Lynus Vaz: Enhanced scripting language

Documenting the new features

I've taken a few ideas from Fabrice Bellard's C OTCC compiler: http://bellard.org/otcc/

Also looking at bash

Here's the POSIX specification for the shell: http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html

And the PXE specification: http://www.pix.net/software/pxeboot/archive/pxespec.pdf

Proposed syntax:

LINES           => LINE '\n' LINES | e
LINE            => WORD | WORD WS ARG_LIST | e
ARG_LIST        => ARG WS ARG_LIST | e
ARG             => WORD
SP              => ' ' | '\t'
WS              => SP | SP WS
NOT_EXP         => (any - { SP, '$(', ')', '${', '}')    /* Represents characters not expanded */
WORD            => NOT_EXP WORD | EXP WORD | NOT_EXP | EXP
EXP             => EXPR_EXP | VAR_EXP                /* Expansions */
EXPR_EXP        => '$(' EXPR ')'
VAR_EXP         => '${' (any - { '}' })+ '}'       
EXPR            => TERM | TERM BIN_OP EXPR | MONO_OP EXPR
TERM            => VAR_EXP | STRING
NUM             => ('+' | '-' )? ( '(' EXPR ')' | (digit)+ )               
STRING          => (any - { '$(', ')', '${', '}', ' ', BIN_OP, MONO_OP})+    /* This will help with string comparison */
BIN_OP          => '*' |  '/' | '%'             /* Convert both operands to integers */
                   | '+' | '-'
                   | '<<' |  '>>'
                   | '<' | '<=' | '>' | '>='
                   | '!=' | '=='                          /* Should also work for strings */
                   | '&'
                   | '|'
                   | '^'
                   | '&&'
                   | '||'
MONO_OP         => '~' | '!'

Syntax for if-else branches:

if <condition>
    <statements>
[ else
    <statements> ]
fi

Proposed syntax for while loops:

while <condition>
do
    <statements>
done

Proposed syntax for for loops:

for <variable> in <value list>
do
    <statements>
done

Pretty similar to the shell syntax, so it should be familiar.