rust-search-extension/extension/search.js

var rootPath = "https://doc.rust-lang.org/";
// This mapping table should match the discriminants of
// `rustdoc::html::item_type::ItemType` type in Rust.
var itemTypes = [
    "mod",
    "externcrate",
    "import",
    "struct",
    "enum",
    "fn",
    "type",
    "static",
    "trait",
    "impl",
    "tymethod",
    "method",
    "structfield",
    "variant",
    "macro",
    "primitive",
    "associatedtype",
    "constant",
    "associatedconstant",
    "union",
    "foreigntype",
    "keyword",
    "existential",
    "attr",
    "derive"
];
// used for special search precedence
var TY_PRIMITIVE = itemTypes.indexOf("primitive");
var TY_KEYWORD = itemTypes.indexOf("keyword");

// The list of search words to query against.
var searchWords = [];
var searchIndex = [];
// Max levenshtein distance.
var MAX_LEV_DISTANCE = 2;
var MAX_RESULTS = 10;
/**
 * Global levenshtein_row2 array which used in function levenshtein().
 * @type {Array}
 */
var levenshtein_row2 = [];
/**
 * Current query lowercase keyword.
 */
var valLower;
var split;


function initSearch(rawSearchIndex) {
    searchWords = buildIndex(rawSearchIndex);
}

function buildIndex(rawSearchIndex) {
    searchIndex = [];
    var searchWords = [];
    for (var crate in rawSearchIndex) {
        if (!rawSearchIndex.hasOwnProperty(crate)) {
            continue;
        }

        searchWords.push(crate);
        searchIndex.push({
            crate: crate,
            ty: 1, // == ExternCrate
            name: crate,
            path: "",
            desc: rawSearchIndex[crate].doc,
            type: null,
        });

        // an array of [(Number) item type,
        //              (String) name,
        //              (String) full path or empty string for previous path,
        //              (String) description,
        //              (Number | null) the parent path index to `paths`]
        //              (Object | null) the type of the function (if any)
        var items = rawSearchIndex[crate].items;
        // an array of [(Number) item type,
        //              (String) name]
        var paths = rawSearchIndex[crate].paths;

        // convert `paths` into an object form
        for (var i = 0; i < paths.length; ++i) {
            paths[i] = {ty: paths[i][0], name: paths[i][1]};
        }

        // convert `items` into an object form, and construct word indices.
        //
        // before any analysis is performed lets gather the search terms to
        // search against apart from the rest of the data.  This is a quick
        // operation that is cached for the life of the page state so that
        // all other search operations have access to this cached data for
        // faster analysis operations
        var len = items.length;
        var lastPath = "";
        for (var i = 0; i < len; ++i) {
            var rawRow = items[i];
            var row = {
                crate: crate, ty: rawRow[0], name: rawRow[1],
                path: rawRow[2] || lastPath, desc: rawRow[3],
                parent: paths[rawRow[4]], type: rawRow[5]
            };
            searchIndex.push(row);
            if (typeof row.name === "string") {
                var word = row.name.toLowerCase();
                searchWords.push(word);
            } else {
                searchWords.push("");
            }
            lastPath = row.path;
        }
    }
    return searchWords;
}

function search(query) {
    return execQuery(buildQuery(query));
}

function buildQuery(raw) {
    var matches, type, query;
    query = raw;

    matches = query.match(/^(fn|mod|struct|enum|trait|type|const|macro)\s*:\s*/i);
    if (matches) {
        type = matches[1].replace(/^const$/, 'constant');
        query = query.substring(matches[0].length);
    }

    return {
        raw: raw,
        query: query,
        type: type,
        id: query + type
    };
}

function execQuery(query) {
    function itemTypeFromName(typename) {
        for (var i = 0; i < itemTypes.length; ++i) {
            if (itemTypes[i] === typename) {
                return i;
            }
        }
        return -1;
    }

    function checkPath(contains, lastElem, ty) {
        if (contains.length === 0) {
            return 0;
        }
        var ret_lev = MAX_LEV_DISTANCE + 1;
        var path = ty.path.split("::");

