C# 2.0 Grammar

A.1.5 Unicode Character Escape Sequences UnicodeEscapeSequence = "\u" FourHexDigits | "\U" FourHexDigits FourHexDigits.. ■ A.1 Lexical Grammar 229A LetterChar is either a Unicode charact

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a p p e n d i x A

C# 2.0 Grammar

T his appendix contains the grammatical summary of the C# 2.0 programming lan-guage Its syntax is described in a concise fashion using the EBNF notation as summarized once again in Table A.1.

The grammar productions are logically grouped into two main grammars: lexical and syntactic The lexical grammar deﬁnes tokens extracted by the lexical analyzer or scanner, and the syntactic grammar is used by the parser to specify how the tokens are organized

to produce valid C# programs.

A* Repetition—zero or more occurrences of A

A+ Repetition—one or more occurrences of A

A? Option—zero or one occurrence of A

A B Sequence—A followed by B

A | B Alternative—A or B

"0" "9" Alternative—one character between 0 and 9 inclusively ( A B ) Grouping—of an A B sequence

Table A.1: Notation for Extended Backus–Naur Form

A.1 Lexical Grammar

Input = InputSection?

InputSection = InputSectionPart+

InputSectionPart = (InputElements? NewLine) | PpDirective

InputElement = Whitespace | Comment | Token

227

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A.1.1 Line Terminators

All line terminators are represented by the Newline production A Newline is either a carriage return (CR) as the \u000D or ‘\r’ character, a line feed (LF) as the \u000A or

‘\n’ character, a (CR) followed by (LF), a line separator (LS) as the \u2028 character, or a paragraph separator (PS) as the \u2029 character.

NewLine = CR | LF | CRLF | LS | PS

A.1.2 White Space

A white space is any character with Unicode Class Zs, a horizontal tab (HT) as the \u0009

or ‘\t’ character, a vertical tab (VT) as the \u000B or ‘\v’ character, or a form feed (FF)

as the \u000C or ‘\f’ character.

Whitespace = AnyCharacterWithUnicodeClassZs | HT | VT | FF

A.1.3 Comments

Comment = SingleLineComment | DelimitedComment

SingleLineComment = "//" InputCharacters?

InputCharacter = AnyUnicodeCharacterExceptANewLine

DelimitedComment = "/*" DelimitedCommentCharacters? "*/"

DelimitedCommentCharacter = NotAsterisk | ("*" NotSlash)

NotAsterisk = AnyUnicodeCharacterExcept "*"

NotSlash = AnyUnicodeCharacterExcept "/"

A.1.4 Tokens

Token = Identifier | Keyword | Literal | OperatorOrPunctuator

Note: null, true, and false are keywords as well as literals.

A.1.5 Unicode Character Escape Sequences

UnicodeEscapeSequence = ("\u" FourHexDigits) | ("\U" FourHexDigits FourHexDigits)

FourHexDigits = HexDigit HexDigit HexDigit HexDigit

A.1.6 Identiﬁers

Identifier = AvailableIdentifier | ("@" IdentifierOrKeyword)

AvailableIdentifier = An IdentifierOrKeyword that is not a Keyword

IdentifierOrKeyword = IdentifierStartCharacter IdentifierPartCharacters?

IdentifierStartCharacter = LetterChar | "_"

IdentifierPartCharacter = LetterChar | DecimalDigitChar | ConnectingChar

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■ A.1 Lexical Grammar 229

A LetterChar is either a Unicode character of classes Lu, Ll, Lt, Lm, Lo, or Nl; or a Unicode-character-escape-sequence representing a character of classes Lu, Ll, Lt, Lm, Lo, or Nl.

A CombiningChar is either a Unicode character of classes Mn or Mc; or a Unicode-character-escape-sequence representing a character of classes Mn or Mc A DecimalDigitChar

is either a Unicode character of the class Nd, or a Unicode-character-escape-sequence representing a character of the class Nd A ConnectingChar is either a Unicode char-acter of the class Pc, or a Unicode-charchar-acter-escape-sequence representing a charchar-acter

of the class Pc A FormattingChar is either a Unicode character of the class Cf, or a Unicode-character-escape-sequence representing a character of the class Cf.

