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// 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.EnumSet;
import java.util.Optional;
/**
* Parses a template String, see {@link Template} for details.
*
* @author hakonhall
*/
class TemplateParser {
private final TemplateDescriptor descriptor;
private final Cursor start;
private final Cursor current;
private final TemplateBuilder templateBuilder;
static TemplateParser parse(String text, TemplateDescriptor descriptor) {
return parse(new TemplateDescriptor(descriptor), new Cursor(text), EnumSet.of(Sentinel.EOT));
}
private static TemplateParser parse(TemplateDescriptor descriptor, Cursor start, EnumSet<Sentinel> sentinel) {
var parser = new TemplateParser(descriptor, start);
parser.parse(parser.templateBuilder.topLevelSectionList(), sentinel);
return parser;
}
private enum Sentinel { ELSE, END, EOT }
private TemplateParser(TemplateDescriptor descriptor, Cursor start) {
this.descriptor = descriptor;
this.start = new Cursor(start);
this.current = new Cursor(start);
this.templateBuilder = new TemplateBuilder(start);
}
Template template() { return templateBuilder.build(); }
private Sentinel parse(SectionList sectionList, EnumSet<Sentinel> sentinels) {
do {
current.advanceTo(descriptor.startDelimiter());
if (!current.equals(start)) {
sectionList.appendLiteralSection(current);
}
if (current.eot()) {
if (!sentinels.contains(Sentinel.EOT)) {
throw new BadTemplateException(start, "Missing end directive for section started");
}
return Sentinel.EOT;
}
Optional<Sentinel> sentinel = parseSection(sectionList, sentinels);
if (sentinel.isPresent()) return sentinel.get();
} while (true);
}
private Optional<Sentinel> parseSection(SectionList sectionList, EnumSet<Sentinel> sentinels) {
current.skip(descriptor.startDelimiter());
if (current.skip(Token.VARIABLE_DIRECTIVE_CHAR)) {
parseVariableSection(sectionList);
} else {
var startOfType = new Cursor(current);
String type = skipId().orElseThrow(() -> new BadTemplateException(current, "Missing section name"));
switch (type) {
case "else" -> {
if (!sentinels.contains(Sentinel.ELSE))
throw new BadTemplateException(startOfType, "Stray 'else'");
parseEndDirective();
return Optional.of(Sentinel.ELSE);
}
case "end" -> {
if (!sentinels.contains(Sentinel.END))
throw new BadTemplateException(startOfType, "Stray 'end'");
parseEndDirective();
return Optional.of(Sentinel.END);
}
case "if" -> parseIfSection(sectionList);
case "list" -> parseListSection(sectionList);
default -> throw new BadTemplateException(startOfType, "Unknown section '" + type + "'");
}
}
return Optional.empty();
}
private void parseVariableSection(SectionList sectionList) {
var nameStart = new Cursor(current);
String name = parseId();
parseEndDelimiter(false);
sectionList.appendVariableSection(name, nameStart, current);
}
private void parseEndDirective() {
parseEndDelimiter(true);
}
private void parseListSection(SectionList sectionList) {
skipRequiredWhitespaces();
var startOfName = new Cursor(current);
String name = parseId();
parseEndDelimiter(true);
TemplateParser bodyParser = parse(descriptor, current, EnumSet.of(Sentinel.END));
current.set(bodyParser.current);
sectionList.appendListSection(name, startOfName, current, bodyParser.templateBuilder.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, templateBuilder);
Sentinel ifSentinel = parse(ifSectionList, EnumSet.of(Sentinel.ELSE, Sentinel.END));
Optional<SectionList> elseSectionList = Optional.empty();
if (ifSentinel == Sentinel.ELSE) {
elseSectionList = Optional.of(new SectionList(current, templateBuilder));
parse(elseSectionList.get(), EnumSet.of(Sentinel.END));
}
sectionList.appendIfSection(negated, name, startOfName, current, ifSectionList, elseSectionList);
}
private void skipRequiredWhitespaces() {
if (!current.skipWhitespaces()) {
throw new BadTemplateException(current, "Expected whitespace");
}
}
private String parseId() {
return skipId().orElseThrow(() -> new BadTemplateException(current, "Expected identifier"));
}
private Optional<String> skipId() { return Token.skipId(current); }
private void parseEndDelimiter(boolean allowSkipNewline) {
boolean removeNewlineCharPresent = current.skip(Token.REMOVE_NEWLINE_CHAR);
if (!current.skip(descriptor.endDelimiter()))
throw new BadTemplateException(current, "Expected section end (" + descriptor.endDelimiter() + ")");
// The presence of the remove-newline-char means the opposite behavior is wanted.
if (allowSkipNewline && (removeNewlineCharPresent != descriptor.removeNewline()))
current.skip('\n');
}
}
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