Copyright (C) 1992, Digital Equipment Corporation
All rights reserved.
See the file COPYRIGHT for a full description.
File: Scanner.m3
Last modified on Thu Dec 8 10:44:07 PST 1994 by kalsow
modified on Sat Mar 16 00:25:08 1991 by muller
modified on Fri Oct 19 10:52:56 1990 by nr@princeton.edu
MODULE M3Scanner;
IMPORT Rd, Thread, Fmt;
IMPORT M3Token, m3scan_M3ID;
CONST
EOFChar = '\000';
TYPE
TK = M3Token.T;
VAR (* CONST after intialization *)
WhiteSpace := ARRAY CHAR OF BOOLEAN { FALSE, .. };
AlphaNumerics := ARRAY CHAR OF BOOLEAN { FALSE, .. };
Digits := ARRAY CHAR OF BOOLEAN { FALSE, .. };
OctalDigits := ARRAY CHAR OF BOOLEAN { FALSE, .. };
HexDigits := ARRAY CHAR OF BOOLEAN { FALSE, .. };
CommentAlert := ARRAY CHAR OF BOOLEAN { FALSE, .. };
CharAlert := ARRAY CHAR OF BOOLEAN { FALSE, .. };
TYPE
Public = T OBJECT METHODS
initFromRd (source : Rd.T;
skip_comments := TRUE;
split_pragmas := TRUE): T;
initFromBuf (buf : Buf;
skip_comments := TRUE;
split_pragmas := TRUE): T;
END;
REVEAL
Default = Public BRANDED "M3Scanner.Default" OBJECT
skip_comments : BOOLEAN := FALSE;
split_pragmas : BOOLEAN := FALSE;
line_start : CARDINAL := 0;
next_offset : CARDINAL := 0;
next_line : CARDINAL := 0;
next_line_start : CARDINAL := 0;
OVERRIDES
next := GetToken;
initFromRd := InitFromRd;
initFromBuf := InitFromBuf;
END;
PROCEDURE InitFromRd (t: Default;
source : Rd.T;
skip_comments : BOOLEAN;
split_pragmas : BOOLEAN): T =
VAR len0, len1: INTEGER;
BEGIN
t.skip_comments := skip_comments;
t.split_pragmas := split_pragmas;
t.line := 1;
t.next_line := 1;
(* read the source *)
TRY
len0 := Rd.Length (source);
t.buffer := NEW (Buf, MAX (0, len0) + 1);
IF (len0 < 0) THEN Err (t, 0, "can't tell how much source there is") END;
len1 := Rd.GetSub (source, t.buffer^);
IF (len0 # len1) THEN Err (t, 0, "couldn't read the entire source") END;
t.buffer [len0] := EOFChar;
EXCEPT
| Rd.Failure => Err (t, 0, "I/O failure reading the source");
| Thread.Alerted => Err (t, 0, "*alerted*");
END;
RETURN t;
END InitFromRd;
PROCEDURE InitFromBuf (t: Default;
buf : Buf;
skip_comments : BOOLEAN;
split_pragmas : BOOLEAN): T =
BEGIN
t.skip_comments := skip_comments;
t.split_pragmas := split_pragmas;
t.line := 1;
t.next_line := 1;
t.buffer := buf;
RETURN t;
END InitFromBuf;
PROCEDURE Err (t: Default; offset: CARDINAL; msg: TEXT) =
BEGIN
t.token := TK.Error;
t.msg := msg;
t.length := offset - t.offset;
t.next_offset := offset;
END Err;
PROCEDURE GetToken (t: Default) =
VAR
buf := t.buffer;
offset := t.next_offset;
ch := buf [offset];
BEGIN
t.line := t.next_line;
t.line_start := t.next_line_start;
LOOP
(* skip white space *)
WHILE (WhiteSpace[ch]) DO
INC (offset);
IF (ch = '\n') THEN
INC (t.line);
INC (t.next_line);
t.line_start := offset;
t.next_line_start := offset;
END;
ch := buf [offset];
END;
(* remember where this token starts *)
t.offset := offset;
t.start := offset;
t.column := offset - t.line_start;
CASE ch OF
| 'a'..'z', 'A'..'Z' =>
(* scan an identifier *)
WHILE AlphaNumerics[ch] DO INC (offset); ch := buf[offset]; END;
t.token := m3scan_M3ID.Classify (SUBARRAY (buf^, t.offset, offset - t.offset));
EXIT;
| '0'..'9' => ScanNumber (t); RETURN;
