/* On-Wiki calculator script. See [[Template:Calculator]]. Created by [[User:Bawolff]]. Forked from https://mdwiki.org/wiki/MediaWiki:Gadget-calculator.js (released under Creative Commons Attribution-ShareAlike 3.0 and 4.0 International Public License). See original source for attribution history
*
* This script is designed with security in mind. Possible security risks:
* * Having a formula that executes JS
* ** To prevent this we do not use eval(). Instead we parse the formula with our own parser into an abstract tree that we evaluate by walking through it
* ** Form submission & DOM clobbering - we prefix the name (and id) attribute of all fields to prevent conflicts
* ** Style injection - we take the style attribute from an existing element that was sanitized by MW. We do not take style from a data attribute.
* ** Client-side DoS - Formulas aren't evaluated without user interaction. Formulas have a max length. Max number of widgets per page. Ultimately, easy to revert slow formulas just like any other vandalism.
*
* Essentially the code works by replacing certain <span> tags with <input>, parsing a custom formula language, setting up a dependency graph based on identifiers, and re-evaluating formulas on change.
*/
(function () {
var mathFuncs = [ 'abs', 'acos', 'acosh', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'cos', 'cosh', 'exp', 'floor', 'hypot',
'log', 'log10', 'log2', 'max', 'min', 'pow', 'random', 'sign', 'sin', 'sinh', 'sqrt', 'tan', 'tanh', 'trunc' ];
var otherFuncs = [ 'ifzero', 'coalesce', 'iffinite', 'ifnan', 'ifpositive', 'ifequal', 'round', 'jsround' ];
var allFuncs = mathFuncs.concat(otherFuncs);
var convertFloat = function ( f ) {
return f.replace( /[×⁰¹²³⁴⁵⁶⁷⁸⁹⁻]/g, function (m) {
return ({'⁰': 0,'¹': 1,'²': 2,'³': 3,'⁴': 4,'⁵': 5,'⁶': 6,'⁷': 7,'⁸': 8,'⁹': 9, '⁻': "-", "×": "e"})[m];
} );
};
// Start parser code.
var Numb = function(n) {
if ( typeof n === 'number' ) {
this.value = n;
}
this.value = parseFloat(n);
}
Numb.prototype.toString = function () { return 'Number<' + this.value + '>'; }
var Ident = function(n) {
this.value = n;
}
Ident.prototype.toString = function () { return 'IDENT<' + this.value + '>'; }
var Operator = function(val, args) {
this.op = val;
this.args = args;
}
var Null = function() { }
var Parser = function( text ) {
this.text = text;
};
var terminals = {
'IDENT': /^[a-zA-Z_][a-zA-Z0-9_]*/,
'NUMBER': /^-?[0-9]+(?:\.[0-9]+)?(?:[eE][0-9]+|×10⁻?[⁰¹²³⁴⁵⁶⁷⁸⁹]+)*/,
'WS': /^\s*/,
'PLUSMINUS': /^[+-]/,
'pi': /^(?:pi|π)(?![A-z_0-9-])/i,
'epsilon': /^EPSILON(?![A-z_0-9-])/,
'Infinity': /^Infinity(?![A-z_0-9-])/i,
'-Infinity': /^Infinity(?![A-z_0-9-])/i,
'NaN': /^NaN(?![A-z_0-9-])/i,
'MULTIPLYDIV': /^[*\/%×÷]/i,
};
Parser.prototype = {
check: function(id) {
if ( terminals[id] ) {
return !!(this.text.match(terminals[id]))
}
return this.text.startsWith( id )
},
consume: function(id) {
if ( terminals[id] ) {
var res = this.text.match(terminals[id]);
this.text = this.text.substring( res[0].length );
return res[0];
}
if ( this.text.startsWith( id ) ) {
this.text = this.text.substring(id.length);
return id;
}
throw new Error( "Expected " + id);
},
parse: function () {
if ( this.text === undefined || this.text === '' ) return new Null();
this.consume( 'WS' );
res = this.expression();
if( this.text.length !== 0 ) {
throw new Error( "Unexpected end of text" );
}
return res;
},
expression: function () {
var text2, res, res2;
res = this.term();
this.consume( 'WS' );
while ( this.check( "PLUSMINUS" )) {
var op = this.consume( "PLUSMINUS" );
res2 = this.term();
res = new Operator( op, [ res, res2 ] );
}
return res;
},
argList: function () {
var args = [];
this.consume( 'WS' );
if ( this.check( ')' ) ) {
this.consume( ')' );
return args;
}
