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Amiga MA Magazine 1998 #6
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jËzyki_programowania
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oberon
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cra.mod
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Oberon Text
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1977-12-31
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Syntax10.Scn.Fnt
MODULE CRA; (* handles the DFA *)
IMPORT Oberon, Texts, Sets, CRS, CRT;
CONST
maxStates = 300;
EOL = 0DX;
State = POINTER TO StateNode;
Action = POINTER TO ActionNode;
Target = POINTER TO TargetNode;
StateNode = RECORD (*state of finite automaton*)
nr: INTEGER; (*state number*)
firstAction: Action; (*to first action of this state*)
endOf: INTEGER; (*nr. of recognized token if state is final*)
ctx: BOOLEAN; (*TRUE: state reached by contextTrans*)
next: State
END;
ActionNode = RECORD (*action of finite automaton*)
typ: INTEGER; (*type of action symbol: char, class*)
sym: INTEGER; (*action symbol*)
tc: INTEGER; (*transition code: normTrans, contextTrans*)
target: Target; (*states after transition with input symbol*)
next: Action;
END;
TargetNode = RECORD (*state after transition with input symbol*)
state: State; (*target state*)
next: Target;
END;
Comment = POINTER TO CommentNode;
CommentNode = RECORD (* info about a comment syntax *)
start,stop: ARRAY 2 OF CHAR;
nested: BOOLEAN;
next: Comment;
END;
Melted = POINTER TO MeltedNode;
MeltedNode = RECORD (* info about melted states *)
set: CRT.Set; (* set of old states *)
state: State; (* new state *)
next: Melted;
END;
firstState: State;
lastState: State; (* last allocated state *)
rootState: State; (* start state of DFA *)
lastSimState: INTEGER; (* last non melted state *)
stateNr: INTEGER; (*number of last allocated state*)
firstMelted: Melted; (* list of melted states *)
firstComment: Comment; (* list of comments *)
out: Texts.Writer; (* current output *)
fram: Texts.Reader; (* scanner frame input *)
PROCEDURE SemErr(nr: INTEGER);
BEGIN CRS.Error(200+nr, CRS.pos)
END SemErr;
PROCEDURE Put(ch: CHAR);
BEGIN Texts.Write(out, ch) END Put;
PROCEDURE PutS(s: ARRAY OF CHAR);
VAR i: INTEGER;
BEGIN i := 0;
WHILE (i < LEN(s)) & (s[i] # 0X) DO
IF s[i] = "$" THEN Texts.WriteLn(out) ELSE Texts.Write(out, s[i]) END;
INC(i)
END PutS;
PROCEDURE PutI(i: INTEGER);
BEGIN Texts.WriteInt(out, i, 0) END PutI;
PROCEDURE PutI2(i, n: INTEGER);
BEGIN Texts.WriteInt(out, i, n) END PutI2;
PROCEDURE PutC(ch: CHAR);
BEGIN
IF (ch < " ") OR (ORD(ch) = 34) THEN PutS("CHR("); PutI(ORD(ch)); Put(")")
ELSE Put(CHR(34)); Put(ch); Put(CHR(34))
END PutC;
PROCEDURE PutRange(s: CRT.Set);
VAR lo, hi: ARRAY 32 OF CHAR; top, i: INTEGER; s1: CRT.Set;
BEGIN
(*----- fill lo and hi *)
top := -1; i := 0;
WHILE i < 128 DO
IF Sets.In(s, i) THEN
INC(top); lo[top] := CHR(i); INC(i);
WHILE (i < 128) & Sets.In(s, i) DO INC(i) END;
hi[top] := CHR(i - 1)
ELSE INC(i)
END
END;
(*----- print ranges *)
IF (top = 1) & (lo[0] = 0X) & (hi[1] = 7FX) & (CHR(ORD(hi[0]) + 2) = lo[1]) THEN