        if (ty.parent && ty.parent.name) {
            path.push(ty.parent.name.toLowerCase());
        }

        if (contains.length > path.length) {
            return MAX_LEV_DISTANCE + 1;
        }
        for (var i = 0; i < path.length; ++i) {
            if (i + contains.length > path.length) {
                break;
            }
            var lev_total = 0;
            var aborted = false;
            for (var x = 0; x < contains.length; ++x) {
                var lev = levenshtein(path[i + x], contains[x]);
                if (lev > MAX_LEV_DISTANCE) {
                    aborted = true;
                    break;
                }
                lev_total += lev;
            }
            if (aborted === false) {
                ret_lev = Math.min(ret_lev, Math.round(lev_total / contains.length));
            }
        }
        return ret_lev;
    }

    function typePassesFilter(filter, type) {
        // No filter
        if (filter < 0) return true;

        // Exact match
        if (filter === type) return true;

        // Match related items
        var name = itemTypes[type];
        switch (itemTypes[filter]) {
            case "constant":
                return (name === "associatedconstant");
            case "fn":
                return (name === "method" || name === "tymethod");
            case "type":
                return (name === "primitive" || name === "keyword");
        }

        // No match
        return false;
    }

    function generateId(ty) {
        if (ty.parent && ty.parent.name) {
            return itemTypes[ty.ty] + ty.path + ty.parent.name + ty.name;
        }
        return itemTypes[ty.ty] + ty.path + ty.name;
    }

    valLower = query.query.toLowerCase();
    split = valLower.split("::");

    var val = valLower,
        typeFilter = itemTypeFromName(query.type),
        results = {};

    for (var z = 0; z < split.length; ++z) {
        if (split[z] === "") {
            split.splice(z, 1);
            z -= 1;
        }
    }

    var nSearchWords = searchWords.length;
    query.inputs = [val];
    query.output = val;
    query.search = val;
    // gather matching search results up to a certain maximum
    // val = val.replace(/\_/g, "");

    // var valGenerics = extractGenerics(val);

    var paths = valLower.split("::");
    var j;
    // "std::option::".split("::") => ["std", "option", ""]
    for (j = 0; j < paths.length; ++j) {
        if (paths[j] === "") {
            paths.splice(j, 1);
            j -= 1;
        }
    }
    val = paths[paths.length - 1];
    var contains = paths.slice(0, paths.length > 1 ? paths.length - 1 : 1);

    for (j = 0; j < nSearchWords; ++j) {
        var ty = searchIndex[j];
        if (!ty) {
            continue;
        }
        var lev_add = 0;
        if (paths.length > 1) {
            var lev = checkPath(contains, paths[paths.length - 1], ty);
            if (lev > MAX_LEV_DISTANCE) {
                continue;
            } else if (lev > 0) {
                lev_add = 1;
            }
        }

        var index = -1;
        // we want lev results to go lower than others
        var lev = MAX_LEV_DISTANCE + 1;
        var fullId = generateId(ty);

        if (searchWords[j].indexOf(val) > -1 ||
            searchWords[j].replace(/_/g, "").indexOf(val) > -1) {
            // filter type: ... queries
            if (typePassesFilter(typeFilter, ty.ty) && results[fullId] === undefined) {
                index = searchWords[j].replace(/_/g, "").indexOf(val);
            }
        }
        if ((lev = levenshtein(searchWords[j], val)) <= MAX_LEV_DISTANCE) {
            if (typePassesFilter(typeFilter, ty.ty) === false) {
                lev = MAX_LEV_DISTANCE + 1;
            } else {
                lev += 1;
            }
        }

        lev += lev_add;
        if (lev > 0 && val.length > 3 && searchWords[j].indexOf(val) > -1) {
            if (val.length < 6) {
                lev -= 1;
            } else {
                lev = 0;
            }
        }

