functions.js

var utils = require("./utils");
var ParseError = require("./ParseError");

// This file contains a list of functions that we parse. The functions map
// contains the following data:

/*
 * Keys are the name of the functions to parse
 * The data contains the following keys:
 *  - numArgs: The number of arguments the function takes.
 *  - argTypes: (optional) An array corresponding to each argument of the
 *              function, giving the type of argument that should be parsed. Its
 *              length should be equal to `numArgs + numOptionalArgs`. Valid
 *              types:
 *               - "size": A size-like thing, such as "1em" or "5ex"
 *               - "color": An html color, like "#abc" or "blue"
 *               - "original": The same type as the environment that the
 *                             function being parsed is in (e.g. used for the
 *                             bodies of functions like \color where the first
 *                             argument is special and the second argument is
 *                             parsed normally)
 *              Other possible types (probably shouldn't be used)
 *               - "text": Text-like (e.g. \text)
 *               - "math": Normal math
 *              If undefined, this will be treated as an appropriate length
 *              array of "original" strings
 *  - greediness: (optional) The greediness of the function to use ungrouped
 *                arguments.
 *
 *                E.g. if you have an expression
 *                  \sqrt \frac 1 2
 *                since \frac has greediness=2 vs \sqrt's greediness=1, \frac
 *                will use the two arguments '1' and '2' as its two arguments,
 *                then that whole function will be used as the argument to
 *                \sqrt. On the other hand, the expressions
 *                  \frac \frac 1 2 3
 *                and
 *                  \frac \sqrt 1 2
 *                will fail because \frac and \frac have equal greediness
 *                and \sqrt has a lower greediness than \frac respectively. To
 *                make these parse, we would have to change them to:
 *                  \frac {\frac 1 2} 3
 *                and
 *                  \frac {\sqrt 1} 2
 *
 *                The default value is `1`
 *  - allowedInText: (optional) Whether or not the function is allowed inside
 *                   text mode (default false)
 *  - numOptionalArgs: (optional) The number of optional arguments the function
 *                     should parse. If the optional arguments aren't found,
 *                     `null` will be passed to the handler in their place.
 *                     (default 0)
 *  - handler: The function that is called to handle this function and its
 *             arguments. The arguments are:
 *              - func: the text of the function
 *              - [args]: the next arguments are the arguments to the function,
 *                        of which there are numArgs of them
 *              - positions: the positions in the overall string of the function
 *                           and the arguments. Should only be used to produce
 *                           error messages
 *             The function should return an object with the following keys:
 *              - type: The type of element that this is. This is then used in
 *                      buildHTML/buildMathML to determine which function
 *                      should be called to build this node into a DOM node
 *             Any other data can be added to the object, which will be passed
 *             in to the function in buildHTML/buildMathML as `group.value`.
 */

var functions = {
    // A normal square root
    "\\sqrt": {
        numArgs: 1,
        numOptionalArgs: 1,
        handler: function(func, optional, body, positions) {
            if (optional != null) {
                throw new ParseError(
                    "Optional arguments to \\sqrt aren't supported yet",
                    this.lexer, positions[1] - 1);
            }

            return {
                type: "sqrt",
                body: body
            };
        }
    },

    // Some non-mathy text
    "\\text": {
        numArgs: 1,
        argTypes: ["text"],
        greediness: 2,
        handler: function(func, body) {
            // Since the corresponding buildHTML/buildMathML function expects a
            // list of elements, we normalize for different kinds of arguments
            // TODO(emily): maybe this should be done somewhere else
            var inner;
            if (body.type === "ordgroup") {
                inner = body.value;
            } else {
                inner = [body];
            }

            return {
                type: "text",
                body: inner
            };
        }
    },

    // A two-argument custom color
    "\\color": {
        numArgs: 2,
        allowedInText: true,
        greediness: 3,
        argTypes: ["color", "original"],
        handler: function(func, color, body) {
            // Normalize the different kinds of bodies (see \text above)
            var inner;
            if (body.type === "ordgroup") {
                inner = body.value;
            } else {
                inner = [body];
            }

            return {
                type: "color",
                color: color.value,
                value: inner
            };
        }
    },

    // An overline
    "\\overline": {
        numArgs: 1,
        handler: function(func, body) {
            return {
                type: "overline",
                body: body
            };
        }
    },

    // A box of the width and height
    "\\rule": {
        numArgs: 2,
        numOptionalArgs: 1,
        argTypes: ["size", "size", "size"],
        handler: function(func, shift, width, height) {
            return {
                type: "rule",
                shift: shift && shift.value,
                width: width.value,
                height: height.value
            };
        }
    },

    // A KaTeX logo
    "\\KaTeX": {
        numArgs: 0,
        handler: function(func) {
            return {
                type: "katex"
            };
        }
    },