Sets.Fill(s1); Sets.Differ(s1, s); PutS("~ ("); PutRange(s1); Put(")")
ELSE
i := 0;
WHILE i <= top DO
IF hi[i] = lo[i] THEN PutS("(ch="); PutC(lo[i])
ELSIF lo[i] = 0X THEN PutS("(ch<="); PutC(hi[i])
ELSIF hi[i] = 7FX THEN PutS("(ch>="); PutC(lo[i])
ELSE PutS("(ch>="); PutC(lo[i]); PutS(") & (ch<="); PutC(hi[i])
END;
Put(")");
IF i < top THEN PutS(" OR ") END;
INC(i)
END
END PutRange;
PROCEDURE PutChCond(ch: CHAR);
BEGIN
PutS("(ch ="); PutC(ch); Put(")")
END PutChCond;
PROCEDURE Length*(s: ARRAY OF CHAR): INTEGER;
VAR i: INTEGER;
BEGIN
i:=0; WHILE (i < LEN(s)) & (s[i] # 0X) DO INC(i) END;
RETURN i
END Length;
PROCEDURE AddAction(act:Action; VAR head:Action);
VAR a,lasta: Action;
BEGIN
a := head; lasta := NIL;
LOOP
IF (a = NIL) (*collecting classes at the front gives better*)
OR (act^.typ < a^.typ) THEN (*performance*)
act^.next := a;
IF lasta = NIL THEN head := act ELSE lasta^.next := act END;
EXIT;
END;
lasta := a; a := a^.next;
END;
END AddAction;
PROCEDURE DetachAction(a:Action; VAR L:Action);
BEGIN
IF L = a THEN L := a^.next ELSIF L # NIL THEN DetachAction(a, L^.next) END
END DetachAction;
PROCEDURE TheAction (state: State; ch: CHAR): Action;
VAR a: Action; set: CRT.Set;
BEGIN
a := state.firstAction;
WHILE a # NIL DO
IF a.typ = CRT.char THEN
IF ORD(ch) = a.sym THEN RETURN a END
ELSIF a.typ = CRT.class THEN
CRT.GetClass(a^.sym, set);
IF Sets.In(set, ORD(ch)) THEN RETURN a END
END;
a := a.next
END;
RETURN NIL
END TheAction;
PROCEDURE AddTargetList(VAR lista, listb: Target);
VAR p,t: Target;
PROCEDURE AddTarget(t: Target; VAR list:Target);
VAR p,lastp: Target;
BEGIN
p:=list; lastp:=NIL;
LOOP
IF (p = NIL) OR (t^.state.nr < p^.state.nr) THEN EXIT END;
IF p^.state = t^.state THEN RETURN END;
lastp := p; p := p^.next
END;
t^.next:=p;
IF lastp=NIL THEN list:=t ELSE lastp^.next:=t END
END AddTarget;
BEGIN
p := lista;
WHILE p # NIL DO
NEW(t); t^.state:=p^.state; AddTarget(t, listb);
p := p^.next
END AddTargetList;
PROCEDURE NewMelted(set: CRT.Set; state: State): Melted;
VAR melt: Melted;
BEGIN
NEW(melt); melt^.set := set; melt^.state := state;
melt^.next := firstMelted; firstMelted := melt;
RETURN melt
END NewMelted;
PROCEDURE NewState(): State;
VAR state: State;
BEGIN
NEW(state); INC(stateNr); state.nr := stateNr;
state.firstAction := NIL; state.endOf := CRT.noSym; state.ctx := FALSE; state.next := NIL;
IF firstState = NIL THEN firstState := state ELSE lastState.next := state END;
lastState := state;
RETURN state
END NewState;
PROCEDURE NewTransition(from, to: State; typ, sym, tc: INTEGER);
VAR a: Action; t: Target;
BEGIN
NEW(t); t^.state := to; t^.next := NIL;
NEW(a); a^.typ := typ; a^.sym := sym; a^.tc := tc; a^.target := t;
AddAction(a, from.firstAction)
END NewTransition;
PROCEDURE NewComment*(from, to: INTEGER; nested: BOOLEAN);
VAR com: Comment;
PROCEDURE MakeStr(gp: INTEGER; VAR s: ARRAY OF CHAR);
VAR i, n: INTEGER; gn: CRT.GraphNode; set: CRT.Set;
BEGIN
i := 0;
WHILE gp # 0 DO
CRT.GetNode(gp, gn);
IF gn.typ = CRT.char THEN
IF i < 2 THEN s[i] := CHR(gn.p1) END; INC(i)
ELSIF gn.typ = CRT.class THEN
CRT.GetClass(gn.p1, set);