| '\'' => ScanChar (t); RETURN;
| '\"' => ScanText (t); RETURN;
| '+' => t.token := TK.Plus; INC (offset); EXIT;
| '-' => t.token := TK.Minus; INC (offset); EXIT;
| '/' => t.token := TK.Slash; INC (offset); EXIT;
| '&' => t.token := TK.Ampersand; INC (offset); EXIT;
| ',' => t.token := TK.Comma; INC (offset); EXIT;
| ';' => t.token := TK.Semi; INC (offset); EXIT;
| '[' => t.token := TK.L_bracket; INC (offset); EXIT;
| '{' => t.token := TK.L_brace; INC (offset); EXIT;
| '^' => t.token := TK.Arrow; INC (offset); EXIT;
| '#' => t.token := TK.Sharp; INC (offset); EXIT;
| ')' => t.token := TK.R_paren; INC (offset); EXIT;
| ']' => t.token := TK.R_bracket; INC (offset); EXIT;
| '}' => t.token := TK.R_brace; INC (offset); EXIT;
| '|' => t.token := TK.Bar; INC (offset); EXIT;
| EOFChar => t.token := TK.EOF; EXIT;
| '*' => (* '*>' '*' *)
INC (offset); ch := buf [offset];
IF (ch = '>')
THEN t.token := TK.End_pragma; INC (offset);
ELSE t.token := TK.Asterisk;
END;
EXIT;
| '=' => (* '=' '=>' *)
INC (offset); ch := buf [offset];
IF (ch = '>')
THEN t.token := TK.Implies; INC (offset);
ELSE t.token := TK.Equal;
END;
EXIT;
| ':' => (* ':' ':=' *)
INC (offset); ch := buf [offset];
IF (ch = '=')
THEN t.token := TK.Assign; INC (offset);
ELSE t.token := TK.Colon;
END;
EXIT;
| '.' => (* '.' '..' *)
INC (offset); ch := buf [offset];
IF (ch = '.')
THEN t.token := TK.Dot_dot; INC (offset);
ELSE t.token := TK.Dot;
END;
EXIT;
| '(' => (* '('*' '(' *)
INC (offset); ch := buf [offset];
IF (ch # '*') THEN t.token := TK.L_paren; EXIT;
ELSIF ScanComment (t) THEN RETURN;
ELSE offset := t.offset; ch := buf [offset];
END;
| '>' => (* '>' '>=' *)
INC (offset); ch := buf [offset];
IF (ch = '=')
THEN t.token := TK.Gr_equal; INC (offset);
ELSE t.token := TK.Greater;
END;
EXIT;
| '<' => (* '<' '<=' '<:' '<*' *)
INC (offset); ch := buf [offset];
IF (ch = '=') THEN t.token := TK.Ls_equal; INC (offset);
ELSIF (ch = ':') THEN t.token := TK.Subtype; INC (offset);
ELSIF (ch # '*') THEN t.token := TK.Less;
ELSIF (NOT t.split_pragmas) THEN ScanPragma (t); RETURN;
ELSE t.token := TK.Begin_pragma; INC (offset);
END;
EXIT;
ELSE
INC (offset);
Err (t, offset, "Illegal character: " & Fmt.Int (ORD (ch)));
EXIT;
END; (*case*)
END; (*loop*)
(* record the length of the token and where we are *)
t.length := offset - t.offset;
t.next_offset := offset;
END GetToken;
PROCEDURE ScanNumber (t: Default) =
VAR
offset := t.offset;
ch := t.buffer [offset];
BEGIN
(* scan the decimal digits *)
WHILE Digits[ch] DO INC (offset); ch := t.buffer [offset]; END;
IF (ch = '_') THEN
(* scan a based integer *)
INC (offset); ch := t.buffer [offset];
IF HexDigits[ch] THEN
WHILE HexDigits[ch] DO INC (offset); ch := t.buffer [offset]; END;
IF (ch = 'L') OR (ch = 'l') THEN
t.token := TK.Long_const;
t.length := offset - t.offset;
t.next_offset := offset + 1;
RETURN;
ELSE
t.token := TK.Card_const;
END;
ELSE
Err (t, offset, "illegal based integer: missing digits");
RETURN;
END;
ELSIF (ch = '.') AND (t.buffer [offset+1] = '.') THEN
(* we saw "dddd.." *)
t.token := TK.Card_const;
ELSIF (ch = '.') THEN
(* scan a floating point number *)
INC (offset); ch := t.buffer [offset];
(* scan the fractional digits *)
