stevenvelozo/precedent

/**
* Word Tree
* @author      Steven Velozo <steven@velozo.com>
* @description Create a tree (directed graph) of Javascript objects, one character per object.
*/

class WordTree
{
    /**
     * WordTree Constructor
     */
    constructor()
    {
        this.ParseTree = {};
    }

    /**
     * Add a child character to a Parse Tree node
     * @method addChild
     * @param {Object} pTree - A parse tree to push the characters into
     * @param {string} pPattern - The string to add to the tree
     * @returns {Object} The resulting leaf node that was added (or found)
     * @private
     */
    addChild (pTree, pPattern)
    {
        if (!pTree.hasOwnProperty(pPattern))
        {
            pTree[pPattern] = {};
        }

        return pTree[pPattern];
    }

    /**
     * Add a child character to a Parse Tree PatternEnd subtree
     * @method addChild
     * @param {Object} pTree - A parse tree to push the characters into
     * @param {string} pPattern - The string to add to the tree
     * @returns {Object} The resulting leaf node that was added (or found)
     * @private
     */
    addEndChild (pTree, pPattern)
    {
        if (!pTree.hasOwnProperty('PatternEnd'))
        {
            pTree.PatternEnd = {};
        }

        pTree.PatternEnd[pPattern] = {};

        return pTree.PatternEnd[pPattern];
    }

    /** Add a Pattern to the Parse Tree
     * @method addPattern
     * @param {Object} pPatternStart - The starting string for the pattern (e.g. "${")
     * @param {string} pPatternEnd - The ending string for the pattern (e.g. "}")
     * @param {function} fParser - The function to parse if this is the matched pattern, once the Pattern End is met.  If this is a string, a simple replacement occurs.
     * @return {bool} True if adding the pattern was successful
     */
    addPattern (pPatternStart, pPatternEnd, fParser)
    {
        if (pPatternStart.length < 1)
        {
            return false;
        }

        if ((typeof(pPatternEnd) === 'string') && (pPatternEnd.length < 1))
        {
            return false;
        }

        let tmpLeaf = this.ParseTree;

        // Add the tree of leaves iteratively
        for (var i = 0; i < pPatternStart.length; i++)
        {
            tmpLeaf = this.addChild(tmpLeaf, pPatternStart[i], i);
        }

        if (!tmpLeaf.hasOwnProperty('PatternEnd'))
        {
            tmpLeaf.PatternEnd = {};
        }

        let tmpPatternEnd = (typeof(pPatternEnd) === 'string') ? pPatternEnd : pPatternStart;
        for (let i = 0; i < tmpPatternEnd.length; i++)
        {
            tmpLeaf = this.addEndChild(tmpLeaf, tmpPatternEnd[i], i);
        }

        tmpLeaf.PatternStartString = pPatternStart;
        tmpLeaf.PatternEndString = tmpPatternEnd;
        tmpLeaf.Parse = (typeof(fParser) === 'function') ? fParser :
                        (typeof(fParser) === 'string') ? () => { return fParser; } :
                        (pData) => { return pData; };

        return true;
    }
}

module.exports = WordTree;