BNF Grammar: Difference between revisions

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! -----------------------------------------------------------------------

! Standard Pascal Grammar

! -----------------------------------------------------------------------

"Name" = 'Pascal'

"Version" = '1973'

"Author" = 'Niklaus Wirth'

"About" = 'PASCAL was developed by NIKLAUS WIRTH of the ETH Technical Institute of Zuerich in 1970-1971.(published in 1973)'

"Case Sensitive" = False

"Start Symbol" = <Program>

{Hex Digit} = {Digit} + [abcdefABCDEF]

{Id Head} = {Letter} + [_]

{Id Tail} = {Id Head} + {Digit}

{String Ch} = {Printable} - ['']

{Char Ch} = {Printable} - ['']

DecLiteral = [123456789]{digit}*

HexLiteral = '$'{Hex Digit}+

FloatLiteral = {Digit}*.{Digit}+

StringLiteral = ''( {String Ch} | '\'{Printable} )* ''

CharLiteral = '' ( {Char Ch} | '\'{Printable} )''

id = {Id Head}{Id Tail}*

<constant> ::= DecLiteral

| StringLiteral

| FloatLiteral

| HexLiteral

| CharLiteral

!=========================================== Program

<Program> ::= <ProgramHeader> <Declarations> <CompoundStatement> '.'

<ProgramHeader> ::= PROGRAM id ';'

| PROGRAM id '(' <IdList> ')' ';'

<Declarations> ::= <ConstantDefinitions> <TypeDefinitions> <VariableDeclarations> <ProcedureDeclarations>

<ConstantDefinitions> ::= CONST <ConstantDefinitionList>

|

<ConstantDefinitionList> ::= <ConstantDef>

| <ConstantDef> <ConstantDefinitionList>

<ConstantDef> ::= id '=' <constant> ';'

<TypeDefinitions> ::= TYPE <TypeDefinitionList>

|

<TypeDefinitionList> ::= <TypeDef>

| <TypeDef> <TypeDefinitionList>

<TypeDef> ::= id '=' <TypeSpecifier> ';'

<VariableDeclarations> ::= VAR <VariableDeclarationList>

|

<VariableDeclarationList> ::= <VariableDec>

| <VariableDec> <VariableDeclarationList>

<VariableDec> ::= <IdList> ':' <TypeSpecifier> ';'

<ProcedureDeclarations> ::= <ProcedureDec> <ProcedureDeclarations>

|

<ProcedureDec> ::= <ProcedureHeader> FORWARD ';'

| <ProcedureHeader> <Declarations> <CompoundStatement> ';'

| <FunctionHeader> FORWARD ';'

| <FunctionHeader> <Declarations> <CompoundStatement> ';'

<ProcedureHeader> ::= PROCEDURE id <Arguments> ';'

<FunctionHeader> ::= FUNCTION id <Arguments> ':' <TypeSpecifier> ';'

<Arguments> ::= '(' <ArgumentList> ')'

|

<ArgumentList> ::= <Arg>

| <Arg> ';' <ArgumentList>

<Arg> ::= <IdList> ':' <TypeSpecifier>

| VAR <IdList> ':' <TypeSpecifier>

<CompoundStatement> ::= BEGIN <StatementList> END

<StatementList> ::= <Statement>

| <Statement> ';' <StatementList>

<Statement> ::= <CompoundStatement>

| <AssignmentStatement>

| <ProcedureCall>

| <ForStatement>

| <WhileStatement>

| <IfStatement>

| <CaseStatement>

| <RepeatStatement>

|

<AssignmentStatement> ::= <Variable> ':=' <Expression>

<ProcedureCall> ::= id <Actuals>

<ForStatement> ::= FOR id ':=' <Expression> TO <Expression> DO <Statement>

| FOR id ':=' <Expression> DOWNTO <Expression> DO <Statement>

<WhileStatement> ::= WHILE <Expression> DO <Statement>

<IfStatement> ::= IF <Expression> THEN <Statement> ELSE <Statement>

<RepeatStatement> ::= REPEAT <StatementList> UNTIL <Expression>

<CaseStatement> ::= CASE <Expression> OF <CaseList> END

<CaseList> ::= <Case>

| <Case> ';' <CaseList>

<Case> ::= <ConstantList> ':' <Statement>

<ConstantList> ::= <constant>

| <constant> ',' <ConstantList>

<Expression> ::= <SimpleExpression>

| <SimpleExpression> '=' <SimpleExpression>

| <SimpleExpression> '<>' <SimpleExpression>

| <SimpleExpression> '<' <SimpleExpression>

| <SimpleExpression> '<=' <SimpleExpression>

| <SimpleExpression> '>' <SimpleExpression>

| <SimpleExpression> '>=' <SimpleExpression>

<SimpleExpression> ::= <Term>

| <SimpleExpression> '+' <Term>

| <SimpleExpression> '-' <Term>

| <SimpleExpression> OR <Term>

<Term> ::= <Factor>

| <Term> '*' <Factor>

| <Term> '/' <Factor>

| <Term> 'DIV' <Factor>

| <Term> 'MOD' <Factor>

| <Term> 'AND' <Factor>

<Factor> ::= '(' <Expression> ')'

| '+' <Factor>

| '-' <Factor>

| NOT <Factor>

| <constant>

| <Variable>

<FunctionCall> ::= id <Actuals>

<Actuals> ::= '(' <ExpressionList> ')'

|

<ExpressionList> ::= <Expression>

| <Expression> ',' <ExpressionList>

<Variable> ::= id

| <Variable> '.' id

| <Variable> '^'

| <Variable> '[' <ExpressionList> ']'

<TypeSpecifier> ::= id

| '^' <TypeSpecifier>

| '(' <IdList> ')'

| <constant> '..' <constant>

| ARRAY '[' <DimensionList> ']' OF <TypeSpecifier>

| RECORD <FieldList> END

| FILE OF <TypeSpecifier>

<DimensionList> ::= <Dimension>

| <Dimension> ',' <DimensionList>

<Dimension> ::= <constant> '..' <constant>

| id

<FieldList> ::= <Field>

| <Field> ';' <FieldList>

<Field> ::= <IdList> ':' <TypeSpecifier>

<IdList> ::= id

| id ',' <IdList>

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