diff options
Diffstat (limited to 'node_modules/fastparse/README.md')
-rw-r--r-- | node_modules/fastparse/README.md | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/node_modules/fastparse/README.md b/node_modules/fastparse/README.md new file mode 100644 index 0000000..ee33c3b --- /dev/null +++ b/node_modules/fastparse/README.md @@ -0,0 +1,118 @@ +# fastparse + +A very simple and stupid parser, based on a statemachine and regular expressions. + +It's not intended for complex languages. It's intended to easily write a simple parser for a simple language. + + + +## Usage + +Pass a description of statemachine to the constructor. The description must be in this form: + +``` javascript +new Parser(description) + +description is { + // The key is the name of the state + // The value is an object containing possible transitions + "state-name": { + // The key is a regular expression + // If the regular expression matches the transition is executed + // The value can be "true", a other state name or a function + + "a": true, + // true will make the parser stay in the current state + + "b": "other-state-name", + // a string will make the parser transit to a new state + + "[cde]": function(match, index, matchLength) { + // "match" will be the matched string + // "index" will be the position in the complete string + // "matchLength" will be "match.length" + + // "this" will be the "context" passed to the "parse" method" + + // A new state name (string) can be returned + return "other-state-name"; + }, + + "([0-9]+)(\\.[0-9]+)?": function(match, first, second, index, matchLength) { + // groups can be used in the regular expression + // they will match to arguments "first", "second" + }, + + // the parser stops when it cannot match the string anymore + + // order of keys is the order in which regular expressions are matched + // if the javascript runtime preserves the order of keys in an object + // (this is not standardized, but it's a de-facto standard) + } +} +``` + +The statemachine is compiled down to a single regular expression per state. So basically the parsing work is delegated to the (native) regular expression logic of the javascript runtime. + + +``` javascript +Parser.prototype.parse(initialState: String, parsedString: String, context: Object) +``` + +`initialState`: state where the parser starts to parse. + +`parsedString`: the string which should be parsed. + +`context`: an object which can be used to save state and results. Available as `this` in transition functions. + +returns `context` + + + + +## Example + +``` javascript +var Parser = require("fastparse"); + +// A simple parser that extracts @licence ... from comments in a JS file +var parser = new Parser({ + // The "source" state + "source": { + // matches comment start + "/\\*": "comment", + "//": "linecomment", + + // this would be necessary for a complex language like JS + // but omitted here for simplicity + // "\"": "string1", + // "\'": "string2", + // "\/": "regexp" + + }, + // The "comment" state + "comment": { + "\\*/": "source", + "@licen[cs]e\\s((?:[^*\n]|\\*+[^*/\n])*)": function(match, licenseText) { + this.licences.push(licenseText.trim()); + } + }, + // The "linecomment" state + "linecomment": { + "\n": "source", + "@licen[cs]e\\s(.*)": function(match, licenseText) { + this.licences.push(licenseText.trim()); + } + } +}); + +var licences = parser.parse("source", sourceCode, { licences: [] }).licences; + +console.log(licences); +``` + + + +## License + +MIT (http://www.opensource.org/licenses/mit-license.php) |