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COMPILER AdaCS
(* A subset of Ada from Fischer/LeBlanc: "Crafting a Compiler" *)
IGNORE CASE
CHARACTERS
letter = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".
digit = "0123456789".
eol = CHR(13).
anyButQuote = ANY - '"' - eol.
COMMENTS
FROM "--" TO eol
TOKENS
id = letter { ["_"] (letter | digit) }.
int = digit { ["_"] digit}.
float = digit { ["_"] digit}
( "." digit { ["_"] digit }
[ ("E" | "e") ["+" | "-"] digit { ["_"] digit } ]
| ("E" | "e") ["+" | "-"] digit { ["_"] digit }
).
str = '"' {anyButQuote | '""'} '"'.
PRODUCTIONS
AdaCS = PragmaList CompUnit {PragmaList CompUnit}.
PragmaList = {Pragma}.
Pragma = "PRAGMA" id ";".
CompUnit = PackDecl.
PackDecl = "PACKAGE" PackSpecOrBody ";".
PackSpecOrBody = id "IS" {SpecDecl} [PrivPart] BodyOpt "END" IdOpt ";"
| "BODY" id "IS" {BodyDecl} {Stat} [ExcPart] "END" IdOpt ";".
BodyOpt = ["BODY" {BodyDecl} {Stat} [ExcPart]].
IdOpt = [id].
SpecDecl = PrivTypeDecl | Decl.
PrivTypeDecl = "TYPE" id "IS" "PRIVATE" ";".
PrivPart = "PRIVATE" PrivItem {PrivItem}.
PrivItem = "SUBTYPE" id "IS" SubtypeDef ";" | "TYPE" id "IS" TypeDef.
BodyDecl = SubprogBodyDecl | Decl.
Decl = ObjDecl | TypeDecl | SubtypeDecl | Pragma
| SubprogBodyDecl | "USE" NameList ";"
| IdList ":" "EXCEPTION" .
ObjDecl = IdList ":" ConstOpt TypeOrSubtype InitOpt ";".
IdList = id { "," id}.
ConstOpt = ["CONSTANT"].
TypeOrSubtype = Type | SubtypeDef.
InitOpt = [":=" Expr].
TypeDecl = "TYPE" id "IS" TypeDef ";" | IncomplTypeDecl.
Type = TypeName | TypeDef.
TypeName = id.
TypeDef = RecTypeDef | ArrTypeDef | EnumTypeDef | "ACCESS" Subtype.
IncomplTypeDecl = "TYPE" id ";".
RecTypeDef = "RECORD" CompList "END" "RECORD".
CompList = CompDecl {CompDecl} | {CompDecl} VarPart | "NULL" ";".
CompDecl = IdList ":" TypeOrSubtype.
VarPart = "CASE" id ":" TypeName "IS" Var {Var} "END" "CASE" ";".
Var = "WHEN" VarChoice "=>" CompList.
VarChoice = SimpleExpr.
ArrTypeDef = UnconstrArrDef | ConstrArrDef.
UnconstrArrDef = "ARRAY" UnconstrIndexList "OF" ElemType.
UnconstrIndexList= "(" IndexSubtypeDef {"," IndexSubtypeDef} ")".
IndexSubtypeDef = TypeName "RANGE" "<>".
ConstrArrDef = "ARRAY" ConstrIndexList "OF" ElemType.
ConstrIndexList = "(" DiscrRange {"," DiscrRange} ")".
ElemType = TypeOrSubtype.
EnumTypeDef = "(" EnumIdList ")".
EnumIdList = id {"," id}.
SubtypeDecl = "SUBTYPE" id "IS" SubtypeDef ";".
Subtype = TypeName | SubtypeDef.
SubtypeDef = [ TypeName ] RangeConstr | TypeName IndexConstr.
RangeConstr = "RANGE" Range.
Range = SimpleExpr ".." SimpleExpr.
IndexConstr = "(" DiscrRange {"," DiscrRange} ")".
DiscrRange = Subtype | Range.
SubprogBodyDecl = SubprogSpec "IS" {BodyDecl} {Stat} [ExcPart] "END" IdOpt ";".
SubprogSpec = "PROCEDURE" id FormalPart | "FUNCTION" Design FormalPart.
Design = id | OpSymbol.
OpSymbol = str.
FormalPart = "(" ParamDeclList ")".
ParamDeclList = ParamDecl {";" ParamDecl}.
ParamDecl = IdList ":" [Mode] TypeOrSubtype.
Mode = "IN" ["OUT"] | "OUT".
ExcPart = "EXCEPTION" {ExcHandler}.
ExcHandler = "WHEN" ExcWhenTail.
ExcWhenTail = "OTHERS" "=>" StatList | Name { "|" Name } "=>" StatList.
Stat = Pragma | NullStat | AssignStat | CallStat | Block | LoopStat
| IfStat | ExitStat | ReturnStat | CaseStat | RaiseStat.
StatList = Stat {Stat}.
NullStat = "NULL" ";".
AssignStat = Name ":=" Expr ";".
CallStat = Name ";".
Block = [id ":"] [DeclPart] "BEGIN" {Stat} [ExcPart] "END" [ id] ";".
DeclPart = "DECLARE" BodyDecl.
ReturnStat = "RETURN" [Expr] ";".
RaiseStat = "RAISE" [Name] ";".
IfStat = "IF" Expr "THEN" StatList {"ELSIF" Expr "THEN" StatList}
[ElsePart] "END" "IF" ";".
ElsePart = "ELSE" StatList.
LoopStat = [id ":"] [IterClause] BasicLoop ";".
BasicLoop = "LOOP" {Stat} "END" "LOOP" ";".
IterClause = "WHILE" Expr | "FOR" id "IN" ["REVERSE"] DiscrRange.
ExitStat = "EXIT" [Name] ["WHEN" Expr] ";".
CaseStat = "CASE" Expr "IS" WhenList OthersOpt "END" "CASE" ";".
WhenList = {ChoiceList "=>" StatList}.
OthersOpt = ["WHEN" "OTHERS" "=>" StatList].
ChoiceList = Choice {"|" Choice}.
Choice = Expr | Expr ".." Expr.
Expr = Rel {LogOp Rel} | Rel {"AND" "THEN" Rel} | Rel {"OR" "ELSE" Rel}.
Rel = SimpleExpr [RelOp SimpleExpr].
SimpleExpr = [UnaryAddOp] Term {AddOp Term}.
Term = Factor {MulOp Factor}.
Factor = Primary ["**" Primary] | "NOT" Primary | "ABS" Primary.
Primary = Literal | Name | "(" Expr ")" | Agg.
Literal = int | float | str.
LogOp = "AND" | "OR".
RelOp = "=" | "/=" | "<" | "<=" | ">" | ">=".
AddOp = "+" | "-" | "&".
UnaryAddOp = "+" | "-".
MulOp = "*" | "/" | "MOD".
Name = SimpleName {NameSuffix} ["." "ALL"].
SimpleName = id.
NameSuffix = "." SelSuffix | "(" Expr {"," Expr}")" | "'" id.
SelSuffix = id | OpSymbol.
Agg = Name "'" "(" Comp {"," Comp}")".
Comp = [AggChoiceList "=>"] Expr.
AggChoiceList = AggChoice {"|" AggChoice}.
AggChoice = SimpleName | SimpleExpr | DiscrRange | "OTHERS".
NameList = Name { "," Name } .
END AdaCS.
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