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| | @node Language Specification
@chapter Specification
@section Introduction
This document specifies the semantics and behavior of the O Programming
Language for compiler designers be informed how the language is designed.
This specification is a DRAFT and will be the discussions drive over olang-dev
mailing list.
@section Language Syntax
This is the O Programming Language EBNF grammar specification[^1]
[^1]: EBNF variant https://github.com/Engelberg/instaparse/tree/v1.4.12 and live
test can be accessed here https://mdkrajnak.github.io/ebnftest/
NOTE: This grammar spec is a DRAFT and it covers only a small portion of the
language.
@verbatim
(* Entry Point *)
<translation-unit> ::= (<ows> <external-declaration> <ows> (<end-of-statement> | <end-of-file>))*
(* Translation Unit *)
<external-declaration> ::= <common-statement> | <function-definition>
(* Variables *)
<variable-definition> ::= 'var' <ws> <variable-name> <ows> ':' <ows> <type> <ows> <variable-initializer>?
<constant-definition> ::= 'const' <ws> <variable-name> <ows> ':' <ows> <type> <ows> <variable-initializer>
<variable-name> ::= <identifier>
<variable-initializer> ::= '=' <ows> <expression>
(* Functions *)
<function-definition> ::= 'fn' <ws> <function-name> <ows> <function-parameters> <ows> ':' <ows> <return-type> <ows> <function-body>
<function-name> ::= <identifier>
<function-parameters> ::= '(' <ows> ')'
<return-type> ::= <type>
<function-body> ::= <block>
<block> ::= '{' <ows> <statement> <ows> (<end-of-statement> <ows> <statement> <ows>)* <end-of-statement>? <ows> '}'
<statement> ::= <common-statement> | <if-statement> | <return-statement>
<if-statement> ::= 'if' <ws> <expression> <ows> <block>
<return-statement> ::= 'return' <ws> <expression>
(* Statements *)
<end-of-statement> ::= ';' | <line-break>
<common-statement> ::= <variable-definition> | <constant-definition> | <assignment>
<assignment> ::= <variable-name> <ows> <assignment-operator> <ows> <expression>
<assignment-operator> ::= '='
| '*='
| '/='
| '%='
| '+='
| '-='
| '<<='
| '>>='
| '&='
| '^='
| '|='
(* Expressions *)
<expression> ::= <binary-expression>
<binary-expression> ::= <logical-or-expression>
<logical-or-expression> ::= <logical-and-expression> (<ows> '||' <ows> <logical-and-expression>)*
<logical-and-expression> ::= <bitwise-or-expression> (<ows> '&&' <ows> <bitwise-or-expression>)*
<bitwise-or-expression> ::= <bitwise-xor-expression> (<ows> '|' <ows> <bitwise-xor-expression>)*
<bitwise-xor-expression> ::= <bitwise-and-expression> (<ows> '^' <ows> <bitwise-and-expression>)*
<bitwise-and-expression> ::= <cmp-equality-expression> (<ows> '&' <ows> <cmp-equality-expression>)*
<cmp-equality-expression> ::= <cmp-relational-expression> (<ows> ('==' | '!=') <ows> <cmp-relational-expression>)*
<cmp-relational-expression> ::= <bitwise-shift-expression> (<ows> ('<' | '>' | '<=' | '>=') <ows> <bitwise-shift-expression>)*
<bitwise-shift-expression> ::= <additive-expression> (<ows> ('<<' | '>>') <ows> <additive-expression>)*
<additive-expression> ::= <multiplicative-expression> (<ows> ('+' | '-') <ows> <multiplicative-expression>)*
<multiplicative-expression> ::= <primary-expression> (<ows> ('*' | '/' | '%') <ows> <primary-expression>)*
<primary-expression> ::= <integer-literal>
| <variable-name>
| '(' <ows> <expression> <ows> ')'
(* Identifiers *)
<type> ::= 'u32'
<identifier> ::= (<alpha> | '_') (<alpha> | <digit> | '_')*
(* Literals *)
<integer-literal> ::= <integer-base10> | <integer-base16>
<integer-base10> ::= #'[1-9]' (<digit> | '_')* | '0'
<integer-base16> ::= #'0[Xx]' <hex-digit> (<hex-digit> | '_')*
(* Utilities *)
<ws> ::= <white-space>+
<ows> ::= <white-space>*
<white-space> ::= <linear-space> | <line-break>
<line-break> ::= #'[\n\v\f\r]' | '\r\n'
<linear-space> ::= #'[ \t]'
<alpha> ::= #'[a-zA-Z]'
<digit> ::= #'[0-9]'
<hex-digit> ::= <digit> | #'[a-fA-F]'
<end-of-file> ::= #'$'
@end verbatim
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