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TMeta.bmx
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TMeta.bmx
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' Generic parsing and lexing system, with BNF-style lightweight input
'=====================================================================
Import BaH.Regex
SuperStrict
Import Brl.Retro
Import Brl.LinkedList
Import Brl.Map
Import Brl.Reflection
Public
' TMetaParser
'=============
Type TMetaParser Extends TParser Abstract
Field _rules:TMap, _start:String, _linked:Int
Global pp:PMeta
Method Parse:TParseNode(toks:TToken[])
If Not _linked Then Link()
Return Super.Parse(toks)
End Method
Method Link()
Local metaData:TToken[] = MetaLexer.ScanString(TTypeId.ForObject(Self).FindField("grammar")._meta)
_rules = CreateMap()
If pp = Null Then pp = New PMeta 'Not safe to initialize globally
For Local i:Int = 0 Until metaData.Length Step 2
Local val:String = metaData[i + 1].value[1..]
AddRule(metaData[i].value, val[..val.Length - 1])
Next
_start = metaData[0].value
_linked = True
End Method
Method AddRule(key:String, rs:String)
Local rp:String[] = rs.Split(":")
Local rule:TParseRule = CompileRule(pp.Parse(BNFLexer.ScanString(rp[0])))
If rp.Length > 1 Then rule.f(rp[1].Trim())
_rules.Insert(key, rule)
End Method
Method CompileRule:TParseRule(r:TParseNode)
If r.term
If r.term.tType = "err" Then Return Commit()
If r.term.value[0..2] = "%!" Then Return ExpectTT(r.term.value[2..])
If r.term.value[0] = "%"[0] Then Return CheckTT(r.term.value[1..])
Return Self.R(r.term.value)
EndIf
Select r.rule
Case "ralt"
Local fst:TParseRule = CompileRule(r.elem[0])
If r.elem[1].elem[0].term
r.elem[1] = r.elem[1].elem[1]
Return Alt([ fst, CompileRule(r.elem[1]) ])
Else
For Local i:Int = 0 Until r.elem[1].elem.Length
r.elem[1].elem[i] = r.elem[1].elem[i].elem[1]
Next
Local rst:TParseRule[] = MapCompile(r.elem[1].elem)
rst = rst[..rst.Length + 1]
For Local i:Int = rst.Length - 1 To 1 Step -1
rst[i] = rst[i - 1]
Next
rst[0] = fst
Return Alt(rst)
EndIf
Case "rcat"
Return Cat(MapCompile(r.elem))
Case "unar"
Local arg:TParseRule = CompileRule(r.elem[0])
Select r.elem[1].term.tType
Case "plus" ; Return Plus([arg])
Case "opt" ; Return Opt([arg])
Case "star" ; Return Rep([arg])
End Select
End Select
End Method
Method MapCompile:TParseRule[](a:TParseNode[])
Local ret:TParseRule[] = New TParseRule[a.Length]
For Local i:Int = 0 Until a.Length
ret[i] = CompileRule(a[i])
Next
Return ret
End Method
Method startRule:TParseRule()
Return TParseRule(_rules.ValueForKey(_start))
End Method
Method GetNamedRule:TParseRule(r:String)
Return TParseRule(_rules.ValueForKey(r))
End Method
End Type
Private
Global MetaLexer:TLexer = TLexer.withRules([..
R("[a-z_][a-z0-9_]*", TLexAction.Store, "key"),..
R("~q[^~q]*~q", TLexAction.Store, "value")..
])
Global BNFLexer:TLexer = TLexer.withRules([..
R("[a-z_][a-z0-9_]*", TLexAction.Store, "name"),..
R("%[a-z_][a-z0-9_]*", TLexAction.Store, "terminal"),..
R("%![a-z_][a-z0-9_]*", TLexAction.Store, "terminal"),..
..
R("\+", TLexAction.Store, "plus"),..
R("\|", TLexAction.Store, "or"),..