        if (index !== -1 || lev <= MAX_LEV_DISTANCE) {
            if (index !== -1 && paths.length < 2) {
                lev = 0;
            }
            if (results[fullId] === undefined) {
                results[fullId] = {
                    id: j,
                    index: index,
                    lev: lev,
                };
            }
            results[fullId].lev = Math.min(results[fullId].lev, lev);
        }
    }

    return sortResults(results);
}

function sortResults(results) {
    var ar = [];
    for (var entry in results) {
        if (results.hasOwnProperty(entry)) {
            ar.push(results[entry]);
        }
    }
    results = ar;
    var nresults = results.length;
    for (var i = 0; i < nresults; ++i) {
        results[i].word = searchWords[results[i].id];
        results[i].item = searchIndex[results[i].id] || {};
    }
    // if there are no results then return to default and fail
    if (results.length === 0) {
        return [];
    }

    results.sort(function(aaa, bbb) {
        var a, b;

        // Sort by non levenshtein results and then levenshtein results by the distance
        // (less changes required to match means higher rankings)
        a = (aaa.lev);
        b = (bbb.lev);
        if (a !== b) {
            return a - b;
        }

        // sort by exact match (mismatch goes later)
        a = (aaa.word !== valLower);
        b = (bbb.word !== valLower);
        if (a !== b) {
            return a - b;
        }

        // sort by item name length (longer goes later)
        a = aaa.word.length;
        b = bbb.word.length;
        if (a !== b) {
            return a - b;
        }

        // sort by item name (lexicographically larger goes later)
        a = aaa.word;
        b = bbb.word;
        if (a !== b) {
            return (a > b ? +1 : -1);
        }

        // sort by index of keyword in item name (no literal occurrence goes later)
        a = (aaa.index < 0);
        b = (bbb.index < 0);
        if (a !== b) {
            return a - b;
        }
        // (later literal occurrence, if any, goes later)
        a = aaa.index;
        b = bbb.index;
        if (a !== b) {
            return a - b;
        }

        // special precedence for primitive and keyword pages
        if ((aaa.item.ty === TY_PRIMITIVE && bbb.item.ty !== TY_KEYWORD) ||
            (aaa.item.ty === TY_KEYWORD && bbb.item.ty !== TY_PRIMITIVE)) {
            return -1;
        }
        if ((bbb.item.ty === TY_PRIMITIVE && aaa.item.ty !== TY_PRIMITIVE) ||
            (bbb.item.ty === TY_KEYWORD && aaa.item.ty !== TY_KEYWORD)) {
            return 1;
        }

        // sort by description (no description goes later)
        a = (aaa.item.desc === '');
        b = (bbb.item.desc === '');
        if (a !== b) {
            return a - b;
        }

        // sort by type (later occurrence in `itemTypes` goes later)
        a = aaa.item.ty;
        b = bbb.item.ty;
        if (a !== b) {
            return a - b;
        }

        // sort by path (lexicographically larger goes later)
        a = aaa.item.path;
        b = bbb.item.path;
        if (a !== b) {
            return (a > b ? +1 : -1);
        }

        // que sera, sera
        return 0;
    });

    for (var i = 0; i < results.length; ++i) {
        var result = results[i];

        // this validation does not make sense when searching by types
        if (result.dontValidate) {
            continue;
        }
        var name = result.item.name.toLowerCase(),
            path = result.item.path.toLowerCase(),
            parent = result.item.parent;

        if (validateResult(name, path, split, parent) === false) {
            result.id = -1;
        }
    }
    return transformResults(results);
}

function transformResults(results, isType) {
    var out = [];
    for (i = 0; i < results.length; ++i) {
        if (results[i].id > -1) {
            var obj = searchIndex[results[i].id];
            obj.lev = results[i].lev;
            if (isType !== true || obj.type) {
                var res = buildHrefAndPath(obj);
                // obj.displayPath = pathSplitter(res[0]);
                obj.displayPath = res[0];
                obj.fullPath = obj.displayPath + obj.name;
                // To be sure than it some items aren't considered as duplicate.
                // obj.fullPath += '|' + obj.ty;
                obj.href = res[1];
                out.push(obj);
                if (out.length >= MAX_RESULTS) {
                    break;
                }
            }
        }
    }
    return out;
}

