Jac Programming Language

https://www.jac-lang.org/learn/
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### Jac-Lang Identifier Patterns

Source: https://www.jac-lang.org/learn/jac_ref

Defines patterns for valid identifiers in Jac-Lang. This includes standard names starting with letters or underscore, and special names prefixed with '<>'.

```jac-lang
KWESC_NAME: /<>[a-zA-Z_][a-zA-Z0-9_]*/
NAME: /[a-zA-Z_][a-zA-Z0-9_]*/
```

--------------------------------

### Jac Language Grammar: Implementations

Source: https://www.jac-lang.org/learn/jac_ref

Defines how implementations for archetypes are declared in Jac. This section covers the syntax for `impl` blocks, specifying which archetype is being implemented and defining its methods or associated data.

```Jac
// [Heading]: Implementations.
impl_def: decorators? KW_IMPL dotted_name impl_spec? impl_tail
impl_spec: inherited_archs | func_decl | event_clause
impl_tail: enum_block | block_tail
```

--------------------------------

### Jac Language: Comments and Whitespace

Source: https://www.jac-lang.org/learn/jac_ref

Explains the comment syntax and whitespace handling in Jac. Jac uses `#` for single-line comments and `#* ... *#` for multi-line comments. Whitespace (indentation) is insignificant for code structure, relying on curly braces.

```Jac
# Single-line comment

#* This is a multiline comment.
   It can span multiple lines. *#

// Jac uses curly braces for code blocks, not indentation.
// The compiler ignores most whitespace.
function example() {
    return true;
}
```

--------------------------------

### Jac Language Grammar: Functions and Abilities

Source: https://www.jac-lang.org/learn/jac_ref

Specifies the syntax for defining functions and abilities in Jac. This includes declarations for regular functions, async functions, and 'can' abilities, along with parameters, return types, and override keywords.

```Jac
// [Heading]: Functions and Abilities.
ability: decorators? KW_ASYNC? (ability_decl | function_decl)

function_decl: KW_OVERRIDE? KW_STATIC? KW_DEF access_tag? named_ref func_decl? (block_tail | KW_ABSTRACT? SEMI)
ability_decl: KW_OVERRIDE? KW_STATIC? KW_CAN access_tag? named_ref? event_clause (block_tail | KW_ABSTRACT? SEMI)
block_tail: code_block | KW_BY expression SEMI
event_clause: KW_WITH expression? (KW_EXIT | KW_ENTRY)

func_decl: (LPAREN func_decl_params? RPAREN) (RETURN_HINT pipe)?
         | (RETURN_HINT pipe)

func_decl_params: (param_var COMMA)* param_var COMMA?
param_var: (STAR_POW | STAR_MUL)? named_ref type_tag (EQ expression)?
         | DIV
         | STAR_MUL
```

--------------------------------

### Jac-Lang Arithmetic and Comparison Operators

Source: https://www.jac-lang.org/learn/jac_ref

Defines standard arithmetic operators (addition, subtraction, multiplication, division, modulo, power, floor division) and comparison operators (equal, less than, greater than, etc.) in Jac-Lang.

```jac-lang
EE: "=="
LT: "<"
GT: ">"
LTE: "<="
GTE: ">="
NE: "!="

PLUS: "+"
MINUS: "-"
STAR_MUL: "*"
DIV: "/"
MOD: "%"
STAR_POW: "**"
FLOOR_DIV: "//"
DECOR_OP: "@"

BW_AND: "&"
BW_OR: "|"
BW_XOR: "^"
BW_NOT: "~"
LSHIFT: "<<"
RSHIFT: ">>"
```

--------------------------------

### Jac Language Grammar: Import and Include Statements

Source: https://www.jac-lang.org/learn/jac_ref

Specifies the syntax for importing modules and specific items from other Jac modules. It covers both direct imports and imports from specific paths, including aliasing. Handles `import`, `from ... import`, and `include` statements.

```Jac
// [Heading]: Import/Include Statements.
import_stmt: KW_IMPORT KW_FROM from_path LBRACE import_items RBRACE
           | KW_IMPORT import_path (COMMA import_path)* SEMI
           | KW_INCLUDE import_path SEMI

from_path: (DOT | ELLIPSIS)* import_path
         | (DOT | ELLIPSIS)+

import_path: (NAME COLON)? (dotted_name | STRING) (KW_AS NAME)?
import_items: (import_item COMMA)* import_item COMMA?
import_item: (KW_DEFAULT | STAR_MUL | named_ref) (KW_AS NAME)?
dotted_name: named_ref (DOT named_ref)*
```

