如何将平面javascript数组转换为嵌套图结构？

var i, j, k, arr = 
[
    [\"a\",\"b\",\"c\"],
    [\"a\",\"b\",\"d\"],
    [\"c\",\"b\",\"e\"],
    [\"c\",\"b\",\"f\"]        
];

var results = [];
var last = results;

for(i = 0; i < arr.length; i = i + 1) {
    var subArr = arr[i];  
    var parentURI = subArr[0], middleURI = subArr[1], childURI = subArr[2]; 
    var parent, middle, child;

    // Find parent or create parent
    parent = getNode(results, parentURI);        
    if(parent === null) {
        results.push({\"uri\": parentURI, \"subItems\": []});
        parent = results[results.length-1];
    }        
    if(typeof parent[\"subItems\"] === \"undefined\") {
        parent[\"subItems\"] = [];
    }

    // Find middle or create middle
    middle = getNode(parent[\"subItems\"], middleURI);
    if(middle === null) {
        parent[\"subItems\"].push({\"uri\": middleURI, \"subItems\": []});
        middle = parent[\"subItems\"][parent[\"subItems\"].length-1];        
    }
    if(typeof middle[\"subItems\"] === \"undefined\") {
        middle[\"subItems\"] = [];
    }    

    // Find child or create child 
    child = getNode(middle[\"subItems\"], childURI);
    if(child === null) {
        middle[\"subItems\"].push({\"uri\": childURI});
        //child = middle[\"subItems\"][middle[\"subItems\"].length-1];            
    }
}

document.write(JSON.stringify(results));

function getNode(arr, uri) {
    var node = null;

    (function recurseArr(arr) {
        for(var i = 0; i < arr.length; i = i + 1) {
            var obj = arr[i];
            if(obj[\"uri\"] === uri) {
                node = arr[i];
                break;   
            } else if(typeof obj[\"subItems\"] !== \"undefined\") {  
                recurseArr(obj[\"subItems\"]);
            }
        }
    })(arr);      

  return node;  
}

var data = [
[\"a\", \"b\", \"c\"],
[\"a\", \"b\", \"d\"],
[\"c\", \"b\", \"e\"],
[\"c\", \"b\", \"f\"]
];

var group = null;

var baseStructure = {
    \"uri\": null,
    \"subItems\": []
};


function find(parent, uri) {
    for (var i = 0; parent.subItems && i < parent.subItems.length; i++) {
        if (parent.subItems[i].uri == uri) {
            return parent.subItems[i];
        }
    }
    return null;
}

function findRecursive(parent, uri) {
    var i, obj;
    //look in children
    for (i = 0; parent.subItems && i < parent.subItems.length; i++) {
        obj = find(parent.subItems[i], uri);
        if (obj !== null) {
            return obj;
        }
    }
    //look recursively in children
    for (i = 0; parent.subItems && i < parent.subItems.length; i++) {
        obj = findRecursive(parent.subItems[i], uri);
        if (obj !== null) {
            return obj;
        }
    }
    return null;
}


for (var i = 0; (group = data[i]); i++) {
    var current = baseStructure;
    for (var j = 0; j < group.length; j++) {
        var obj = find(current, group[j]);

        if (obj === null && j === 0) {
            obj = findRecursive(current, group[j]);
        }

        if (obj === null) {
            //create a new one if not found
            obj = {
                uri: group[j]
            };
            if(current.subItems === undefined)
            {
                current.subItems = [];
            }
            current.subItems.push(obj);
        }
        current = obj;
    }
}