177 lines
5.9 KiB
Markdown
177 lines
5.9 KiB
Markdown
# Language Reference
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## Grammar
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```
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Root = many(TopLevelItem) "EOF"
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TopLevelItem = ErrorValueDecl | CompTimeExpression(Block) | TopLevelDecl | TestDecl
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TestDecl = "test" String Block
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TopLevelDecl = option(VisibleMod) (FnDef | ExternDecl | GlobalVarDecl | UseDecl)
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ErrorValueDecl = "error" Symbol ";"
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GlobalVarDecl = VariableDeclaration ";"
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VariableDeclaration = option("comptime") ("var" | "const") Symbol option(":" TypeExpr) "=" Expression
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ContainerMember = (ContainerField | FnDef | GlobalVarDecl)
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ContainerField = Symbol option(":" Expression) ","
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UseDecl = "use" Expression ";"
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ExternDecl = "extern" option(String) (FnProto | VariableDeclaration) ";"
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FnProto = option("coldcc" | "nakedcc" | "stdcallcc") "fn" option(Symbol) ParamDeclList option("->" TypeExpr)
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VisibleMod = "pub" | "export"
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FnDef = option("inline" | "extern") FnProto Block
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ParamDeclList = "(" list(ParamDecl, ",") ")"
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ParamDecl = option("noalias" | "comptime") option(Symbol ":") (TypeExpr | "...")
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Block = "{" many(Statement) option(Expression) "}"
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Statement = Label | VariableDeclaration ";" | Defer(Block) | Defer(Expression) ";" | BlockExpression(Block) | Expression ";" | ";"
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Label = Symbol ":"
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TypeExpr = PrefixOpExpression | "var"
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BlockOrExpression = Block | Expression
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Expression = ReturnExpression | BreakExpression | AssignmentExpression
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AsmExpression = "asm" option("volatile") "(" String option(AsmOutput) ")"
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AsmOutput = ":" list(AsmOutputItem, ",") option(AsmInput)
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AsmInput = ":" list(AsmInputItem, ",") option(AsmClobbers)
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AsmOutputItem = "[" Symbol "]" String "(" (Symbol | "->" TypeExpr) ")"
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AsmInputItem = "[" Symbol "]" String "(" Expression ")"
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AsmClobbers= ":" list(String, ",")
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UnwrapExpression = BoolOrExpression (UnwrapMaybe | UnwrapError) | BoolOrExpression
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UnwrapMaybe = "??" Expression
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UnwrapError = "%%" option("|" Symbol "|") Expression
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AssignmentExpression = UnwrapExpression AssignmentOperator UnwrapExpression | UnwrapExpression
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AssignmentOperator = "=" | "*=" | "/=" | "%=" | "+=" | "-=" | "<<=" | ">>=" | "&=" | "^=" | "|=" | "*%=" | "+%=" | "-%=" | "<<%="
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BlockExpression(body) = Block | IfExpression(body) | TryExpression(body) | TestExpression(body) | WhileExpression(body) | ForExpression(body) | SwitchExpression | CompTimeExpression(body)
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CompTimeExpression(body) = "comptime" body
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SwitchExpression = "switch" "(" Expression ")" "{" many(SwitchProng) "}"
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SwitchProng = (list(SwitchItem, ",") | "else") "=>" option("|" option("*") Symbol "|") Expression ","
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SwitchItem = Expression | (Expression "..." Expression)
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ForExpression(body) = option("inline") "for" "(" Expression ")" option("|" option("*") Symbol option("," Symbol) "|") body option("else" BlockExpression(body))
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BoolOrExpression = BoolAndExpression "or" BoolOrExpression | BoolAndExpression
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ReturnExpression = option("%") "return" option(Expression)
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BreakExpression = "break" option(Expression)
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Defer(body) = option("%") "defer" body
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IfExpression(body) = "if" "(" Expression ")" body option("else" BlockExpression(body))
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TryExpression(body) = "if" "(" Expression ")" option("|" option("*") Symbol "|") body "else" "|" Symbol "|" BlockExpression(body)
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TestExpression(body) = "if" "(" Expression ")" option("|" option("*") Symbol "|") body option("else" BlockExpression(body))
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WhileExpression(body) = option("inline") "while" "(" Expression ")" option("|" option("*") Symbol "|") option(":" "(" Expression ")") body option("else" option("|" Symbol "|") BlockExpression(body))
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BoolAndExpression = ComparisonExpression "and" BoolAndExpression | ComparisonExpression
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ComparisonExpression = BinaryOrExpression ComparisonOperator BinaryOrExpression | BinaryOrExpression
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ComparisonOperator = "==" | "!=" | "<" | ">" | "<=" | ">="
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BinaryOrExpression = BinaryXorExpression "|" BinaryOrExpression | BinaryXorExpression
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BinaryXorExpression = BinaryAndExpression "^" BinaryXorExpression | BinaryAndExpression
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BinaryAndExpression = BitShiftExpression "&" BinaryAndExpression | BitShiftExpression
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BitShiftExpression = AdditionExpression BitShiftOperator BitShiftExpression | AdditionExpression
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BitShiftOperator = "<<" | ">>" | "<<%"
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AdditionExpression = MultiplyExpression AdditionOperator AdditionExpression | MultiplyExpression
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AdditionOperator = "+" | "-" | "++" | "+%" | "-%"
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MultiplyExpression = CurlySuffixExpression MultiplyOperator MultiplyExpression | CurlySuffixExpression
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CurlySuffixExpression = TypeExpr option(ContainerInitExpression)
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MultiplyOperator = "*" | "/" | "%" | "**" | "*%"
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PrefixOpExpression = PrefixOp PrefixOpExpression | SuffixOpExpression
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SuffixOpExpression = PrimaryExpression option(FnCallExpression | ArrayAccessExpression | FieldAccessExpression | SliceExpression)
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FieldAccessExpression = "." Symbol
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FnCallExpression = "(" list(Expression, ",") ")"
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ArrayAccessExpression = "[" Expression "]"
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SliceExpression = "[" Expression ".." option(Expression) "]"
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ContainerInitExpression = "{" ContainerInitBody "}"
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ContainerInitBody = list(StructLiteralField, ",") | list(Expression, ",")
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StructLiteralField = "." Symbol "=" Expression
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PrefixOp = "!" | "-" | "~" | "*" | ("&" option("const") option("volatile")) | "?" | "%" | "%%" | "??" | "-%"
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PrimaryExpression = Number | String | CharLiteral | KeywordLiteral | GroupedExpression | GotoExpression | BlockExpression(BlockOrExpression) | Symbol | ("@" Symbol FnCallExpression) | ArrayType | (option("extern") FnProto) | AsmExpression | ("error" "." Symbol) | ContainerDecl
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ArrayType = "[" option(Expression) "]" option("const") TypeExpr
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GotoExpression = "goto" Symbol
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GroupedExpression = "(" Expression ")"
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KeywordLiteral = "true" | "false" | "null" | "continue" | "undefined" | "error" | "this" | "unreachable"
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ContainerDecl = option("extern" | "packed") ("struct" | "enum" | "union") "{" many(ContainerMember) "}"
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```
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## Operator Precedence
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```
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x() x[] x.y
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!x -x -%x ~x *x &x ?x %x %%x ??x
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x{}
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* / % ** *%
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+ - ++ +% -%
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<< >>
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&
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^
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== != < > <= >=
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and
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or
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?? %%
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= *= /= %= += -= <<= >>= &= ^= |=
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```
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