Add if section

15 files changed, 273 insertions, 153 deletions

diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Form.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Form.java
index 00e2e87fc5a..c95885d7753 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Form.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Form.java
@@ -3,6 +3,7 @@ package com.yahoo.vespa.hosted.node.admin.task.util.template;
 
 import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
 
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -13,25 +14,25 @@ import java.util.Optional;
  * @see Template
  * @author hakonhall
  */
-public class Form extends Section {
-    private final Form parent;
+public class Form {
+    private Form parent = null;
+    private final CursorRange range;
     private final List<Section> sections;
 
-    private final Map<String, String> variables;
+    private final Map<String, String> values = new HashMap<>();
     private final Map<String, SubformSection> subforms;
 
-    Form(Form parent, CursorRange range, List<Section> sections, Map<String, String> variables,
-         Map<String, SubformSection> subforms) {
-        super(range);
-        this.parent = parent;
+    Form(CursorRange range, List<Section> sections, Map<String, SubformSection> subforms) {
+        this.range = new CursorRange(range);
         this.sections = List.copyOf(sections);
-        this.variables = variables; // Mutable and referenced by the variable sections
         this.subforms = Map.copyOf(subforms);
     }
 
+    void setParent(Form parent) { this.parent = parent; }
+
     /** Set the value of a variable expression, e.g. %{=color}. */
     public Form set(String name, String value) {
-        variables.put(name, value);
+        values.put(name, value);
         return this;
     }
 
@@ -52,24 +53,30 @@ public class Form extends Section {
     public Form add(String name) {
         var section = subforms.get(name);
         if (section == null) {
-            throw new NoSuchNameTemplateException(this, name);
+            throw new NoSuchNameTemplateException(range, name);
         }
         return section.add();
     }
 
     public String render() {
-        var buffer = new StringBuilder((int) (range().length() * 1.2 + 128));
+        var buffer = new StringBuilder((int) (range.length() * 1.2 + 128));
         appendTo(buffer);
         return buffer.toString();
     }
 
-    @Override
     public void appendTo(StringBuilder buffer) {
         sections.forEach(section -> section.appendTo(buffer));
     }
 
+    /** Returns a deep copy of this. No changes to this affects the returned form, and vice versa. */
+    Form copy() {
+        var builder = new FormBuilder(range.start());
+        sections.forEach(section -> section.appendCopyTo(builder.topLevelSectionList()));
+        return builder.build();
+    }
+
     Optional<String> getVariableValue(String name) {
-        String value = variables.get(name);
+        String value = values.get(name);
         if (value != null) return Optional.of(value);
         if (parent != null) {
             return parent.getVariableValue(name);
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/FormBuilder.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/FormBuilder.java
index d0274d7777a..833e5916fce 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/FormBuilder.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/FormBuilder.java
@@ -2,67 +2,80 @@
 package com.yahoo.vespa.hosted.node.admin.task.util.template;
 
 import com.yahoo.vespa.hosted.node.admin.task.util.text.Cursor;
-import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
 
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.function.Consumer;
 
 /**
  * @author hakonhall
  */
 class FormBuilder {
-    private final List<Section> sections = new ArrayList<>();
-    private final Map<String, String> variables = new HashMap<>();
+    /** The top-level section list in this form. */
+    private final SectionList sectionList;
+    private final List<Section> allSections = new ArrayList<>();
+    private final Map<String, VariableSection> sampleVariables = new HashMap<>();
+    private final Map<String, IfSection> sampleIfSections = new HashMap<>();
     private final Map<String, SubformSection> subforms = new HashMap<>();
-    private final Form parent;
-    private final CursorRange range;
 
-    static Form build(Form parent, CursorRange range, List<Consumer<FormBuilder>> sections) {
-        var builder = new FormBuilder(parent, range);
-        sections.forEach(section -> section.accept(builder));
-        return builder.build();
+    FormBuilder(Cursor start) {
+        this.sectionList = new SectionList(start, this);
     }
 
-    private FormBuilder(Form parent, CursorRange range) {
-        this.parent = parent;
-        this.range = new CursorRange(range);
-    }
+    SectionList topLevelSectionList() { return sectionList; }
 
-    FormBuilder addLiteralSection(CursorRange range) {
-        sections.add(new LiteralSection(range));
-        return this;
+    void addLiteralSection(LiteralSection section) {
+        allSections.add(section);
     }
 
