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/*
 * Copyright 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.safehtml.rebind;

import com.google.gwt.dev.util.Preconditions;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

/**
 * A representation of a parsed HTML template.
 *
 * 

A parsed template is represented as a sequence of template chunks. * *

A chunk may correspond to a literal string or to a formal template * parameter. * *

Parameter chunks have an attribute that refers to the index of the * corresponding template method parameter, as well as an attribute that * represents the HTML context the template parameter appeared in. */ final class ParsedHtmlTemplate { /** * A representation of the context of a point within a HTML document. A * context consists of a type (such as "plain text", "attribute"), as well as * a HTML tag and attribute name where applicable. */ static final class HtmlContext { /** * The possible types of HTML context. */ static enum Type { /** * Regular inner text HTML context. */ TEXT, /** * Value of a HTML attribute. */ ATTRIBUTE_VALUE, /** * At the very start of a URL-valued attribute. */ URL_ATTRIBUTE_START, /** * A template parameter that comprises an entire URL-valued attribute. */ URL_ATTRIBUTE_ENTIRE, /** * CSS (style) context. */ CSS, /** * CSS (style) attribute context. */ CSS_ATTRIBUTE, /** * At the very start of a CSS (style) attribute context. */ CSS_ATTRIBUTE_START } private final Type type; private final String tag; private final String attribute; /** * Creates a HTML context. * * @param type the {@link Type} of this context */ public HtmlContext(Type type) { this(type, null, null); } /** * Creates a HTML context. * * @param type the {@link Type} of this context * @param tag the HTML tag this context corresponds to, if applicable; null * otherwise * @param attribute the HTML attribute this context corresponds to, if * applicable; null otherwise */ public HtmlContext(Type type, String tag, String attribute) { Preconditions.checkArgument((type != Type.TEXT) || ((tag == null) && (attribute == null)), "tag and attribute must be null for context \"TEXT\""); this.type = type; this.tag = tag; this.attribute = attribute; } /** * Returns the attribute of this HTML context. */ public String getAttribute() { return attribute; } /** * Returns the tag of this HTML context. */ public String getTag() { return tag; } /** * Returns the type of this HTML context. */ public Type getType() { return type; } @Override public String toString() { return "(" + getType() + "," + getTag() + "," + getAttribute() + ")"; } } /** * Represents a template chunk corresponding to a literal string. */ static final class LiteralChunk implements TemplateChunk { private final StringBuilder chunk; /** * Creates a literal chunk corresponding to an empty string. */ public LiteralChunk() { chunk = new StringBuilder(); } /** * Creates a literal chunk corresponding to the provided string. */ public LiteralChunk(String literal) { chunk = new StringBuilder(literal); } public Kind getKind() { return Kind.LITERAL; } public String getLiteral() { return chunk.toString(); } @Override public String toString() { return String.format("L(%s)", getLiteral()); } void append(String s) { chunk.append(s); } } /** * Represents a template chunk corresponding to a template parameter. */ static final class ParameterChunk implements TemplateChunk { private final HtmlContext context; private final int parameterIndex; /** * Creates a parameter chunk. * * @param context the HTML context this parameter appears in * @param parameterIndex the index of the template parameter that this chunk * refers to */ public ParameterChunk(HtmlContext context, int parameterIndex) { this.context = context; this.parameterIndex = parameterIndex; } /** * Returns the HTML context this parameter appears in. */ public HtmlContext getContext() { return context; } public Kind getKind() { return Kind.PARAMETER; } /** * Returns the index of the template parameter that this chunk refers to. */ public int getParameterIndex() { return parameterIndex; } @Override public String toString() { return String.format("P(%s,%d)", getContext(), getParameterIndex()); } } /** * Represents a parsed chunk of a template. * *

There are two kinds of chunks: Those representing literal strings and * those representing template parameters. */ interface TemplateChunk { /** * Distinguishes different kinds of {@link TemplateChunk}. */ public static enum Kind { LITERAL, PARAMETER, } /** * Returns the {@link Kind} of this template chunk. */ Kind getKind(); } /* * The chunks of this parsed template. */ private final LinkedList chunks; /** * Initializes an empty parsed HTML template. */ public ParsedHtmlTemplate() { chunks = new LinkedList(); } /** * Adds a literal string to the template. * * If the currently last chunk of the parsed template is a literal chunk, the * provided string literal will be appended to that chunk. I.e., consecutive * literal chunks are automatically coalesced. * @param literal the string to be added as a literal chunk */ public void addLiteral(String literal) { if (chunks.isEmpty() || (chunks.getLast().getKind() != TemplateChunk.Kind.LITERAL)) { chunks.add(new LiteralChunk(literal)); } else { ((LiteralChunk) chunks.getLast()).append(literal); } } /** * Adds a parameter chunk to the template. * * @param chunk the chunk to be added */ public void addParameter(ParameterChunk chunk) { chunks.add(chunk); } /** * Returns the chunks of this parsed template. * *

The returned list is unmodifiable. */ public List getChunks() { return Collections.unmodifiableList(chunks); } @Override public String toString() { return chunks.toString(); } }





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