IF Sets.Elements(set, n) # 1 THEN SemErr(26) END;
IF i < 2 THEN s[i] := CHR(n) END; INC(i)
ELSE SemErr(22)
END;
gp := gn.next
END;
IF i > 2 THEN SemErr(25) ELSIF i < 2 THEN s[i] := 0X END
END MakeStr;
BEGIN
NEW(com);
MakeStr(from, com^.start); MakeStr(to, com^.stop);
com^.nested := nested;
com^.next := firstComment; firstComment := com
END NewComment;
PROCEDURE MakeSet(p: Action; VAR set: CRT.Set);
BEGIN
IF p^.typ = CRT.class THEN CRT.GetClass(p^.sym, set)
ELSE Sets.Clear(set); Sets.Incl(set, p^.sym)
END MakeSet;
PROCEDURE ChangeAction(a: Action; set: CRT.Set);
VAR nr: INTEGER;
BEGIN
IF Sets.Elements(set, nr) = 1 THEN a^.typ := CRT.char; a^.sym := nr
ELSE
nr := CRT.ClassWithSet(set);
IF nr < 0 THEN nr := CRT.NewClass("#0", set) END; (*class with dummy name*)
a^.typ := CRT.class; a^.sym := nr
END ChangeAction;
PROCEDURE CombineShifts;
VAR state: State; n: INTEGER; a, b, c: Action; seta, setb: CRT.Set;
BEGIN
state := firstState;
WHILE state # NIL DO
a := state.firstAction;
WHILE a # NIL DO
b := a^.next;
WHILE b # NIL DO
IF (a^.target^.state = b^.target^.state) & (a^.tc = b^.tc) THEN
MakeSet(a, seta); MakeSet(b, setb); Sets.Unite(seta, setb);
ChangeAction(a, seta);
c := b; b := b^.next; DetachAction(c, a)
ELSE b := b^.next
END
END;
a := a^.next
END;
state := state.next
END CombineShifts;
PROCEDURE DeleteRedundantStates;
action: Action;
state, s1, s2: State;
used: CRT.Set;
newState: ARRAY maxStates OF State;
PROCEDURE FindUsedStates(state: State);
VAR action: Action;
BEGIN
IF Sets.In(used, state.nr) THEN RETURN END;
Sets.Incl(used, state.nr);
action := state.firstAction;
WHILE action # NIL DO
FindUsedStates(action^.target^.state);
action:=action^.next
END
END FindUsedStates;
PROCEDURE DelUnused;
VAR state: State;
BEGIN
state := firstState.next; lastState := firstState; stateNr := 0; (*firstState has number 0*)
WHILE state # NIL DO
IF Sets.In(used, state.nr) THEN INC(stateNr); state.nr := stateNr; lastState := state
ELSE lastState.next := state.next
END;
state := state.next
END
END DelUnused;
BEGIN
Sets.Clear(used); FindUsedStates(firstState);
(*---------- combine equal final states ------------*)
s1 := firstState.next; (*first state cannot be final*)
WHILE s1 # NIL DO
IF Sets.In(used, s1.nr) & (s1.endOf # CRT.noSym) & (s1.firstAction = NIL) & ~ s1.ctx THEN
s2 := s1.next;
WHILE s2 # NIL DO
IF Sets.In(used, s2.nr) & (s1.endOf = s2.endOf) & (s2.firstAction = NIL) & ~ s2.ctx THEN
Sets.Excl(used, s2.nr); newState[s2.nr] := s1
END;
s2 := s2.next
END
END;
s1 := s1.next
END;
state := firstState; (*> state := firstState.next*)
WHILE state # NIL DO
IF Sets.In(used, state.nr) THEN
action := state.firstAction;
WHILE action # NIL DO
IF ~ Sets.In(used, action.target.state.nr) THEN
action^.target^.state := newState[action.target.state.nr]
END;
action := action^.next
END
END;
state := state.next
END;
DelUnused
END DeleteRedundantStates;
PROCEDURE ConvertToStates*(gp0, sp: INTEGER);
(*note: gn.line is abused as a state number!*)
VAR n: INTEGER; S: ARRAY maxStates OF State; gn: CRT.GraphNode;
PROCEDURE TheState(gp: INTEGER): State;
VAR state: State; gn: CRT.GraphNode;
BEGIN