A.1.7 Keywords

abstract as base bool break

byte case catch char checked

class const continue decimal default

delegate do double else enum

event explicit extern false finally

fixed float for foreach goto

if implicit in int interface

internal is lock long namespace

new null object operator out

override params private protected public

readonly ref return sbyte sealed

short sizeof stackalloc static string

struct switch this throw true

try typeof uint ulong unchecked

unsafe ushort using virtual void

volatile while

A.1.8 Literals

Literal = BooleanLiteral | IntegerLiteral | RealLiteral

| CharacterLiteral | StringLiteral | NullLiteral BooleanLiteral = "true" | "false"

IntegerLiteral = DecimalIntLiteral | HexIntLiteral

DecimalIntLiteral = DecimalDigits IntegerTypeSuffix?

DecimalDigit = "0" "9"

IntegerTypeSuffix = "U" | "u" | "L" | "l" | "Ul" | "ul" | "Lu" | "lu" | "UL" | "uL" | "LU" | "lU" HexIntegerLiteral = ("0x" | "0X") HexDigits IntegerTypeSuffix?

HexDigit = "0 9" | "A" "F" | "a" "f"

RealLiteral = ( DecimalDigits "." DecimalDigits ExponentPart? RealTypeSuffix? )

| ( "." DecimalDigits ExponentPart? RealTypeSuffix? )

| ( DecimalDigits ExponentPart RealTypeSuffix? )

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ExponentPart = ("e" | "E") Sign? DecimalDigits

Sign = "+" | "-"

RealTypeSuffix = "F" | "f" | "D" | "d" | "M" | "m"

CharacterLiteral = "’" Character "’"

Character = SingleCharacter | SimpleEscapeSequence | HexEscapeSequence | UnicodeEscapeSequence SingleCharacter = Any Character Except Quote, Escape, and NewLine

SimpleEscapeSequence = "\’" | "\\" | "\0" | "\a" | "\b" | "\f" | "\n" | "\r" | "\t" | "\v" | DQuote DQuote = "\"" (\u0022)

Quote = "’" (\u0027)

Escape = "\\" (\u005C)

HexEscapeSequence = "\x" HexDigit HexDigit? HexDigit? HexDigit?

StringLiteral = RegularStringLiteral | VerbatimStringLiteral

RegularStringLiteral = " RegularStringLiteralCharacters? "

RegularStringLiteralCharacter = SingleRegularStringLiteralCharacter | SimpleEscapeSequence

| HexadecimalEscapeSequence | UnicodeEscapeSequence SingleRegularStringLiteralCharacter = Any Character Except DQuote, Escape, and NewLine

VerbatimStringLiteral = "@" DQuote VerbatimStringLiteralCharacters? DQuote

VerbatimStringLiteralCharacter = SingleVerbatimStringLiteralCharacter | QuoteEscapeSequence SingleVerbatimStringLiteralCharacter = Any Character Except DQuote

QuoteEscapeSequence = "\’"

NullLiteral = "null"

A.1.9 Operators and Punctuators

{ } [ ] ( ) , = ;

+ - * / % & | ˆ ! ˜

= < > ? :: ++ && || ->

== != <= >= += -= *= /= %= &=

|= ˆ= <<= << > > > >=

A.1.10 Preprocessing Directives

ConditionalSymbol = Any IdentifierOrKeyword Except "true" or "false"

PpExpr = Whitespace? PpOrExpr Whitespace?

PpOrExpr = PpAndExpr (Whitespace? "||" Whitespace? PpAndExpr)*

PpAndExpr = PpEqualityExpr (Whitespace? "&&" Whitespace? PpEqualityExpr)*

PpEqualityExpr = PpUnaryExpr (Whitespace? ("==" | "!=") Whitespace? PpUnaryExpr)*

PpUnaryExpr = ("!" Whitespace? PpPrimaryExpr)*

PpPrimaryExpr = "true" | "false" | ConditionalSymbol | "(" Whitespace? PpExpr Whitespace? ")" PpDeclaration = Whitespace? "#" Whitespace? ("define"|"undef") Whitespace ConditionalSymbol PpNewLine

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■ A.2 Syntactic Grammar 231

PpIfSection = Whitespace? "#" Whitespace? "if" Whitespace PpExpr PpNewLine ConditionalSection? PpElifSection = Whitespace? "#" Whitespace? "elif" Whitespace PpExpr PpNewLine ConditionalSection? PpElseSection = Whitespace? "#" Whitespace? "else" PpNewLine ConditionalSection?

PpEndifLine = Whitespace? "#" Whitespace? "endif" PpNewLine

ConditionalSection = InputSection | SkippedSection

SkippedSection = SkippedSectionPart+

SkippedSectionPart = (SkippedCharacters? NewLine) | PpDirective

SkippedCharacters = Whitespace? NotNumberSign InputCharacters?