R("\?", TLexAction.Store, "opt"),..
R("\*", TLexAction.Store, "star"),..
R("=", TLexAction.Store, "eql"),..
R("!", TLexAction.Store, "err"),..
R("@", TLexAction.Store, "any"),..
R("\(", TLexAction.Store, "lparen"),..
R("\)", TLexAction.Store, "rparen")..
])
Function R:TLexRule(r:String, a(l:TLexer), res:String = "", m:String = "")
Return TLexRule.Create(r, a, res, m)
End Function
Type PMeta Extends TParser
Field root:TParseRule, rcat:TParseRule, ralt:TParseRule, unar:TParseRule, atom:TParseRule, nest:TParseRule
Method startRule:TParseRule()
Return root
End Method
Method New()
root = R("ralt")
ralt = Cat([ R("rcat"), Rep([ CheckTT("or"), R("rcat") ]) ])
rcat = Plus([ Alt([ CheckTT("err"), CheckTT("any"), R("unar") ]) ])
unar = Cat([ R("atom"), Opt([ Alt([ CheckTT("plus"), CheckTT("opt"), CheckTT("star") ]) ]) ])
atom = Alt([ CheckTT("name"), CheckTT("terminal"), R("nest") ])
nest = Cat([ CheckTT("lparen"), R("ralt"), CheckTT("rparen") ]).f("- @ - ^")
End Method
End Type
Public
' TParser
'=========
Type TParseNode
Field name:String, rule:String, term:TToken
Field elem:TParseNode[]
Method n:TParseNode(s:String)
name = s ; Return Self
End Method
Method ToString:String()
Function show:String(n:TParseNode, pad:Int)
Local id:String = LSet("", pad)
If n.name = "#Nil" Then Return id + "[NIL]~n"
If n.term Then Return id + n.name + ": { '" + n.term.value + "' : " + n.term.tType + " }~n"
Local s:String = id + n.name + ": " + n.rule + "~n"
For Local e:TParseNode = EachIn n.elem
s :+ show(e, pad + 2)
Next
Return s
End Function
Return show(Self, 0)
End Method
Method GetElem:TParseNode(name:String)
For Local e:Int = 0 Until elem.Length
If elem[e].name = name Then Return elem[e]
Next
Return Null
End Method
Function Leaf:TParseNode(t:ttoken)
Local n:TParseNode = New Self ; n.term = t ; Return n
End Function
Function Node:TParseNode(b:TParseNode[])
Local n:TParseNode = New Self ; n.elem = b ; Return n
End Function
Function Nil:TParseNode()
Local n:TParseNode = New Self ; n.name = "#Nil" ; Return n
End Function
End Type
Type TParser Abstract
Method Parse:TParseNode(toks:TToken[])
Self.toks = toks ; ct = 0 ; epstk = Null ; edstk = Null ; rdepth = 0
Local ret:TParseNode = startRule().run(Self)
If ret Then ret.name = "@root"
Return ret
End Method
Method Cat:TParseRule(rs:TParseRule[]) Final
Return TParseRule.Make("Cat", Self, "", rs)
End Method
Method Alt:TParseRule(rs:TParseRule[]) Final
Return TParseRule.Make("Alt", Self, "", rs)
End Method
Method Opt:TParseRule(rs:TParseRule[]) Final
Return TParseRule.Make("Opt", Self, "", rs)
End Method
Method Rep:TParseRule(rs:TParseRule[]) Final
Return TParseRule.Make("Rep", Self, "", rs)
End Method
Method Err:TParseRule(msg:String) Final
Return TParseRule.Make("Err", Self, msg, Null)
End Method
Method Plus:TParseRule(rs:TParseRule[]) Final
Return TParseRule.Make("Plus", Self, "", rs)
End Method
Method CheckTT:TParseRule(t:String) Final
Return TParseRule.Make("CTT", Self, t, Null)
End Method
Method CheckVal:TParseRule(v:String) Final