IF Digits[ch] THEN
WHILE Digits[ch] DO INC (offset); ch := t.buffer [offset]; END;
ELSE
Err (t, offset, "missing digits in real fraction");
RETURN;
END;
(* check for the exponent *)
IF (ch = 'e') OR (ch = 'E') THEN
t.token := TK.Real_const;
ELSIF (ch = 'd') OR (ch = 'D') THEN
t.token := TK.Longreal_const;
ELSIF (ch = 'x') OR (ch = 'X') THEN
t.token := TK.Extended_const;
ELSE (* real constant with no exponent *)
t.token := TK.Real_const;
t.next_offset := offset;
t.length := offset - t.offset;
RETURN;
END;
INC (offset); ch := t.buffer [offset]; (* eat the e/d/x *)
(* get the exponent sign *)
IF (ch = '+') OR (ch = '-') THEN
INC (offset); ch := t.buffer [offset];
END;
(* finally, get the exponent digits *)
IF Digits[ch] THEN
WHILE Digits[ch] DO INC (offset); ch := t.buffer [offset]; END;
ELSE
Err (t, offset, "missing digits in real exponent");
END;
ELSE
(* scanned a simple decimal integer *)
IF (ch = 'L') OR (ch = 'l') THEN
t.token := TK.Long_const;
t.length := offset - t.offset;
t.next_offset := offset + 1;
ELSE
t.token := TK.Card_const;
END;
END;
t.length := offset - t.offset;
t.next_offset := offset;
END ScanNumber;
PROCEDURE ScanChar (t: Default) =
VAR
offset : CARDINAL := t.offset+1;
ch : CHAR := t.buffer [offset];
BEGIN
IF NOT CharAlert [ch] THEN
(* a simple character literal *)
INC (offset); ch := t.buffer[offset];
ELSIF (ch = '\'') THEN
INC (offset);
Err (t, offset, "missing character in character literal");
RETURN;
ELSIF (ch = '\n') OR (ch = '\r') OR (ch = '\f') THEN
Err (t, offset, "end-of-line encountered in character literal");
RETURN;
ELSIF (ch = '\\') THEN
INC (offset);
IF NOT ScanEscape (t, offset) THEN
Err (t, offset, "unknown escape sequence in character literal");
RETURN;
END;
ch := t.buffer [offset];
ELSIF (ch = EOFChar) THEN
Err (t, offset, "EOF encountered in character literal");
RETURN;
ELSE
(* a simple character literal *)
INC (offset); ch := t.buffer[offset];
END;
IF (ch # '\'') THEN
Err (t, offset, "missing closing quote on character literal");
RETURN;
END;
INC (offset); (* eat the closing quote *)
t.token := TK.Char_const;
t.length := offset - t.offset;
t.next_offset := offset;
END ScanChar;
PROCEDURE ScanText (t: Default) =
VAR
offset : CARDINAL := t.offset+1;
ch : CHAR := t.buffer [offset];
BEGIN
LOOP
IF NOT CharAlert [ch] THEN
INC (offset); ch := t.buffer [offset];
ELSIF (ch = '\"') THEN
INC (offset);
EXIT;
ELSIF (ch = '\n') OR (ch = '\r') OR (ch = '\f') THEN
Err (t, offset, "end-of-line encountered in text literal");
RETURN;
ELSIF (ch = '\\') THEN
INC (offset);
IF NOT ScanEscape (t, offset) THEN
Err (t, offset, "unknown escape sequence in text literal");
RETURN;
END;
ch := t.buffer [offset];
ELSIF (ch = EOFChar) THEN
Err (t, offset, "EOF encountered in text literal");
RETURN;
ELSE (* a simple character *)
INC (offset); ch := t.buffer [offset];
END;
END;
t.token := TK.Text_const;
t.length := offset - t.offset;
t.next_offset := offset;
END ScanText;
PROCEDURE ScanEscape (t: Default; VAR offset: CARDINAL): BOOLEAN =
VAR ch := t.buffer [offset];
BEGIN
INC (offset);
IF (ch = 'n') OR (ch = 't') OR (ch = 'r') OR (ch = 'f')
OR (ch = '\\') OR (ch = '\'') OR (ch = '\"') THEN