NotNumberSign = Any InputCharacter Except "#"

PpLine = Whitespace? "#" Whitespace? "line" Whitespace LineIndicator PpNewLine

LineIndicator = (DecimalDigits Whitespace FileName) | DecimalDigits | "default"

FileName = "\"" FileNameCharacters "\""

FileNameCharacter = Any InputCharacter Except "\""

PpDiagnostic = Whitespace? "#" Whitespace? ("error" | "warning") PpMessage

PpMessage = NewLine | (Whitespace InputCharacters? NewLine)

PpRegion = PpStartRegion ConditionalSection? PpEndRegion

PpStartRegion = Whitespace? "#" Whitespace? "region" PpMessage

PpEndRegion = Whitespace? "#" Whitespace? "endregion" PpMessage

PpPragma = Whitespace? "#" Whitespace? "pragma" PragmaBody PpNewLine

PragmaBody = PragmaWarningBody

PragmaWarningBody = "warning" Whitespace WarningAction ( Whitespace WarningList )?

WarningAction = "disable" | "restore"

WarningList = DecimalDigits ( Whitespace? "," Whitespace? DecimalDigits )*

A.2 Syntactic Grammar

A.2.1 Namespace, Type, and Simple Names

NamespaceName = NamespaceOrTypeName

TypeName = NamespaceOrTypeName

NamespaceOrTypeName = ( Identifier TypeArgumentList? )

| ( "." Identifier TypeArgumentList? )*

| QualifiedAliasMember SimpleName = Identifier TypeArgumentList?

QualifiedAliasMember = Identifier "::" Identifier TypeArgumentList?

A.2.2 Types

Type = ValueType | ReferenceType | TypeParameter

ValueType = StructType | EnumType | NullableType

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SimpleType = NumericType | "bool"

NumericType = IntegralType | RealType | "decimal" | "char"

EnumType = TypeName

NullableType = ValueType "?"

ReferenceType = ClassType | InterfaceType | ArrayType | DelegateType

ClassType = TypeName | "object" | "string"

InterfaceType = TypeName

ArrayType = NonArrayType RankSpecifiers

NonArrayType = Type

RankSpecifier = "[" DimSeparators? "]"

DimSeparators = ","+

DelegateType = TypeName

A.2.3 Variables

VariableReference = Expr

A.2.4 Expressions

Argument = Expr | ("ref" | "out") VariableReference

PrimaryExpr = PrimaryNoArrayCreationExpr | ArrayCreationExpr

PrimaryNoArrayCreationExpr = Literal | SimpleName | ParenthesizedExpr | MemberAccess

| PostDecrementExpr | ObjectCreationExpr | DelegateCreationExpr | TypeofExpr

| AnonymousMethodExpr

ParenthesizedExpr = "(" Expr ")"

MemberAccess = ( PrimaryExpr "." Identifier TypeArgumentList? )

| ( PredefinedType "." Identifier TypeArgumentList? )

| ( QualifiedAliasMember "." Identifier ) InvocationExpr = PrimaryExpr "(" ArgumentList? ")"

ElementAccess = PrimaryNoArrayCreationExpr "[" ExprList "]"

ThisAccess = "this"

BaseAccess = "base" ( "." Identifier ) | ( "[" ExprList "]" )

PostIncrementExpr = PrimaryExpr "++"

PostDecrementExpr = PrimaryExpr " "

ObjectCreationExpr = "new" Type "(" ArgumentList? ")"

DelegateCreationExpr = "new" DelegateType "(" Expr ")"

TypeofExpr = "typeof" "(" Type | "void" ")"

CheckedExpr = "checked" "(" Expr ")"

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DefaultValueExpr = "default" "(" Type ")"

AnonymousMethodExpr = "delegate" AnonymousMethodSignature? Block

| ( "new" ArrayType ArrayInitializer ) UnaryExpr = PreIncExpr | PreDecExpr | CastExpr | ( ("+"|"-"|"!"|"˜"|"*")? PrimaryExpr ) PreIncExpr = "++" UnaryExpr

