Wherever it is possible, we use also the EBNF for description of
lexical symbols through ASCII set characters. Otherwise, we will use
natural language sentences in < and >.
Lexical symbols are identifiers, numbers, character constants, strings, operators, delimiters, and comments. White characters (blanks and line breaks) must not occur within the symbols (except in comments, and as the blanks in strings). The white characters are ignored unless they are essential to separate two consecutive lexical symbols. Upper- and lower-case letters are considered to be distinct.
Ident = Letter {Letter | Digit}
Letter = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j"
| "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" | "s" | "t"
| "u" | "v" | "w" | "x" | "y" | "z"
| "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J"
| "K" | "L" | "M" | "N" | "O" | "P" | "Q" | "R" | "S" | "T"
| "U" | "V" | "W" | "X" | "Y" | "Z"
| "_"
OctalDigit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7"
Digit = OctalDigit | "8" | "9"
HexDigit = Digit | "a" | "A" | "b" | "B" | "c" | "C"
| "d" | "D" | "e" | "E" | "f" | "F"
Examples:
line line2 next_line NextLine
0x or 0X are hexadecimal integer
numbers. Otherwise, integer numbers starting with 0
are octal integer numbers. Octal integer numbers should not
contain 8 or 9. If an integer number has
the suffix l or L, it is a long number (see
long values in the section "Types and Values"). Floating
point numbers are distinguished from decimal integer numbers
by the presence of the decimal point . or an exponent
in the number representation. You can put _ in
number digit sequences unless it is the first symbol of the
sequence. It can be useful for readability of long digit
sequences.
Number = Integer | Long | FloatingPointNumber
DigitSeq = Digit { Digit | "_" }
HexDigitSeq = HexDigit { HexDigit "_" }
Integer = DigitSeq | "0" ("x" | "X") HexDigitSeq
Long = Integer ("l" | "L")
FloatingPointNumber = DigitSeq "." [ DigitSeq ] [Exponent]
| DigitSeq [Exponent]
Exponent = ("e" | "E") [ "+" | "-" ] DigitSeq
Examples:
10
10L
222_222_222_222_222_222_222_222_222_222_222_222_222_222_222_222l
100.
1e2
1000.000_1E+0
1___000__000_000
0xafad_1f34_17ff_
\a - ASCII character alert\b - ASCII character backspace\f - ASCII character form feed\n - ASCII character new line\r - ASCII character carriage return\t - ASCII character horizontal tab\v - ASCII character vertical tab\code - A character with the code
given by up to tree octal digits\xcode - A character with the code
given by two hexdecimal digits\ucode - A character with the code
given by four hexdecimal digits\Ucode - A character with the code
given by eight hexdecimal digits\char - The character char for all
remaining charactersTo denote a single quote mark use the sequence \'.
The double quote mark can be represented either by \"
or simply by ". To represent a backslash inside the
character constant, use two consecutive ASCII backslashes.
Character = "'" Char "'"
Char = <any character except for the single quote ',
backslash \, or line break>
| SimpleEscapeSeq
| OctalEscapeSeq
SimpleEscapeSeq = <one of \' \" \\ \a \b \f \n \r \t \v>
OctalEscapeSeq = "\" OctalDigit [ OctalDigit [ OctalDigit ] ]
Examples:
'a' '\'' '\\' '\12' '"'
\". The single
quote mark can be represented either by \' or simply
by '. To represent a backslash inside the character
constant, use two consecutive ASCII backslashes.
String = '"' {Char} '"'
Examples:
"This is Dino" "Don't worry\n"
Another variant of a string representation uses
back-quotes `. A character inside the back-quotes
are present in the string as it is, in other words, the escape
sequences do not work in such representation. To denote the
back-quote in such string representation use double
back-qoutes. The newline may not be in such string
representation. It means that a string with back-quotes can
reside only on one program line.
String = '`' {Char} '`'
Examples:
`\p{Greek}+` `back qoute `` is here`
%{ and %}. It represents a
C code fragment which is compiled and loaded into Dino
interpreter during the program execution
C_CODE = "%{" <any char sequence not containing pair %}> "%}"
An example:
%{ static val_t dino_var; %}
OperatorOrDelimeter = "?" | ":" | "|" | "||" | "&" | "&&" | "^"
| "==" | "!=" | "===" | "!==" | "<" | ">"
| "<=" | ">=" | "<<" | ">>" | ">>>" | "@"
| "+" | "-" | "/" | "*" | "%" | "!" | "~"
| "#" | ".+" | ".*" | ".&" | ".^" | ".|"
| "(" | ")" | "[" | "]" | "{" | "}"
| "." | "," | ";" | "=" | "*=" | "/="
| "%=" | "+=" | "-=" | "@=" | "<<=" | ">>="
| ">>>=" | "&=" | "^=" | "|=" | "++" | "--"
| "..." | Keyword
Keyword = "_" | "break" | "case" | "catch" | "char" | "class"
| "continue" | "else" | "expose" | "extern" | "final"
| "fiber" | "float" | "for" | "former" | "friend" | "fun"
| "hide" | "hideblock" | "if" | "in" | "int"
| "later" | "long" | "new" | "nil" | "obj"
| "pmatch" | "priv" | "pub" | "return" | "rmatch"
| "tab" | "thread" | "this" | "throw" | "try" | "type"
| "use" | "val" | "var" | "vec" | "wait"
/* and finishing with */. The
second type comment starts with // and finishes with
the first line break or with the end of file.
Comment = "/*" <arbitrary char. sequence not containing pair */> "*/"
| "//" <arbitrary char. sequence finishing on line break>