com.google.gitiles.doc.TocFormatter.java Source code

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Here is the source code for com.google.gitiles.doc.TocFormatter.java

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// Copyright 2015 Google Inc. All Rights Reserved.
//
// 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.gitiles.doc;

import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
import com.google.common.hash.Hashing;
import com.google.gitiles.doc.html.HtmlBuilder;

import org.apache.commons.lang3.StringUtils;
import org.pegdown.ast.HeaderNode;
import org.pegdown.ast.Node;
import org.pegdown.ast.RootNode;

import java.nio.charset.StandardCharsets;

/** Outputs outline from HeaderNodes in the AST. */
class TocFormatter {
    private final HtmlBuilder html;
    private final int maxLevel;

    private RootNode root;
    private Boolean hasToc;
    private int countH1;
    private BiMap<HeaderNode, String> ids;

    private int level;

    TocFormatter(HtmlBuilder html, int maxLevel) {
        this.html = html;
        this.maxLevel = maxLevel;
    }

    void setRoot(RootNode doc) {
        root = doc;
        hasToc = null;
        ids = HashBiMap.create();
    }

    boolean include(HeaderNode h) {
        init();
        if (!hasToc) {
            return false;
        } else if (h.getLevel() == 1) {
            return countH1 > 1;
        }
        return h.getLevel() <= maxLevel;
    }

    String idFromHeader(HeaderNode header) {
        String id = ids.get(header);
        if (id == null) {
            String title = MarkdownUtil.getInnerText(header);
            if (title == null) {
                return null;
            }

            id = idFromTitle(title);
            if (ids.values().contains(id)) {
                id = String.format("%s-%x", id, Hashing.md5().hashString(id, StandardCharsets.UTF_8).asInt());
            }
            ids.put(header, id);
        }
        return id;
    }

    void format() {
        init();

        int startLevel = countH1 > 1 ? 1 : 2;
        hasToc = true;
        level = startLevel;

        html.open("div").attribute("class", "toc").attribute("role", "navigation").open("h2")
                .appendAndEscape("Contents").close("h2").open("div").attribute("class", "toc-aux").open("ul");
        outline(root);
        while (level >= startLevel) {
            html.close("ul");
            level--;
        }
        html.close("div").close("div");
    }

    private void outline(Node node) {
        if (node instanceof HeaderNode) {
            outline((HeaderNode) node);
        } else {
            for (Node child : node.getChildren()) {
                outline(child);
            }
        }
    }

    private void outline(HeaderNode h) {
        if (!include(h)) {
            return;
        }

        String id = idFromHeader(h);
        if (id == null) {
            return;
        }

        while (level > h.getLevel()) {
            html.close("ul");
            level--;
        }
        while (level < h.getLevel()) {
            html.open("ul");
            level++;
        }

        html.open("li").open("a").attribute("href", "#" + id).appendAndEscape(MarkdownUtil.getInnerText(h))
                .close("a").close("li");
    }

    private static String idFromTitle(String title) {
        StringBuilder b = new StringBuilder(title.length());
        for (char c : StringUtils.stripAccents(title).toCharArray()) {
            if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9')) {
                b.append(c);
            } else if (c == ' ') {
                if (b.length() > 0 && b.charAt(b.length() - 1) != '-' && b.charAt(b.length() - 1) != '_') {
                    b.append('-');
                }
            } else if (b.length() > 0 && b.charAt(b.length() - 1) != '-' && b.charAt(b.length() - 1) != '_') {
                b.append('_');
            }
        }
        while (b.length() > 0) {
            char c = b.charAt(b.length() - 1);
            if (c == '-' || c == '_') {
                b.setLength(b.length() - 1);
                continue;
            }
            break;
        }
        return b.toString();
    }

    private void init() {
        if (hasToc == null) {
            hasToc = false;
            init(root);
        }
    }

    private void init(Node node) {
        if (node instanceof TocNode) {
            hasToc = true;
            return;
        } else if (node instanceof HeaderNode && ((HeaderNode) node).getLevel() == 1) {
            countH1++;
            return;
        }
        for (Node child : node.getChildren()) {
            init(child);
            if (hasToc && countH1 > 1) {
                break;
            }
        }
    }
}