Value slots, preencoded control flow, and bytecode codegen

htmlflow-core/src/main/java/htmlflow/HtmlFlow.java

@@ -69,6 +69,7 @@ private static PreprocessingVisitor preprocessing(
          * accumulated in the internal StringBuffer out.
          */
         preView.getVisitor().resolve(null);
+        pre.getFirst().compile();
         return pre;
     }
 
@@ -94,6 +95,7 @@ private static PreprocessingVisitorMfe preprocessingMfe(
         template.resolve(preView);
         // second process
         preView.getVisitor().resolve(null);
+        processView.getFirst().compile();
         return processView;
     }
 
@@ -123,6 +125,7 @@ private static PreprocessingVisitorAsync preprocessingAsync(
          * accumulated in the internal StringBuffer out.
          */
         preView.getVisitor().resolve(null);
+        pre.getFirst().compile();
         return pre;
     }
 

htmlflow-core/src/main/java/htmlflow/continuations/HtmlContinuation.java

@@ -24,6 +24,8 @@
  */
 package htmlflow.continuations;
 
+import htmlflow.continuations.codegen.ChainCompiler;
+import htmlflow.continuations.codegen.ChainCompiler.Renderer;
 import htmlflow.visitor.HtmlVisitor;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
@@ -54,6 +56,9 @@ public abstract class HtmlContinuation {
     /** Next HtmlContinuation */
     public final HtmlContinuation next;
 
+    /** The bytecode of the chain starting in this node, or null when it was not compiled. */
+    private Renderer compiled;
+
     /**
      * @param currentDepth Indentation depth associated to this block.
      */
@@ -69,6 +74,25 @@ protected HtmlContinuation(
         this.next = next;
     }
 
+    /**
+     * Compiles the chain starting in this node. We call it from the preprocessing, before any
+     * visitor is bound to the chain.
+     */
+    public final void compile() {
+        compiled = ChainCompiler.compile(this);
+    }
+
+    /**
+     * Creates a copy of this HtmlContinuation with a new visitor, which emits HTML through the
+     * generated bytecode whenever the chain was compiled. If a thread does not observe the
+     * compiled field, then it uses the linked chain, which produces the same HTML.
+     */
+    public final HtmlContinuation compiledCopy(HtmlVisitor visitor) {
+        return compiled == null
+            ? copy(visitor)
+            : new HtmlContinuationSyncCompiled(compiled, this, visitor);
+    }
+
     public HtmlContinuation getNext() {
         return next;
     }

htmlflow-core/src/main/java/htmlflow/continuations/HtmlContinuationSyncCompiled.java

@@ -0,0 +1,84 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025, xmlet HtmlFlow
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package htmlflow.continuations;
+
+import htmlflow.continuations.codegen.ChainCompiler.Renderer;
+import htmlflow.visitor.HtmlVisitor;
+
+/**
+ * HtmlContinuation for a sequence of static blocks and value slots that we compiled to bytecode.
+ * The generated code appends straight to a StringBuilder, so when the output is some other
+ * Appendable we fall back to the linked chain.
+ *
+ * @author Bernardo Pereira
+ */
+final class HtmlContinuationSyncCompiled extends HtmlContinuation {
+
+    private final Renderer renderer;
+
+    private final HtmlContinuation template;
+
+    /** The equivalent linked chain, which we only create when some render needs it. */
+    private HtmlContinuation chain;
+
+    HtmlContinuationSyncCompiled(
+        Renderer renderer,
+        HtmlContinuation template,
+        HtmlVisitor visitor
+    ) {
+        super(-1, false, visitor, null);
+        this.renderer = renderer;
+        this.template = template;
+    }
+
+    /**
+     * We do not synchronize here because concurrent calls just produce equal chains, and all the
+     * fields of an HtmlContinuation are final.
+     */
+    private HtmlContinuation chain() {
+        HtmlContinuation built = chain;
+        if (built == null) chain = built = template.copy(visitor);
+        return built;
+    }
+
+    /**
+     * We override execute rather than emitHtml because a compiled chain has no indentation to
+     * restore and no next node.
+     */
+    @Override
+    public void execute(Object model) {
+        Appendable out = visitor.out();
+        if (out instanceof StringBuilder) {
+            renderer.render(visitor, (StringBuilder) out, model);
+        } else {
+            chain().execute(model);
+        }
+    }
+
+    @Override
+    public HtmlContinuation copy(HtmlVisitor v) {
+        return new HtmlContinuationSyncCompiled(renderer, template, v);
+    }
+}

htmlflow-core/src/main/java/htmlflow/continuations/HtmlContinuationSyncForEach.java