--------------------------------

### Jac Language Grammar: With Entry Blocks

Source: https://www.jac-lang.org/learn/jac_ref

Defines the `with entry` block structure in Jac, used for executing code within a specific entry context. This allows for scoped execution related to entry points or specific contexts.

```Jac
// [Heading]: With entry blocks.
free_code: KW_WITH KW_ENTRY (COLON NAME)? code_block
```

--------------------------------

### Jac Language Grammar: Global Variables

Source: https://www.jac-lang.org/learn/jac_ref

Details the declaration of global variables in Jac. This grammar rule covers the use of keywords like `let` or `global` and how variables are assigned values, potentially with access control.

```Jac
// [Heading]: Global variables.
global_var: (KW_LET | KW_GLOBAL) access_tag? assignment_list SEMI
assignment_list: (assignment | named_ref) (COMMA (assignment | named_ref))* COMMA?
```

--------------------------------

### Jac-Lang Comments and Whitespace Handling

Source: https://www.jac-lang.org/learn/jac_ref

Defines how comments (single-line and multi-line) and whitespace (spaces, tabs, newlines) are handled and ignored by the lexer in Jac-Lang. This ensures clean tokenization.

```jac-lang
// ************************************************************************* //
// Comments and Whitespace                                                   //
// ************************************************************************* //

COMMENT.4: /#\*(.|
|
)*?\*#|#.*/
WS.-2: /[ \t\f\r\n]+/+
%ignore COMMENT
%ignore WS
```

--------------------------------

### Jac Language Grammar: Enumerations

Source: https://www.jac-lang.org/learn/jac_ref

Defines the syntax for creating enumerations (enums) in Jac. This includes how enums are declared, their access modifiers, inheritance, and the structure for defining enum members and their values.

```Jac
// [Heading]: Enumerations.
enum: decorators? enum_decl
enum_decl: KW_ENUM access_tag? NAME inherited_archs? (enum_block | SEMI)
enum_block: LBRACE assignment_list (py_code_block | free_code)* RBRACE
```

--------------------------------

### Jac Language Grammar: Code Blocks and Statements

Source: https://www.jac-lang.org/learn/jac_ref

Outlines the general structure of code blocks and the various types of statements that can be included within them in Jac. This covers control flow statements like `if`, `while`, `for`, `try`, `match`, and `switch`.

```Jac
// [Heading]: Codeblocks and Statements.
code_block: LBRACE statement* RBRACE

statement: import_stmt
       | ability
       | has_stmt
       | archetype
       | impl_def
       | if_stmt
       | while_stmt
       | for_stmt
       | try_stmt
       | match_stmt
       | switch_stmt
       | with_stmt
```

--------------------------------

### Jac-Lang Formatted String Prefixes

Source: https://www.jac-lang.org/learn/jac_ref

Defines prefixes for formatted and raw-formatted strings in Jac-Lang, supporting double quotes, single quotes, and triple-quoted variants. These are used for string interpolation and raw string handling.

```jac-lang
RF_DQ_START.3: /[rR][fF]"|[fF][rR]"/
RF_SQ_START.3: /[rR][fF]'|[fF][rR]'
RF_TDQ_START.3: /[rR][fF]\"\"\"|[fF][rR]\"\"\"/
RF_TSQ_START.3: /[rR][fF]'''|[fF][rR]'''/

F_DQ_START.2: /[fF]\"/
F_SQ_START.2: /[fF]'/
F_TDQ_START.2: /[fF]\"\"\"/
F_TSQ_START.2: /[fF]'''/
```