IF gp = 0 THEN state := NewState(); state.endOf := sp; RETURN state
ELSE CRT.GetNode(gp, gn); RETURN S[gn.line]
END
END TheState;
PROCEDURE Step(from: State; gp: INTEGER);
VAR gn: CRT.GraphNode;
BEGIN
IF gp = 0 THEN RETURN END;
CRT.GetNode(gp, gn);
CASE gn.typ OF
CRT.class, CRT.char: NewTransition(from, TheState(ABS(gn.next)), gn.typ, gn.p1, gn.p2)
| CRT.alt: Step(from, gn.p1); Step(from, gn.p2)
| CRT.opt, CRT.iter: Step(from, ABS(gn.next)); Step(from, gn.p1)
END
END Step;
PROCEDURE FindTrans(gp: INTEGER; state: State);
VAR gn: CRT.GraphNode; new: BOOLEAN;
BEGIN
IF gp = 0 THEN RETURN END; (*end of graph*)
CRT.GetNode(gp, gn);
IF gn.line # 0 THEN RETURN END; (*already visited*)
new := state = NIL;
IF new THEN state := NewState() END;
INC(n); S[n] := state; gn.line := n; CRT.PutNode(gp, gn);
IF CRT.DelGraph(gp) THEN state.endOf := sp END; (*state is end state*)
CASE gn.typ OF
CRT.class, CRT.char: FindTrans(ABS(gn.next), NIL);
| CRT.opt: FindTrans(ABS(gn.next), NIL); FindTrans(gn.p1, state)
| CRT.iter: FindTrans(ABS(gn.next), state); FindTrans(gn.p1, state)
| CRT.alt: FindTrans(gn.p1, state); FindTrans(gn.p2, state)
END;
IF new OR (state = firstState) & (gp = gp0) THEN (*start of a group of equally numbered nodes*)
Step(state, gp)
END
END FindTrans;
BEGIN
IF CRT.DelGraph(gp0) THEN SemErr(20) END;
CRT.GetNode(gp0, gn);
IF gn.typ = CRT.iter THEN SemErr(21) END;
n := 0; FindTrans(gp0, firstState)
END ConvertToStates;
PROCEDURE MatchDFA* (s: ARRAY OF CHAR; sp: INTEGER; VAR matchedSp: INTEGER);
VAR state, to: State; a: Action; i, len: INTEGER;
BEGIN (*s with quotes*)
state := firstState; i := 1; len := Length(s) - 1;
LOOP (*try to match s against existing DFA*)
IF i = len THEN EXIT END;
a := TheAction(state, s[i]);
IF a = NIL THEN EXIT END;
state := a.target.state; INC(i)
END;
WHILE i < len DO (*make new DFA for s[i..len-1]*)
to := NewState();
NewTransition(state, to, CRT.char, ORD(s[i]), CRT.normTrans);
state := to; INC(i)
END;
matchedSp := state.endOf;
IF state.endOf = CRT.noSym THEN state.endOf := sp END
END MatchDFA;
PROCEDURE SplitActions(a, b: Action);
VAR c: Action; seta, setb, setc: CRT.Set;
PROCEDURE CombineTransCodes(t1, t2: INTEGER; VAR result:INTEGER);
BEGIN
IF t1 = CRT.contextTrans THEN result := t1 ELSE result := t2 END
END CombineTransCodes;
BEGIN
MakeSet(a, seta); MakeSet(b, setb);
IF Sets.Equal(seta, setb) THEN
AddTargetList(b^.target, a^.target);
CombineTransCodes(a^.tc, b^.tc, a^.tc);
DetachAction(b, a)
ELSIF Sets.Includes(seta, setb) THEN
setc := seta; Sets.Differ(setc, setb);
AddTargetList(a^.target, b^.target);
CombineTransCodes(a^.tc, b^.tc, b^.tc);
ChangeAction(a, setc)
ELSIF Sets.Includes(setb, seta) THEN
setc := setb; Sets.Differ(setc, seta);
AddTargetList(b^.target, a^.target);
CombineTransCodes(a^.tc, b^.tc, a^.tc);
ChangeAction(b, setc)
ELSE
Sets.Intersect(seta, setb, setc);
Sets.Differ(seta, setc);
Sets.Differ(setb, setc);
ChangeAction(a, seta);
ChangeAction(b, setb);
NEW(c); c^.target:=NIL;
CombineTransCodes(a^.tc, b^.tc, c^.tc);
AddTargetList(a^.target, c^.target);
AddTargetList(b^.target, c^.target);
ChangeAction(c, setc);