Return TParseRule.Make("CV", Self, v, Null)
End Method
Method ExpectTT:TParseRule(t:String) Final
Return TParseRule.Make("ETT", Self, t, Null)
End Method
Method Commit:TParseRule() Final
Return TParseRule.Make("Commit", Self, "", Null)
End Method
Method Any:TParseRule() Final
Return TParseRule.Make("Any", Self, "", Null)
End Method
Method R:TParseRule(n:String) Final
Return TParseRule.Make("Named", Self, n, Null)
End Method
Field toks:TToken[], ct:Int, epstk:Int[], edstk:Int[], rdepth:Int
Method _ctok:TToken() Final
If ct < toks.Length Then Return toks[ct] Else Return Null
End Method
Method _incr:TParseNode() Final
Local tok:TToken = toks[ct] ; ct :+ 1
Return TParseNode.Leaf(tok)
End Method
Method _back(pos:Int) Final
If epstk
Local ep:Int = epstk[epstk.Length - 1]
If pos < ep Then Throw ParseError.Make(toks[ep], "error trying to complete '" + toks[ep - 1].value + "'")
EndIf
ct = pos
End Method
Method _popErrs() Final
Local c:Int = 0
For Local p:Int = edstk.Length - 1 To 0 Step -1
If edstk[p] = rdepth Then c :+ 1 Else Exit
Next
If c
edstk = edstk[.. edstk.Length - c]
epstk = epstk[.. edstk.Length]
EndIf
rdepth :- 1
End Method
Method _pushErr() Final
edstk :+ [rdepth] ; epstk :+ [ct]
End Method
Method GetNamedRule:TParseRule(r:String)
Return TParseRule(TTypeId.ForObject(Self).FindField(r).Get(Self))
End Method
Method startRule:TParseRule() Abstract
End Type
Type TParseRule Abstract
Field r:String, args:TParseRule[], _f:String[]
Method run:TParseNode(p:TParser) Abstract
Method f:TParseRule(filt:String)
If args.Length = 1 And CatRule(args[0]) <> Null Then args[0].f filt
End Method
Function Make:TParseRule(subt:String, p:TParser, r:String, args:TParseRule[])
Local t:TParseRule = TParseRule(TTypeId.ForName(subt + "Rule").NewObject())
If args And args.Length > 1 And subt <> "Cat" And subt <> "Alt"
args = [p.Cat(args)]
EndIf
t.r = r ; t.args = args
Return t
End Function
End Type
Private
Type CatRule Extends TParseRule
Method run:TParseNode(p:TParser)
Local pos:Int = p.ct, el:TParseNode[] = New TParseNode[args.Length], cct:Int = 0
p.rdepth :+ 1
For Local d:Int = 0 Until args.Length
el[d - cct] = args[d].run(p)
If el[d - cct] = Null
p._back(pos) ; p._popErrs ; Return Null
ElseIf el[d - cct] = CommitRule.Nil
cct :+ 1
EndIf
Next
If cct Then el = el[0..(el.Length - cct)]
p._popErrs
Return filter(el, p)
End Method
Method filter:TParseNode(el:TParseNode[], p:TParser)
Local ls:TList = CreateList(), ct:Int = 0, noFold:Int = False
If _f
If _f.Length <= el.Length Then Throw ParseError.Make(p._ctok(), "filter pattern is wrong length for rule")
For Local e:Int = 0 Until el.Length
If el[e] <> OptRule.Nil
If _f[e][0] = "@"[0]
If _f[e].Length > 1 Then el[e].name = _f[e][1..] Else el[e].name = "@" + ct
ls.AddLast el[e] ; ct :+ 1
ElseIf _f[e][0] = "<"[0]
Local prev:TParseNode = el[e - 1]
If prev <> OptRule.Nil
If prev.elem
el[e].name = "@" + prev.elem.Length
prev.elem = prev.elem + [el[e]]
Else
el[e].name = "@1"
prev = TParseNode.Node([prev, el[e]])
prev.name = prev.elem[0].name ; prev.elem[0].name = "@0"