    "\\phantom": {
        numArgs: 1,
        handler: function(func, body) {
            var inner;
            if (body.type === "ordgroup") {
                inner = body.value;
            } else {
                inner = [body];
            }

            return {
                type: "phantom",
                value: inner
            };
        }
    }
};

// Extra data needed for the delimiter handler down below
var delimiterSizes = {
    "\\bigl" : {type: "open",    size: 1},
    "\\Bigl" : {type: "open",    size: 2},
    "\\biggl": {type: "open",    size: 3},
    "\\Biggl": {type: "open",    size: 4},
    "\\bigr" : {type: "close",   size: 1},
    "\\Bigr" : {type: "close",   size: 2},
    "\\biggr": {type: "close",   size: 3},
    "\\Biggr": {type: "close",   size: 4},
    "\\bigm" : {type: "rel",     size: 1},
    "\\Bigm" : {type: "rel",     size: 2},
    "\\biggm": {type: "rel",     size: 3},
    "\\Biggm": {type: "rel",     size: 4},
    "\\big"  : {type: "textord", size: 1},
    "\\Big"  : {type: "textord", size: 2},
    "\\bigg" : {type: "textord", size: 3},
    "\\Bigg" : {type: "textord", size: 4}
};

var delimiters = [
    "(", ")", "[", "\\lbrack", "]", "\\rbrack",
    "\\{", "\\lbrace", "\\}", "\\rbrace",
    "\\lfloor", "\\rfloor", "\\lceil", "\\rceil",
    "<", ">", "\\langle", "\\rangle",
    "/", "\\backslash",
    "|", "\\vert", "\\|", "\\Vert",
    "\\uparrow", "\\Uparrow",
    "\\downarrow", "\\Downarrow",
    "\\updownarrow", "\\Updownarrow",
    "."
];

/*
 * This is a list of functions which each have the same function but have
 * different names so that we don't have to duplicate the data a bunch of times.
 * Each element in the list is an object with the following keys:
 *  - funcs: A list of function names to be associated with the data
 *  - data: An objecty with the same data as in each value of the `function`
 *          table above
 */
var duplicatedFunctions = [
    // Single-argument color functions
    {
        funcs: [
            "\\blue", "\\orange", "\\pink", "\\red",
            "\\green", "\\gray", "\\purple"
        ],
        data: {
            numArgs: 1,
            allowedInText: true,
            greediness: 3,
            handler: function(func, body) {
                var atoms;
                if (body.type === "ordgroup") {
                    atoms = body.value;
                } else {
                    atoms = [body];
                }

                return {
                    type: "color",
                    color: "katex-" + func.slice(1),
                    value: atoms
                };
            }
        }
    },

    // There are 2 flags for operators; whether they produce limits in
    // displaystyle, and whether they are symbols and should grow in
    // displaystyle. These four groups cover the four possible choices.

    // No limits, not symbols
    {
        funcs: [
            "\\arcsin", "\\arccos", "\\arctan", "\\arg", "\\cos", "\\cosh",
            "\\cot", "\\coth", "\\csc", "\\deg", "\\dim", "\\exp", "\\hom",
            "\\ker", "\\lg", "\\ln", "\\log", "\\sec", "\\sin", "\\sinh",
            "\\tan","\\tanh"
        ],
        data: {
            numArgs: 0,
            handler: function(func) {
                return {
                    type: "op",
                    limits: false,
                    symbol: false,
                    body: func
                };
            }
        }
    },

    // Limits, not symbols
    {
        funcs: [
            "\\det", "\\gcd", "\\inf", "\\lim", "\\liminf", "\\limsup", "\\max",
            "\\min", "\\Pr", "\\sup"
        ],
        data: {
            numArgs: 0,
            handler: function(func) {
                return {
                    type: "op",
                    limits: true,
                    symbol: false,
                    body: func
                };
            }
        }
    },

    // No limits, symbols
    {
        funcs: [
            "\\int", "\\iint", "\\iiint", "\\oint"
        ],
        data: {
            numArgs: 0,
            handler: function(func) {
                return {
                    type: "op",
                    limits: false,
                    symbol: true,
                    body: func
                };
            }
        }
    },

    // Limits, symbols
    {
        funcs: [
            "\\coprod", "\\bigvee", "\\bigwedge", "\\biguplus", "\\bigcap",
            "\\bigcup", "\\intop", "\\prod", "\\sum", "\\bigotimes",
            "\\bigoplus", "\\bigodot", "\\bigsqcup", "\\smallint"
        ],
        data: {
            numArgs: 0,
            handler: function(func) {
                return {
                    type: "op",
                    limits: true,
                    symbol: true,
                    body: func
                };
            }
        }
    },

