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ECMAScript_5.peg
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ECMAScript_5.peg
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; The entire ECMAScript language as a Parser Expression Grammar
; Parser rules which share a name with ECMA-262 productions are intended to match the same language (though not necessarily with the same derivation).
Program ←
(S? (Statement / FunctionDeclaration))* S?
FunctionBody ←
(S? (Statement / FunctionDeclaration))* S?
FunctionDeclaration ←
FunctionTok S? Identifier S? "(" S? FormalParameterList? S? ")" S? "{" S? FunctionBody S? "}"
FunctionExpression ←
FunctionTok S? Identifier? S? "(" S? FormalParameterList? S? ")" S? "{" S? FunctionBody S? "}"
FormalParameterList ←
Identifier ("," S? Identifier)*
UseStrictDirective ←
"use" S "strict" S ( "," !(LineTerminator) SourceCharacter )*
; Statements
Statement
← Block
/ VariableStatement
/ EmptyStatement
/ ExpressionStatement
/ IfStatement
/ IterationStatement
/ ContinueStatement
/ BreakStatement
/ ReturnStatement
/ WithStatement
/ LabelledStatement
/ SwitchStatement
/ ThrowStatement
/ TryStatement
/ DebuggerStatement
Block ← "{" (S? Statement)* S? "}"
VariableStatement ←
VarTok S? VariableDeclaration (S? "," S? VariableDeclaration)* EOS
VariableDeclaration ←
Identifier (S? "=" !("=") S? AssignmentExpression)?
VariableDeclarationNoIn ←
Identifier (S? "=" !("=") S? AssignmentExpressionNoIn)?
VariableDeclarationListNoIn ←
VariableDeclarationNoIn (S? "," S? VariableDeclarationNoIn)*
; an empty statement is marked by an explicit semicolon, ASI does not apply
EmptyStatement ← ";"
ExpressionStatement ← !("{" / FunctionTok) Expression EOS
IfStatement ← IfTok S? "(" S? Expression S? ")" S? Statement (S? ElseTok S? Statement)?
IterationStatement ←
DoWhileStatement
/ WhileStatement
/ ForInStatement
/ ForStatement
DoWhileStatement ←
DoTok S? Statement S? WhileTok S? "(" S? Expression S? ")" EOS
WhileStatement ←
WhileTok S? "(" S? Expression S? ")" S? Statement
ForInStatement ←
ForTok S? "(" (ForInLeft/ForInVarLeft) InTok S? Expression S? ")" S? Statement
ForInLeft ← S? LeftHandSideExpression S?
ForInVarLeft ← S? VarTok S? VariableDeclarationNoIn S?
ForStatement ←
ForTok S? "(" S? (ForInit/ForVarInit)? S? ";" S? ForTest? S? ";" S? ForUpdate? S? ")" S? Statement
ForInit ← ExpressionNoIn
ForVarInit ← VarTok S? VariableDeclarationListNoIn
ForTest ← Expression
ForUpdate ← Expression
ContinueStatement ←
ContinueTok SnoLB? (Identifier EOS / EOSnoLB)
BreakStatement ←
BreakTok SnoLB? (Identifier EOS / EOSnoLB)
ReturnStatement ←
ReturnTok SnoLB? (EOSnoLB / Expression EOS)
WithStatement ←
WithTok S? "(" S? Expression S? ")" S? Statement
LabelledStatement ←
Identifier S? ":" S? Statement
SwitchStatement ←
SwitchTok S? "(" S? Expression S? ")" S? "{" CaseClause* (DefaultClause CaseClause*)? S? "}"
CaseClause ←
S? CaseTok S? Expression S? ":" (S? Statement)*
DefaultClause ←
S? DefaultTok S? ":" (S? Statement)*
ThrowStatement ←
ThrowTok SnoLB? (EOSnoLB / Expression EOS)
TryStatement ←
TryTok S? Block S? (Catch S? Finally? / Finally)
Catch ←
CatchTok S? "(" S? Identifier S? ")" S? Block
Finally ←
FinallyTok S? Block
DebuggerStatement ←
DebuggerTok S? EOS
; Expressions
Expression ←
AssignmentExpression (S? "," S? AssignmentExpression)*
ExpressionNoIn ←
AssignmentExpressionNoIn (S? "," S? AssignmentExpressionNoIn)*
AssignmentExpression ←
LeftHandSideExpression S? AssignmentOperator S? AssignmentExpression
/ ConditionalExpression
AssignmentExpressionNoIn ←
LeftHandSideExpression S? AssignmentOperator S? AssignmentExpressionNoIn
/ ConditionalExpressionNoIn
AssignmentOperator ←
"=" !("=") / "*=" / "/=" / "%=" / "+=" / "-=" / "<<=" / ">>=" / ">>>=" / "&=" / "^=" / "|="
ConditionalExpression ←
LogicalOrExpression (S? "?" S? AssignmentExpression S? ":" S? AssignmentExpression)?
