65 lines
1.5 KiB
JavaScript
65 lines
1.5 KiB
JavaScript
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var fs = require('fs')
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var pegjs = require('pegjs')
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var overrideAction = require('pegjs-override-action')
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var input = __dirname + '/grammar.pegjs'
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var output = __dirname + '/parser.js'
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var overrides = __dirname + '/overrides.js'
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if (require.main === module) {
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if (process.argv[2] == '-w') {
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watch()
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} else {
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console.log(getSource())
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}
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}
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function getSource () {
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delete require.cache[require.resolve('./overrides')]
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var grammar = fs.readFileSync(input, 'utf8')
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var parserSource = pegjs.buildParser(grammar, {
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output: "source",
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allowedStartRules: [
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'script',
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'command',
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'argument',
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'continuationStart'
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],
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plugins: [overrideAction],
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overrideActionPlugin: require('./overrides')
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})
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return 'module.exports = ' + parse + '\n' +
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'var parser=' + parserSource + '\n' +
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'module.exports.SyntaxError = parser.SyntaxError\n';
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function parse (input, opts) {
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// Wrap parser.parse to allow specifying the start rule
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// as a shorthand option
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if (!opts) {
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opts = {}
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}
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else if (typeof opts == 'string') {
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opts = { startRule: opts }
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}
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return parser.parse(input, opts)
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}
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}
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function watch () {
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fs.watchFile(input, onChange)
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fs.watchFile(overrides, onChange)
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function onChange (curr, prev) {
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if (curr.mtime > prev.mtime) {
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try {
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var source = getSource()
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fs.writeFileSync(output, source)
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console.error("Wrote " + output)
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} catch (err) {
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console.error(err.message)
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}
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}
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}
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}
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