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    if (theme === null) { theme = 'light'; }

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    // Syntax highlighting Configuration
    hljs.configure({
        tabReplace: '    ', // 4 spaces
        languages: [],      // Languages used for auto-detection
    });

    $('code').each(function(i, block) {
        hljs.highlightBlock(block);
    });
    
    // Adding the hljs class gives code blocks the color css
    // even if highlighting doesn't apply
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        switch (e.keyCode) {
            case KEY_CODES.NEXT_KEY:
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                if($('.nav-chapters.next').length) {
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    // Interesting DOM Elements
    var html = $("html");
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    // Toggle sidebar
    $("#sidebar-toggle").click(function(event){
        if ( html.hasClass("sidebar-hidden") ) {
            html.removeClass("sidebar-hidden").addClass("sidebar-visible");
            localStorage.setItem('sidebar', 'visible');
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            html.removeClass("sidebar-visible").addClass("sidebar-hidden");
            localStorage.setItem('sidebar', 'hidden');
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            if(sidebar.position().left === 0){
                html.addClass("sidebar-hidden");
                localStorage.setItem('sidebar', 'hidden');
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                html.addClass("sidebar-visible");
                localStorage.setItem('sidebar', 'visible');
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    // Scroll sidebar to current active section
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    if(activeSection.length) {
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    // Print button
    $("#print-button").click(function(){
        var printWindow = window.open("print.html");
    });

    if( url.substring(url.lastIndexOf('/')+1) == "print.html" ) {
        window.print();
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            var popup = $('<div class="theme-popup"></div>')
                .append($('<div class="theme" id="light">Light <span class="default">(default)</span><div>'))
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        localStorage.setItem('theme', theme);

        $('body').removeClass().addClass(theme);
    }


    // Hide Rust code lines prepended with a specific character
    var hiding_character = "#";

    $("code.language-rust").each(function(i, block){

        var code_block = $(this);
        var pre_block = $(this).parent();
        // hide lines
        var lines = code_block.html().split("\n");
        var first_non_hidden_line = false;
        var lines_hidden = false;

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            if($.trim(lines[n])[0] == hiding_character){
                if(first_non_hidden_line){
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                else {
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                }
                lines_hidden = true;
            }
            else if(first_non_hidden_line) {
                lines[n] = "\n" + lines[n];
            }
            else {
                first_non_hidden_line = true;
            }
        }
        code_block.html(lines.join(""));

        // If no lines were hidden, return
        if(!lines_hidden) { return; }

        // add expand button
        pre_block.prepend("<div class=\"buttons\"><i class=\"fa fa-expand\"></i></div>");

        pre_block.find("i").click(function(e){
            if( $(this).hasClass("fa-expand") ) {
                $(this).removeClass("fa-expand").addClass("fa-compress");
                pre_block.find("span.hidden").removeClass("hidden").addClass("unhidden");
            }
            else {
                $(this).removeClass("fa-compress").addClass("fa-expand");
                pre_block.find("span.unhidden").removeClass("unhidden").addClass("hidden");
            }
        });
    });


    // Process playpen code blocks
    $(".playpen").each(function(block){
        var pre_block = $(this);
        // Add play button
        var buttons = pre_block.find(".buttons");
        if( buttons.length === 0 ) {
            pre_block.prepend("<div class=\"buttons\"></div>");
            buttons = pre_block.find(".buttons");
        }
        buttons.prepend("<i class=\"fa fa-play play-button\"></i>");
        buttons.prepend("<i class=\"fa fa-copy clip-button\"><i class=\"tooltiptext\"></i></i>");

        buttons.find(".play-button").click(function(e){
            run_rust_code(pre_block);
        });
        buttons.find(".clip-button").mouseout(function(e){
            hideTooltip(e.currentTarget);
        });
    });

    var clipboardSnippets = new Clipboard('.clip-button', {
        text: function(trigger) {
            hideTooltip(trigger);
            return trigger.parentElement.parentElement.textContent;
        }
    });
    clipboardSnippets.on('success', function(e) {
            e.clearSelection();
            showTooltip(e.trigger, "Copied!");
    });
    clipboardSnippets.on('error', function(e) {
            showTooltip(e.trigger, "Clipboard error!");
    });

});

function hideTooltip(elem) {
    elem.firstChild.innerText="";
    elem.setAttribute('class', 'fa fa-copy clip-button');
}

function showTooltip(elem, msg) {
    elem.firstChild.innerText=msg;
    elem.setAttribute('class', 'fa fa-copy tooltipped');
}

function run_rust_code(code_block) {
    var result_block = code_block.find(".result");
    if(result_block.length === 0) {
        code_block.append("<code class=\"result hljs language-bash\"></code>");
        result_block = code_block.find(".result");
    }

    var text = code_block.find(".language-rust").text();

    var params = {
        version: "stable",
        optimize: "0",
        code: text,
    };

    if(text.includes("#![feature")) {
        params.version = "nightly";
    }

    result_block.text("Running...");

    $.ajax({
        url: "https://play.rust-lang.org/evaluate.json",
        method: "POST",
        crossDomain: true,
        dataType: "json",
        contentType: "application/json",
        data: JSON.stringify(params),
        success: function(response){
            result_block.text(response.result);
        }
    });
}