RETURN TRUE;
END;
IF NOT OctalDigits [ch] THEN RETURN FALSE END;
ch := t.buffer [offset]; INC (offset);
IF NOT OctalDigits [ch] THEN RETURN FALSE END;
ch := t.buffer [offset]; INC (offset);
RETURN OctalDigits [ch];
END ScanEscape;
PROCEDURE ScanComment (t: Default): BOOLEAN =
VAR
nest := 1;
start := t.offset;
offset := start + 2; (* skip the opening '(' and '*' *)
ch := t.buffer [offset];
my_line := t.line;
l_start := t.line_start;
BEGIN
WHILE (nest > 0) DO
(************** UNSAFE VERSION **********************
VAR p: UNTRACED REF CHAR;
p := ADR (t.buffer[offset]);
WHILE NOT CommentAlert[ch] DO INC (p); ch := p^; END;
offset := p - ADR (t.buffer[0]);
******************************************************)
WHILE NOT CommentAlert[ch] DO INC (offset); ch := t.buffer[offset]; END;
IF (ch = '*') THEN
INC (offset); ch := t.buffer [offset];
IF (ch = ')') THEN
INC (offset); ch := t.buffer[offset];
DEC (nest);
END;
ELSIF (ch = '(') THEN
INC (offset); ch := t.buffer [offset];
IF (ch = '*') THEN
INC (offset); ch := t.buffer[offset];
INC (nest);
END;
ELSIF (ch = EOFChar) THEN
t.next_line := my_line;
t.next_line_start := l_start;
Err (t, offset, "EOF encountered in comment");
RETURN TRUE;
ELSIF (ch = '\n') THEN
INC (offset); ch := t.buffer [offset];
INC (my_line); l_start := offset;
ELSE
INC (offset); ch := t.buffer [offset];
END;
END;
IF t.skip_comments THEN
t.offset := offset;
t.line := my_line;
t.line_start := l_start;
RETURN FALSE;
ELSE
t.token := TK.Comment;
t.length := offset - t.offset;
t.next_offset := offset;
t.next_line := my_line;
t.next_line_start := l_start;
RETURN TRUE;
END;
END ScanComment;
PROCEDURE ScanPragma (t: Default) =
VAR
start := t.offset;
offset := start + 2; (* skip the opening '<' and '*' *)
ch := t.buffer [offset];
my_line := t.line;
l_start := t.line_start;
BEGIN
(* scan the entire pragma as a string *)
WHILE (ch # '*') OR (t.buffer[offset+1] # '>') DO
IF (ch = EOFChar) THEN
Err (t, offset, "EOF encountered in pragma");
RETURN;
END;
INC (offset);
IF (ch = '\n') THEN INC (my_line); l_start := offset; END;
ch := t.buffer [offset];
END;
INC (offset, 2);
t.token := TK.Begin_pragma;
t.length := offset - t.offset;
t.next_offset := offset;
t.next_line := my_line;
t.next_line_start := l_start;
END ScanPragma;
BEGIN
WhiteSpace [' '] := TRUE;
WhiteSpace ['\n'] := TRUE;
WhiteSpace ['\t'] := TRUE;
WhiteSpace ['\r'] := TRUE;
WhiteSpace ['\f'] := TRUE;
AlphaNumerics ['_'] := TRUE;
FOR c := 'a' TO 'z' DO AlphaNumerics [c] := TRUE END;
FOR c := 'A' TO 'Z' DO AlphaNumerics [c] := TRUE END;
FOR c := '0' TO '9' DO AlphaNumerics [c] := TRUE END;
FOR c := '0' TO '9' DO Digits [c] := TRUE END;
FOR c := '0' TO '7' DO OctalDigits [c] := TRUE END;
FOR c := '0' TO '9' DO HexDigits [c] := TRUE END;
FOR c := 'a' TO 'f' DO HexDigits [c] := TRUE END;
FOR c := 'A' TO 'F' DO HexDigits [c] := TRUE END;
CommentAlert ['*'] := TRUE;
CommentAlert ['('] := TRUE;
CommentAlert [EOFChar] := TRUE;
CommentAlert ['\n'] := TRUE;
CharAlert ['\''] := TRUE;
CharAlert ['\"'] := TRUE;
CharAlert ['\n'] := TRUE;
CharAlert ['\r'] := TRUE;
CharAlert ['\f'] := TRUE;
CharAlert ['\\'] := TRUE;
CharAlert [EOFChar] := TRUE;
END M3Scanner.