tracery.js

/**
 * @author Kate
 */

var tracery = function() {
    var rng = Math.random;

    var setRng = function setRng(newRng) {
        rng = newRng;
    }

    var TraceryNode = function(parent, childIndex, settings) {
        this.errors = [];

        // No input? Add an error, but continue anyways
        if (settings.raw === undefined) {
            this.errors.push("Empty input for node");
            settings.raw = "";
        }

        // If the root node of an expansion, it will have the grammar passed as the 'parent'
        //  set the grammar from the 'parent', and set all other values for a root node
        if ( parent instanceof tracery.Grammar) {
            this.grammar = parent;
            this.parent = null;
            this.depth = 0;
            this.childIndex = 0;
        } else {
            this.grammar = parent.grammar;
            this.parent = parent;
            this.depth = parent.depth + 1;
            this.childIndex = childIndex;
        }

        this.raw = settings.raw;
        this.type = settings.type;
        this.isExpanded = false;

        if (!this.grammar) {
            this.errors.push("No grammar specified for this node " + this);
        }

    };

    TraceryNode.prototype.toString = function() {
        return "Node('" + this.raw + "' " + this.type + " d:" + this.depth + ")";
    };

    // Expand the node (with the given child rule)
    //  Make children if the node has any
    TraceryNode.prototype.expandChildren = function(childRule, preventRecursion) {
        this.children = [];
        this.finishedText = "";

        // Set the rule for making children,
        // and expand it into section
        this.childRule = childRule;
        if (this.childRule !== undefined) {
            var sections = tracery.parse(childRule);

            // Add errors to this
            if (sections.errors.length > 0) {
                this.errors = this.errors.concat(sections.errors);

            }

            for (var i = 0; i < sections.length; i++) {
                this.children[i] = new TraceryNode(this, i, sections[i]);
                if (!preventRecursion)
                    this.children[i].expand(preventRecursion);

                // Add in the finished text
                this.finishedText += this.children[i].finishedText;
            }
        } else {
            // In normal operation, this shouldn't ever happen
            this.errors.push("No child rule provided, can't expand children");
        }
    };

    // Expand this rule (possibly creating children)
    TraceryNode.prototype.expand = function(preventRecursion) {

        if (!this.isExpanded) {
            this.isExpanded = true;

            this.expansionErrors = [];

            // Types of nodes
            // -1: raw, needs parsing
            //  0: Plaintext
            //  1: Tag ("#symbol.mod.mod2.mod3#" or "#[pushTarget:pushRule]symbol.mod")
            //  2: Action ("[pushTarget:pushRule], [pushTarget:POP]", more in the future)

            switch(this.type) {
            // Raw rule
            case -1:

                this.expandChildren(this.raw, preventRecursion);
                break;

            // plaintext, do nothing but copy text into finsihed text
            case 0:
                this.finishedText = this.raw;
                break;

            // Tag
            case 1:
                // Parse to find any actions, and figure out what the symbol is
                this.preactions = [];
                this.postactions = [];

                var parsed = tracery.parseTag(this.raw);

                // Break into symbol actions and modifiers
                this.symbol = parsed.symbol;
                this.modifiers = parsed.modifiers;

                // Create all the preactions from the raw syntax
                for (var i = 0; i < parsed.preactions.length; i++) {
                    this.preactions[i] = new NodeAction(this, parsed.preactions[i].raw);
                }
                for (var i = 0; i < parsed.postactions.length; i++) {
                    //   this.postactions[i] = new NodeAction(this, parsed.postactions[i].raw);
                }

                // Make undo actions for all preactions (pops for each push)
                for (var i = 0; i < this.preactions.length; i++) {
                    if (this.preactions[i].type === 0)
                        this.postactions.push(this.preactions[i].createUndo());
                }

                // Activate all the preactions
                for (var i = 0; i < this.preactions.length; i++) {
                    this.preactions[i].activate();
                }

                this.finishedText = this.raw;

                // Expand (passing the node, this allows tracking of recursion depth)

                var selectedRule = this.grammar.selectRule(this.symbol, this, this.errors);

                this.expandChildren(selectedRule, preventRecursion);

                // Apply modifiers
                // TODO: Update parse function to not trigger on hashtags within parenthesis within tags,
                //   so that modifier parameters can contain tags "#story.replace(#protagonist#, #newCharacter#)#"
                for (var i = 0; i < this.modifiers.length; i++) {
                    var modName = this.modifiers[i];
                    var modParams = [];
                    if (modName.indexOf("(") > 0) {
                        var regExp = /\(([^)]+)\)/;

