>
+     * 
+     * The actual parameters are parsed taking the factory parameters into account:
+     * <ol>
+     * <li>Named actual params are processed first and the relevant values are assigned, e.g. the param with name {@code age}
+     * has the
+     * value {@code 10},</li>
+     * <li>Then, if the number of actual params is greater or equals to the number of factory params the values are set
+     * according to position of factory params,</li>
+     * <li>Otherwise, the values are set according to position but params with no default value take precedence.</li>
+     * <li>Finally, all unset parameters that define a default value are initialized with the default value.</li>
+     * </ol>
+     * 
+     * @return the factory parameters
      * @see #cacheFactoryConfig()
+     * @see BlockInfo#getParameters()
      */
     default ParametersInfo getParameters() {
         return ParametersInfo.EMPTY;
@@ -93,6 +118,11 @@ interface BlockInfo extends ParserDelegate {
 
         String getLabel();
 
+        /**
+         * Undeclared params with default values are included.
+         * 
+         * @return the map of parameters
+         */
         Map<String, String> getParameters();
 
         default String getParameter(String name) {
@@ -196,6 +226,10 @@ default SectionBlock getBlock(String label) {
 
     }
 
+    /**
+     * 
+     * @see Parameter
+     */
     public static final class ParametersInfo implements Iterable<List<Parameter>> {
 
         public static Builder builder() {
@@ -236,19 +270,27 @@ public static class Builder {
             }
 
             public Builder addParameter(String name) {
-                return addParameter(SectionHelperFactory.MAIN_BLOCK_NAME, name, null);
+                return addParameter(Parameter.builder(name));
             }
 
             public Builder addParameter(String name, String defaultValue) {
-                return addParameter(SectionHelperFactory.MAIN_BLOCK_NAME, name, defaultValue);
+                return addParameter(Parameter.builder(name).defaultValue(defaultValue));
+            }
+
+            public Builder addParameter(Parameter.Builder param) {
+                return addParameter(param.build());
             }
 
             public Builder addParameter(Parameter param) {
                 return addParameter(SectionHelperFactory.MAIN_BLOCK_NAME, param);
             }
 
             public Builder addParameter(String blockLabel, String name, String defaultValue) {
-                return addParameter(blockLabel, new Parameter(name, defaultValue, false));
+                return addParameter(blockLabel, Parameter.builder(name).defaultValue(defaultValue));
+            }
+
+            public Builder addParameter(String blockLabel, Parameter.Builder parameter) {
+                return addParameter(blockLabel, parameter.build());
             }
 
             public Builder addParameter(String blockLabel, Parameter parameter) {