@@ -0,0 +1,68 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025, xmlet HtmlFlow
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package htmlflow.continuations;
+
+import htmlflow.visitor.HtmlVisitor;
+import java.util.function.Function;
+
+/**
+ * HtmlContinuation for a loop body, which we emit once for each item. The body includes its own
+ * leading indentation.
+ *
+ * @author Bernardo Pereira
+ */
+public class HtmlContinuationSyncForEach<M, E> extends HtmlContinuationSync {
+
+    private final Function<M, ? extends Iterable<E>> items;
+
+    private final HtmlContinuation item;
+
+    public HtmlContinuationSyncForEach(
+        Function<M, ? extends Iterable<E>> items,
+        HtmlContinuation item,
+        HtmlVisitor visitor,
+        HtmlContinuation next
+    ) {
+        super(-1, false, visitor, next);
+        this.items = items;
+        this.item = item;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    protected final void emitHtml(Object model) {
+        for (E e : items.apply((M) model)) item.execute(e);
+    }
+
+    @Override
+    public HtmlContinuation copy(HtmlVisitor v) {
+        return new HtmlContinuationSyncForEach<>(
+            items,
+            item.copy(v),
+            v,
+            next != null ? next.copy(v) : null
+        );
+    }
+}

htmlflow-core/src/main/java/htmlflow/continuations/HtmlContinuationSyncValue.java

@@ -0,0 +1,171 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025, xmlet HtmlFlow
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package htmlflow.continuations;
+
+import htmlflow.visitor.HtmlVisitor;
+import htmlflow.visitor.Tags;
+import htmlflow.visitor.escape.HtmlEscapers;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.ToDoubleFunction;
+import java.util.function.ToIntFunction;
+import java.util.function.ToLongFunction;
+
+/**
+ * HtmlContinuation for a single value read from the model. The markup around the value stays in
+ * the neighbor static HTML blocks, which are preencoded.
+ *
+ * @author Bernardo Pereira
+ */
+public class HtmlContinuationSyncValue extends HtmlContinuationSync {
+
+    public enum Kind {
+        /** The value as it is, without escaping. */
+        RAW,
+        /** The value with HTML escaping. */
+        TEXT,
+        INT,
+        LONG,
+        DOUBLE,
+        BOOLEAN,
+        /** An attribute that we only write when the accessor does not return null. */
+        ATTR_NULLABLE,
+    }
+
+    private final Kind kind;
+    private final Object accessor;
+
+    /** The name of the attribute, which we only use for the Kind ATTR_NULLABLE. */
+    private final String attributeName;
+
+    /**
+     * Sets indentation to -1 to inform that visitor should continue with previous indentation.
+     * A value slot changes neither the depth nor the isClosed of the visitor.
+     */
+    public HtmlContinuationSyncValue(
+        Kind kind,
+        Object accessor,
+        String attributeName,
+        HtmlVisitor visitor,
+        HtmlContinuation next
+    ) {
+        super(-1, false, visitor, next);
+        this.kind = kind;
+        this.accessor = accessor;
+        this.attributeName = attributeName;
+    }
+
+    public Kind kind() {
+        return kind;
+    }
+
+    public Object accessor() {
+        return accessor;
+    }
+
+    public String attributeName() {
+        return attributeName;
+    }
+
+    /**
+     * Escapes the value of a textOf slot.
+     *
+     * @apiNote The generated bytecode invokes this method by its name, so renaming it makes
+     *     every compiled chain fall back to the linked one.
+     */
+    public static String text(Object value) {
+        return HtmlEscapers.htmlEscaper().escape(String.valueOf(value));
+    }
+
+    /**
+     * Writes an attribute of an attrOfNullable slot, only when the value is not null.
+     *
+     * @apiNote The generated bytecode invokes this method by its name, as in {@link #text}.
+     */
+    public static void attrNullable(
+        HtmlVisitor visitor,
+        String name,
+        Object value
+    ) {
+        if (value != null) Tags.addAttribute(
+            visitor.out(),
+            name,
+            String.valueOf(value)
+        );
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    protected final void emitHtml(Object model) {
+        if (kind == Kind.ATTR_NULLABLE) {
+            attrNullable(
+                visitor,
+                attributeName,
+                ((Function<Object, ?>) accessor).apply(model)
+            );
+        } else {
+            visitor.write(rendered(model));
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    private String rendered(Object model) {
+        switch (kind) {
+            case INT:
+                return Integer.toString(
+                    ((ToIntFunction<Object>) accessor).applyAsInt(model)
+                );
+            case LONG:
+                return Long.toString(
+                    ((ToLongFunction<Object>) accessor).applyAsLong(model)
+                );
+            case DOUBLE:
+                return Double.toString(
+                    ((ToDoubleFunction<Object>) accessor).applyAsDouble(model)
+                );
+            case BOOLEAN:
+                return Boolean.toString(
+                    ((Predicate<Object>) accessor).test(model)
+                );
+            case TEXT:
+                return text(((Function<Object, ?>) accessor).apply(model));
+            default:
+                return String.valueOf(
+                    ((Function<Object, ?>) accessor).apply(model)
+                );
+        }
+    }
+
+    @Override
+    public HtmlContinuation copy(HtmlVisitor v) {
+        return new HtmlContinuationSyncValue(
+            kind,
+            accessor,
+            attributeName,
+            v,
+            next != null ? next.copy(v) : null
+        );
+    }
+}