main.py [-h] [--output path] [--depth int] [--size int] [--dynamic] 
        [--sep str] [--preamble str] [--verbose] 
        file

positional arguments:
file           file with grammar

optional arguments:
-h, --help      show this help message and exit
--output path   output file (default: stdout)
--depth int     depth of derivation tree (default: 150)
--size int      size of derivation tree (default: 10000)
--dynamic       save output string in dynamic grammar
--sep str       derivation symbol in productions (default: '=')
--preamble str  put this string in the preamble of output file (default: "")
--verbose       displays details about the process

1. Terminal symbols have the form:

    <term> = '[^']+' or "[^"]+"
   

2. Nonterminal symbols have the form:

    <nonterm> = [\w/][\w/^<>-]*
   

3. Production have the form:

    <production> = <nonterm> <sep> <altsyms>, where <altsyms> = <syms> or <syms> <alt> <altsyms>
                                                    <syms>    = <sym> or <sym> <syms>
                                                    <sym>     = <term> or <nonterm>
                                                    <alt>     = |
                                                    <sep> is defined by --sep
   

4. Multiline productions separeted by \ are allowed.

5. Lines started with # are connents, with % are directives.

6. There are four directives

• set the start symbol of grammar:

    % start <nonterm> 
  

• set the indent token of grammar:

    % indent <nonterm> 
  

• set the dedent token of grammar:

    % dedent <nonterm> 
  

• set symbols such that additional productions can be inserted in derivation tree before subtrees corresponding these symbols:

    % syntax <nonterm> ... <nonterm>
  

• set a production that are not taken into account when calculating the depth of derivation tree:

    % skip  
    <production>
  

• set an additional production that can be inserted in derivation tree:

    % add  
    <production>
  

Directives 'syntax' and 'add' are considered only for dynamic grammars mode. This mode can be turned on by --dynamic.

% start S
% syntax S
S = C
% skip
S = C '\n' S               # this production is skipped in calculating the depth of derivation tree
C = V '=' E
V = 'x' | 'y' | 'z'
E = V \
  | '(' E '+' E ')' \
  | E '*' E \
  | 'a'
% add
E = '(' E '-' E ')'  | 'b' # this production is marked as addition in dynamic grammars
% add
V = 'u'                    # and this is also

x = ( a * a + a * a )
%syntax: E = ( E - E )
y = ( a * ( x - a ) + a )
%syntax: E = b
z = ( z + b )