PreDecExpr = " " UnaryExpr

CastExpr = "(" Type ")" UnaryExpr

MultiplicativeExpr = UnaryExpr (MulOp UnaryExpr)*

AdditiveExpr = MultiplicativeExpr (AddOp MultiplicativeExpr)*

ShiftExpr = AdditiveExpr (ShiftOp AdditiveExpr)*

RelationalExpr = ShiftExpr ( (RelOp ShiftExpr) | (TypeTestingOp Type) )*

EqualityExpr = RelationalExpr (EquOp RelationalExpr)*

AndExpr = EqualityExpr ("&" EqualityExpr)*

ExclusiveOrExpr = AndExpr ("ˆ" AndExpr)*

InclusiveOrExpr = ExclusiveOrExpr ("|" ExclusiveOrExpr)*

ConditionalAndExpr = InclusiveOrExpr ("&&" InclusiveOrExpr)*

ConditionalOrExpr = ConditionalAndExpr ("||" ConditionalAndExpr)*

NullCoalescingExpr = ConditionalOrExpr ("??" ConditionalOrExpr)*

ConditionalExpr = NullCoalescingExpr | ( NullCoalescingExpr "?" Expr ":" Expr)

Assignment = UnaryExpr AssignmentOp Expr

AssignmentOp = "=" | "+=" | "-=" | "*=" | "/=" | "%=" | "&=" | "|=" | "ˆ=" | "<<=" | ">>=" MulOp = "*" | "/" | "%"

AddOp = "+" | "-"

ShiftOp = "<<" | ">>"

RelOp = "<" | ">" | "<=" | ">="

TypeTestingOp = "is" | "as"

EquOp = "==" | "!="

Expr = ConditionalExpr | Assignment

ConstantExpr = Expr

BooleanExpr = Expr

A.2.5 Statements

Stmt = EmbeddedStmt | LabeledStmt | DeclStmt

EmbeddedStmt = ExprStmt | EmptyStmt | Block | SelectionStmt | IterationStmt

| UsingStmt | YieldStmt

ExprStmt = StmtExpr ";"

StmtExpr = InvocationExpr | ObjectCreationExpr | Assignment

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EmptyStmt = ";"

Block = "{" Stmts? "}"

SelectionStmt = IfStmt | SwitchStmt

IfStmt = "if" "(" BooleanExpr ")" EmbeddedStmt ( "else" EmbeddedStmt )?

BooleanExpr = Expr

SwitchStmt = "switch" "(" Expr ")" SwitchBlock

SwitchBlock = "{" SwitchSections? "}"

SwitchSection = SwitchLabels Stmts

SwitchLabel = ( "case" ConstantExpr ":" ) | ( "default" ":" )

IterationStmt = WhileStmt | DoStmt | ForStmt | ForeachStmt

WhileStmt = "while" "(" BooleanExpr ")" EmbeddedStmt

DoStmt = "do" EmbeddedStmt "while" "(" BooleanExpr ")" ";"

ForStmt = "for" "(" ForInitializer? ";" ForCondition? ";" ForIterator? ")" EmbeddedStmt ForInitializer = LocalVariableDecl | StmtExprList

ForCondition = BooleanExpr

ForIterator = StmtExprList

ForeachStmt = "foreach" "(" Type Identifier "in" Expr ")" EmbeddedStmt

JumpStmt = BreakStmt | ContinueStmt | GotoStmt | ReturnStmt | ThrowStmt

BreakStmt = "break" ";"

ContinueStmt = "continue" ";"

GotoStmt = "goto" ( Identifier | ("case" ConstantExpr) | Default ) ";"

ReturnStmt = "return" Expr? ";"

ThrowStmt = "throw" Expr? ";"

TryStmt = "try" Block ( CatchClauses | FinallyClause )? | ( CatchClauses FinallyClause )? CatchClauses = ( SpecificCatchClauses GeneralCatchClause? )

| ( SpecificCatchClauses? GeneralCatchClause )

SpecificCatchClauses = SpecificCatchClause+

SpecificCatchClause = "catch" "(" ClassType Identifier? ")" Block

GeneralCatchClause = "catch" Block

FinallyClause = "finally" Block

CheckedStmt = "checked" Block

UncheckedStmt = "unchecked" Block

LockStmt = "lock" "(" Expr ")" EmbeddedStmt

UsingStmt = "using" "(" ResourceAcquisition ")" EmbeddedStmt

YieldStmt = ("yield" "return" Expr) | ("yield" "break")

ResourceAcquisition = LocalVariableDecl | Expr

LabeledStmt = Identifier ":" Stmt

DeclStmt = ( LocalVariableDecl | LocalConstantDecl ) ";"

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LocalVariableDecltor = Identifier ( "=" LocalVariableInitializer )?

LocalVariableInitializer = Expr | ArrayInitializer

LocalConstantDecl = "const" Type ConstantDecltorList

ConstantDecltor = Identifier "=" ConstantExpr

A.2.6 Namespaces

CompilationUnit = ExternAliasDirectives? UsingDirectives? GlobalAttributes? NamespaceMemberDecls? NamespaceDecl = "namespace" QualifiedIdentifier NamespaceBody ";"?

