src/generic/Dev/Mod/CPR.cp

   1 MODULE DevCPR;
   2
   3   IMPORT Strings, DevCPM, DevCPT;
   4
   5   CONST
   6     MaxIdLen = LEN(DevCPT.Name);
   7
   8     (* symbol values *)
   9     null = 0;
  10     if = 1; then = 2; else = 3; elsif = 4; end = 5;
  11     new = 6; error = 7; ident = 8; plus = 9; minus = 10;
  12     not = 11; and = 12; or = 13; rpar = 14; lpar = 15; defined = 16;
  13     endcom = 17; eof = 18;
  14
  15   TYPE
  16     Context = POINTER TO RECORD
  17       next: Context; (* upper level block *)
  18       alt: BOOLEAN;  (* else branch *)
  19       val: BOOLEAN;  (* condition value, inverted if alt *)
  20       ref: INTEGER   (* ELSIF count *)
  21     END;
  22
  23     Selector = POINTER TO RECORD
  24       next: Selector;
  25       name: DevCPT.Name;
  26       val: BOOLEAN
  27     END;
  28
  29   VAR
  30     ch: CHAR; (* current character *)
  31     name: DevCPT.Name; (* ident *)
  32
  33   VAR
  34     sym: BYTE; (* parser symbol *)
  35     fold: INTEGER; (* condition folding *)
  36     scope: Selector;
  37     top: Context;
  38
  39   PROCEDURE err (n: SHORTINT);
  40   BEGIN DevCPM.err(n)
  41   END err;
  42
  43   PROCEDURE Identifier (VAR sym: BYTE);
  44     VAR i, res: INTEGER; n: ARRAY MaxIdLen OF CHAR;
  45   BEGIN i := 0;
  46     REPEAT
  47       n[i] := ch; INC(i); DevCPM.Get(ch)
  48     UNTIL ~Strings.IsIdent(ch) OR (i = MaxIdLen);
  49     IF i = MaxIdLen THEN err(240); DEC(i) END ;
  50     n[i] := 0X; Strings.StringToUtf8(n, name, res); sym := ident;
  51     IF res = 1 (*truncated*) THEN err(240) END
  52   END Identifier;
  53
  54   PROCEDURE Get (VAR sym: BYTE);
  55   BEGIN
  56     DevCPM.errpos := DevCPM.curpos - 1;
  57     WHILE (ch # DevCPM.Eot) & ((ch <= " ") OR (ch = 0A0X)) DO DevCPM.Get(ch) END;
  58     DevCPM.startpos := DevCPM.curpos - 1;
  59     CASE ch OF
  60     | DevCPM.Eot: sym := eof
  61     | "&": sym := and; DevCPM.Get(ch)
  62     | "(": sym := lpar; DevCPM.Get(ch)
  63     | ")": sym := rpar; DevCPM.Get(ch)
  64     | "*":
  65         sym := null; DevCPM.Get(ch);
  66         IF ch = ">" THEN sym := endcom; DevCPM.Get(ch) END
  67     | "+": sym := plus; DevCPM.Get(ch)
  68     | "-": sym := minus; DevCPM.Get(ch)
  69     | "D": Identifier(sym); IF name = "DEFINED" THEN sym := defined END
  70     | "E": Identifier(sym);
  71         IF name = "END" THEN sym := end
  72         ELSIF name = "ELSE" THEN sym := else
  73         ELSIF name = "ELSIF" THEN sym := elsif
  74         ELSIF name = "ERROR" THEN sym := error
  75         END
  76     | "I": Identifier(sym); IF name = "IF" THEN sym := if END
  77     | "N": Identifier(sym); IF name = "NEW" THEN sym := new END
  78     | "O": Identifier(sym); IF name = "OR" THEN sym := or END
  79     | "T": Identifier(sym); IF name = "THEN" THEN sym := then END
  80     | "A".."C", "J".."M", "P".."S", "U".."Z", "a".."z", "_": Identifier(sym)
  81     | "~": sym := not; DevCPM.Get(ch)
  82     ELSE
  83       IF Strings.IsIdent(ch) THEN Identifier(sym) ELSE sym := null; DevCPM.Get(ch) END
  84     END
  85   END Get;
  86
  87   PROCEDURE New (IN name: DevCPT.Name; val: BOOLEAN);
  88     VAR s: Selector;
  89   BEGIN
  90     s := scope;
  91     WHILE (s.next # NIL) & (s.next.name$ # name$) DO s := s.next END;
  92     IF s.next = NIL THEN NEW(s.next); s.next.name := name$; s.next.val := val
  93     ELSE err(1)
  94     END
  95   END New;
  96
  97   PROCEDURE Old (IN name: DevCPT.Name): Selector;
  98     VAR s: Selector;
  99   BEGIN
 100     s := scope;
 101     WHILE (s.next # NIL) & (s.next.name$ # name$) DO s := s.next END;
 102     IF s.next = NIL THEN
 103       err(0); NEW(s.next); s.next.name := name$; s.next.val := FALSE
 104     END;
 105     RETURN s.next
 106   END Old;
 107
 108   PROCEDURE Find (IN name: DevCPT.Name): Selector;
 109     VAR s: Selector;
 110   BEGIN
 111     s := scope;
 112     WHILE (s.next # NIL) & (s.next.name$ # name$) DO s := s.next END;
 113     RETURN s.next
 114   END Find;
 115
 116   PROCEDURE Set* (IN name: DevCPT.Name; val: BOOLEAN);
 117     VAR s: Selector;
