artichoke-lang/docs/grammar.ebnf
erick-alcachofa d0599d374f
feat: Add language grammar and adjusted tokenizer
Signed-off-by: erick-alcachofa <erick@artichoke.dev>

This commit lays the foundational groundwork for the artichoke language
parser by introducing the formal language grammar specification.

The tokenizer was updated to include new operators and keywords, also
added the posibility to handle comments.

Key Additions:
- Implemented support for C-style block comments (`/* ... */`),
  including error handling for unclosed comments.
- Added all necessary tokens for missing keywords (e.g., `module`,
  `export`, `using`, `match`, `loop`) and operators (e.g., `+=`, `:=`,
  `.#`, `.*`, `.@`).
- The `Token` enum has been expanded to reflect the full language
  feature set.

Documentation:
- Added `docs/grammar.ebnf` which contains the official, well-structured
  EBNF grammar for the language.
- Added `docs/readme.md` providing a detailed technical overview of the
  language's features, syntax, and semantics.

BREAKING CHANGE: The `kwVariant` and `kwMut` tokens have been removed to
align with the updated language design defined in the new grammar.
2025-10-01 18:51:09 -06:00

349 lines
8.3 KiB
EBNF

/*
================================================================================
| |
| The Artichoke Programming Language |
| Official EBNF Grammar |
| |
================================================================================
*/
/* --- Program Structure --- */
/* A program is a sequence of top-level declarations and statements. */
<program> =
( <import_statement>
| <module_statement>
| <alias_statement>
| <struct_declaration>
| <enum_declaration>
| <function_declaration> )*
<module_statement> =
"export"? "module" <namespaced_identifier> "{"
( <module_statement>
| <alias_statement>
| <struct_declaration>
| <enum_declaration>
| <function_declaration> )*
"}"
<import_statement> =
"import" <import_target> ";"
<import_target> =
<namespaced_identifier>
| <namespaced_identifier> "::" "*"
<alias_statement> =
"using" <identifier> "=" <namespaced_identifier> ";"
/* --- Declarations --- */
/* Rules for defining functions, structs, enums, and their components. */
<function_declaration> =
"export"? "fn" <identifier> <generic_params> "(" <fn_params> ")" ( "->" <type> )? <code_block>
<fn_params> =
<fn_params_list>?
<fn_params_list> =
"this" <type> ("," <fn_param> ( "," <fn_param> )* )?
| <fn_param> ( "," <fn_param> )*
<fn_param> =
<identifier> ":" <type>
<struct_declaration> =
"export"? "struct" <identifier> <generic_params> "{" <struct_members> "}"
<struct_members> =
<struct_member> ( "," <struct_member> )*
<struct_member> =
<identifier> ":" <type>
<enum_declaration> =
"export"? "enum" <identifier> <generic_params> "{" <enum_members> "}"
<enum_members> =
<enum_member> ( "," <enum_member> )*
<enum_member> =
<identifier> ( "(" <type> ")" )?
<generic_params> =
( "<" <generic_params_list> ">" )?
<generic_params_list> =
<generic_param> ( "," <generic_param> )*
<generic_param> =
"typename" <identifier>
/* --- Statements & Control Flow --- */
/* Rules for code blocks, variable declarations, and control structures. */
<code_block> =
"{" <statements>? "}"
<statements> =
<statement> ( <statement> )*
<statement> =
<variable_declaration> ";"
| <if_statement>
| <loop_statement>
| <defer_statement> ";"
| <errdefer_statement> ";"
| <return_statement> ";"
| <break_statement> ";"
| <continue_statement> ";"
| <expression_statement>
| <alias_statement>
| <match_statement>
| <switch_statement>
<variable_declaration> =
<variable_declarator> <identifier> ( ":" <type> )? "=" <expression>
| <variable_declarator> <identifier> ":" <type> ( "=" <expression> )?
<variable_declarator> =
"let"
| "def"
<if_statement> =
"if" "(" <expression> ")" <variable_unwrapper>? <code_block>
<else_statement>?
<else_statement> =
"else" <variable_unwrapper>? <code_block>
| "else" <if_statement>
<variable_unwrapper> =
"|" <identifier> "|"
<loop_statement> =
(<identifier> ":=")? (
<c_for_statement>
| <range_for_statement>
| <while_statement>
| <do_while_statement>
| <inf_loop_statement>
)
<c_for_statement> =
"for" "(" <variable_declaration>? ";" <expression> ";" <expression> ")"
<code_block>
<range_for_statement> =
"for" "(" <variable_declarator> <identifier> ":=" <expression> ")"
<code_block>
<while_statement> =
"while" "(" <expression> ")" <variable_unwrapper>? <code_block>
<else_statement>?
<do_while_statement> =
"do" <code_block> "while" "(" <expression> ")"
<inf_loop_statement> =
"loop" <code_block>
<match_statement> =
