71 lines
2.4 KiB
JavaScript
71 lines
2.4 KiB
JavaScript
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import nearley from 'nearley';
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import compile from 'nearley/lib/compile.js';
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import generate from 'nearley/lib/generate.js';
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import nearleyGrammar from 'nearley/lib/nearley-language-bootstrapped.js';
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import moo from 'moo';
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import tokens from './tokens.js';
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import { readFileSync } from 'fs';
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import minify from './minify.js';
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const grammarFile = 'grammar.ne';
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function createParser() {
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// Parse the grammar source into an AST
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const grammarParser = new nearley.Parser(nearleyGrammar);
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grammarParser.feed(readFileSync(grammarFile).toString());
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const grammarAst = grammarParser.results[0]; // TODO check for errors
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// Compile the AST into a set of rules
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const grammarInfoObject = compile(grammarAst, {});
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// Generate JavaScript code from the rules
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const grammarJs = generate(grammarInfoObject, "grammar");
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const lexer = moo.compile(tokens);
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// lexer.__proto__.formatError = function(token, message) {
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// if (token == null) {
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// // An undefined token indicates EOF
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// var text = this.buffer.slice(this.index)
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// var token = {
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// text: text,
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// offset: this.index,
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// lineBreaks: text.indexOf('\n') === -1 ? 0 : 1,
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// line: this.line,
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// col: this.col,
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// }
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// }
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// var start = Math.max(0, token.offset - token.col + 1)
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// var eol = token.lineBreaks ? token.text.indexOf('\n') : token.text.length
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// var firstLine = this.buffer.substring(start, token.offset + eol)
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// message += " at line " + token.line + " col " + token.col + ":\n\n"
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// message += " " + firstLine + "\n"
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// message += " " + Array(token.col).join(" ") + "^"
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// return message
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// }
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// Pretend this is a CommonJS environment to catch exports from the grammar.
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const module = { exports: {} };
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eval(grammarJs);
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const grammar = module.exports;
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return new nearley.Parser(nearley.Grammar.fromCompiled(grammar))
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}
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export default function createAst(location) {
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const parser = createParser();
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const contents = readFileSync(location).toString();
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// parser.reportError = function(token) {
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// return JSON.stringify(token, null, 2);
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// var message = this.lexer.formatError(token, 'invalid syntax') + '\n';
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// message += 'Unexpected ' + (token.type ? token.type + ' token: ' : '');
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// message +=
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// JSON.stringify(token.value !== undefined ? token.value : token) + '\n';
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// return message;
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// };
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parser.feed(contents);
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parser.finish();
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return parser.results[0];
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}
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