QualifiedIdentifier = Identifier ( "." Identifier )*

NamespaceBody = "{" ExternAliasDirectives? UsingDirectives? NamespaceMemberDecls? "}"

UsingDirective = "using" ( UsingAliasDirective | NamespaceName ) ";"

UsingAliasDirective = Identifier "=" NamespaceOrTypeName

ExternAliasDirective = "extern" "alias" Identifier ";"

NamespaceMemberDecl = NamespaceDecl | TypeDecl

TypeDecl = ClassDecl | StructDecl | InterfaceDecl | EnumDecl | DelegateDecl

A.2.7 Classes

ClassDecl = Attributes? ClassModifiers? "partial"? "class" Identifier

TypeParameterList? ClassBase? TypeParameterConstraintsClauses? ClassBody ";"? ClassModifier = "new" | "public" | "protected" | "internal" | "private"

ClassBody = "{" ClassMemberDecls? "}"

ClassMemberDecl = ConstantDecl | FieldDecl | MethodDecl | PropertyDecl | EventDecl

| IndexerDecl | OperatorDecl | ConstructorDecl | DestructorDecl

| StaticConstructorDecl | TypeDecl | GenericMethodDecl ConstantDecl = Attributes? ConstantModifiers? "const" Type ConstantDecltorList ";"

ConstantModifier = "new" | "public" | "protected" | "internal" | "private"

ConstantDecltor = Identifier "=" ConstantExpr

FieldDecl = Attributes? FieldModifiers? Type VariableDecltors ";"

FieldModifier = "new" | "public" | "protected" | "internal" | "private"

| "static" | "readonly" | "volatile" VariableDecltor = Identifier ( "=" VariableInitializer )?

VariableInitializer = Expression | ArrayInitializer

MethodDecl = MethodHeader MethodBody

MemberName = Identifier | (InterfaceType "." Identifier)

MethodBody = Block | ";"

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FixedParameter = Attributes? ParameterModifier? Type Identifier

ParameterModifier = "ref" | "out"

ParameterArray = Attributes? "params" ArrayType Identifier

PropertyDecl = Attributes? PropertyModifiers? Type MemberName "{" AccessorDecls "}" PropertyModifier = "new" | "public" | "protected" | "internal" | "private" | "static"

SetAccessorDecl = Attributes? AccessorModifier? "set" AccessorBody

AccessorModifier = "protected | "internal" | "private"

| ("protected" "internal") | ("internal" "protected") AccessorBody = Block | ";"

EventDecl = Attributes? EventModifiers? Event Type (VariableDecltors ";")

| (MemberName "{" EventAccessorDecls "}") EventModifier = "new" | "public" | "protected" | "internal" | "private" | "static"

RemoveAccessorDecl = Attributes? "remove" Block

IndexerDecl = Attributes? IndexerModifiers? IndexerDecltor "{" AccessorDecls "}"

OperatorDecl = Attributes? OperatorModifiers OperatorDecltor OperatorBody

OperatorModifier = "public" | "static" | "extern"

OperatorDecltor = UnaryOpDecltor | BinaryOpDecltor | ConversionOpDecltor

UnaryOpDecltor = Type "operator" OverloadableUnaryOp "(" Type Identifier ")"

OverloadableUnaryOp = "+" | "-" | "!" | "˜" | "++" | " " | "true" | "false"

BinaryOpDecltor = Type "operator" OverloadableBinaryOp

"(" Type Identifier "," Type Identifier ")" OverloadableBinaryOp = "+" | "-" | "*" | "/" | "%" | "&" | "|" | "ˆ" | "<<"

| ">>" | "==" | "!=" | ">" | "<" | ">=" | "<=" ConversionOpDecltor = ( Implicit | Explicit )? "operator" Type "(" Type Identifier ")" OperatorBody = Block | ";"

ConstructorDecl = Attributes? ConstructorModifiers? ConstructorDecltor ConstructorBody ConstructorModifier = "public" | "protected" | "internal" | "private" | "extern"

ConstructorDecltor = Identifier "(" FormalParameterList? ")" ConstructorInitializer? ConstructorInitializer = ":" ( "base" | "this" )? "(" ArgumentList? ")"

ConstructorBody = Block | ";"

StaticConstructorDecl = Attributes? StaticConstructorModifiers

Identifier "(" ")" StaticConstructorBody StaticConstructorModifiers = ( "extern"? "static" ) | ( "static" "extern"? )

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