function buildHrefAndPath(item) {
    var displayPath;
    var href;
    var type = itemTypes[item.ty];
    var name = item.name;

    if (type === 'mod') {
        displayPath = item.path + '::';
        href = rootPath + item.path.replace(/::/g, '/') + '/' +
            name + '/index.html';
    } else if (type === "primitive" || type === "keyword") {
        displayPath = "";
        href = rootPath + item.path.replace(/::/g, '/') +
            '/' + type + '.' + name + '.html';
    } else if (type === "externcrate") {
        displayPath = "";
        href = rootPath + name + '/index.html';
    } else if (item.parent !== undefined) {
        var myparent = item.parent;
        var anchor = '#' + type + '.' + name;
        var parentType = itemTypes[myparent.ty];
        if (parentType === "primitive") {
            displayPath = myparent.name + '::';
        } else {
            displayPath = item.path + '::' + myparent.name + '::';
        }
        href = rootPath + item.path.replace(/::/g, '/') +
            '/' + parentType +
            '.' + myparent.name +
            '.html' + anchor;
    } else {
        displayPath = item.path + '::';
        href = rootPath + item.path.replace(/::/g, '/') +
            '/' + type + '.' + name + '.html';
    }
    return [displayPath, href];
}


/**
 * Validate performs the following boolean logic. For example:
 * "File::open" will give IF A PARENT EXISTS => ("file" && "open")
 * exists in (name || path || parent) OR => ("file" && "open") exists in
 * (name || path )
 *
 * This could be written functionally, but I wanted to minimise
 * functions on stack.
 *
 * @param  {[string]} name   [The name of the result]
 * @param  {[string]} path   [The path of the result]
 * @param  {[string]} keys   [The keys to be used (["file", "open"])]
 * @param  {[object]} parent [The parent of the result]
 * @return {[boolean]}       [Whether the result is valid or not]
 */
function validateResult(name, path, keys, parent) {
    for (var i = 0; i < keys.length; ++i) {
        // each check is for validation so we negate the conditions and invalidate
        if (!(
            // check for an exact name match
            name.indexOf(keys[i]) > -1 ||
            // then an exact path match
            path.indexOf(keys[i]) > -1 ||
            // next if there is a parent, check for exact parent match
            (parent !== undefined &&
                parent.name.toLowerCase().indexOf(keys[i]) > -1) ||
            // lastly check to see if the name was a levenshtein match
            levenshtein(name, keys[i]) <= MAX_LEV_DISTANCE)) {
            return false;
        }
    }
    return true;
}

/**
 * A function to compute the Levenshtein distance between two strings
 * Licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported
 * Full License can be found at http://creativecommons.org/licenses/by-sa/3.0/legalcode
 * This code is an unmodified version of the code written by Marco de Wit
 * and was found at http://stackoverflow.com/a/18514751/745719
 */
function levenshtein(s1, s2) {
    if (s1 === s2) {
        return 0;
    }
    var s1_len = s1.length, s2_len = s2.length;
    if (s1_len && s2_len) {
        var i1 = 0, i2 = 0, a, b, c, c2, row = levenshtein_row2;
        while (i1 < s1_len) {
            row[i1] = ++i1;
        }
        while (i2 < s2_len) {
            c2 = s2.charCodeAt(i2);
            a = i2;
            ++i2;
            b = i2;
            for (i1 = 0; i1 < s1_len; ++i1) {
                c = a + (s1.charCodeAt(i1) !== c2 ? 1 : 0);
                a = row[i1];
                b = b < a ? (b < c ? b + 1 : c) : (a < c ? a + 1 : c);
                row[i1] = b;
            }
        }
        return b;
    }
    return s1_len + s2_len;
}

window.rootPath = rootPath;
window.initSearch = initSearch;
window.search = search;