                        // Todo: ignore any escaped commas.  For now, commas always split
                        var results = regExp.exec(this.modifiers[i]);
                        if (!results || results.length < 2) {
                        } else {
                            var modParams = results[1].split(",");
                            modName = this.modifiers[i].substring(0, modName.indexOf("("));
                        }

                    }

                    var mod = this.grammar.modifiers[modName];

                    // Missing modifier?
                    if (!mod) {
                        this.errors.push("Missing modifier " + modName);
                        this.finishedText += "((." + modName + "))";
                    } else {
                        this.finishedText = mod(this.finishedText, modParams);

                    }

                }

                // Perform post-actions
                for (var i = 0; i < this.postactions.length; i++) {
                    this.postactions[i].activate();
                }
                break;
            case 2:

                // Just a bare action?  Expand it!
                this.action = new NodeAction(this, this.raw);
                this.action.activate();

                // No visible text for an action
                // TODO: some visible text for if there is a failure to perform the action?
                this.finishedText = "";
                break;

            }

        } else {
            //console.warn("Already expanded " + this);
        }

    };

    TraceryNode.prototype.clearEscapeChars = function() {

        this.finishedText = this.finishedText.replace(/\\\\/g, "DOUBLEBACKSLASH").replace(/\\/g, "").replace(/DOUBLEBACKSLASH/g, "\\");
    };

    // An action that occurs when a node is expanded
    // Types of actions:
    // 0 Push: [key:rule]
    // 1 Pop: [key:POP]
    // 2 function: [functionName(param0,param1)] (TODO!)
    function NodeAction(node, raw) {
        /*
         if (!node)
         console.warn("No node for NodeAction");
         if (!raw)
         console.warn("No raw commands for NodeAction");
         */

        this.node = node;

        var sections = raw.split(":");
        this.target = sections[0];

        // No colon? A function!
        if (sections.length === 1) {
            this.type = 2;

        }

        // Colon? It's either a push or a pop
        else {
            this.rule = sections[1];
            if (this.rule === "POP") {
                this.type = 1;
            } else {
                this.type = 0;
            }
        }
    }


    NodeAction.prototype.createUndo = function() {
        if (this.type === 0) {
            return new NodeAction(this.node, this.target + ":POP");
        }
        // TODO Not sure how to make Undo actions for functions or POPs
        return null;
    };

    NodeAction.prototype.activate = function() {
        var grammar = this.node.grammar;
        switch(this.type) {
        case 0:
            // split into sections (the way to denote an array of rules)
            this.ruleSections = this.rule.split(",");
            this.finishedRules = [];
            this.ruleNodes = [];
            for (var i = 0; i < this.ruleSections.length; i++) {
                var n = new TraceryNode(grammar, 0, {
                    type : -1,
                    raw : this.ruleSections[i]
                });

                n.expand();

                this.finishedRules.push(n.finishedText);
            }

            // TODO: escape commas properly
            grammar.pushRules(this.target, this.finishedRules, this);
            break;
        case 1:
            grammar.popRules(this.target);
            break;
        case 2:
            grammar.flatten(this.target, true);
            break;
        }

    };

    NodeAction.prototype.toText = function() {
        switch(this.type) {
        case 0:
            return this.target + ":" + this.rule;
        case 1:
            return this.target + ":POP";
        case 2:
            return "((some function))";
        default:
            return "((Unknown Action))";
        }
    };

    // Sets of rules
    // Can also contain conditional or fallback sets of rulesets)
    function RuleSet(grammar, raw) {
        this.raw = raw;
        this.grammar = grammar;
        this.falloff = 1;

        if (Array.isArray(raw)) {
            this.defaultRules = raw;
        } else if ( typeof raw === 'string' || raw instanceof String) {
            this.defaultRules = [raw];
        } else if (raw === 'object') {
            // TODO: support for conditional and hierarchical rule sets
        }

    };

    RuleSet.prototype.selectRule = function(errors) {
        // console.log("Get rule", this.raw);
        // Is there a conditional?
        if (this.conditionalRule) {
            var value = this.grammar.expand(this.conditionalRule, true);
            // does this value match any of the conditionals?
            if (this.conditionalValues[value]) {
                var v = this.conditionalValues[value].selectRule(errors);
                if (v !== null && v !== undefined)
                    return v;
            }
            // No returned value?
        }