ConditionalExpressionNoIn ←
LogicalOrExpressionNoIn (S? "?" S? AssignmentExpressionNoIn S? ":" S? AssignmentExpressionNoIn)?
LogicalOrExpression ←
LogicalAndExpression (S? "||" S? LogicalAndExpression)*
LogicalOrExpressionNoIn ←
LogicalAndExpressionNoIn (S? "||" S? LogicalAndExpressionNoIn)*
LogicalAndExpression ←
BitwiseOrExpression (S? "&&" S? BitwiseOrExpression)*
LogicalAndExpressionNoIn ←
BitwiseOrExpressionNoIn (S? "&&" S? BitwiseOrExpressionNoIn)*
BitwiseOrExpression ←
BitwiseXOrExpression (S? "|" !("=") S? BitwiseXOrExpression)*
BitwiseOrExpressionNoIn ←
BitwiseXOrExpressionNoIn (S? "|" !("=") S? BitwiseXOrExpressionNoIn)*
BitwiseXOrExpression ←
BitwiseAndExpression (S? "^" !("=") S? BitwiseAndExpression)*
BitwiseXOrExpressionNoIn ←
BitwiseAndExpressionNoIn (S? "^" !("=") S? BitwiseAndExpressionNoIn)*
BitwiseAndExpression ←
EqualityExpression (S? "&" !("=") S? EqualityExpression)*
BitwiseAndExpressionNoIn ←
EqualityExpressionNoIn (S? "&" !("=") S? EqualityExpressionNoIn)*
EqualityExpression ←
RelationalExpression (S? EqualityOp S? RelationalExpression)*
EqualityExpressionNoIn ←
RelationalExpressionNoIn (S? EqualityOp S? RelationalExpressionNoIn)*
EqualityOp ← "===" / "!==" / "==" / "!="
RelationalExpression ←
ShiftExpression (S? RelationalOp S? ShiftExpression)*
RelationalExpressionNoIn ←
ShiftExpression (S? RelationalOpNoIn S? ShiftExpression)*
RelationalOp ←
"<=" / ">=" / "<" / ">" / InstanceOfTok / InTok
RelationalOpNoIn ←
"<=" / ">=" / "<" / ">" / InstanceOfTok
ShiftExpression ←
AdditiveExpression (S? ShiftOp S? AdditiveExpression)*
ShiftOp ←
"<<" / ">>>" / ">>"
AdditiveExpression ←
MultiplicativeExpression (S? AdditiveOp S? MultiplicativeExpression)*
AdditiveOp ←
"+" !("+"/"=")
/ "-" !("-"/"=")
MultiplicativeExpression ←
UnaryExpression (S? MultiplicativeOp S? UnaryExpression)*
MultiplicativeOp ←
("*" / "/" / "%") !("=")
UnaryExpression ←
PostfixExpression
/ DeleteExpression
/ VoidExpression
/ TypeofExpression
/ PreIncrementExpression
/ PreDecrementExpression
/ UnaryPlusExpression
/ UnaryMinusExpression
/ BitwiseNotExpression
/ LogicalNotExpression
DeleteExpression ← DeleteTok S? UnaryExpression
VoidExpression ← VoidTok S? UnaryExpression
TypeofExpression ← TypeofTok S? UnaryExpression
PreIncrementExpression ← "++" S? UnaryExpression
PreDecrementExpression ← "--" S? UnaryExpression
UnaryPlusExpression ← "+" S? UnaryExpression
UnaryMinusExpression ← "-" S? UnaryExpression
BitwiseNotExpression ← "~" S? UnaryExpression
LogicalNotExpression ← "!" S? UnaryExpression
; why isn't ++a++ a valid UnaryExpression?
; answer: it is, and parses as ++(a++), the evaluation of which must throw a ReferenceError per spec
PostfixExpression ←
LeftHandSideExpression (SnoLB? (PostIncrementOp/PostDecrementOp))?
PostIncrementOp ← "++"
PostDecrementOp ← "--"
; This LHSExpression adheres to the spec, which gives semantics for CallExpression and NewExpression
; See ECMAScript_5_streamable.peg for an alternative approach.