-    FormBuilder addVariableSection(CursorRange range, String name, Cursor nameOffset) {
-        var section = new VariableSection(range, name, nameOffset);
-        sections.add(section);
-        return this;
-    }
+    void addVariableSection(VariableSection section) {
+        // It's OK if the same name is used in an if-directive (as long as the value is boolean,
+        // determined when set on a form).
+
+        SubformSection existing = subforms.get(section.name());
+        if (existing != null)
+            throw new NameAlreadyExistsTemplateException(section.name(), existing.nameOffset(),
+                                                         section.nameOffset());
 
-    FormBuilder addSubformSection(CursorRange range, String name, Template body) {
-        checkNameIsAvailable(name, range);
-        var section = new SubformSection(range, name, body);
-        sections.add(section);
-        subforms.put(section.name(), section);
-        return this;
+        sampleVariables.put(section.name(), section);
+        allSections.add(section);
     }
 
-    private Form build() {
-        var form = new Form(parent, range, sections, variables, subforms);
-        sections.forEach(section -> section.setForm(form));
-        return form;
+    void addIfSection(IfSection section) {
+        // It's OK if the same name is used in a variable section (as long as the value is boolean,
+        // determined when set on a form).
+
+        SubformSection subform = subforms.get(section.name());
+        if (subform != null)
+            throw new NameAlreadyExistsTemplateException(section.name(), subform.nameOffset(),
+                                                         section.nameOffset());
+
+        sampleIfSections.put(section.name(), section);
+        allSections.add(section);
     }
 
-    private void checkNameIsAvailable(String name, CursorRange range) {
-        if (nameIsDefined(name)) {
-            throw new NameAlreadyExistsTemplateException(name, range);
-        }
+    void addSubformSection(SubformSection section) {
+        VariableSection variableSection = sampleVariables.get(section.name());
+        if (variableSection != null)
+            throw new NameAlreadyExistsTemplateException(section.name(), variableSection.nameOffset(),
+                                                         section.nameOffset());
+
+        IfSection ifSection = sampleIfSections.get(section.name());
+        if (ifSection != null)
+            throw new NameAlreadyExistsTemplateException(section.name(), ifSection.nameOffset(),
+                                                         section.nameOffset());
+
+        SubformSection previous = subforms.put(section.name(), section);
+        if (previous != null)
+            throw new NameAlreadyExistsTemplateException(section.name(), previous.nameOffset(),
+                                                         section.nameOffset());
+        allSections.add(section);
     }
 
-    private boolean nameIsDefined(String name) {
-        return variables.containsKey(name) || subforms.containsKey(name);
+    Form build() {
+        var form = new Form(sectionList.range(), sectionList.sections(), subforms);
+        allSections.forEach(section -> section.setForm(form));
+        return form;
     }
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/IfSection.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/IfSection.java
new file mode 100644
index 00000000000..33e62750f69
--- /dev/null
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/IfSection.java
@@ -0,0 +1,57 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.hosted.node.admin.task.util.template;
+
+import com.yahoo.vespa.hosted.node.admin.task.util.text.Cursor;
+import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
+
+import java.util.Optional;
+
+/**
+ * @author hakonhall
+ */
+public class IfSection extends Section {
+    private final boolean negated;
+    private final String name;
+    private final Cursor nameOffset;
+    private final SectionList ifSections;
+
+    public IfSection(CursorRange range, boolean negated, String name, Cursor nameOffset,
+                     SectionList ifSections) {
+        super(range);
+        this.negated = negated;
+        this.name = name;
+        this.nameOffset = nameOffset;
+        this.ifSections = ifSections;
+    }
+
+    String name() { return name; }
+    Cursor nameOffset() { return nameOffset; }
+
+    @Override
+    void appendTo(StringBuilder buffer) {
+        Optional<String> stringValue = form().getVariableValue(name);
+        if (stringValue.isEmpty())
+            throw new TemplateNameNotSetException(name, nameOffset);
+
+        final boolean value;
+        if (stringValue.get().equals("true")) {
+            value = true;
+        } else if (stringValue.get().equals("false")) {
+            value = false;
+        } else {
+            throw new NotBooleanValueTemplateException(name);
+        }
+
+        boolean condition = negated ? !value : value;
+        if (condition) {
+            ifSections.sections().forEach(section -> section.appendTo(buffer));
+        }
+    }
+
+    @Override
+    void appendCopyTo(SectionList sectionList) {
+        SectionList ifSectionCopy = new SectionList(ifSections.range().start(), sectionList.formBuilder());
+        ifSections.sections().forEach(section -> section.appendCopyTo(ifSectionCopy));
+        sectionList.appendIfSection(negated, name, nameOffset, range().end(), ifSectionCopy);
+    }
+}
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/LiteralSection.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/LiteralSection.java
index 852056fa283..c03653253af 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/LiteralSection.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/LiteralSection.java
@@ -18,4 +18,9 @@ class LiteralSection extends Section {
     void appendTo(StringBuilder buffer) {
         range().appendTo(buffer);
     }
+
+    @Override
+    void appendCopyTo(SectionList sectionList) {
+        sectionList.appendLiteralSection(range().end());
+    }
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/NoSuchNameTemplateException.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/NoSuchNameTemplateException.java
index f6d630846a2..706d347d39d 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/NoSuchNameTemplateException.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/NoSuchNameTemplateException.java
@@ -1,11 +1,13 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.hosted.node.admin.task.util.template;
 