        // Is there a ranked order?
        if (this.ranking) {
            for (var i = 0; i < this.ranking.length; i++) {
                var v = this.ranking.selectRule();
                if (v !== null && v !== undefined)
                    return v;
            }

            // Still no returned value?
        }

        if (this.defaultRules !== undefined) {
            var index = 0;
            // Select from this basic array of rules

            // Get the distribution from the grammar if there is no other
            var distribution = this.distribution;
            if (!distribution)
                distribution = this.grammar.distribution;

            switch(distribution) {
            case "shuffle":

                // create a shuffle desk
                if (!this.shuffledDeck || this.shuffledDeck.length === 0) {
                    // make an array
                    this.shuffledDeck = fyshuffle(Array.apply(null, {
                        length : this.defaultRules.length
                    }).map(Number.call, Number), this.falloff);

                }

                index = this.shuffledDeck.pop();

                break;
            case "weighted":
                errors.push("Weighted distribution not yet implemented");
                break;
            case "falloff":
                errors.push("Falloff distribution not yet implemented");
                break;
            default:

                index = Math.floor(Math.pow(rng(), this.falloff) * this.defaultRules.length);
                break;
            }

            if (!this.defaultUses)
                this.defaultUses = [];
            this.defaultUses[index] = ++this.defaultUses[index] || 1;
            return this.defaultRules[index];
        }

        errors.push("No default rules defined for " + this);
        return null;

    };

    RuleSet.prototype.clearState = function() {

        if (this.defaultUses) {
            this.defaultUses = [];
        }
    };

    function fyshuffle(array, falloff) {
        var currentIndex = array.length,
            temporaryValue,
            randomIndex;

        // While there remain elements to shuffle...
        while (0 !== currentIndex) {

            // Pick a remaining element...
            randomIndex = Math.floor(rng() * currentIndex);
            currentIndex -= 1;

            // And swap it with the current element.
            temporaryValue = array[currentIndex];
            array[currentIndex] = array[randomIndex];
            array[randomIndex] = temporaryValue;
        }

        return array;
    }

    var Symbol = function(grammar, key, rawRules) {
        // Symbols can be made with a single value, and array, or array of objects of (conditions/values)
        this.key = key;
        this.grammar = grammar;
        this.rawRules = rawRules;

        this.baseRules = new RuleSet(this.grammar, rawRules);
        this.clearState();

    };

    Symbol.prototype.clearState = function() {

        // Clear the stack and clear all ruleset usages
        this.stack = [this.baseRules];

        this.uses = [];
        this.baseRules.clearState();
    };

    Symbol.prototype.pushRules = function(rawRules) {
        var rules = new RuleSet(this.grammar, rawRules);
        this.stack.push(rules);
    };

    Symbol.prototype.popRules = function() {
        this.stack.pop();
    };

    Symbol.prototype.selectRule = function(node, errors) {
        this.uses.push({
            node : node
        });

        if (this.stack.length === 0) {
            errors.push("The rule stack for '" + this.key + "' is empty, too many pops?");
            return "((" + this.key + "))";
        }

        return this.stack[this.stack.length - 1].selectRule();
    };

    Symbol.prototype.getActiveRules = function() {
        if (this.stack.length === 0) {
            return null;
        }
        return this.stack[this.stack.length - 1].selectRule();
    };

    Symbol.prototype.rulesToJSON = function() {
        return JSON.stringify(this.rawRules);
    };

    var Grammar = function(raw, settings) {
        this.modifiers = {};
        this.loadFromRawObj(raw);
    };

    Grammar.prototype.clearState = function() {
        var keys = Object.keys(this.symbols);
        for (var i = 0; i < keys.length; i++) {
            this.symbols[keys[i]].clearState();
        }
    };

    Grammar.prototype.addModifiers = function(mods) {

        // copy over the base modifiers
        for (var key in mods) {
            if (mods.hasOwnProperty(key)) {
                this.modifiers[key] = mods[key];
            }
        };

    };

    Grammar.prototype.loadFromRawObj = function(raw) {

        this.raw = raw;
        this.symbols = {};
        this.subgrammars = [];

        if (this.raw) {
            // Add all rules to the grammar
            for (var key in this.raw) {
                if (this.raw.hasOwnProperty(key)) {
                    this.symbols[key] = new Symbol(this, key, this.raw[key]);
                }
            }
        }
    };