AddAction(c, a)
END SplitActions;
PROCEDURE MakeUnique(state: State; VAR changed:BOOLEAN);
VAR a, b: Action;
PROCEDURE Overlap(a, b: Action): BOOLEAN;
VAR seta, setb: CRT.Set;
BEGIN
IF a^.typ = CRT.char THEN
IF b^.typ = CRT.char THEN RETURN a^.sym = b^.sym
ELSE CRT.GetClass(b^.sym, setb); RETURN Sets.In(setb, a^.sym)
END
ELSE
CRT.GetClass(a^.sym, seta);
IF b^.typ = CRT.char THEN RETURN Sets.In(seta, b^.sym)
ELSE CRT.GetClass(b^.sym, setb); RETURN ~ Sets.Different(seta, setb)
END
END
END Overlap;
BEGIN
a := state.firstAction; changed := FALSE;
WHILE a # NIL DO
b := a^.next;
WHILE b # NIL DO
IF Overlap(a, b) THEN SplitActions(a, b); changed:=TRUE END;
b := b^.next;
END;
a:=a^.next
END MakeUnique;
PROCEDURE MeltStates(state: State; VAR correct:BOOLEAN);
action: Action;
ctx: BOOLEAN;
endOf: INTEGER;
melt: Melted;
set: CRT.Set;
s: State;
changed: BOOLEAN;
PROCEDURE AddMeltedSet(nr: INTEGER; VAR set: CRT.Set);
VAR m: Melted;
BEGIN
m := firstMelted;
WHILE (m # NIL) & (m^.state.nr # nr) DO m := m^.next END;
IF m = NIL THEN HALT(98) END;
Sets.Unite(set, m^.set);
END AddMeltedSet;
PROCEDURE GetStateSet(t: Target; VAR set: CRT.Set; VAR endOf: INTEGER; VAR ctx:BOOLEAN);
VAR statenr: INTEGER; (*lastS: State;*)
BEGIN
Sets.Clear(set); endOf := CRT.noSym; ctx := FALSE; (*lastS := NIL;*)
WHILE t # NIL DO
statenr := t.state.nr;
IF statenr <= lastSimState THEN Sets.Incl(set, statenr)
ELSE AddMeltedSet(statenr, set)
END;
IF t^.state^.endOf # CRT.noSym THEN
IF (endOf = CRT.noSym) OR (endOf = t^.state^.endOf)
(*OR (lastS^.firstAction # NIL) & (t^.state^.firstAction = NIL)*) THEN
endOf := t^.state.endOf; (*lastS := t^.state*)
ELSE
PutS("$Tokens "); PutI(endOf); PutS(" and "); PutI(t^.state.endOf);
PutS(" cannot be distinguished.$");
correct:=FALSE
END
END;
IF t^.state.ctx THEN ctx := TRUE;
IF t.state.endOf # CRT.noSym THEN
PutS("$Ambiguous CONTEXT clause.$"); correct := FALSE
END
END;
t := t^.next
END
END GetStateSet;
PROCEDURE FillWithActions(state: State; targ: Target);
VAR action,a: Action;
BEGIN
WHILE targ # NIL DO
action := targ^.state.firstAction;
WHILE action # NIL DO
NEW(a); a^ := action^; a^.target := NIL;
AddTargetList(action^.target, a^.target);
AddAction(a, state.firstAction);
action:=action^.next
END;
targ:=targ^.next
END;
END FillWithActions;
PROCEDURE KnownMelted(set:CRT.Set; VAR melt: Melted): BOOLEAN;
BEGIN
melt := firstMelted;
WHILE melt # NIL DO
IF Sets.Equal(set, melt^.set) THEN RETURN TRUE END;
melt := melt^.next
END;
RETURN FALSE
END KnownMelted;
BEGIN
action := state.firstAction;
WHILE action # NIL DO
IF action^.target^.next # NIL THEN (*more than one target state*)
GetStateSet(action^.target, set, endOf, ctx);
IF ~ KnownMelted(set, melt) THEN
s := NewState(); s.endOf := endOf; s.ctx := ctx;
FillWithActions(s, action^.target);
REPEAT MakeUnique(s, changed) UNTIL ~ changed;
melt := NewMelted(set, s);
END;
action^.target^.next:=NIL;
action^.target^.state := melt^.state
END;
action := action^.next
END;
Texts.Append(Oberon.Log, out.buf)
END MeltStates;
PROCEDURE MakeDeterministic*(VAR correct: BOOLEAN);
VAR state: State; changed: BOOLEAN;