LeftHandSideExpression ←
CallExpression
/ NewExpression
CallExpression ←
MemberExpression S? Arguments (S? Arguments / S? BracketAccessor / S? DotAccessor)*
BracketAccessor ←
"[" S? Expression S? "]"
DotAccessor ←
"." S? IdentifierName
Arguments ←
"(" S? ArgumentList? S? ")"
ArgumentList ←
AssignmentExpression (S? "," S? AssignmentExpression)*
NewExpression ←
MemberExpression
/ NewTok S? NewExpression
MemberExpression ←
( PrimaryExpression
/ FunctionExpression
/ NewTok S? MemberExpression S? Arguments
) ( S? "[" S? Expression S? "]"
/ S? "." S? IdentifierName
)*
PrimaryExpression ←
ThisTok
/ Identifier
/ Literal
/ ArrayLiteral
/ ObjectLiteral
/ "(" S? Expression S? ")"
ArrayLiteral ←
"[" Elision? S? "]"
/ "[" ElementList S? "]"
/ "[" ElementList S? "," Elision? S? "]"
ElementList ←
Elision? S? AssignmentExpression (S? "," Elision? S? AssignmentExpression)*
Elision ←
(S? ",") Elision?
ObjectLiteral ←
"{" ( S? PropertyNameAndValueList S? ","? )? S? "}"
PropertyNameAndValueList ←
PropertyAssignment (S? "," S? PropertyAssignment)*
PropertyAssignment ←
PropertyName S? ":" S? AssignmentExpression
/ PropertyGetter
/ PropertySetter
PropertyGetter ←
"get" S? PropertyName S? "(" S? ")" S? "{" S? FunctionBody S? "}"
PropertySetter ←
"set" S? PropertyName S? "(" S? PropertySetParameterList S? ")" S? "{" S? FunctionBody S? "}"
PropertyName ←
IdentifierName / StringLiteral / NumericLiteral
PropertySetParameterList ←
Identifier
; Lexical tokens
Literal
← NullLiteral
/ BooleanLiteral
/ NumericLiteral
/ StringLiteral
/ RegularExpressionLiteral
NullLiteral
← NullTok
BooleanLiteral
← TrueTok
/ FalseTok
NumericLiteral ← DecimalLiteral !(IdentifierStart)
/ HexIntegerLiteral !(IdentifierStart)
DecimalLiteral ← DecimalIntegerLiteral "." DecimalDigit* ExponentPart?
/ "." DecimalDigit+ ExponentPart?
/ DecimalIntegerLiteral ExponentPart?
DecimalIntegerLiteral ← "0"
/ [1-9] DecimalDigit*
DecimalDigit ← [0-9]
ExponentPart ← [eE] SignedInteger
SignedInteger ← DecimalDigit+
/ "+" DecimalDigit+
/ "-" DecimalDigit+
HexIntegerLiteral ← "0x" HexDigit+
/ "0X" HexDigit+
DQ ← [U+0022]
SQ ← [U+0027]
StringLiteral ← DQ DoubleStringCharacter* DQ
/ SQ SingleStringCharacter* SQ
RS ← [U+005C]
DoubleStringCharacter ← !( DQ / RS / LineTerminator ) SourceCharacter
/ RS EscapeSequence
/ LineContinuation
SingleStringCharacter ← !( SQ / RS / LineTerminator ) SourceCharacter
/ RS EscapeSequence
/ LineContinuation
LineContinuation ← RS LineTerminatorSequence
EscapeSequence ← CharacterEscapeSequence
/ "0" !(DecimalDigit)
/ HexEscapeSequence
/ UnicodeEscapeSequence
CharacterEscapeSequence ← SingleEscapeCharacter
/ NonEscapeCharacter
SingleEscapeCharacter ← [ U+0027 U+0022 U+005C b f n r t v ]
NonEscapeCharacter ← !(EscapeCharacter / LineTerminator) SourceCharacter
EscapeCharacter ← SingleEscapeCharacter
/ DecimalDigit
/ [ x u ]
HexEscapeSequence ← "x" HexDigit HexDigit
UnicodeEscapeSequence ← "u" HexDigit{4}
RegularExpressionLiteral ← "/" RegularExpressionBody "/" RegularExpressionFlags
RegularExpressionBody ← RegularExpressionFirstChar RegularExpressionChar*
RegularExpressionFirstChar ← !( LineTerminator / [ * U+005C / [ ] ) SourceCharacter
/ RegularExpressionBackslashSequence
/ RegularExpressionClass
RegularExpressionChar ← !( LineTerminator / [ U+005C / [ ] ) SourceCharacter
/ RegularExpressionBackslashSequence
/ RegularExpressionClass