--------------------------------

### Jac-Lang Null and Boolean Literals

Source: https://www.jac-lang.org/learn/jac_ref

Defines the literal representations for null and boolean values in Jac-Lang. 'None' represents null, while 'True' and 'False' represent boolean states.

```jac-lang
NULL.1: "None"
BOOL.1: /True|False/
```

--------------------------------

### Jac-Lang Assignment Operators

Source: https://www.jac-lang.org/learn/jac_ref

Defines various assignment operators in Jac-Lang, including simple assignment, augmented assignments (add, subtract, multiply, etc.), and bitwise augmented assignments.

```jac-lang
EQ: "="
WALRUS_EQ: ":="

ADD_EQ: "+="
SUB_EQ: "-="
MUL_EQ: "*="
DIV_EQ: "/="
MOD_EQ: "%="
MATMUL_EQ: "@="
STAR_POW_EQ: "**="
FLOOR_DIV_EQ: "//="

BW_AND_EQ: "&="
BW_OR_EQ: "|="
BW_XOR_EQ: "^="
LSHIFT_EQ: "<<="
RSHIFT_EQ: ">>="
```

--------------------------------

### Jac-Lang Keywords

Source: https://www.jac-lang.org/learn/jac_ref

Defines keywords for control flow, scope, and language constructs in Jac-Lang. These are fundamental for parsing and understanding Jac-Lang code.

```jac-lang
KW_SEM: "sem"
KW_ASSERT: "assert"
KW_IF: "if"
KW_ELIF: "elif"
KW_ELSE: "else"
KW_FOR: "for"
KW_TO: "to"
KW_BY: "by"
KW_WHILE: "while"
KW_CONTINUE: "continue"
KW_BREAK: "break"
KW_DISENGAGE: "disengage"
KW_YIELD: "yield"
KW_SKIP: "skip"
KW_REPORT: "report"
KW_RETURN: "return"
KW_DELETE: "del"
KW_TRY: "try"
KW_EXCEPT: "except"
KW_FINALLY: "finally"
KW_RAISE: "raise"
KW_IN: "in"
KW_IS: "is"
KW_PRIV: "priv"
KW_PUB: "pub"
KW_PROT: "protect"
KW_HAS: "has"
KW_GLOBAL: "glob"
KW_CAN: "can"
KW_DEF: "def"
KW_STATIC: "static"
KW_OVERRIDE: "override"
KW_MATCH: "match"
KW_SWITCH: "switch"
KW_CASE: "case"
KW_DEFAULT: "default"
KW_CLIENT: "cl"

KW_INIT: "init"
KW_POST_INIT: "postinit"

KW_HERE: "here"
KW_VISITOR: "visitor"
KW_SELF: "self"
KW_SUPER: "super"
KW_ROOT: "root"

KW_NIN.1: /\bnot\s+in\b/
KW_ISN.1: /\bis\s+not\b/
KW_AND.1: /&&|and/
KW_OR.1:  /\|\||or/
NOT: "not" // TODO:AST: Rename to KW_NOT
```

--------------------------------

### Jac Language Grammar: Tests

Source: https://www.jac-lang.org/learn/jac_ref

Defines the structure for writing tests in Jac. This includes the `test` keyword, optional naming of tests, and the code block containing the test logic.

```Jac
// [Heading]: Tests.
test: KW_TEST NAME? code_block
```

--------------------------------

### Jac Language Grammar: Base Module Structure

Source: https://www.jac-lang.org/learn/jac_ref

Defines the fundamental structure of a Jac module, including how modules are declared and the different types of top-level statements they can contain. This grammar dictates the organization of Jac code files.

```Jac
start: module

module: (toplevel_stmt (tl_stmt_with_doc | toplevel_stmt)*)?
       | STRING        (tl_stmt_with_doc | toplevel_stmt)*

tl_stmt_with_doc: STRING toplevel_stmt

toplevel_stmt: KW_CLIENT? onelang_stmt
       | KW_CLIENT LBRACE onelang_stmt* RBRACE
       | py_code_block
```