PROCEDURE FindCtxStates; (*find states reached by a context transition*)
VAR a: Action; state: State;
BEGIN
state := firstState;
WHILE state # NIL DO
a := state.firstAction;
WHILE a # NIL DO
IF a^.tc = CRT.contextTrans THEN a^.target^.state.ctx := TRUE END;
a := a^.next
END;
state := state.next
END;
END FindCtxStates;
BEGIN
IF lastState = NIL THEN lastSimState := 0 ELSE lastSimState := lastState.nr END;
FindCtxStates;
state := firstState;
WHILE state # NIL DO
REPEAT MakeUnique(state, changed) UNTIL ~ changed;
state := state.next
END;
correct := TRUE;
state := firstState;
WHILE state # NIL DO MeltStates(state, correct); state := state.next END;
DeleteRedundantStates;
CombineShifts
END MakeDeterministic;
PROCEDURE PrintSymbol(typ, val, width: INTEGER);
VAR name: CRT.Name; len: INTEGER;
BEGIN
IF typ = CRT.class THEN
CRT.GetClassName(val, name); PutS(name); len := Length(name)
ELSIF (val >= ORD(" ")) & (val < 127) & (val # 34) THEN
Put(CHR(34)); Put(CHR(val)); Put(CHR(34)); len:=3
ELSE
PutS("CHR("); PutI2(val, 2); Put(")"); len:=7
END;
WHILE len < width DO Put(" "); INC(len) END
END PrintSymbol;
PROCEDURE PrintStates*;
VAR action: Action; first: BOOLEAN; state: State; i: INTEGER; targ: Target; set: CRT.Set; name: CRT.Name;
BEGIN
PutS("$-------- states ---------$");
state := firstState;
WHILE state # NIL DO
action := state.firstAction; first:=TRUE;
IF state.endOf = CRT.noSym THEN PutS(" ")
ELSE PutS("E("); PutI2(state.endOf, 2); Put(")")
END;
PutI2(state.nr, 3); Put(":"); IF action = NIL THEN PutS(" $") END;
WHILE action # NIL DO
IF first THEN Put(" "); first:=FALSE ELSE PutS(" ") END;
PrintSymbol(action^.typ, action^.sym, 0); Put(" ");
targ := action^.target;
WHILE targ # NIL DO
PutI(targ^.state.nr); Put(" "); targ := targ^.next;
END;
IF action^.tc = CRT.contextTrans THEN PutS(" context$") ELSE PutS(" $") END;
action := action^.next
END;
state := state.next
END;
PutS("$-------- character classes ---------$");
i := 0;
WHILE i <= CRT.maxC DO
CRT.GetClass(i, set); CRT.GetClassName(i, name); PutS(name); PutS(": ");
Sets.Print(out, set, 80, 13); Texts.WriteLn(out);
INC(i)
END;
Texts.Append(Oberon.Log, out.buf)
END PrintStates;
PROCEDURE GenComment(com:Comment);
PROCEDURE GenBody;
BEGIN
PutS(" LOOP$");
PutS(" IF "); PutChCond(com^.stop[0]); PutS(" THEN$");
IF Length(com^.stop) = 1 THEN
PutS(" DEC(level); oldEols := chLine - startLine; NextCh;$");
PutS(" IF level = 0 THEN RETURN TRUE END;$");
ELSE
PutS(" NextCh;$");
PutS(" IF "); PutChCond(com^.stop[1]); PutS(" THEN$");
PutS(" DEC(level); oldEols := chLine - startLine; NextCh;$");
PutS(" IF level=0 THEN RETURN TRUE END$");
PutS(" END;$");
END;
IF com^.nested THEN
PutS(" ELSIF "); PutChCond(com^.start[0]); PutS(" THEN$");
IF Length(com^.start) = 1 THEN
PutS(" INC(level); NextCh;$");
ELSE
PutS(" NextCh;$");
PutS(" IF "); PutChCond(com^.start[1]); PutS(" THEN$");
PutS(" INC(level); NextCh;$");
PutS(" END;$");
END;
END;
PutS(" ELSIF ch = EOF THEN RETURN FALSE$");
PutS(" ELSE NextCh END;$");
PutS(" END;$");
END GenBody;
BEGIN
PutS(" IF "); PutChCond(com^.start[0]); PutS(" THEN$");
IF Length(com^.start) = 1 THEN
