#
# The IttyBitty Language
# ======================
#
# A program consists of one or more statements,
#   with the permissible token types and list of statement
#   grammar rules described below
#
# Note that tokens must all be whitespace delimited,
#   token names begin with a lowercase letter,
#   non-terminal language component names begin with an uppercase letter
#
# Comments in IttyBitty begin with a # and go to eoln
#   and are removed by the tokenizer

# Tokens:
# =======
# variable        [a-zA-Z]+
# integer         [-]?[0-9]+
# quote            "
# text            between quotes, this is any block of non-whitespace
#                   characters that does not contain a quote
# mathop          +, -, *, /, %
# assignop        =
# compop          ==, <, !=, <=, >=, >
# keyword         if, while, print
# bracket         ( )
# delimiter       { }
# unknown         any otherwise unrecognized string of non-whitespace characters

# Grammar rules
# =============
# Program --> StatementList
# StatementList --> Statement
# StatementList --> Statement StatementList
# Statement --> VarAssign
# Statement --> Loop
# Statement --> Conditional
# Statement --> Print
# VarAssign --> variable assignop Expression
# Print --> print Value
# Print --> print Text
# Text --> quote WordList quote
# WordList --> text
# WordList --> text WordList
# Conditional --> if Condition Block
# Loop --> while Condition Block
# Condition --> bracket-( Value compop Value bracket-)
# Value --> variable
# Value --> integer
# Block --> delimiter-{ StatementList delimiter-}
# Expression --> Value
# Expression --> Value mathop Expression

# Sample program
# --------------
# print " Welcome! "
# mid = 3
# x = -4
# y = 10
# while ( x < y ) {
#    if ( x == mid ) {
#       print " mid point reached "
#    }
#    print " x is "
#    print x
#    x = x + 1
# }