ls.RemoveLast() ; ls.AddLast prev
EndIf
Else
el[e].name = "@0"
prev = TParseNode.Node([el[e]])
If _f[e - 1].Length > 1 Then prev.name = _f[e - 1][1..] Else prev.name = "@" + ct
ls.AddLast prev ; ct :+ 1
EndIf
EndIf
EndIf
Next
If _f[el.Length] <> "^" Then noFold = True
Else
For Local e:Int = 0 Until el.Length
If el[e] <> OptRule.Nil
ls.AddLast(el[e])
el[e].name = "@" + ct ; ct :+ 1
EndIf
Next
EndIf
el = TParseNode[](ls.ToArray())
If el = Null Then Return OptRule.Nil
If (el.Length > 1) Or noFold Then Return TParseNode.Node(el) Else Return el[0]
End Method
Method f:TParseRule(filt:String)
_f = filt.Split(" ")
If _f[_f.Length - 1] <> "^"
_f = _f[.._f.Length + 1] ; _f[_f.Length - 1] = ""
EndIf
Return Self
End Method
End Type
Type AltRule Extends TParseRule
Method run:TParseNode(p:TParser)
Local pos:Int = p.ct
For Local d:TParseRule = EachIn args
Local n:TParseNode = d.run(p) ; If n Then Return n
p._back(pos)
Next
Return Null
End Method
Method f:TParseRule(filt:String)
RuntimeError "Cannot apply a filter string to an Alt rule"
End Method
End Type
Type OptRule Extends TParseRule
Global Nil:TParseNode = TParseNode.Nil()
Method run:TParseNode(p:TParser)
Local n:TParseNode = args[0].run(p)
If n Then Return n Else Return Nil
End Method
End Type
Type RepRule Extends TParseRule
Method run:TParseNode(p:TParser)
Return RunF(Self, p)
End Method
Function RunF:TParseNode(s:TParseRule, p:TParser)
Local match:TParseNode, ls:TList
Repeat
Local pos:Int = p.ct
match = s.args[0].run(p)
If match = Null Or match = OptRule.Nil
p._back(pos) ; Exit
Else
If ls = Null Then ls = CreateList()
ls.AddLast(match)
EndIf
Forever
If ls = Null
Return OptRule.Nil
Else
Local ret:TParseNode[] = TParseNode[](ls.ToArray())
' If ret.Length > 1
For Local i:Int = 0 Until ret.Length
ret[i].name = "@" + i
Next
Return TParseNode.Node(ret)
' Else
' Return ret[0]
' EndIf
EndIf
End Function
End Type
Type ErrRule Extends TParseRule
Method run:TParseNode(p:TParser)
Throw ParseError.Make(p._ctok(), r)
End Method
End Type
Type PlusRule Extends TParseRule
Method run:TParseNode(p:TParser)
Local ret:TParseNode = RepRule.RunF(Self, p)
If ret = OptRule.Nil Then Return Null Else Return ret
End Method
End Type
Type CTTRule Extends TParseRule
Method run:TParseNode(p:TParser)
If p._ctok() And p._ctok().tType = r Then Return p._incr() Else Return Null
End Method
End Type
Type CVRule Extends TParseRule
Method run:TParseNode(p:TParser)
If p._ctok() And p._ctok().value = r Then Return p._incr() Else Return Null
End Method
End Type
Type ETTRule Extends TParseRule
Method run:TParseNode(p:TParser)
If p._ctok() And p._ctok().tType = r Then Return p._incr() Else Throw ParseError.Gen(p._ctok(), r)
End Method
End Type
Type CommitRule Extends TParseRule
Global Nil:TParseNode = TParseNode.Nil()
Method run:TParseNode(p:TParser)
p._pushErr ; Return Nil
End Method
End Type
Type AnyRule Extends TParseRule
Method run:TParseNode(p:TParser)
If p._ctok() Then Return p._incr() Else Return Null
End Method
End Type