+import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
+
 /**
  * @author hakonhall
  */
 public class NoSuchNameTemplateException extends TemplateException {
-    public NoSuchNameTemplateException(Section section, String name) {
-        super("No such element '" + name + "' in the " + describeSection(section.range()));
+    public NoSuchNameTemplateException(CursorRange range, String name) {
+        super("No such element '" + name + "' in the " + describeSection(range));
     }
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/NotBooleanValueTemplateException.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/NotBooleanValueTemplateException.java
new file mode 100644
index 00000000000..6c6d157bb47
--- /dev/null
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/NotBooleanValueTemplateException.java
@@ -0,0 +1,11 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.hosted.node.admin.task.util.template;
+
+/**
+ * @author hakonhall
+ */
+public class NotBooleanValueTemplateException extends TemplateException {
+    public NotBooleanValueTemplateException(String name) {
+        super(name + " was set to a non-boolean value: must be true or false");
+    }
+}
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Section.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Section.java
index f12dfb8d8b7..234915770f8 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Section.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Section.java
@@ -25,4 +25,6 @@ abstract class Section {
     protected CursorRange range() { return range; }
 
     abstract void appendTo(StringBuilder buffer);
+
+    abstract void appendCopyTo(SectionList sectionList);
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SectionList.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SectionList.java
index b5017246f31..679888678bf 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SectionList.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SectionList.java
@@ -6,7 +6,6 @@ import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.function.Consumer;
 
 /**
  * A mutable list of sections at the same level that can be used to build a form, e.g. the if-body.
@@ -14,42 +13,51 @@ import java.util.function.Consumer;
  * @author hakonhall
  */
 class SectionList {
-    private TemplateBuilder templateBuilder;
-
     private final Cursor start;
     private final Cursor end;
+    private final FormBuilder formBuilder;
 
-    private final List<Consumer<FormBuilder>> sections = new ArrayList<>();
+    private final List<Section> sections = new ArrayList<>();
 
-    SectionList(Cursor start) {
+    SectionList(Cursor start, FormBuilder formBuilder) {
         this.start = new Cursor(start);
         this.end = new Cursor(start);
+        this.formBuilder = formBuilder;
     }
 
-    /** Must be invoked once before any other method. */
-    void setTemplateBuilder(TemplateBuilder templateBuilder) {
-        this.templateBuilder = templateBuilder;
-    }
+    CursorRange range() { return new CursorRange(start, end); }
+    FormBuilder formBuilder() { return formBuilder; }
+    List<Section> sections() { return List.copyOf(sections); }
 
     void appendLiteralSection(Cursor end) {
         CursorRange range = verifyAndUpdateEnd(end);
-        sections.add((FormBuilder builder) -> builder.addLiteralSection(range));
+        var section = new LiteralSection(range);
+        formBuilder.addLiteralSection(section);
+        sections.add(section);
     }
 
-    void appendVariableSection(String name, Cursor nameOffset, Cursor end) {
+    VariableSection appendVariableSection(String name, Cursor nameOffset, Cursor end) {
         CursorRange range = verifyAndUpdateEnd(end);
-        templateBuilder.addVariable(name, nameOffset);
-        sections.add(formBuilder -> formBuilder.addVariableSection(range, name, nameOffset));
+        var section = new VariableSection(range, name, nameOffset);
+        formBuilder.addVariableSection(section);
+        sections.add(section);
+        return section;
     }
 