PutS(" NextCh;$");
GenBody;
PutS(" END;");
ELSE
PutS(" NextCh;$");
PutS(" IF "); PutChCond(com^.start[1]); PutS(" THEN$");
PutS(" NextCh;$");
GenBody;
PutS(" ELSE$");
PutS(" IF ch = EOL THEN DEC(chLine); lineStart := oldLineStart END;$");
PutS(" DEC(chPos, 2); Texts.OpenReader(r, src, chPos+1); NextCh; RETURN FALSE$");
PutS(" END$");
PutS(" END;");
END;
END GenComment;
PROCEDURE CopyFramePart (stopStr: ARRAY OF CHAR); (*Copy from file <fram> to file <out> until <stopStr>*)
VAR ch, startCh: CHAR; i, j, high: INTEGER;
BEGIN
startCh := stopStr[0]; high := Length(stopStr) - 1; Texts.Read (fram, ch);
WHILE ch # 0X DO
IF ch = startCh THEN (* check if stopString occurs *)
i := 0;
REPEAT
IF i = high THEN RETURN END; (*stopStr[0..i] found; no unrecognized character*)
Texts.Read (fram, ch); INC(i);
UNTIL ch # stopStr[i];
(*stopStr[0..i-1] found; 1 unrecognized character*)
j := 0; WHILE j < i DO Texts.Write(out, stopStr[j]); INC(j) END
ELSE Texts.Write (out, ch); Texts.Read(fram, ch)
END
END CopyFramePart;
PROCEDURE GenLiterals;
VAR
i, j, k, l: INTEGER;
key: ARRAY 128 OF CRT.Name;
knr: ARRAY 128 OF INTEGER;
ch: CHAR;
sn: CRT.SymbolNode;
BEGIN
(*-- sort literal list*)
i := 0; k := 0;
WHILE i <= CRT.maxT DO
CRT.GetSym(i, sn);
IF sn.struct = CRT.litToken THEN
j := k-1; WHILE (j >= 0) & (sn.name < key[j]) DO key[j+1] := key[j]; knr[j+1] := knr[j]; DEC(j) END;
key[j+1] := sn.name; knr[j+1] := i; INC(k)
END;
INC(i)
END;
(*-- print case statement*)
IF k > 0 THEN
PutS(" IF (lexeme[0] >= "); PutC(key[0, 1]); PutS(") & (lexeme[0] <= "); PutC(key[k-1, 1]); PutS(") THEN$");
PutS(" CASE lexeme[0] OF$");
i := 0;
WHILE i < k DO
ch := key[i, 1]; (*key[i, 0] = quote*)
PutS(" | "); PutC(ch); j := i;
REPEAT
IF i = j THEN PutS(": IF lexeme = ") ELSE PutS(" ELSIF lexeme = ") END;
PutS(key[i]); PutS(" THEN sym := "); PutI(knr[i]); Put(CHR(13));
INC(i)
UNTIL (i = k) OR (key[i, 1] # ch);
PutS(" END$");
END;
PutS(" ELSE$ END$ END;$")
END GenLiterals;
PROCEDURE WriteState(state: State);
VAR action: Action; first, ctxEnd: BOOLEAN; sn: CRT.SymbolNode; endOf: INTEGER;
set: CRT.Set;
BEGIN
endOf := state.endOf;
IF (endOf > CRT.maxT) & (endOf # CRT.noSym) THEN (*pragmas have been moved*)
endOf := CRT.maxT + CRT.maxSymbols - endOf
END;
PutS(" | "); PutI2(state.nr, 2); PutS(": ");
first:=TRUE; ctxEnd := state.ctx;
action := state.firstAction;
WHILE action # NIL DO
IF first THEN PutS("IF "); first:=FALSE ELSE PutS(" ELSIF ") END;
IF action^.typ = CRT.char THEN PutChCond(CHR(action^.sym))
ELSE CRT.GetClass(action^.sym, set); PutRange(set)
END;
PutS(" THEN");
IF action.target.state.nr # state.nr THEN
PutS(" state := "); PutI(action.target.state.nr); Put(";")
END;
IF action^.tc = CRT.contextTrans THEN PutS(" INC(apx)"); ctxEnd := FALSE
ELSIF state.ctx THEN PutS(" apx := 0")
END;
PutS(" $");
action := action^.next
END;
IF state.firstAction # NIL THEN PutS(" ELSE ") END;
IF endOf = CRT.noSym THEN PutS("sym := noSym; ")
ELSE (*final state*)
CRT.GetSym(endOf, sn);
IF ctxEnd THEN (*final context state: cut appendix*)
PutS("chPos := chPos - apx - 1; Texts.OpenReader(r, src, chPos+1); NextCh; ")