"match" "(" <expression> ")" "{" <match_case>* <default_case>? "}"
<switch_statement> =
"switch" "(" <expression> ")" "{" <switch_case>* <default_case>? "}"
<match_case> =
( <type_name> | <scoped_access_expression> ) ( "(" <identifier> ")" )? "->" <code_block>
<switch_case> =
<expression> "->" <code_block>
<default_case> =
"_" "->" <code_block>
<break_statement> =
"break" <identifier>?
<continue_statement> =
"continue" <identifier>?
<defer_statement> =
"defer" ( <expression> | <code_block> )
<errdefer_statement> =
"errdefer" ( <expression> | <code_block> )
<return_statement> =
"return" <expression>?
<expression_statement> =
<expression> ";"
/* --- Expressions & Operator Precedence --- */
/* The full expression hierarchy, from lowest to highest precedence. */
<expression> =
<assign_expression>
<assign_expression> =
<bool_or_expression> ( ( <assign_op> | <compound_assign_op> ) <expression> )?
<bool_or_expression> =
<bool_and_expression> ( ( "||" | "or" ) <bool_and_expression> )*
<bool_and_expression> =
<compare_expression> ( ( "&&" | "and" ) <compare_expression> )*
<compare_expression> =
<bitwise_expression> ( <compare_op> <bitwise_expression> )?
<bitwise_expression> =
<bitwise_shift_expression> ( <bitwise_op> <bitwise_shift_expression> )*
<bitwise_shift_expression> =
<addition_expression> ( <bitshift_op> <addition_expression> )*
<addition_expression> =
<multiply_expression> ( <addition_op> <multiply_expression> )*
<multiply_expression> =
<prefix_expression> ( <multiply_op> <prefix_expression> )*
<prefix_expression> =
<prefix_op>* <primary_expression>
<primary_expression> =
<primary_type_expression> ( <suffix_op> | <fn_call_arguments> )*
/* --- Primary Expressions & Literals --- */
/* The highest-precedence expressions, including literals and grouped expressions. */
<primary_type_expression> =
<char_literal>
| <null_literal>
| <string_literal>
| <number_literal>
| <boolean_literal>
| <grouped_expression>
| <identifier>
| <struct_literal>
| <scoped_access_expression>
| <reflection_expression>
<grouped_expression> =
"(" <expression> ")"
<scoped_access_expression> =
<type_name> "::" <identifier>
<reflection_expression> =
( <primary_expression> | <type_name> | <scoped_access_expression> ) ".@" <identifier>?
<fn_call_arguments> =
"(" <expression_list> ")"
<expression_list> =
(<expression> ",")* <expression>?
<struct_literal> =
<type> "{" ( <named_field_list> | <positional_field_list> )? ","? "}"
<named_field_list> =
<named_field_init> ( "," <named_field_init> )*
<named_field_init> =
<identifier> ":" <expression>
<positional_field_list> =
<expression> ( "," <expression> )*
<null_literal> =
"null"
<boolean_literal> =
"true"
| "false"
<number_literal> = /* Assumed to be defined by the tokenizer */
<string_literal> = /* Assumed to be defined by the tokenizer */
<char_literal> = /* Assumed to be defined by the tokenizer */
/* --- Operators --- */
/* Definitions for all operator token sets. */
<assign_op> = "="
<compound_assign_op> = "+=" | "-=" | "*=" | "/=" | "%=" | "&=" | "|=" | "<<=" | ">>=" | "||=" | "&&="
<compare_op> = "==" | "!=" | ">" | "<" | ">=" | "<="
<bitwise_op> = "&" | "^" | "|"
<bitshift_op> = "<<" | ">>"
<addition_op> = "+" | "-"
<multiply_op> = "*" | "/" | "%"
<prefix_op> = "!" | "-" | "~" | "&" | "*"
<suffix_op> =
"[" <expression>? ":" <expression>? "]"
| "[" <expression> "]"
| ".[" <expression> "]"
| "." <identifier>
| "->" <identifier>
| ".#"
| ".*"
/* --- Type System --- */
/* Rules for defining types, type names, and type qualifiers. */
<type> =
<type_qualifier_chain> <type_name>
<type_qualifier_chain> =
( "*" | "[]" ) <type_qualifier_chain>?
| "$" <type_qualifier_chain_after_mutable>?
| "?" <type_qualifier_chain_after_optional>?
<type_qualifier_chain_after_optional> =
( "*" | "[]" ) <type_qualifier_chain>?
| "$" <type_qualifier_chain_after_mutable>?
<type_qualifier_chain_after_mutable> =
( "*" | "[]" ) <type_qualifier_chain>?
| "?" <type_qualifier_chain_after_optional>?
<type_name> =
<namespaced_identifier> ( "<" <types_list> ">" )?
<namespaced_identifier> =
<identifier>
| <identifier> "::" <namespaced_identifier>
<types_list> =
<type> ( "," <types_list> )*
/* --- Lexical Tokens & Base Definitions --- */
/* The lowest-level building blocks of the language. */
<identifier> =
<nondigit> <identifier_tail>
<identifier_tail> =
<empty>
| <nondigit> <identifier_tail>
| <digit> <identifier_tail>
<nondigit> = "_" | [a-z] | [A-Z]
<digit> = <zero> | <nonzero_digit>
<zero> = "0"
<nonzero_digit> = [1-9]
<empty> = E /* Represents an empty terminal string */