pcal_grammar.js

module.exports = grammar({
  name: 'pluscal',

  extras: $ => [
    /\s|\r?\n/
  ],

  rules: {
    pcal_source_file: $ => $.pcal_algorithm,

    pcal_algorithm: $ => seq(
      choice('--algorithm', seq('--fair', 'algorithm')),
      $.pcal_name,
      optional($.pcal_var_decls),
      optional($.pcal_definitions),
      repeat($.pcal_macro),
      repeat($.pcal_procedure),
      choice($.pcal_algorithm_body, repeat1($.pcal_process)),
      'end',
      'algorithm'
    ),
    pcal_stmt: $ => seq(
      optional(seq($.pcal_label, ':', optional(choice('+', '-')))),
      $.pcal_unlabeled_stmt
    ),
    pcal_definitions: $ => seq(
      'define',
      $.pcal_defs,
      'end',
      'define',
      optional(';')
    ),
    pcal_macro: $ => seq(
      'macro',
      $.pcal_name,
      '(',
      optional(seq($.pcal_variable, repeat(seq(',', $.pcal_variable)))),
      ')',
      $.pcal_algorithm_body,
      'end',
      'macro',
      optional(';')
    ),
    pcal_procedure: $ => seq(
      'procedure',
      $.pcal_name,
      '(',
      optional(seq($.pcal_p_var_decl, repeat(seq(',', $.pcal_p_var_decl)))),
      ')',
      optional($.pcal_p_var_decls),
      $.pcal_algorithm_body,
      'end',
      'procedure',
      optional(';')
    ),
    pcal_process: $ => seq(
      optional(seq('fair', optional('+'))),
      'process',
      $.pcal_name,
      choice('=', '\in'),
      $.pcal_expr,
      optional($.pcal_var_decls),
      $.pcal_algorithm_body,
      'end',
      'process',
      optional(';')
    ),
    pcal_var_decls: $ => seq(
      choice('variable', 'variables'),
      repeat1($.pcal_var_decl)
    ),
    pcal_var_decl: $ => seq(
      $.pcal_variable,
      optional(seq(choice('=', '\in'), $.pcal_expr)),
      choice(';', ',')
    ),
    pcal_p_var_decls: $ => seq(
      choice('variable', 'variables'),
      repeat1(seq($.pcal_p_var_decl, choice(';', ',')))
    ),
    pcal_p_var_decl: $ => seq(
      $.pcal_variable,
      optional(seq('=', $.pcal_expr))
    ),
    pcal_algorithm_body: $ => seq(
      'begin',
      repeat1($.pcal_stmt)
    ),
    pcal_unlabeled_stmt: $ => choice(
      $.pcal__assign,
      $.pcal__if,
      $.pcal__while,
      $.pcal_either,
      $.pcal__with,
      $.pcal__await,
      $.pcal_print,
      $.pcal_assert,
      $.pcal_skip,
      $.pcal__return,
      $.pcal__goto,
      $.pcal_call,
      $.pcal_macro_call,
    ),
    pcal__assign: $ => seq(
      $.pcal_lhs, 
      ':=',
      $.pcal_expr,
      repeat(seq('||', $.pcal_lhs, ':=', $.pcal_expr))
    ),
    pcal_lhs: $ => seq(
      $.pcal_variable,
      repeat(choice(
        seq('[', $.pcal_expr, repeat(seq(',', $.pcal_expr)), ']'),
        seq('.', $.pcal_field)
      ))
    ),
    pcal__if: $ => seq(
      'if',
      $.pcal_expr,
      'then',
      repeat1($.pcal_stmt),
      repeat(seq('elsif', $.pcal_expr, 'then', repeat1($.pcal_stmt))),
      optional(seq('else', repeat1($.pcal_stmt))),
      'end',
      'if',
      ';'
    ),
    pcal__while: $ => seq(
      'while',
      $.pcal_expr,
      'do',
      repeat1($.pcal_stmt),
      'end',
      'while',
      ';'
    ),
    pcal_either: $ => seq(
      'either',
      repeat1($.pcal_stmt),
      repeat1(seq('or', repeat1($.pcal_stmt))),
      'end',
      'either',
      ';'
    ),
    pcal__with: $ => seq(
      'with',
      repeat1(seq(
        $.pcal_variable,
        choice('=', '\in'),
        $.pcal_expr,
        choice(',', ';')
      )),
      'do',
      repeat1($.pcal_stmt),
      'end',
      'with',
      ';'
    ),
    pcal__await: $ => seq(
      choice('await', 'when'),
      $.pcal_expr,
      ';'
    ),
    pcal_print: $ => seq('print', $.pcal_expr, ';'),
    pcal_assert: $ => seq('assert', $.pcal_expr, ';'),
    pcal_skip: $ => seq('skip', ';'),
    pcal__return: $ => seq('return', ';'),
    pcal__goto: $ => seq('goto', $.pcal_label, ';'),
    pcal_call: $ => seq('call', $.pcal_macro_call),
    pcal_macro_call: $ => seq(
      $.pcal_name,
      '(',
      optional(seq(
        $.pcal_expr,
        repeat(
          seq(
            ',',
            $.pcal_expr
          )
        )
      )),
      ')',
      ';'
    ),
    // pcal_TODO: proper definitions below
    pcal_variable: $ => /\w*[A-Za-z]\w*/,
    pcal_field: $ => /\w*[A-Za-z]\w*/,
    pcal_name: $ => /\w*[A-Za-z]\w*/,
    pcal_label: $ => /\w*[A-Za-z]\w*/,
    pcal_expr: $ => /.*/,
    pcal_defs: $ => /.*/,
  }
});