9.6 KiB
9.6 KiB
Language Reference
Grammar
Root = many(TopLevelDecl) "EOF"
TopLevelDecl = many(Directive) option(VisibleMod) (FnDef | ExternDecl | RootExportDecl | Import | ContainerDecl | GlobalVarDecl | ErrorValueDecl | CImportDecl | TypeDecl)
CImportDecl = "c_import" Block
TypeDecl = "type" "Symbol" "=" TypeExpr ";"
ErrorValueDecl = "error" "Symbol" ";"
GlobalVarDecl = VariableDeclaration ";"
VariableDeclaration = ("var" | "const") "Symbol" option(":" TypeExpr) "=" Expression
ContainerDecl = ("struct" | "enum") "Symbol" "{" many(StructMember) "}"
StructMember = many(Directive) option(VisibleMod) (StructField | FnDef)
StructField = "Symbol" option(":" Expression) ",")
Import = "import" "String" ";"
RootExportDecl = "export" "Symbol" "String" ";"
ExternDecl = "extern" (FnProto | VariableDeclaration) ";"
FnProto = "fn" option("Symbol") ParamDeclList option("->" TypeExpr)
Directive = "#" "Symbol" "(" "String" ")"
VisibleMod = "pub" | "export"
FnDef = option("inline") FnProto Block
ParamDeclList = "(" list(ParamDecl, ",") ")"
ParamDecl = option("noalias") option("Symbol" ":") TypeExpr | "..."
Block = "{" list(option(Statement), ";") "}"
Statement = Label | VariableDeclaration ";" | Defer ";" | NonBlockExpression ";" | BlockExpression
Label = "Symbol" ":"
Expression = BlockExpression | NonBlockExpression
TypeExpr = PrefixOpExpression
NonBlockExpression = ReturnExpression | AssignmentExpression
AsmExpression = "asm" option("volatile") "(" "String" option(AsmOutput) ")"
AsmOutput = ":" list(AsmOutputItem, ",") option(AsmInput)
AsmInput = ":" list(AsmInputItem, ",") option(AsmClobbers)
AsmOutputItem = "[" "Symbol" "]" "String" "(" ("Symbol" | "->" TypeExpr) ")"
AsmInputItem = "[" "Symbol" "]" "String" "(" Expression ")"
AsmClobbers= ":" list("String", ",")
UnwrapExpression = BoolOrExpression (UnwrapMaybe | UnwrapError) | BoolOrExpression
UnwrapMaybe = "??" Expression
UnwrapError = "%%" option("|" "Symbol" "|") Expression
AssignmentExpression = UnwrapExpression AssignmentOperator UnwrapExpression | UnwrapExpression
AssignmentOperator = "=" | "*=" | "/=" | "%=" | "+=" | "-=" | "<<=" | ">>=" | "&=" | "^=" | "|=" | "&&=" | "||="
BlockExpression = IfExpression | Block | WhileExpression | ForExpression | SwitchExpression
SwitchExpression = "switch" "(" Expression ")" "{" many(SwitchProng) "}"
SwitchProng = (list(SwitchItem, ",") | "else") "=>" option("|" "Symbol" "|") Expression ","
SwitchItem = Expression | (Expression "..." Expression)
WhileExpression = "while" "(" Expression ")" Expression
ForExpression = "for" "(" Expression ")" option("|" "Symbol" option("," "Symbol") "|") Expression
BoolOrExpression = BoolAndExpression "||" BoolOrExpression | BoolAndExpression
ReturnExpression = option("%" | "?") "return" option(Expression)
Defer = option("%" | "?") "defer" option(Expression)
IfExpression = IfVarExpression | IfBoolExpression
IfBoolExpression = "if" "(" Expression ")" Expression option(Else)
IfVarExpression = "if" "(" ("const" | "var") "Symbol" option(":" TypeExpr) "?=" Expression ")" Expression Option(Else)
Else = "else" Expression
BoolAndExpression = ComparisonExpression "&&" BoolAndExpression | ComparisonExpression
ComparisonExpression = BinaryOrExpression ComparisonOperator BinaryOrExpression | BinaryOrExpression
ComparisonOperator = "==" | "!=" | "<" | ">" | "<=" | ">="
BinaryOrExpression = BinaryXorExpression "|" BinaryOrExpression | BinaryXorExpression
BinaryXorExpression = BinaryAndExpression "^" BinaryXorExpression | BinaryAndExpression
BinaryAndExpression = BitShiftExpression "&" BinaryAndExpression | BitShiftExpression
BitShiftExpression = AdditionExpression BitShiftOperator BitShiftExpression | AdditionExpression
BitShiftOperator = "<<" | ">>"
AdditionExpression = MultiplyExpression AdditionOperator AdditionExpression | MultiplyExpression
AdditionOperator = "+" | "-" | "++"
MultiplyExpression = CurlySuffixExpression MultiplyOperator MultiplyExpression | CurlySuffixExpression
CurlySuffixExpression = TypeExpr option(ContainerInitExpression)
MultiplyOperator = "*" | "/" | "%"
PrefixOpExpression = PrefixOp PrefixOpExpression | SuffixOpExpression
SuffixOpExpression = PrimaryExpression option(FnCallExpression | ArrayAccessExpression | FieldAccessExpression | SliceExpression)
FieldAccessExpression = "." "Symbol"
FnCallExpression = "(" list(Expression, ",") ")"
ArrayAccessExpression = "[" Expression "]"
SliceExpression = "[" Expression "..." option(Expression) "]" option("const")
ContainerInitExpression = "{" ContainerInitBody "}"
ContainerInitBody = list(StructLiteralField, ",") | list(Expression, ",")
StructLiteralField = "." "Symbol" "=" Expression
PrefixOp = "!" | "-" | "~" | "*" | ("&" option("const")) | "?" | "%" | "%%" | "??"