-    void appendSubformSection(String name, Cursor nameCursor, Cursor end, Template body) {
+    void appendIfSection(boolean negated, String name, Cursor nameOffset, Cursor end,
+                                SectionList ifSections) {
         CursorRange range = verifyAndUpdateEnd(end);
-        templateBuilder.addSubform(name, nameCursor);
-        sections.add(formBuilder -> formBuilder.addSubformSection(range, name, body));
+        var section = new IfSection(range, negated, name, nameOffset, ifSections);
+        formBuilder.addIfSection(section);
+        sections.add(section);
     }
 
-    CursorRange range() { return new CursorRange(start, end); }
-    List<Consumer<FormBuilder>> sections() { return List.copyOf(sections); }
+    void appendSubformSection(String name, Cursor nameOffset, Cursor end, Form body) {
+        CursorRange range = verifyAndUpdateEnd(end);
+        var section = new SubformSection(range, name, nameOffset, body);
+        formBuilder.addSubformSection(section);
+        sections.add(section);
+    }
 
     private CursorRange verifyAndUpdateEnd(Cursor newEnd) {
         var range = new CursorRange(this.end, newEnd);
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SubformSection.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SubformSection.java
index 360a37964b2..fa65589d7d5 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SubformSection.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/SubformSection.java
@@ -1,6 +1,7 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.hosted.node.admin.task.util.template;
 
+import com.yahoo.vespa.hosted.node.admin.task.util.text.Cursor;
 import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
 
 import java.util.ArrayList;
@@ -13,26 +14,44 @@ import java.util.List;
  * @author hakonhall
  */
 class SubformSection extends Section {
-    private final Template body;
     private final String name;
+    private final Cursor nameOffset;
+    private final Form body;
     private final List<Form> elements = new ArrayList<>();
 
-    SubformSection(CursorRange range, String name, Template body) {
+    SubformSection(CursorRange range, String name, Cursor nameOffset, Form body) {
         super(range);
         this.name = name;
+        this.nameOffset = new Cursor(nameOffset);
         this.body = body;
     }
 
     String name() { return name; }
+    Cursor nameOffset() { return new Cursor(nameOffset); }
+
+    @Override
+    void setForm(Form form) {
+        super.setForm(form);
+        body.setParent(form);
+    }
 
     Form add() {
-        var form = body.instantiate(form());
-        elements.add(form);
-        return form;
+        Form element = body.copy();
+        element.setParent(form());
+        elements.add(element);
+        return element;
     }
 
     @Override
     void appendTo(StringBuilder buffer) {
         elements.forEach(form -> form.appendTo(buffer));
     }
+
+    @Override
+    void appendCopyTo(SectionList sectionList) {
+        // avoid copying elements for now
+        // Optimization: Reuse body in copy, since it is only used for copying.
+
+        sectionList.appendSubformSection(name, nameOffset, range().end(), body);
+    }
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Template.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Template.java
index 47ff28b2d6b..a3ffcf46bdf 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Template.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/Template.java
@@ -1,13 +1,6 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.hosted.node.admin.task.util.template;
 
-import com.yahoo.vespa.hosted.node.admin.task.util.text.Cursor;
-import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
-
-import java.util.List;
-import java.util.Map;
-import java.util.function.Consumer;
-
 /**
  * The Java representation of a template text.
  *
@@ -18,6 +11,7 @@ import java.util.function.Consumer;
  *     section: literal | variable | subform
  *     literal: plain text not containing %{
  *     variable: %{=identifier}
+ *     if: %{if [!]identifier}template[%{else}template]%{end}
  *     subform: %{form identifier}template%{end}
  *     identifier: a valid Java identifier
  * </pre>
@@ -38,18 +32,7 @@ import java.util.function.Consumer;
  * @author hakonhall
  */
 public class Template {
-    private final CursorRange range;
-    private final List<Consumer<FormBuilder>> sections;
-    private final Map<String, Cursor> variables;
-    private final Map<String, Cursor> subforms;
-
-    public Template(CursorRange range, List<Consumer<FormBuilder>> sections,
-                    Map<String, Cursor> variables, Map<String, Cursor> subforms) {
-        this.range = new CursorRange(range);
-        this.sections = List.copyOf(sections);
-        this.variables = Map.copyOf(variables);
-        this.subforms = Map.copyOf(subforms);
-    }
+    private final Form form;
 
     public static Template from(String text) { return from(text, new TemplateDescriptor()); }
 