--------------------------------

### Jac Language Grammar: Archetype Member Blocks

Source: https://www.jac-lang.org/learn/jac_ref

Details the contents of an archetype's body, known as a member block. It specifies how members like variables, abilities, nested archetypes, and implementations are declared within an archetype.

```Jac
// [Heading]: Class Archetype bodies.
member_block: LBRACE member_stmt* RBRACE
member_stmt: STRING? (py_code_block | ability | archetype | impl_def | has_stmt | free_code)
has_stmt: KW_STATIC? (KW_LET | KW_HAS) access_tag? has_assign_list SEMI
has_assign_list: (has_assign_list COMMA)? typed_has_clause
typed_has_clause: named_ref type_tag (EQ expression | KW_BY KW_POST_INIT)?
type_tag: COLON pipe
```

--------------------------------

### Jac-Lang JSX Contextual Tokens

Source: https://www.jac-lang.org/learn/jac_ref

Defines tokens specific to JSX syntax within Jac-Lang, including opening tags, self-closing tags, tag endings, closing tags, fragments, and text content. These allow embedding UI-like structures.

```jac-lang
// JSX opening tag start: < followed by identifier or uppercase
// Using lower priority so it doesn't interfere with LT operator
JSX_OPEN_START.2: /<(?=[A-Z_a-z])/ 

// JSX self-closing end: />
JSX_SELF_CLOSE: /\/>/

// JSX tag end: > (used for both opening and closing)
JSX_TAG_END: />/

// JSX closing tag start: </
JSX_CLOSE_START: /<\//

// JSX fragment open: <>
JSX_FRAG_OPEN: /<>/ 

// JSX fragment close: </>
JSX_FRAG_CLOSE: /<\/>/

// JSX identifier (NAME in JSX context) - allows hyphens for attributes like data-age, aria-label
JSX_NAME: /[A-Z_a-z][A-Z_a-z0-9\-]*/

// JSX text content (anything except < > { } and must not start/end with whitespace-only)
// Using negative priority so it's only matched as last resort within JSX
JSX_TEXT.-1: /[^<>{}\n]+/
```

--------------------------------

### Jac-Lang String Conversion Operator

Source: https://www.jac-lang.org/learn/jac_ref

Defines the conversion operator used in Jac-Lang, indicated by '!'. It's followed by a set of characters that specify the type of conversion.

```jac-lang
CONV: /![rRsSaA]/
```

--------------------------------

### Jac-Lang String Literals

Source: https://www.jac-lang.org/learn/jac_ref

Defines regular expressions for matching various string literal formats in Jac-Lang, including raw, bytes, and triple-quoted strings. Handles escape sequences.

```jac-lang
STRING: /(r?b?|b?r?)("(?!\").*?(?<!\\)(\\\\)*?"|'(?!'').*?(?<!\\)(\\\\)*?')/i
       | /(r?b?|b?r?)""".*?(?<!\\)(\\\\)*?"""|'''.*?(?<!\\)(\\\\)*?'''/is
```

--------------------------------

### Jac Language Grammar: Inline Python Code

Source: https://www.jac-lang.org/learn/jac_ref

Specifies how inline Python code blocks are integrated into Jac programs using the `PYNLINE` token. This allows embedding Python scripts directly within Jac source files.

```Jac
// [Heading]: Inline python.
py_code_block: PYNLINE
```

--------------------------------

### Jac-Lang Other Operators

Source: https://www.jac-lang.org/learn/jac_ref

Defines specialized operators in Jac-Lang, including pipe forwarding/backward, dot forwarding/backward. These are likely used for functional programming patterns or specific data flow mechanisms.

```jac-lang
A_PIPE_FWD: ":>"
A_PIPE_BKWD: "<:"
PIPE_FWD: "|>"
PIPE_BKWD: "<|"
DOT_FWD: ".>"
DOT_BKWD: "<."
```

