generate-parser.js

// Parser Generator
// ================
// Use jison to generate an SPDX Expression parser based on a
// Bison-style BNF grammar.

var Generator = require('jison').Generator;
var options = {
  type: 'slr',
  moduleType: 'commonjs',
  moduleName: 'spdxparse'
};

var words = ['AND', 'OR', 'WITH'];

var quote = function(argument) {
  return '\'' + argument + '\'';
};

var ret = function(token) {
  return function(character) {
    return [character, 'return ' +  quote(token) + ';'];
  };
};

var grammar = {
  lex: {
    macros: {},
    rules: [
      ['$', 'return ' + quote('EOS') + ';'],
      ['\\s+', '/* skip whitespace */'],
      ['\\+', 'return ' + quote('PLUS') + ';'],
      ['\\(', 'return ' + quote('OPEN') + ';'],
      ['\\)', 'return ' + quote('CLOSE') + ';'],
      [':', 'return ' + quote('COLON') + ';'],
      [
        'DocumentRef-([0-9A-Za-z-+.]+)',
        'return ' + quote('DOCUMENTREF') + ';'
      ],
      [
        'LicenseRef-([0-9A-Za-z-+.]+)',
        'return ' + quote('LICENSEREF') + ';'
      ]
    ]
      .concat(words.map(function(word) {
        return [word, 'return ' + quote(word) + ';'];
      }))
      .concat(require('spdx-license-ids').map(ret('LICENSE')))
      .concat(require('spdx-exceptions').map(ret('EXCEPTION')))
  },
  operators: [
    ['left', 'OR'],
    ['left', 'AND'],
    ['right', 'PLUS', 'WITH']
  ],
  tokens: [
    'CLOSE',
    'COLON',
    'EXCEPTION',
    'LICENSE',
    'LICENSEREF',
    'OPEN',
    'PLUS'
  ]
    .concat(words)
    .join(' '),
  start: 'start',
  bnf: {
    start: [
      ['expression EOS', 'return $$ = $1;']
    ],
    simpleExpression: [
      [
        'LICENSE',
        '$$ = { license: yytext };'
      ],
      [
        'LICENSE PLUS',
        '$$ = { license: $1, plus: true };'
      ],
      [
        'LICENSEREF',
        '$$ = { license: yytext };'
      ],
      [
        'DOCUMENTREF COLON LICENSEREF',
        '$$ = { license: yytext };'
      ]
    ],
    expression: [
      [
        'simpleExpression',
        '$$ = $1;'
      ],
      [
        'simpleExpression WITH EXCEPTION',
        [
          '$$ = { exception: $3 };',
          '$$.license = $1.license;',
          'if ($1.hasOwnProperty(\'plus\')) {',
          '  $$.plus = $1.plus;',
          '}'
        ].join('\n')
      ],
      [
        'expression AND expression',
        '$$ = { conjunction: \'and\', left: $1, right: $3 };'
      ],
      [
        'expression OR expression',
        '$$ = { conjunction: \'or\', left: $1, right: $3 };'
      ],
      [
        'OPEN expression CLOSE',
        '$$ = $2'
      ]
    ]
  }
};

console.log(new Generator(grammar, options).generate());