@@ -57,7 +40,9 @@ public class Template {
         return TemplateParser.parse(text, descriptor).template();
     }
 
-    public Form instantiate() { return instantiate(null); }
+    Template(Form form) {
+        this.form = form;
+    }
 
-    Form instantiate(Form parent) { return FormBuilder.build(parent, range, sections); }
+    public Form instantiate() { return form.copy(); }
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateBuilder.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateBuilder.java
deleted file mode 100644
index d63ed7c9e70..00000000000
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateBuilder.java
+++ /dev/null
@@ -1,48 +0,0 @@
-// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.vespa.hosted.node.admin.task.util.template;
-
-import com.yahoo.vespa.hosted.node.admin.task.util.text.Cursor;
-
-import java.util.HashMap;
-import java.util.Map;
-
-/**
- * @author hakonhall
- */
-class TemplateBuilder {
-    private final SectionList sections;
-
-    /** Example location (value) of a variable name (key). */
-    private final Map<String, Cursor> variables = new HashMap<>();
-
-    /** Location of the name of each subform. */
-    private final Map<String, Cursor> subforms = new HashMap<>();
-
-    TemplateBuilder(Cursor start) {
-        sections = new SectionList(start);
-        sections.setTemplateBuilder(this);
-    }
-
-    SectionList sectionList() { return sections; }
-
-    void addVariable(String name, Cursor nameOffset) {
-        Cursor existing = subforms.get(name);
-        if (existing != null)
-            throw new NameAlreadyExistsTemplateException(name, existing, nameOffset);
-        variables.put(name, new Cursor(nameOffset));
-    }
-
-    void addSubform(String name, Cursor nameCursor) {
-        Cursor existing = variables.get(name);
-        if (existing != null)
-            throw new NameAlreadyExistsTemplateException(name, existing, nameCursor);
-
-        existing = subforms.put(name, nameCursor);
-        if (existing != null)
-            throw new NameAlreadyExistsTemplateException(name, existing, nameCursor);
-    }
-
-    Template build() {
-        return new Template(sections.range(), sections.sections(), variables, subforms);
-    }
-}
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateNameNotSetException.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateNameNotSetException.java
index 0c715df2efd..d65c2a7c4d6 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateNameNotSetException.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateNameNotSetException.java
@@ -8,6 +8,6 @@ import com.yahoo.vespa.hosted.node.admin.task.util.text.Cursor;
  */
 public class TemplateNameNotSetException extends TemplateException {
     public TemplateNameNotSetException(String name, Cursor nameOffset) {
-        super(name + " at " + nameOffset.calculateLocation().lineAndColumnText() + " has not been set");
+        super("Variable at " + nameOffset.calculateLocation().lineAndColumnText() + " has not been set: " + name);
     }
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateParser.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateParser.java
index b97745df3a6..ac38a23d4ad 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateParser.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateParser.java
@@ -15,7 +15,7 @@ class TemplateParser {
     private final TemplateDescriptor descriptor;
     private final Cursor start;
     private final Cursor current;
-    private final TemplateBuilder templateBuilder;
+    private final FormBuilder formBuilder;
 
     static TemplateParser parse(String text, TemplateDescriptor descriptor) {
         return parse(new TemplateDescriptor(descriptor), new Cursor(text), EnumSet.of(Sentinel.EOT));
@@ -23,20 +23,20 @@ class TemplateParser {
 
     private static TemplateParser parse(TemplateDescriptor descriptor, Cursor start, EnumSet<Sentinel> sentinel) {
         var parser = new TemplateParser(descriptor, start);
-        parser.parse(parser.templateBuilder.sectionList(), sentinel);
+        parser.parse(parser.formBuilder.topLevelSectionList(), sentinel);
         return parser;
     }
 
     private enum Sentinel { END, EOT }
 
-    TemplateParser(TemplateDescriptor descriptor, Cursor start) {
+    private TemplateParser(TemplateDescriptor descriptor, Cursor start) {
         this.descriptor = descriptor;
         this.start = new Cursor(start);
         this.current = new Cursor(start);
-        this.templateBuilder = new TemplateBuilder(start);
+        this.formBuilder = new FormBuilder(start);
     }
 