PrimaryExpression = "Number" | "String" | "CharLiteral" | KeywordLiteral | GroupedExpression | GotoExpression | BlockExpression | "Symbol" | ("@" "Symbol" FnCallExpression) | ArrayType | (option("extern") FnProto) | AsmExpression | ("error" "." "Symbol")
ArrayType = "[" option(Expression) "]" option("const") TypeExpr
GotoExpression = "goto" "Symbol"
GroupedExpression = "(" Expression ")"
KeywordLiteral = "true" | "false" | "null" | "break" | "continue" | "undefined" | "error" | "type"
Operator Precedence
x() x[] x.y
!x -x ~x *x &x ?x %x %%x
x{}
* / %
+ - ++
<< >>
&
^
|
== != < > <= >=
&&
||
?? %%
= *= /= %= += -= <<= >>= &= ^= |= &&= ||=
Types
Numeric Types
Type name C equivalent Description
i8 int8_t signed 8-bit integer
u8 uint8_t unsigned 8-bit integer
i16 int16_t signed 16-bit integer
u16 uint16_t unsigned 16-bit integer
i32 int32_t signed 32-bit integer
u32 uint32_t unsigned 32-bit integer
i64 int64_t signed 64-bit integer
u64 uint64_t unsigned 64-bit integer
f32 float 32-bit IEE754 floating point
f64 double 64-bit IEE754 floating point
isize intptr_t signed pointer sized integer
usize uintptr_t unsigned pointer sized integer
c_short short for ABI compatibility with C
c_ushort unsigned short for ABI compatibility with C
c_int int for ABI compatibility with C
c_uint unsigned int for ABI compatibility with C
c_long long for ABI compatibility with C
c_ulong unsigned long for ABI compatibility with C
c_longlong long long for ABI compatibility with C
c_ulonglong unsigned long long for ABI compatibility with C
c_long_double long double for ABI compatibility with C
Boolean Type
The boolean type has the name bool and represents either true or false.
Function Type
TODO
Fixed-Size Array Type
Example: The string "aoeu" has type [4]u8.
The size is known at compile time and is part of the type.
Slice Type
A slice can be obtained with the slicing syntax: array[start...end]
Example: "aoeu"[0...2] has type []u8.
Struct Type
TODO
Enum Type
TODO
Maybe Type
TODO
Pure Error Type
TODO
Error Union Type
TODO
Pointer Type
TODO
Unreachable Type
The unreachable type has the name unreachable. TODO explanation
Void Type
The void type has the name void. void types are zero bits and are omitted
from codegen.
Expressions
Literals
Character and String Literals
Literal Example Characters Escapes Null Term Type
Byte 'H' All ASCII Byte No u8
UTF-8 Bytes "hello" All Unicode Byte & Unicode No [5]u8
UTF-8 C string c"hello" All Unicode Byte & Unicode Yes &const u8
Escape Name
\xNN hexadecimal 8-bit character code (exactly 2 digits)
\n Newline
\r Carriage return
\t Tab
\\ Backslash
\0 Null
\' Single quote
\" Double quote
Unicode Escapes
| Escape | Name |
|---|---|
| \u{NNNNNN} | hexadecimal 24-bit Unicode character code (up to 6 digits) |
Numeric Literals
Number literals Example Exponentiation
Decimal integer 98222 N/A
Hex integer 0xff N/A
Octal integer 0o77 N/A
Binary integer 0b11110000 N/A
Floating-point 123.0E+77 Optional
Hex floating point TODO TODO
Identifiers
TODO
Declarations
Declarations have type void.
Function Declarations
TODO
Variable Declarations
TODO
Struct Declarations
TODO
Enum Declarations
TODO
Built-in Functions
Built-in functions are prefixed with @.
@typeof
@typeof(expression)
@sizeof
@sizeof(type)
Overflow Arithmetic
Overflow arithmetic functions have defined behavior on overflow or underflow.
The functions take an integer type, two variables of the specified type, and a pointer to a variable of the specified type where the result is stored. The functions return a boolean value: true of overflow/underflow occurred, false otherwise.
Function Operation
@add_with_overflow(T: type, a: T, b: T, x: &T) -> bool *x = a + b
@sub_with_overflow(T: type, a: T, b: T, x: &T) -> bool *x = a - b
@mul_with_overflow(T: type, a: T, b: T, x: &T) -> bool *x = a * b
@memset
@memset(dest, char, len)
@memcpy
@memcpy(dest, source, len)
@member_count
@member_count(enum_type)
Max and Min Value
@max_value(type)
@min_value(type)