RegularExpressionBackslashSequence ← RS !(LineTerminator) SourceCharacter
RegularExpressionClass ← "[" RegularExpressionClassChar* "]"
RegularExpressionClassChar ← !(LineTerminator / [ U+005C U+005D ]) SourceCharacter
/ RegularExpressionBackslashSequence
RegularExpressionFlags ← IdentifierPart*
SourceCharacter ← [ U+0000-U+10FFFF ]
WhiteSpace ← [ U+0009
U+000B
U+000C
U+0020
U+0085
U+00A0
U+200B
U+FEFF
[:Zs:] ]
LF ← [ U+000A ]
CR ← [ U+000D ]
LS ← [ U+2028 ]
PS ← [ U+2029 ]
LineTerminator ← LF / CR / LS / PS
LineTerminatorSequence ← LF / CR LF / CR / LS / PS
Comment ← MultiLineComment
/ SingleLineComment
MultiLineComment ← "/*" (!("*/") SourceCharacter)* "*/"
MultiLineCommentNoLB ← "/*" (!("*/") !(LineTerminator) SourceCharacter)* "*/"
SingleLineComment ← "//" [^ U+000A U+000D U+2028 U+2029 ]*
S ← ( WhiteSpace / LineTerminatorSequence / Comment )+
SnoLB ← ( WhiteSpace / SingleLineComment / MultiLineCommentNoLB )+
; end of statement
EOS
← S? ";"
/ SnoLB? LineTerminatorSequence
/ SnoLB? &("}")
/ S? EOF
; end of statement in a "no linebreak here" context
; EOSnoLB will consume a linebreak, but it won't extend to the next line
EOSnoLB
← SnoLB? ";"
/ SnoLB? LineTerminatorSequence
/ SnoLB? &("}")
/ SnoLB? EOF
EOF
← !(SourceCharacter)
ReservedWord
← ( Keyword
/ FutureReservedWord
/ "null"
/ "true"
/ "false"
) !(IdentifierPart)
Keyword
← "break" / "case" / "catch" / "continue" / "debugger" / "default" / "delete" / "do" / "else" / "finally" / "for" / "function" / "if" / "instanceof" / "in" / "new" / "return" / "switch" / "this" / "throw" / "try" / "typeof" / "var" / "void" / "while" / "with"
FutureReservedWord
← "abstract" / "boolean" / "byte" / "char" / "class" / "const" / "double" / "enum" / "export" / "extends" / "final" / "float" / "goto" / "implements" / "import" / "interface" / "int" / "long" / "native" / "package" / "private" / "protected" / "public" / "short" / "static" / "super" / "synchronized" / "throws" / "transient" / "volatile"
Identifier ← !(ReservedWord) IdentifierName
IdentifierName ← IdentifierStart IdentifierPart*
IdentifierStart ← UnicodeLetter
/ "$"
/ "_"
/ RS UnicodeEscapeSequence
IdentifierPart ← IdentifierStart
/ [ [:Mn:] [:Mc:]
[:Nd:]
[:Pc:] ]
UnicodeLetter ← [ [:Lu:]
[:Ll:]
[:Lt:]
[:Lm:]
[:Lo:]
[:Nl:] ]
HexDigit ← [ 0-9 a-f A-F ]
FalseTok ← "false" !(IdentifierPart)
TrueTok ← "true" !(IdentifierPart)
NullTok ← "null" !(IdentifierPart)
BreakTok ← "break" !(IdentifierPart)
ContinueTok ← "continue" !(IdentifierPart)
DebuggerTok ← "debugger" !(IdentifierPart)
InTok ← "in" !(IdentifierPart)
InstanceOfTok ← "instanceof" !(IdentifierPart)
DeleteTok ← "delete" !(IdentifierPart)
FunctionTok ← "function" !(IdentifierPart)
NewTok ← "new" !(IdentifierPart)
ThisTok ← "this" !(IdentifierPart)
TypeofTok ← "typeof" !(IdentifierPart)
VoidTok ← "void" !(IdentifierPart)
IfTok ← "if" !(IdentifierPart)
ElseTok ← "else" !(IdentifierPart)
DoTok ← "do" !(IdentifierPart)
WhileTok ← "while" !(IdentifierPart)
ForTok ← "for" !(IdentifierPart)
VarTok ← "var" !(IdentifierPart)
ReturnTok ← "return" !(IdentifierPart)
CaseTok ← "case" !(IdentifierPart)
DefaultTok ← "default" !(IdentifierPart)
SwitchTok ← "switch" !(IdentifierPart)
ThrowTok ← "throw" !(IdentifierPart)
CatchTok ← "catch" !(IdentifierPart)
FinallyTok ← "finally" !(IdentifierPart)
TryTok ← "try" !(IdentifierPart)
WithTok ← "with" !(IdentifierPart)