    Grammar.prototype.createRoot = function(rule) {
        // Create a node and subnodes
        var root = new TraceryNode(this, 0, {
            type : -1,
            raw : rule,
        });

        return root;
    };

    Grammar.prototype.expand = function(rule, allowEscapeChars) {
        var root = this.createRoot(rule);
        root.expand();
        if (!allowEscapeChars)
            root.clearEscapeChars();

        return root;
    };

    Grammar.prototype.flatten = function(rule, allowEscapeChars) {
        var root = this.expand(rule, allowEscapeChars);

        return root.finishedText;
    };

    Grammar.prototype.toJSON = function() {
        var keys = Object.keys(this.symbols);
        var symbolJSON = [];
        for (var i = 0; i < keys.length; i++) {
            var key = keys[i];
            symbolJSON.push(' "' + key + '" : ' + this.symbols[key].rulesToJSON());
        }
        return "{\n" + symbolJSON.join(",\n") + "\n}";
    };

    // Create or push rules
    Grammar.prototype.pushRules = function(key, rawRules, sourceAction) {

        if (this.symbols[key] === undefined) {
            this.symbols[key] = new Symbol(this, key, rawRules);
            if (sourceAction)
                this.symbols[key].isDynamic = true;
        } else {
            this.symbols[key].pushRules(rawRules);
        }
    };

    Grammar.prototype.popRules = function(key) {
        if (!this.symbols[key])
            this.errors.push("Can't pop: no symbol for key " + key);
        this.symbols[key].popRules();
    };

    Grammar.prototype.selectRule = function(key, node, errors) {
        if (this.symbols[key]) {
            var rule = this.symbols[key].selectRule(node, errors);

            return rule;
        }

        // Failover to alternative subgrammars
        for (var i = 0; i < this.subgrammars.length; i++) {

            if (this.subgrammars[i].symbols[key])
                return this.subgrammars[i].symbols[key].selectRule();
        }

        // No symbol?
        errors.push("No symbol for '" + key + "'");
        return "((" + key + "))";
    };

    // Parses a plaintext rule in the tracery syntax
    tracery = {

        createGrammar : function(raw) {
            return new Grammar(raw);
        },

        // Parse the contents of a tag
        parseTag : function(tagContents) {

            var parsed = {
                symbol : undefined,
                preactions : [],
                postactions : [],
                modifiers : []
            };
            var sections = tracery.parse(tagContents);
            var symbolSection = undefined;
            for (var i = 0; i < sections.length; i++) {
                if (sections[i].type === 0) {
                    if (symbolSection === undefined) {
                        symbolSection = sections[i].raw;
                    } else {
                        throw ("multiple main sections in " + tagContents);
                    }
                } else {
                    parsed.preactions.push(sections[i]);
                }
            }

            if (symbolSection === undefined) {
                //   throw ("no main section in " + tagContents);
            } else {
                var components = symbolSection.split(".");
                parsed.symbol = components[0];
                parsed.modifiers = components.slice(1);
            }
            return parsed;
        },

        parse : function(rule) {
            var depth = 0;
            var inTag = false;
            var sections = [];
            var escaped = false;

            var errors = [];
            var start = 0;

            var escapedSubstring = "";
            var lastEscapedChar = undefined;

            if (rule === null) {
                var sections = [];
                sections.errors = errors;

                return sections;
            }

            function createSection(start, end, type) {
                if (end - start < 1) {
                    if (type === 1)
                        errors.push(start + ": empty tag");
                    if (type === 2)
                        errors.push(start + ": empty action");

                }
                var rawSubstring;
                if (lastEscapedChar !== undefined) {
                    rawSubstring = escapedSubstring + "\\" + rule.substring(lastEscapedChar + 1, end);

                } else {
                    rawSubstring = rule.substring(start, end);
                }
                sections.push({
                    type : type,
                    raw : rawSubstring
                });
                lastEscapedChar = undefined;
                escapedSubstring = "";
            };

            for (var i = 0; i < rule.length; i++) {

                if (!escaped) {
                    var c = rule.charAt(i);

                    switch(c) {

                    // Enter a deeper bracketed section
                    case '[':
                        if (depth === 0 && !inTag) {
                            if (start < i)
                                createSection(start, i, 0);
                            start = i + 1;
                        }
                        depth++;
                        break;

                    case ']':
                        depth--;

