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// Copyright Vespa.ai. 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.file.FileWriter;
import com.yahoo.vespa.hosted.node.admin.task.util.file.UnixPath;
import com.yahoo.vespa.hosted.node.admin.task.util.text.CursorRange;
import java.nio.file.Path;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
/**
* The Java representation of a template text.
*
* <p>A template is a sequence of literal text and dynamic sections defined by %{...} directives:</p>
*
* <pre>
* template: section*
* section: literal | variable | list
* literal: plain text not containing %{
* variable: %{=id}
* if: %{if [!]id}template[%{else}template]%{end}
* list: %{list id}template%{end}
* id: a valid Java identifier
* </pre>
*
* <p>Other directive delimiters than "%{" and "}" may be used, see {@link TemplateDescriptor}.</p>
*
* <p>Fill the template with variable values ({@link #set(String, String) set()}, set if conditions
* ({@link #set(String, boolean)}), add list elements ({@link #add(String) add()}, etc, and finally
* render it as a String ({@link #render()}).</p>
*
* <p>To reuse a template, create the template and work on snapshots of that ({@link #snapshot()}).</p>
*
* @see TemplateDescriptor
* @author hakonhall
*/
public class Template implements Form {
private Template parent = null;
private final CursorRange range;
private final List<Section> sections;
private final Map<String, String> values = new HashMap<>();
private final Map<String, ListSection> lists;
public static Template at(Path path) { return at(path, new TemplateDescriptor()); }
public static Template at(Path path, TemplateDescriptor descriptor) {
String content = new UnixPath(path).readUtf8File();
return Template.from(content, descriptor);
}
public static Template from(String text) { return from(text, new TemplateDescriptor()); }
public static Template from(String text, TemplateDescriptor descriptor) {
return TemplateParser.parse(text, descriptor).template();
}
Template(CursorRange range, List<Section> sections, Map<String, ListSection> lists) {
this.range = new CursorRange(range);
this.sections = List.copyOf(sections);
this.lists = Map.copyOf(lists);
}
/** Set the value of a variable, e.g. %{=color}. */
@Override
public Template set(String name, String value) {
values.put(name, value);
return this;
}
@Override
public ListElement add(String name) { return new ListElement(addElement(name)); }
public String render() {
var buffer = new StringBuilder((int) (range.length() * 1.2 + 128));
appendTo(buffer);
return buffer.toString();
}
public void appendTo(StringBuilder buffer) { sections.forEach(section -> section.appendTo(buffer)); }
/** Returns a deep copy of this. No changes to this affects the returned template, and vice versa. */
public Template snapshot() {
var builder = new TemplateBuilder(range.start());
sections.forEach(section -> section.appendCopyTo(builder.topLevelSectionList()));
Template template = builder.build();
values.forEach(template::set);
return template;
}
public FileWriter getFileWriterTo(Path path) {
String content = render();
return new FileWriter(path, () -> content);
}
/** Must be called (if there is a parent) before any other method. */
void setParent(Template parent) { this.parent = parent; }
Template addElement(String name) {
var section = lists.get(name);
if (section == null) {
throw new NoSuchNameTemplateException(range, name);
}
return section.add();
}
Optional<String> getVariableValue(String name) {
String value = values.get(name);
if (value != null) return Optional.of(value);
if (parent != null) return parent.getVariableValue(name);
return Optional.empty();
}
}
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