Type NamedRule Extends TParseRule
Method run:TParseNode(p:TParser)
Local ret:TParseNode = p.GetNamedRule(r).run(p)
If ret And ret.rule = "" Then ret.rule = r
Return ret
End Method
End Type
Type ParseError
Field msg:String
Method ToString:String()
Return "TParser: " + msg
End Method
Function Make:ParseError(t:TToken, msg:String = "")
Local e:ParseError = New Self
e.msg = "error in " + t.file + " at line " + t.l + ", col " + t.c + ": " + msg
Return e
End Function
Function Gen:ParseError(t:TToken, ex:String)
Return Make(t, "expecting {" + ex + "} but found {" + t.tType + "}")
End Function
End Type
Public
' TLexer
'========
Type TToken
Field value:String, tType:String
Field file:String, l:Int, c:Int
Function Make:TToken(v:String, ty:String, f:String, l:Int, c:Int)
Local t:TToken = New TToken
t.value = v ; t.tType = ty ; t.file = f ; t.l = l ; t.c = c
Return t
End Function
End Type
Type TLexer
Field rules:TLexRule[]
Field cFile:LexFile
Field out:TList, matchR:TLexRule, matchS:String
Field csMode:Int, guardMode:Int, mode:String
Field istk:TList, prev:TList
Function withRules:TLexer(r:TLexRule[])
Local l:TLexer = New TLexer
l.rules = r
l.Reset
Return l
End Function
Method SetCaseSensitivity(cs:Int)
csMode = cs
End Method
Method SetGuardMode(gm:Int)
guardMode = gm
End Method
Method Reset()
istk = CreateList() ; prev = CreateList() ; out = Null ; cFile = Null ; mode = ""
End Method
Method ScanFile:TToken[](name:String)
Return TToken[](ScanLFile(Self, LexFile.fromFile(name)).ToArray())
End Method
Method ScanString:TToken[](s:String)
Return TToken[](ScanLFile(Self, LexFile.fromString(s)).ToArray())
End Method
Method GuardFileName(f:LexFile)
If guardMode Then prev.AddLast(f.dir + f.name)
End Method
End Type
Type TLexRule
Field rule:TRegEx, pattern:String
Field action(l:TLexer), result:String, mode:String
Function Create:TLexRule(rs:String, act(l:TLexer), result:String = "", mode:String = "")
Local r:TLexRule = New TLexRule
r.rule = TRegEx.Create("\G" + rs, Null) ; r.pattern = rs
If result = "" And act = TLexAction.Store Then result = rs
r.action = act ; r.result = result ; r.mode = mode
Return r
End Function
End Type
Type TLexAction
Function Store(l:TLexer)
Local fname:String = l.cFile.name ; If fname <> "<string>" Then fname :+ " [" + l.cFile.dir + fname + "]"
l.out.AddLast TToken.Make(l.matchS, l.matchR.result, fname, l.cFile.cLine, l.cFile.cCol)
End Function
Function Mode(l:TLexer)
l.mode = l.matchR.result
End Function
Function Error(l:TLexer)
Throw LexError.Make(l, l.matchR.result)
End Function
Function Discard(l:TLexer)
End Function
Function Incl(l:TLexer)
l.matchS = FilterIncludeString(l.matchS, l.matchR.result) 'Shorten the token to just the file path
TryIncludeFile(l, l.matchS)
End Function
End Type
Private
Type LexFile
Field dir:String, name:String
Field stream:String, sLen:Int, cPtr:Int, cLine:Int, cCol:Int
Function fromFile:LexFile(name:String)
name = RealPath(name)
Local f:LexFile = New LexFile
f.name = StripDir(name) ; f.dir = ExtractDir(name) + "/"
