76 lines
1.8 KiB
JavaScript
76 lines
1.8 KiB
JavaScript
/* This is a grammar written to be compiled by PEG.js, this is the most human readable form of the parser */
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/* Here are our tokens that get spit out by our parser, then all combined once the "start" rule finishes */
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{
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function TokenList(tokens) {
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this.getValue = function() {
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var tokenListResult = 0;
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for (var i = 0; i < tokens.length; i++) {
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tokenListResult += tokens[i].getValue()
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}
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return tokenListResult;
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}
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}
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function AdditiveToken(valueToken) {
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this.getValue = function() {
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return valueToken.getValue();
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}
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}
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function SubtractiveToken(valueToken) {
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this.getValue = function() {
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return -1 * valueToken.getValue();
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}
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}
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function RollToken(countToken, sizeToken) {
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this.getValue = function() {
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//Figure out how many times we are rolling, and what size die to use.
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var count = countToken.getValue();
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var size = sizeToken.getValue();
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var rollResult = 0;
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for (var i = 0; i < count; i++) {
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rollResult += Math.ceil(Math.random() * size);
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}
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return rollResult;
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}
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}
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function NumberToken(num) {
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this.getValue = function() {
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return num;
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}
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}
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}
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/* Here is the grammar itself, what defines all the work that gets done parsing the input */
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start
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= tokens:tokenList { return tokens.getValue() }
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tokenList
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= roll:dieRoll mod:modifier* {return new TokenList([roll, new TokenList(mod)]) }
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modifier
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= additive
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/ subtractive
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additive
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= "+" number:number { return new AdditiveToken(number) }
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subtractive
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= "-" number:number { return new SubtractiveToken(number) }
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number
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= dieRoll
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/ integer
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dieRoll
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= count:integer "d" size:integer { return new RollToken(count, size) }
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integer "integer"
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= digits:[0-9]+ { return new NumberToken(parseInt(digits.join(""), 10)); }
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