    // Fractions
    {
        funcs: [
            "\\dfrac", "\\frac", "\\tfrac",
            "\\dbinom", "\\binom", "\\tbinom"
        ],
        data: {
            numArgs: 2,
            greediness: 2,
            handler: function(func, numer, denom) {
                var hasBarLine;
                var leftDelim = null;
                var rightDelim = null;
                var size = "auto";

                switch (func) {
                    case "\\dfrac":
                    case "\\frac":
                    case "\\tfrac":
                        hasBarLine = true;
                        break;
                    case "\\dbinom":
                    case "\\binom":
                    case "\\tbinom":
                        hasBarLine = false;
                        leftDelim = "(";
                        rightDelim = ")";
                        break;
                    default:
                        throw new Error("Unrecognized genfrac command");
                }

                switch (func) {
                    case "\\dfrac":
                    case "\\dbinom":
                        size = "display";
                        break;
                    case "\\tfrac":
                    case "\\tbinom":
                        size = "text";
                        break;
                }

                return {
                    type: "genfrac",
                    numer: numer,
                    denom: denom,
                    hasBarLine: hasBarLine,
                    leftDelim: leftDelim,
                    rightDelim: rightDelim,
                    size: size
                };
            }
        }
    },

    // Left and right overlap functions
    {
        funcs: ["\\llap", "\\rlap"],
        data: {
            numArgs: 1,
            allowedInText: true,
            handler: function(func, body) {
                return {
                    type: func.slice(1),
                    body: body
                };
            }
        }
    },

    // Delimiter functions
    {
        funcs: [
            "\\bigl", "\\Bigl", "\\biggl", "\\Biggl",
            "\\bigr", "\\Bigr", "\\biggr", "\\Biggr",
            "\\bigm", "\\Bigm", "\\biggm", "\\Biggm",
            "\\big",  "\\Big",  "\\bigg",  "\\Bigg",
            "\\left", "\\right"
        ],
        data: {
            numArgs: 1,
            handler: function(func, delim, positions) {
                if (!utils.contains(delimiters, delim.value)) {
                    throw new ParseError(
                        "Invalid delimiter: '" + delim.value + "' after '" +
                            func + "'",
                        this.lexer, positions[1]);
                }

                // \left and \right are caught somewhere in Parser.js, which is
                // why this data doesn't match what is in buildHTML.
                if (func === "\\left" || func === "\\right") {
                    return {
                        type: "leftright",
                        value: delim.value
                    };
                } else {
                    return {
                        type: "delimsizing",
                        size: delimiterSizes[func].size,
                        delimType: delimiterSizes[func].type,
                        value: delim.value
                    };
                }
            }
        }
    },

    // Sizing functions (handled in Parser.js explicitly, hence no handler)
    {
        funcs: [
            "\\tiny", "\\scriptsize", "\\footnotesize", "\\small",
            "\\normalsize", "\\large", "\\Large", "\\LARGE", "\\huge", "\\Huge"
        ],
        data: {
            numArgs: 0
        }
    },

    // Style changing functions (handled in Parser.js explicitly, hence no
    // handler)
    {
        funcs: [
            "\\displaystyle", "\\textstyle", "\\scriptstyle",
            "\\scriptscriptstyle"
        ],
        data: {
            numArgs: 0
        }
    },

    // Accents
    {
        funcs: [
            "\\acute", "\\grave", "\\ddot", "\\tilde", "\\bar", "\\breve",
            "\\check", "\\hat", "\\vec", "\\dot"
            // We don't support expanding accents yet
            // "\\widetilde", "\\widehat"
        ],
        data: {
            numArgs: 1,
            handler: function(func, base) {
                return {
                    type: "accent",
                    accent: func,
                    base: base
                };
            }
        }
    },

    // Infix generalized fractions
    {
        funcs: ["\\over", "\\choose"],
        data: {
            numArgs: 0,
            handler: function (func) {
                var replaceWith;
                switch (func) {
                    case "\\over":
                        replaceWith = "\\frac";
                        break;
                    case "\\choose":
                        replaceWith = "\\binom";
                        break;
                    default:
                        throw new Error("Unrecognized infix genfrac command");
                }
                return {
                    type: "infix",
                    replaceWith: replaceWith
                };
            }
        }
    }
];

var addFuncsWithData = function(funcs, data) {
    for (var i = 0; i < funcs.length; i++) {
        functions[funcs[i]] = data;
    }
};

// Add all of the functions in duplicatedFunctions to the functions map
for (var i = 0; i < duplicatedFunctions.length; i++) {
    addFuncsWithData(duplicatedFunctions[i].funcs, duplicatedFunctions[i].data);
}

// Set default values of functions
for (var f in functions) {
    if (functions.hasOwnProperty(f)) {
        var func = functions[f];

        functions[f] = {
            numArgs: func.numArgs,
            argTypes: func.argTypes,
            greediness: (func.greediness === undefined) ? 1 : func.greediness,
            allowedInText: func.allowedInText ? func.allowedInText : false,
            numOptionalArgs: (func.numOptionalArgs === undefined) ? 0 :
                func.numOptionalArgs,
            handler: func.handler
        };
    }
}

module.exports = {
    funcs: functions
};