LMD ScriptPack Guide

BNF Syntax

<Unit> ::=
  [<UsesClause>] {<VarSection> | <ConstSection> | <ProcedureDecl>}
  [begin <StmtList> end ";"]

<UsesClause> ::=
  uses <Identifier> {"," <Identifier>} ";"

<VarSection> ::=
  var <VarDecl> ";" {<VarDecl> ";"}

<VarDecl> ::=
  <Identifier> ({"," <Identifier>} | "=" <Expression>)

<ConstSection> ::=
  const <ConstDecl> ";" {<ConstDecl> ";"}

<ConstDecl> ::=
  <Identifier> "=" <Expression>

<ProcedureDecl> ::=
  (procedure | function) <Identifier> ["(" <ParamsDecl> ")"] ";"
  {<VarSection> | <ConstSection>}
  begin <StmtList> end ";"

<ParamsDecl> ::=
  <ParamDecl> {";" <ParamDecl>}

<ParamDecl> ::=
  (var | out | const ) <Identifier>

<Statement> ::=
  <Designator> [":=" <Expression>] |
  <CompoundStmt> |
  <IfStmt> |
  <CaseStmt> |
  <RepeatStmt> |
  <WhileStmt> |
  <ForStmt> |
  <TryStmt> |
  <RaiseStmt> |
  <EmptyStmt>

<StmtList> ::=
  <Statement> ";" {<Statement> ";"}

<EmptyStmt> ::= // Special processing. We look for one of these tokens,
                // but not really skips it.
  ";" |
  else |
  until |
  end

<CompoundStmt> ::=
  begin <StmtList> end

<IfStmt> ::=
  if <Expression> then <Statement> [else <Statement>]

<CaseStmt> ::=
  case <Expression> of <CaseSelector> ";" {<CaseSelector> ";"}
  [else <StmtList>] end

<CaseSelector> ::=
  <CaseLabel> {"," <CaseLabel>} ":" <Statement>

<CaseLabel> ::=
  <Expression> [".." <Expression>]

<RepeatStmt> ::=
  repeat <StmtList> until <Expression>

<WhileStmt> ::=
  while <Expression> do <Statement>

<ForStmt> ::=
  for <Identifier> ":=" <Expression> (to | downto) <Expression> do
  <Statement>

<TryStmt> ::=
  try [<StmtList>] (except (<ExceptionBlock> | <StmtList>) |
                    finally <StmtList>)
  end

<ExceptionBlock> ::=
  {on [<Identifier> ":"] <Expression> do <Statement> ";"}
  [else <StmtList>]

<RaiseStmt> ::=
  raise [<Expression>]

<Expression> ::=
    <SimpleExpression> {<RelOp> <SimpleExpression>}

<SimpleExpression> ::=
    <Term> {<AddOp> <Term>}

<Term> ::=
    <Factor> {<MulOp> <Factor>}

<Factor> ::=
    <Designator> |
    INT_LITERAL |
    FLOAT_LITERAL |
    STRING_LITERAL |
    nil |
    "(" <Expression> ")" |
    not <Factor> |
    "-" <Factor> |
    "+" <Factor> |
    <SetConstructor> |
    array "[" <ArrayDim> {"," <ArrayDim>} "]" [of <Identifier>]
    "@" <Identifier>

<ArrayDim> ::=
  <Expression> [".." <Expression>]

<RelOp> ::=
    ">" |
    "<" |
    "<=" |
    ">=" |
    "<>" |
    "=" |
    in |
    is

<AddOp> ::=
    "+" |
    "-" |
    or |
    xor

<MulOp> ::=
    "*" |
    "/" |
    div |
    mod |
    and |
    shl |
    shr

<Designator> ::=
    <Identifier> {"." <Identifier> |
                  "[" <Expression> {"," <Expression>} "]" |
                  "(" [<Expression> {"," <Expression>}] ")"}

<SetConstructor> ::=
    "[" [<SetElement> {"," <SetElement>}] "]"

<SetElement> ::=
    <Expression> [".." <Expression>]

<Identifier> ::=
  IDENTIFIER