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ybparser.bmx
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ybparser.bmx
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' YBC parser
' from the B grammar found in "User's Reference to B"
SuperStrict
Import "TMeta.bmx" 'Get this here: http://www.blitzbasic.com/codearcs/codearcs.php?code=3090
Function YBParseFile:TParseNode(file:String)
Global p:YBParser, l:TLexer
If FileType(file) = 0 Then Throw "File '" + file + "' does not exist" ElseIf FileType(file) <> 1 Then Throw "'" + file + "' is not a valid source file"
If p = Null Then p = New YBParser
If l = Null Then l = YBLexer.Get()
Local toks:TList = ListFromArray(l.ScanFile(file))
Local k:TLink = toks.FirstLink() ; If k Then k = k.NextLink() 'Normalize token stream (remove duplicate separators and handle character escapes)
While k
Local t:TToken = TToken(k.Value())
If t.ttype = "separator" And TToken(k.PrevLink().Value()).ttype = "separator"
k.Remove()
ElseIf t.ttype = "cconst" Or t.ttype = "sconst"
t.value = ApplyCharEscapes(t.value)
EndIf
k = k.NextLink()
Wend
Local tree:TParseNode = p.Parse(TToken[](toks.ToArray()))
Local newTop:TList = CreateList() 'Normalize toplevel (remove null statements)
For Local n:TParseNode = EachIn tree.elem
If n.rule <> "NullSt" Then newTop.AddLast n
Next
tree.elem = TParseNode[](newTop.ToArray())
Return tree
End Function
Type YBParser Extends TMetaParser Final
Field grammar:TMap {..
Program = "Definition* : @ ^"..
..
Definition = "FunDef | VarDef | NullSt"..
VarDef = "%name VarDefDim? VarDefVal* IVal? %!separator : @name @dim @inits < -"..
VarDefDim = "%lbracket ! Constant? %!rbracket : @ @dim @ ^".. 'intentionally not dropped
VarDefVal = "IVal %comma : @ - ^"..
FunDef = "%name %lparen ! NameRep* %name? %!rparen Statement : @name - @args < - @body"..
NameRep = "%name %comma : @ - ^"..
..
IVal = "Constant | %name"..
Constant = "%iconst | %cconst | %sconst"..
..
Statement = "LocalVarSt | ExtrnVarSt | CaseSt | BreakSt | DefaultSt | LabelSt | BlockSt | IfSt | WhileSt | SwitchSt | GotoSt | ReturnSt | ValSt | NullSt"..
LocalVarSt = "%auto ! LocalVarRep* LocalVarDef %!separator : - @names < -"..
LocalVarDef = "%name (VarDefDim | Constant?) : @name @dim"..
LocalVarRep = "LocalVarDef %comma : @ - ^"..
ExtrnVarSt = "%extrn ! NameRep* %!name %separator : - @names < -"..
LabelSt = "%name %colon : @name -"..
CaseSt = "%case ! Constant %!colon : - @case -"..
BreakSt = "%break %!separator : @break -"..
DefaultSt = "%default %!colon : @default -"..
BlockSt = "%lbrace ! StatementList %!rbrace : - @ - ^"..
StatementList = "Statement*"..
IfSt = "%if ! %!lparen RValue %!rparen Statement ElseSt? : - - @expr - @then @else"..
ElseSt = "%else Statement : - @ ^"..
WhileSt = "%while ! %!lparen RValue %!rparen Statement : - - @expr - @body"..
SwitchSt = "%switch ! RValue Statement : - @expr @body"..
GotoSt = "%goto RValue %!separator : - @dst -"..
ReturnSt = "%return ! ReturnVal? %!separator : @ @val -".. 'not dropped
ReturnVal = "%lparen ! RValue %!rparen : - @ - ^"..
ValSt = "RValue %!separator : @val -"..
NullSt = "%separator : @nil"..
..
RValue = "AssignLeft* TernaryExpr : @L @R ^"..
AssignLeft = "UnaryExpr AssignOp : @lv @op"..
AssignOp = "%equals | %aor | %aand | %aeq | %aneq | %alt | %aleq | %agt | %ageq | %ashl | %ashr | %aminus | %aplus | %amod | %atimes | %adiv"..
TernaryExpr = "OrExpr TernaryBody? : @expr @tail ^"..
TernaryBody = "%qmark ! RValue %!colon RValue : - @then - @else"..
OrExpr = "AndExpr (%or AndExpr)* : @L @R ^"..
AndExpr = "EqExpr (%and EqExpr)* : @L @R ^"..
EqExpr = "RelExpr ((%eq | %neq) RelExpr)* : @L @R ^"..
RelExpr = "ShiftExpr ((%lt | %leq | %gt | %geq) ShiftExpr)* : @L @R ^"..