END;
PutS("sym := "); PutI(endOf); PutS("; ");
IF sn.struct = CRT.classLitToken THEN PutS("CheckLiteral; ") END
END;
PutS("RETURN$");
IF state.firstAction # NIL THEN PutS(" END;$") END
END WriteState;
PROCEDURE *Show (t: Texts.Text; op: INTEGER; beg, end: LONGINT);
END Show;
PROCEDURE WriteScanner*;
scanner: ARRAY 32 OF CHAR;
name: ARRAY 64 OF CHAR;
startTab: ARRAY 128 OF INTEGER;
com: Comment;
i, j, l: INTEGER;
gn: CRT.GraphNode;
sn: CRT.SymbolNode;
state: State;
t: Texts.Text;
PROCEDURE FillStartTab;
VAR action: Action; i, targetState: INTEGER; class: CRT.Set;
BEGIN
startTab[0] := stateNr + 1; (*eof*)
i := 1; WHILE i < 128 DO startTab[i] := 0; INC(i) END;
action := firstState.firstAction;
WHILE action # NIL DO
targetState := action.target.state.nr;
IF action^.typ = CRT.char THEN
startTab[action^.sym] := targetState
ELSE
CRT.GetClass(action^.sym, class); i := 0;
WHILE i < 128 DO
IF Sets.In(class, i) THEN startTab[i] := targetState END;
INC(i)
END
END;
action := action^.next
END
END FillStartTab;
BEGIN
FillStartTab;
CRT.GetNode(CRT.root, gn); CRT.GetSym(gn.p1, sn);
COPY(sn.name, scanner); l := Length(scanner); scanner[l] := "S"; scanner[l+1] := 0X;
NEW(t); Texts.Open(t, "Scanner.FRM"); Texts.OpenReader(fram, t, 0);
IF t.len = 0 THEN
Texts.WriteString(out, "Scanner.FRM not found"); Texts.WriteLn(out);
Texts.Append(Oberon.Log, out.buf); HALT(99)
END;
Texts.Append(Oberon.Log, out.buf);
(*------- *S.MOD -------*)
CopyFramePart("-->modulename"); PutS(scanner);
CopyFramePart("-->declarations"); PutS(" noSym = "); PutI(CRT.maxT); Put(";");
CopyFramePart("-->comment");
com := firstComment;
WHILE com # NIL DO GenComment(com); com := com^.next END;
CopyFramePart("-->literals"); GenLiterals;
CopyFramePart("-->GetSy1");
IF ~ Sets.In(CRT.ignored, ORD(EOL)) THEN PutS(" IF oldEols > 0 THEN DEC(oldEols); ch := EOL END;$") END;
PutS(" WHILE (ch=20X)"); IF ~ Sets.Empty(CRT.ignored) THEN PutS(" OR ") END;
PutRange(CRT.ignored); PutS(" DO NextCh END;");
IF firstComment # NIL THEN
PutS("$ IF ("); com := firstComment;
WHILE com # NIL DO
PutChCond(com^.start[0]);
IF com^.next # NIL THEN PutS(" OR ") END;
com := com^.next
END;
PutS(") & Comment() THEN Get(sym); RETURN END;")
END;
CopyFramePart("-->GetSy2");
state := firstState.next;
WHILE state # NIL DO WriteState(state); state := state.next END;
PutS(" | "); PutI2(stateNr + 1, 2); PutS(": sym := 0; ch := 0X; RETURN$");
CopyFramePart("-->initialization");
i := 0;
WHILE i < 32 DO
j := 0; PutS(" ");
WHILE j < 4 DO
PutS("start["); PutI(4*i+j); PutS("]:="); PutI(startTab[4*i+j]); PutS("; ");
INC(j)
END;
Texts.WriteLn(out);
INC(i)
END;
CopyFramePart("-->modulename"); PutS(scanner); Put(".");
NEW(t); t.notify := Show; Texts.Open(t, ""); Texts.Append(t, out.buf);
l := Length(scanner); scanner[l] := "."; scanner[l+1] := "M"; scanner[l+2] := "o"; scanner[l+3] := "d"; scanner[l+4] := 0X;
Texts.Close(t, scanner)
END WriteScanner;
PROCEDURE Init*;
BEGIN
firstState := NIL; lastState := NIL; stateNr := -1;
rootState := NewState();
firstMelted := NIL; firstComment := NIL
END Init;
BEGIN
Texts.OpenWriter(out)
END CRA.