args[args.length] = this.expression();
this.consume( 'WS' );
while ( this.check( ',' ) ) {
this.consume( ',' );
this.consume( 'WS' );
args[args.length] = this.expression();
}
this.consume( 'WS' );
this.consume( ')' );
return args;
},
term: function () {
var text2, res, res2;
res = this.factor();
this.consume( 'WS' );
while ( this.check( "MULTIPLYDIV" )) {
var op = this.consume( "MULTIPLYDIV" );
if ( op === '×' ) op = '*';
if ( op === '÷' ) op = '/';
res2 = this.term();
res = new Operator( op, [ res, res2 ] );
}
return res;
},
factor: function () {
if ( this.check( 'pi' ) ) {
this.consume( 'pi' );
return new Numb( Math.PI )
}
if ( this.check( 'Infinity' ) ) {
this.consume( 'Infinity' );
return new Numb( Infinity );
}
if ( this.check( '-Infinity' ) ) {
this.consume( '-Infinity' );
return new Numb( -Infinity );
}
if ( this.check( 'NaN' ) ) {
this.consume( 'NaN' );
return new Numb( NaN );
}
if ( this.check( 'epsilon' ) ) {
this.consume( 'epsilon' );
return new Numb( Number.EPSILON );
}
for ( var i in allFuncs ) {
if ( this.check( allFuncs[i] + '(' ) ) {
this.consume(allFuncs[i] + '(');
var argList = this.argList()
return new Operator( allFuncs[i], argList );
}
}
if ( this.check( 'IDENT' ) ) {
return new Ident( this.consume( 'IDENT' ) );
}
if ( this.check( 'NUMBER' ) ) {
return new Numb( convertFloat( this.consume( 'NUMBER' ) ) );
}
if ( this.check( '(' ) ) {
this.consume( '(' );
res = this.expression();
this.consume( ')' );
return res;
}
throw new Error( "Expected term");
},
};
// End parser code.
// Based on https://floating-point-gui.de/errors/comparison/
var almostEquals = function( a, b ) {
var absA = Math.abs(a);
var absB = Math.abs(b);
var diff = Math.abs(a-b);
var epsilon = Number.EPSILON; /// Not sure if this is a good value for epsilon
var minNormal = Math.pow( 2, -1022 );
if ( a===b) {
return true;
}
// Min normal of double = 2^-1022
if ( a==0 || b==0 || absA+absB < minNormal ) {
return diff < epsilon * minNormal;
}
return diff / Math.min((absA + absB), Number.MAX_VALUE) < epsilon;
}
// Evaluate the value of an AST at runtime.
var evaluate = function( ast, elmList ) {
if ( ast instanceof Numb ) {
return ast.value;
}
if ( ast instanceof Ident ) {
var elm = elmList[ast.value];
if ( elm.tagName === 'INPUT' ) {
if ( elm.type === 'radio' || elm.type === 'checkbox' ) {
return elm.checked ? 1 : 0;
}
return parseFloat( elm.value );
} else {
return parseFloat( convertFloat( elm.textContent ) );
}
}
if ( ast instanceof Operator ) {
evaledArgs = ast.args.map( function (i) { return evaluate( i, elmList ) } );
if ( mathFuncs.indexOf(ast.op) !== -1 ) {
return Math[ast.op].apply( Math, evaledArgs );
}
if ( 'coalesce' === ast.op ) {
for ( var k = 0; k < evaledArgs.length; k++ ) {
if ( !isNaN( evaledArgs[k] ) ) {
return evaledArgs[k];
}
}
return NaN;
}
if ( 'ifzero' === ast.op ) {
if ( evaledArgs.length !== 3 ) {
return NaN;
}
return almostEquals( evaledArgs[0], 0 ) ? evaledArgs[1] : evaledArgs[2];
}
if ( 'ifequal' === ast.op ) {
if ( evaledArgs.length !== 4 ) {
return NaN;
}
return almostEquals( evaledArgs[0], evaledArgs[1] ) ? evaledArgs[2] : evaledArgs[3];
}
if ( 'iffinite' === ast.op ) {
if ( evaledArgs.length !== 3 ) {
return NaN;
}
return isFinite( evaledArgs[0] ) ? evaledArgs[1] : evaledArgs[2];
}
if ( 'ifnan' === ast.op ) {
if ( evaledArgs.length !== 3 ) {
return NaN;
}
return isNaN( evaledArgs[0] ) ? evaledArgs[1] : evaledArgs[2];
}
if ( 'ifpositive' === ast.op ) {
if ( evaledArgs.length !== 3 ) {
return NaN;
}
return evaledArgs[0] >= 0 ? evaledArgs[1] : evaledArgs[2]
}
// js Math.round is weird. Do our own version. Based on https://stackoverflow.com/questions/11832914/how-to-round-to-at-most-2-decimal-places-if-necessary
// This does round-half away from zero, with floating point error correction.