f.stream = LoadText(name) ; f.sLen = Len(f.stream) ; f.cLine = 1 ; f.cCol = 1
Return f
End Function
Function fromString:LexFile(s:String)
Local f:LexFile = New LexFile
f.name = "<string>" ; f.dir = ""
f.stream = s ; f.sLen = Len(s) ; f.cLine = 1 ; f.cCol = 1
Return f
End Function
Method Increment(count:Int)
For Local c:Int = 1 To count
If stream[cPtr] < 32 'Only count printable characters in the column field
If stream[cPtr] = 10 Then cLine :+ 1 ; cCol = 1
Else
cCol :+ 1
EndIf
cPtr :+ 1
Next
End Method
End Type
Type LexError
Field msg:String
Function Make:LexError(l:TLexer, msg:String)
Local e:LexError = New LexError, fname:String = l.cFile.name ; If fname <> "<string>" Then fname :+ " [" + l.cFile.dir + fname + "]"
e.msg = "error in " + fname + " at line " + l.cFile.cLine + ", col " + l.cFile.cCol + ": "
If msg <> "" Then e.msg :+ msg Else e.msg :+ "unexpected character '" + l.cFile.stream[l.cFile.cPtr] + "'"
Return e
End Function
Method ToString:String()
Return "TLexer: " + msg
End Method
End Type
Function ScanLFile:TList(l:TLexer, f:LexFile)
l.cFile = f
l.istk.AddLast f
l.GuardFileName f
TRegEx.options = New TRegExOptions
TRegEx.options.targetIsMultiline = False
TRegEx.options.caseSensitive = l.csMode
l.mode = ""
l.out = CreateList()
Repeat
Local token:String, rule:TLexRule
While l.cFile.cPtr < l.cFile.sLen
Local cf:LexFile = l.cFile
token = "" ; rule = Null
For Local r:TLexRule = EachIn l.rules
If l.mode = r.mode
Local cMatch:TRegExMatch = r.rule.Find(cf.stream, cf.cPtr)
If cMatch
If Len(cMatch.SubExp()) > Len(token) Then token = cMatch.SubExp() ; rule = r
EndIf
EndIf
Next
If rule 'Something matched successfully!
l.matchS = token ; l.matchR = rule
rule.action(l)
cf.Increment Len(token)
Else
cf.Increment 1
EndIf
l.matchR = Null ; l.matchS = ""
Wend
If l.cFile <> f 'Pop back to the previous file in the Include
l.istk.RemoveLast
l.cFile = LexFile(l.istk.Last())
Else
Exit 'If it's f, we're done
EndIf
Forever
Local out:TList = l.out
l.Reset
Return out
End Function
' Use a simple set of filter chars to chop the path out of an Include directive
Function FilterIncludeString:String(inc:String, filter:String)
For Local i:Int = 1 To Len(filter)
Local p:Int = Instr(inc, Mid(filter, i, 1))
If p Then inc = Mid(inc, p + 1) ; Exit
Next
For Local i:Int = 1 To Len(filter)
Local p:Int = Instr(inc, Mid(filter, i, 1))
If p Then inc = Left(inc, p - 1) ; Exit
Next
Return inc
End Function
' Try to include a source file, guards and recursion checks permitting
Function TryIncludeFile(l:TLexer, file:String)
file = RealPath(file)
If l.guardMode 'Auto-guarded includes: check if it's been used already, if so ignore it
For Local name:String = EachIn l.prev
If name = file Then Return '...return without actually changing it
Next
EndIf
For Local f:LexFile = EachIn l.istk 'Check against the currently-open files
If f.dir + f.name = file
Throw LexError.Make(l, "Cannot recursively include '" + file)
EndIf
Next
l.cFile = LexFile.fromFile(file)
l.istk.AddLast l.cFile ; l.GuardFileName l.cFile
End Function
Public