ShiftExpr = "AddExpr ((%shl | %shr) AddExpr)* : @L @R ^"..
AddExpr = "MulExpr ((%plus | %minus) MulExpr)* : @L @R ^"..
MulExpr = "UnaryExpr ((%times | %div | %mod) UnaryExpr)* : @L @R ^"..
UnaryExpr = "(%minus | %plus | %and | %not | %times | %incr | %decr)* PostfixExpr : @op @val ^"..
PostfixExpr = "AtomicExpr (Index | FunCall | %incr | %decr)* : @val @op ^"..
Index = "%lbracket ! RValue %!rbracket : - @elem -"..
FunCall = "%lparen ! RValueRep* RValue? %!rparen : @ @args < @".. 'not dropped
RValueRep = "RValue %comma : @ - ^"..
AtomicExpr = "Constant | %name | ParenExpr"..
ParenExpr = "%lparen ! RValue %!rparen : - @ - ^"..
}
End Type
Type YBLexer Final
Function Get:TLexer()
Global Store(_:TLexer) = TLexAction.Store, Mode(_:TLexer) = TLexAction.Mode, Discard(_:TLexer) = TLexAction.Discard
Global l:TLexer = TLexer.withRules([..
R("[0-9]*", Store, "iconst"),.. 'int
R("'([^']|\*')*'", Store, "cconst"),.. 'char
R("~q([^~q]|\*~q)*~q", Store, "sconst"),.. 'string
..
R("/\*", Mode, "COMMENT", ""),.. 'C89-style comments only
R(".", Discard, "", "COMMENT"),..
R("\*/", Mode, "", "COMMENT"),..
..
R("\+\+", Store, "incr"),.. 'Any Regex operators need to be escaped with \
R("--", Store, "decr"),..
R("!", Store, "not"),..
R("\|", Store, "or"),..
R("&", Store, "and"),..
R("==", Store, "eq"),..
R("!=", Store, "neq"),..
R("<", Store, "lt"),..
R("<=", Store, "leq"),..
R(">", Store, "gt"),..
R(">=", Store, "geq"),..
R("<<", Store, "shr"),..
R(">>", Store, "shl"),..
R("-", Store, "minus"),..
R("\+", Store, "plus"),..
R("%", Store, "mod"),..
R("\*", Store, "times"),..
R("/", Store, "div"),..
R("\?", Store, "qmark"),..
R(":", Store, "colon"),..
R(";", Store, "separator"),..
R("\(", Store, "lparen"),..
R("\)", Store, "rparen"),..
R("\[", Store, "lbracket"),..
R("\]", Store, "rbracket"),..
R("\{", Store, "lbrace"),..
R("\}", Store, "rbrace"),..
R(",", Store, "comma"),..
..
R("=", Store, "equals"),.. 'assignment
R("=\|", Store, "aor"),..
R("=&", Store, "aand"),..
R("===", Store, "aeq"),..
R("=!=", Store, "aneq"),..
R("=<", Store, "alt"),..
R("=<=", Store, "aleq"),..
R("=>", Store, "agt"),..
R("=>=", Store, "ageq"),..
R("=<<", Store, "ashr"),..
R("=>>", Store, "ashl"),..
R("=-", Store, "aminus"),..
R("=\+", Store, "aplus"),..
R("=%", Store, "amod"),..
R("=\*", Store, "atimes"),..
R("=/", Store, "adiv"),..
..
R("auto", Store, "auto"),.. 'Keywords
R("extrn", Store, "extrn"),..
R("case", Store, "case"),..
R("default", Store, "default"),..
R("break", Store, "break"),..
R("if", Store, "if"),..
R("else", Store, "else"),..
R("while", Store, "while"),..
R("switch", Store, "switch"),..
R("goto", Store, "goto"),..
R("return", Store, "return"),..
..
R("[a-z_.][a-z0-9_.]*", Store, "name"),..
..
R("[^[:space:]]", TLexAction.Error).. 'Raise an error over any other printable character
])
l.SetCaseSensitivity False
l.SetGuardMode False
Return l
Function R:TLexRule(r:String, a(l:TLexer), res:String = "", m:String = "")
Return TLexRule.Create(r, a, res, m)
End Function
End Function
End Type
Private
Function ApplyCharEscapes:String(s:String)
s = s[1..s.Length - 1]
s = s.Replace("*0", "\0")
s = s.Replace("*e", "\0x03")
s = s.Replace("*(", "{")
s = s.Replace("*)", "}")
s = s.Replace("*t", "\t")
s = s.Replace("**", "*")
s = s.Replace("*'", "'")
s = s.Replace("*~q", "\~q")
s = s.Replace("*n", "\n")
Return s
End Function
Public