                        // End a bracketed section
                        if (depth === 0 && !inTag) {
                            createSection(start, i, 2);
                            start = i + 1;
                        }
                        break;

                    // Hashtag
                    //   ignore if not at depth 0, that means we are in a bracket
                    case '#':
                        if (depth === 0) {
                            if (inTag) {
                                createSection(start, i, 1);
                                start = i + 1;
                            } else {
                                if (start < i)
                                    createSection(start, i, 0);
                                start = i + 1;
                            }
                            inTag = !inTag;
                        }
                        break;

                    case '\\':
                        escaped = true;
                        escapedSubstring = escapedSubstring + rule.substring(start, i);
                        start = i + 1;
                        lastEscapedChar = i;
                        break;
                    }
                } else {
                    escaped = false;
                }
            }
            if (start < rule.length)
                createSection(start, rule.length, 0);

            if (inTag) {
                errors.push("Unclosed tag");
            }
            if (depth > 0) {
                errors.push("Too many [");
            }
            if (depth < 0) {
                errors.push("Too many ]");
            }

            // Strip out empty plaintext sections

            sections = sections.filter(function(section) {
                if (section.type === 0 && section.raw.length === 0)
                    return false;
                return true;
            });
            sections.errors = errors;
            return sections;
        },
    };

    function isVowel(c) {
        var c2 = c.toLowerCase();
        return (c2 === 'a') || (c2 === 'e') || (c2 === 'i') || (c2 === 'o') || (c2 === 'u');
    };

    function isAlphaNum(c) {
        return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9');
    };
    function escapeRegExp(str) {
        return str.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
    }

    var baseEngModifiers = {

        replace : function(s, params) {
            //http://stackoverflow.com/questions/1144783/replacing-all-occurrences-of-a-string-in-javascript
            return s.replace(new RegExp(escapeRegExp(params[0]), 'g'), params[1]);
        },

        capitalizeAll : function(s) {
            var s2 = "";
            var capNext = true;
            for (var i = 0; i < s.length; i++) {

                if (!isAlphaNum(s.charAt(i))) {
                    capNext = true;
                    s2 += s.charAt(i);
                } else {
                    if (!capNext) {
                        s2 += s.charAt(i);
                    } else {
                        s2 += s.charAt(i).toUpperCase();
                        capNext = false;
                    }

                }
            }
            return s2;
        },

        capitalize : function(s) {
            return s.charAt(0).toUpperCase() + s.substring(1);
        },

        a : function(s) {
            if (s.length > 0) {
                if (s.charAt(0).toLowerCase() === 'u') {
                    if (s.length > 2) {
                        if (s.charAt(2).toLowerCase() === 'i')
                            return "a " + s;
                    }
                }

                if (isVowel(s.charAt(0))) {
                    return "an " + s;
                }
            }

            return "a " + s;

        },

        firstS : function(s) {
            console.log(s);
            var s2 = s.split(" ");

            var finished = baseEngModifiers.s(s2[0]) + " " + s2.slice(1).join(" ");
            console.log(finished);
            return finished;
        },

        s : function(s) {
            switch (s.charAt(s.length -1)) {
            case 's':
                return s + "es";
                break;
            case 'h':
                return s + "es";
                break;
            case 'x':
                return s + "es";
                break;
            case 'y':
                if (!isVowel(s.charAt(s.length - 2)))
                    return s.substring(0, s.length - 1) + "ies";
                else
                    return s + "s";
                break;
            default:
                return s + "s";
            }
        },
        ed : function(s) {
            switch (s.charAt(s.length -1)) {
            case 's':
                return s + "ed";
                break;
            case 'e':
                return s + "d";
                break;
            case 'h':
                return s + "ed";
                break;
            case 'x':
                return s + "ed";
                break;
            case 'y':
                if (!isVowel(s.charAt(s.length - 2)))
                    return s.substring(0, s.length - 1) + "ied";
                else
                    return s + "d";
                break;
            default:
                return s + "ed";
            }
        }
    };

    tracery.baseEngModifiers = baseEngModifiers; 
    // Externalize
    tracery.TraceryNode = TraceryNode;

    tracery.Grammar = Grammar;
    tracery.Symbol = Symbol;
    tracery.RuleSet = RuleSet;

    tracery.setRng = setRng;

    return tracery;
}();

module.exports = tracery;