if ( 'round' === ast.op ) {
var decimals = evaledArgs.length >= 2 ? evaledArgs[2] : 0;
var p = Math.pow( 10, decimals );
var n = (evaledArgs[0] * p) * (1 + Number.EPSILON);
return Math.round(n)/p;
}
// In case anyone wants normal js round.
if ( ast.op === 'jsround' ) {
return Math.round.apply( Math, evaledArgs );
}
if ( evaledArgs.length !== 2 ) {
throw new Error( "Unexpected number of args for " + ast.op );
}
if ( ast.op === '*' ) return evaledArgs[0]*evaledArgs[1];
if ( ast.op === '/' ) return evaledArgs[0]/evaledArgs[1];
if ( ast.op === '+' ) return evaledArgs[0]+evaledArgs[1];
if ( ast.op === '-' ) return evaledArgs[0]-evaledArgs[1];
if ( ast.op === '%' ) return evaledArgs[0]%evaledArgs[1];
throw new Error( "Unrecognized operator " + ast.op );
}
return NaN;
}
// Start dependency graph code
var getIdentifiers = function( tree ) {
if ( tree instanceof Ident ) {
return new Set([tree.value]);
}
if ( tree instanceof Operator ) {
var res = new Set([]);
for ( var i = 0; i < tree.args.length; i++ ) {
getIdentifiers( tree.args[i] ).forEach( function (x) { res.add(x) } );
}
return res;
}
return new Set();
}
var buildBacklinks = function (items) {
var backlinks = {};
for ( var item in items ) {
var idents = getIdentifiers( items[item] );
// Set does not do for..in loops, and this version MW forbids for..of
idents.forEach( function (ident) {
if ( !backlinks[ident] ) {
backlinks[ident] = [];
}
backlinks[ident].push( item );
} );
}
return backlinks;
};
// End dependency graph code
// Start code that does setup and HTML interaction.
var setup = function ( $content ) {
var elms = Array.from( $content.find( '.calculator-field' ) );
new CalculatorWidgets( elms );
}
var CalculatorWidgets = function( elms ) {
this.itemList = {};
this.elmList = {};
this.backlinks = {};
this.inProgressRefresh = undefined;
if (elms.length > 200) {
console.log( "Too many calculator widgets on page" );
return;
}
for ( var i in elms ) {
var elm = elms[i];
var formula = elm.dataset.calculatorFormula;
if ( formula && formula.length > 2000 ) {
console.log( "Skipping element with too long formula" );
continue;
}
var type = elm.dataset.calculatorType;
var readonly = !!elm.dataset.calculatorReadonly;
var id = elm.id;
if ( !id ) {
id = 'calculator-field-auto' + Math.floor( Math.random()*10000000 );
}
var defaultVal = elm.textContent;
if ( type === undefined || !id.match( /^calculator-field-[a-zA-Z_][a-zA-Z0-9_]*$/ ) ) {
console.log( "Skipping " + id );
continue;
}
try {
var formulaAST = (new Parser( formula )).parse();
} catch( e ) {
console.log( "Error parsing formula of " + id + ": " + e.message );
continue;
}
if ( type !== 'plain' ) {
var input = document.createElement( 'input' );
input.className = 'calculator-field-live';
input.readOnly = readonly
input.value = parseFloat(defaultVal);
input.style.cssText = elm.style.cssText; // This should be safe because elm's css was sanitized by MW
if ( elm.dataset.calculatorSize ) {
var size = parseInt( elm.dataset.calculatorSize );
input.size = size
// Browsers are pretty inconsistent so also set as css
input.style.width = type === 'number' ? ( size + 2 ) + 'ch' : size + 'ch';
}
if ( elm.dataset.calculatorSize ) input.size = elm.dataset.calculatorSize
if ( elm.dataset.calculatorMax ) input.max = elm.dataset.calculatorMax
if ( elm.dataset.calculatorMin ) input.min = elm.dataset.calculatorMin
if ( elm.dataset.calculatorPlaceholder ) input.placeholder = elm.dataset.calculatorPlaceholder
if ( elm.dataset.calculatorStep ) input.step = elm.dataset.calculatorStep
if ( elm.dataset.calculatorPrecision ) input.dataset.calculatorPrecision = elm.dataset.calculatorPrecision
if ( elm.dataset.calculatorExponentialPrecision ) input.dataset.calculatorExponentialPrecision = elm.dataset.calculatorExponentialPrecision
if ( elm.dataset.calculatorDecimals ) input.dataset.calculatorDecimals = elm.dataset.calculatorDecimals
if ( elm.dataset.calculatorNanText ) input.dataset.calculatorNanText = elm.dataset.calculatorNanText
// Name is primarily for radio groups. Prefix to prevent dom clobbering or in case it ends up in a form somehow.