 118   BEGIN
 119     s := scope;
 120     WHILE (s.next # NIL) & (s.next.name$ # name$) DO s := s.next END;
 121     IF s.next = NIL THEN NEW(s.next) END;
 122     s.next.name := name$; s.next.val := val
 123   END Set;
 124
 125   PROCEDURE ^ Expression (VAR x: BOOLEAN);
 126
 127   PROCEDURE Factor (VAR x: BOOLEAN);
 128   BEGIN
 129     IF sym = ident THEN
 130       x := Old(name).val; Get(sym);
 131     ELSIF sym = defined THEN
 132       Get(sym);
 133       IF sym = lpar THEN
 134         Get(sym);
 135         IF sym = ident THEN
 136           x := Find(name) # NIL;
 137           Get(sym)
 138         ELSE err(48)
 139         END;
 140         IF sym # rpar THEN err(23)
 141         ELSE Get(sym)
 142         END
 143       ELSE err(40)
 144       END
 145     ELSIF sym = lpar THEN
 146       Get(sym); Expression(x);
 147       IF sym # rpar THEN err(23)
 148       ELSE Get(sym)
 149       END
 150     ELSIF sym = not THEN
 151       Get(sym); Factor(x); x := ~x
 152     ELSE
 153       x := FALSE;
 154       err(13)
 155     END
 156   END Factor;
 157
 158   PROCEDURE Term (VAR x: BOOLEAN);
 159     VAR y: BOOLEAN;
 160   BEGIN
 161     Factor(x);
 162     WHILE sym = and DO
 163       Get(sym); Factor(y); x := x & y
 164     END
 165   END Term;
 166
 167   PROCEDURE Expression (VAR x: BOOLEAN);
 168     VAR y: BOOLEAN;
 169   BEGIN
 170     Term(x);
 171     WHILE sym = or DO
 172       Get(sym); Term(y); x := x OR y
 173     END
 174   END Expression;
 175
 176   PROCEDURE If (cond: BOOLEAN);
 177     VAR c: Context;
 178   BEGIN
 179     NEW(c); c.next := top; c.alt := FALSE; c.val := cond; c.ref := 0; top := c;
 180     INC(fold)
 181   END If;
 182
 183   PROCEDURE Else;
 184   BEGIN
 185     IF top.alt THEN err(14) (* double ELSE *)
 186     ELSE top.alt := TRUE; top.val := ~top.val;
 187     END
 188   END Else;
 189
 190   PROCEDURE End;
 191     VAR i, ref: INTEGER;
 192   BEGIN
 193     i := 0; ref := top.ref; DEC(fold, ref + 1);
 194     WHILE (top # NIL) & (i <= ref) DO top := top.next; INC(i) END;
 195     IF top = NIL THEN err(51); fold := 0; If(TRUE) END
 196   END End;
 197
 198   PROCEDURE Printable* (): BOOLEAN;
 199     VAR c: Context;
 200   BEGIN
 201     c := top;
 202     WHILE (c # NIL) & c.val DO c := c.next END;
 203     RETURN c = NIL
 204   END Printable;
 205
 206   PROCEDURE Parse*;
 207     VAR val: BOOLEAN;
 208   BEGIN
 209     Get(sym);
 210     IF sym = new THEN
 211       Get(sym);
 212       IF sym = ident THEN New(name, FALSE); Get(sym)
 213       ELSE err(48)
 214       END
 215     ELSIF sym = error THEN
 216       IF Printable() THEN err(501) END; Get(sym)
 217     ELSIF sym = ident THEN
 218       Get(sym);
 219       IF sym = plus THEN Old(name).val := TRUE; Get(sym)
 220       ELSIF sym = minus THEN Old(name).val := FALSE; Get(sym)
 221       ELSE err(41)
 222       END
 223     ELSIF sym = if THEN
 224       Get(sym); Expression(val); If(val);
 225       IF sym = then THEN Get(sym)
 226       ELSE err(27)
 227       END
 228     ELSIF sym = elsif THEN
 229       IF fold <= 1 THEN err(14) END; (* ELSIF without IF *)
 230       Else; Get(sym); Expression(val); If(val); INC(top.ref);
 231       IF sym = then THEN Get(sym)
 232       ELSE err(27)
 233       END
 234     ELSIF sym = else THEN
 235       IF fold <= 1 THEN err(14) END; (* ELSE without IF *)
 236       Else; Get(sym)
 237     ELSIF sym = end THEN
 238       IF fold <= 1 THEN err(14) END; (* END without IF *)
 239       End; Get(sym)
 240     ELSE
 241       err(14)
 242     END;
 243     IF sym # endcom THEN err(5) ELSE DevCPM.errpos := DevCPM.curpos - 1 END
 244   END Parse;
 245
 246   PROCEDURE Check*;
 247   BEGIN
 248     IF fold # 1 THEN err(14) END
 249   END Check;
 250
 251   PROCEDURE Close*;
 252   BEGIN
 253     ch := " "; sym := eof; name := "";
 254     fold := 0; top := NIL; scope := NIL
 255   END Close;
 256
 257   PROCEDURE Init*;
 258     VAR s: Selector;
 259   BEGIN
 260     Close;
 261     If(TRUE);
 262     NEW(scope);
 263     New("TRUE", TRUE);
 264     New("FALSE", FALSE)
 265   END Init;
 266
 267 END DevCPR.