--------------------------------

### Jac Language Grammar: Class Archetypes

Source: https://www.jac-lang.org/learn/jac_ref

Defines the structure for declaring archetypes (classes, objects, nodes, edges, walkers) in Jac. This includes support for decorators, access modifiers, inheritance, and asynchronous definitions.

```Jac
// [Heading]: Class Archetypes.
archetype: decorators? KW_ASYNC? archetype_decl
         | enum

archetype_decl: arch_type access_tag? NAME inherited_archs? (member_block | SEMI)
decorators: (DECOR_OP atomic_chain)+
access_tag: COLON ( KW_PROT | KW_PUB | KW_PRIV )
inherited_archs: LPAREN (atomic_chain COMMA)* atomic_chain RPAREN


arch_type: KW_WALKER
          | KW_OBJECT
          | KW_EDGE
          | KW_NODE
          | KW_CLASS
```

--------------------------------

### Jac Language Grammar: Semstrings

Source: https://www.jac-lang.org/learn/jac_ref

Specifies the declaration of Semstrings in Jac, a feature for defining semantic strings. This includes the basic assignment syntax for these special string types.

```Jac
// [Heading]: Semstrings.
sem_def: KW_SEM dotted_name (EQ | KW_IS) STRING SEMI
```

--------------------------------

### Jac-Lang Braced Delimiters

Source: https://www.jac-lang.org/learn/jac_ref

Defines double curly brace delimiters used in Jac-Lang, likely for specific formatting or templating contexts. These are distinct from standard block delimiters.

```jac-lang
D_RBRACE: "}}"
D_LBRACE: "{{"
```

--------------------------------

### Jac-Lang Spatial Object Operators

Source: https://www.jac-lang.org/learn/jac_ref

Defines operators used for spatial relationships and object communication in Jac-Lang. These include bidirectional, left, and right arrows, with variations for parameterized connections.

```jac-lang
ARROW_BI: "<-->"
ARROW_L: "<--"
ARROW_R: "-->"
ARROW_L_P1: "<-:"
ARROW_R_P2: ":->"
ARROW_L_P2: ":<-"
ARROW_R_P1: "->:"
CARROW_BI: "<++>"
CARROW_L: "<++"
CARROW_R: "++>"
CARROW_L_P1: "<+ :"
CARROW_R_P2: ":+>"
CARROW_L_P2: ":<+"
CARROW_R_P1: "+> :"
```

--------------------------------

### Jac-Lang Formatted String Text Content

Source: https://www.jac-lang.org/learn/jac_ref

Regular expressions for capturing the text content within formatted and raw-formatted strings in Jac-Lang. These expressions handle escape sequences and differentiate between quote types.

```jac-lang
F_TEXT_DQ.-1: /[^"{}\\n]+|\\./
F_TEXT_SQ.-1: /[^'{} \\n]+|\\./
F_TEXT_TDQ.-1: /(?:[^"{}\\n]|\"(?!\"))+|\\./s
F_TEXT_TSQ.-1: /(?:[^'{}\\n]|'(?!''))+|\\./s
RF_TEXT_DQ.-1: /[^"{}]+/ 
RF_TEXT_SQ.-1: /[^'{}]+/ 
RF_TEXT_TDQ.-1: /(?:[^"{}\\]|\"(?!\"))+/s
RF_TEXT_TSQ.-1: /(?:[^'{} \\n]|'(?!''))+/s
F_FORMAT_TEXT.-1: /[^{}]+/
```

--------------------------------

### Jac-Lang Numeric Literals

Source: https://www.jac-lang.org/learn/jac_ref

Defines regular expressions for various numeric literal types in Jac-Lang, including floats, hexadecimal, binary, octal, and integers. Supports underscores for readability.

```jac-lang
FLOAT: /(\d+(\.\d*)|\.\d+)([eE][+-]?\d+)?|\d+([eE][-+]\d+)/
HEX.1: /0[xX][0-9a-fA-F_]+/
BIN.1: /0[bB][01_]+/
OCT.1: /0[oO][0-7_]+/
INT: /[0-9][0-9_]*/
```

--------------------------------

### Jac-Lang String Literal Endings

Source: https://www.jac-lang.org/learn/jac_ref

Defines the closing characters for various string literal types in Jac-Lang. These are crucial for correctly parsing the end of strings, including triple-quoted ones.

```jac-lang
F_DQ_END: "\""
F_SQ_END: "'"
F_TDQ_END: "\"\"\""
F_TSQ_END: "'''"
```
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