if ( elm.dataset.calculatorName ) input.name = 'calcgadget-' + elm.dataset.calculatorName
if ( type === 'number' || type === 'text' || type === 'radio' || type === 'checkbox' ) {
input.type = type;
}
if ( type === 'radio' || type === 'checkbox' ) {
input.onchange = this.changeHandler.bind(this); // some browsers dont fire oninput for checkboxrs/radio
if ( !isNaN( defaultVal ) && !almostEquals( defaultVal, 0 ) ) {
input.checked = true;
}
}
input.id = id;
elm.replaceWith( input );
elm = input;
input.oninput = this.changeHandler.bind(this);
} else {
elm.classList.remove( 'calculator-field' );
elm.classList.add( 'calculator-field-live' );
}
var itemId = id.replace( /^calculator-field-/, '' );
this.itemList[itemId] = formulaAST;
this.elmList[itemId] = elm;
}
this.backlinks = buildBacklinks( this.itemList );
}
CalculatorWidgets.prototype.changeHandler = function(e) {
this.inProgressRefresh = {};
var itemId = e.target.id.replace( /^calculator-field-/, '' );
this.inProgressRefresh[itemId] = true;
for ( var i in this.backlinks[itemId] ) {
this.refresh( this.backlinks[itemId][i] );
}
if ( e.target.type === 'radio' ) {
// when a radio element gets checked, others get unchecked.
// Note: This is a bit sketchy if multiple wikipage contents are added with overlapping names
// It should work in the live preview case, since hopefully older elements with conflicting
// names would no longer be live, but might not work fully correctly in the general case.
var otherElms = document.getElementsByName( e.target.name );
for ( var l = 0; l < otherElms.length; l++ ) {
if ( otherElms[l].id === e.target.id ) {
continue;
}
var oElmId = otherElms[l].id.replace( /^calculator-field-/, '' );
if ( this.backlinks[oElmId] ) {
for ( var k in this.backlinks[oElmId] ) {
this.refresh( this.backlinks[oElmId][k] );
}
}
}
}
this.inProgressRefresh = undefined;
}
var format = function ( n, options ) {
var res = n.toString();
if ( typeof n !== "number" ) {
return res;
}
if ( isNaN( n ) && options.calculatorNanText ) {
return options.calculatorNanText;
}
if ( !isNaN( parseInt( options.calculatorDecimals ) ) ) {
res = n.toFixed( parseInt( options.calculatorDecimals ) );
}
if ( !isNaN( parseInt( options.calculatorPrecision ) ) ) {
res = n.toPrecision( parseInt( options.calculatorPrecision ) );
}
if ( !isNaN( parseInt( options.calculatorExponentialPrecision ) ) ) {
res = n.toExponential( parseInt( options.calculatorExponentialPrecision ) );
}
res = res.replace( /e([+-])([0-9]+)$/, function (m, sign, exp) {
var tmp = "×10";
if ( sign === '-' ) {
tmp += '⁻';
}
tmp += exp.replace( /[0-9]/g, function (m) {
return [ '⁰', '¹', '²', '³', '⁴', '⁵', '⁶', '⁷', '⁸', '⁹' ][m];
} );
return tmp;
} );
return res;
}
CalculatorWidgets.prototype.refresh = function (itemId) {
if ( !this.itemList[itemId] || this.itemList[itemId] instanceof Null ) {
// This should not happen.
console.log( "Tried to refresh field with no formula" );
return;
}
if ( this.inProgressRefresh[itemId] ) {
console.log( "Loop Detected! Skipping " + itemId );
return;
}
this.inProgressRefresh[itemId] = true;
var res = evaluate( this.itemList[itemId], this.elmList );
var elm = this.elmList[itemId];
if ( elm.tagName === 'INPUT' ) {
elm.value = elm.type === "number" ? res : format( res, elm.dataset );
if ( elm.type === 'radio' || elm.type === 'checkbox' ) {
elm.checked = !isNaN( res ) && !almostEquals( res, 0 );
}
} else {
elm.textContent = format( res, elm.dataset );
}
for ( var i in this.backlinks[itemId] ) {
this.refresh( this.backlinks[itemId][i] );
}
}
mw.hook( 'wikipage.content' ).add( setup );
} )();
