How to use PEGjs in Node.js

This time I will bring you how to use PEGjs inNode.js, what are theprecautionswhen using PEGjs in Node.js, the following is a practical case, let’s go together take a look.

(1)Install pegjs

npm install pegjs

(2)grammer.pegjs

start = additive additive = left:multiplicative "+" right:additive { return left + right; } / multiplicative multiplicative = left:primary "*" right:multiplicative { return left * right; } / primary primary = integer / "(" additive:additive ")" { return additive; }integer "integer" = digits:[0-9]+ { return parseInt(digits.join(""), 10); }

(3)main.js

var fs=require('fs');var PEG=require("pegjs"); fs.readFile('./grammer.pegjs','utf8',function(err,data){ var parser=PEG.buildParser(data); var result=parser.parse('1+2*3'); console.log(result); // 7});

Note:
If The pegjs command line tool is required, and pegjs needs to be installed both in the project and globally.

npm install pegjs -g npm install pegjs pegjs grammer.pegjs parser.js

can generate a parser, parser.js

var parser=require('./parser.js'); parser.parse('1+2*3'); // 7

I believe you have mastered the method after reading the case in this article, and there will be more exciting things. Please pay attention to php Chinese websiteOtherrelated articles!

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