-    Template template() { return templateBuilder.build(); }
+    Template template() { return new Template(formBuilder.build()); }
 
     private Sentinel parse(SectionList sectionList, EnumSet<Sentinel> sentinels) {
         do {
@@ -60,7 +60,6 @@ class TemplateParser {
     }
 
     private Optional<Sentinel> parseSection(SectionList sectionList, EnumSet<Sentinel> sentinels) {
-        var startOfDirective = new Cursor(current);
         current.skip(descriptor.startDelimiter());
 
         if (current.skip(Token.VARIABLE_DIRECTIVE_CHAR)) {
@@ -78,6 +77,9 @@ class TemplateParser {
                 case "form":
                     parseSubformSection(sectionList);
                     break;
+                case "if":
+                    parseIfSection(sectionList);
+                    break;
                 default:
                     throw new BadTemplateException(startOfType, "Unknown section '" + type + "'");
             }
@@ -106,7 +108,21 @@ class TemplateParser {
         TemplateParser bodyParser = parse(descriptor, current, EnumSet.of(Sentinel.END));
         current.set(bodyParser.current);
 
-        sectionList.appendSubformSection(name, startOfName, current, bodyParser.template());
+        sectionList.appendSubformSection(name, startOfName, current, bodyParser.formBuilder.build());
+    }
+
+    private void parseIfSection(SectionList sectionList) {
+        skipRequiredWhitespaces();
+        boolean negated = current.skip(Token.NEGATE_CHAR);
+        current.skipWhitespaces();
+        var startOfName = new Cursor(current);
+        String name = parseId();
+        parseEndDelimiter(true);
+
+        SectionList ifSectionList = new SectionList(current, formBuilder);
+        parse(ifSectionList, EnumSet.of(Sentinel.END));
+
+        sectionList.appendIfSection(negated, name, startOfName, current, ifSectionList);
     }
 
     private void skipRequiredWhitespaces() {
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/VariableSection.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/VariableSection.java
index b384a2deb5a..bf211a01190 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/VariableSection.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/template/VariableSection.java
@@ -21,6 +21,7 @@ class VariableSection extends Section {
     }
 
     String name() { return name; }
+    Cursor nameOffset() { return new Cursor(nameOffset); }
 
     @Override
     void appendTo(StringBuilder buffer) {
@@ -28,4 +29,9 @@ class VariableSection extends Section {
                              .orElseThrow(() -> new TemplateNameNotSetException(name, nameOffset));
         buffer.append(value);
     }
+
+    @Override
+    void appendCopyTo(SectionList sectionList) {
+        sectionList.appendVariableSection(name, nameOffset, range().end());
+    }
 }
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateFileTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateFileTest.java
index c316d4efe86..121d4fd8d25 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateFileTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/template/TemplateFileTest.java
@@ -83,6 +83,43 @@ class TemplateFileTest {
                      form.render());
     }
 
+    @Test
+    void verifyIfSection() {
+        Template template = Template.from("Hello%{if cond} world%{end}!");
+        assertEquals("Hello world!", template.instantiate().set("cond", true).render());
+        assertEquals("Hello!", template.instantiate().set("cond", false).render());
+    }
+
+    @Test
+    void verifyComplexIfSection() {
+        Template template = Template.from("%{if cond|}\n" +
+                                          "var: %{=varname}\n" +
+                                          "if: %{if !inner}inner is false%{end}\n" +
+                                          "subform: %{form formname}subform%{end}\n" +
+                                          "%{end|}\n");
+
+        assertEquals("", template.instantiate().set("cond", false).render());
+
+        assertEquals("var: varvalue\n" +
+                     "if: \n" +
+                     "subform: \n",
+                     template.instantiate()
+                             .set("cond", true)
+                             .set("varname", "varvalue")
+                             .set("inner", true)
+                             .render());
+
+        Form form = template.instantiate()
+                            .set("cond", true)
+                            .set("varname", "varvalue")
+                            .set("inner", false);
+        form.add("formname");
+
+        assertEquals("var: varvalue\n" +
+                     "if: inner is false\n" +
+                     "subform: subform\n", form.render());
+    }
+
     private Form getForm(String filename) {
         return TemplateFile.read(Path.of("src/test/resources/" + filename)).instantiate();
     }