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Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 68K/cpm68k_pgms/utils/LEXI.C
Sepp J Morris 31738079c4 Upload 
Digital Research
2020-11-06 18:50:37 +01:00

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#
/*
Copyright (C) 1976
by the
Board of Trustees
of the
University of Illinois
All rights reserved
NAME:
lexi
FUNCTION:
This is the token scanner for indent
ALGORITHM:
1) Strip off intervening blanks and/or tabs.
2) If it is an alphanumeric token, move it to the token buffer "token".
Check if it is a special reserved word that indent will want to
know about.
3) Non-alphanumeric tokens are handled with a big switch statement. A
flag is kept to remember if the last token was a "unary delimiter",
which forces a following operator to be unary as opposed to binary.
PARAMETERS:
None
RETURNS:
An integer code indicating the type of token scanned.
GLOBALS:
buf_ptr =
had_eof
last_u_d = Set to true iff this token is a "unary delimiter"
CALLS:
fill_buffer
printf (lib)
CALLED BY:
main
NOTES:
Start of comment is passed back so that the comment can be scanned by
pr_comment.
Strings and character literals are returned just like identifiers.
HISTORY:
initial coding November 1976 D A Willcox of CAC
1/7/77 D A Willcox of CAC Fix to provide proper handling
of "int a -1;"
*/
/* Here we have the token scanner for indent. It scans off one token and
puts it in the global variable "token". It returns a code, indicating the
type of token scanned. */
#include "indntglo.h";
#include "indntcod.h";
#define alphanum 1
#define opchar 3
struct templ {
char *rwd;
int rwcode;
};
struct templ specials[] =
{
"switch", 1,
"case", 2,
"struct", 3,
"default", 2,
"int", 4,
"char", 4,
"float", 4,
"double", 4,
"long", 4,
"short", 4,
"typdef", 4,
"unsigned", 4,
"register", 4,
"static", 4,
"global", 4,
"extern", 4,
"if", 5,
"while", 5,
"for", 5,
"else", 6,
"do", 6,
"sizeof", 0,
0, 0
};
char chartype[128] =
{ /* this is used to facilitate the decision of what type
(alphanumeric, operator) each character is */
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 3, 0, 0, 1, 3, 3, 0,
0, 0, 3, 3, 0, 3, 3, 3,
1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 0, 0, 3, 3, 3, 3,
0, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 0, 0, 0, 3, 1,
0, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 0, 3, 0, 3, 0
};
int last_nl = true;
/* this is true if the last thing scanned was a newline */
int lexi () {
register char *tok;
/* local pointer to next char in token */
register int i;
/* local loop counter */
register char *j;
/* used for searching thru list of reserved words */
int unary_delim;
/* this is set to 1 if the current token forces a following operator to be
unary */
static int last_code;
/* the last token type returned */
static int l_struct;
/* set to 1 if the last token was 'struct' */
int found_it;
int code; /* internal code to be returned */
char qchar; /* the delimiter character for a string */
tok = token; /* point to start of place to save token */
unary_delim = false;
col_1 = last_nl; /* tell world that this token started in column
1 iff the last thing scanned was nl */
last_nl = false;
while (*buf_ptr == ' ' || *buf_ptr == '\t') {
/* get rid of blanks */
col_1 = false; /* leading blanks imply token is not in column 1
*/
if (++buf_ptr >= buf_end)
fill_buffer ();
}
/*----------------------------------------------------------*\
| Scan an alphanumeric token
\*----------------------------------------------------------*/
if (chartype[*buf_ptr & 0177] == alphanum) {
register char c;
/* we have a character or number */
while (chartype[c = *buf_ptr & 0177] == alphanum
|| c=='-' && tok[-1]=='e' && ('0'<=token[0]||token[0]<='9')) {
/* copy it over */
*tok++ = *buf_ptr++;
if (buf_ptr >= buf_end)
fill_buffer ();
}
*tok++ = '\0';
if (l_struct) { /* if last token was 'struct', then this token
should be treated as a declaration */
l_struct = false;
last_code = ident;
last_u_d = true;
return (decl);
}
last_u_d = false; /* operator after indentifier is binary */
for (i = 0; specials[i].rwd != 0; ++i) {
/* this loop will check if the token is a keyword. if so, a following
operator is unary */
last_code = ident; /* remember that this is the code we will return
*/
j = specials[i].rwd;
/* point at ith reserved word */
tok = token; /* point at scanned toekn */
found_it = true; /* set to false if not found */
do {
if (*tok++ != *j) {
found_it = false;
break;
}
} while (*j++);
if (found_it) { /* we have a keyword */
last_u_d = true;
switch (specials[i].rwcode) {
case 1: /* it is a switch */
return (swstmt);
case 2: /* a case or default */
return (casestmt);
case 3: /* a "struct" */
l_struct = true;
/* Next time around, we will want to know that we have had
a 'struct' */
case 4: /* one of the declaration keywords */
if(p_l_follow) break; /* inside parens: cast */
last_code = decl;
return (decl);
case 5: /* if, while, for */
return (sp_paren);
case 6: /* do, else */
return (sp_nparen);
default: /* all others are treated like any other
identifier */
return (ident);
} /* end of switch */
} /* end of if (found_it) */
}
if (last_code == decl) /* if this is a declared variable, then
following sign is unary */
last_u_d = true; /* will make "int a -1" work */
last_code = ident;
return (ident); /* the ident is not in the list */
} /* end of procesing for alpanum character */
/*----------------------------------------------------------*\
| Scan a non-alphanumeric token
\*----------------------------------------------------------*/
*tok++ = *buf_ptr; /* if it is only a one-character token, it is
moved here */
*tok = '\0';
if (++buf_ptr >= buf_end)
fill_buffer ();
switch (*token) {
case '\n':
unary_delim = last_u_d;
last_nl = true; /* remember that we just had a newline */
code = (had_eof ? 0 : newline);
/* if data has been exausted, the newline is a dummy, and we should
return code to stop */
break;
case '\'': /* start of quoted character */
qchar = '\''; /* remember final delimiter */
goto copy_lit; /* and go to common literal code */
case '"': /* start of string */
qchar = '"';
copy_lit:
do { /* copy the string */
while (1) { /* move one character or [/<char>]<char> */
if (*buf_ptr == '\n') {
/* check for unterminated literal */
printf ("%d: Unterminated literal\n", line_no);
goto stop_lit;
/* Don't copy any more */
}
*tok = *buf_ptr++;
if (buf_ptr >= buf_end)
fill_buffer ();
if (had_eof || ((tok - token) > (bufsize - 2))) {
printf ("Unterminated literal\n");
++tok;
goto stop_lit;
/* get outof literal copying loop */
}
if (*tok == '\\') {
/* if escape, copy extra char */
if (*buf_ptr == '\n')
/* check for escaped newline */
++line_no;
*(++tok) = *buf_ptr++;
++tok; /* we must increment this again because we
copied two chars */
if (buf_ptr >= buf_end)
fill_buffer ();
}
else
break; /* we copied one character */
} /* end of while (1) */
} while (*tok++ != qchar);
stop_lit:
code = ident;
break;
case ('('):
case ('['):
unary_delim = true;
code = lparen;
break;
case (')'):
case (']'):
code = rparen;
break;
case '#':
unary_delim = last_u_d;
code = preesc;
break;
case '?':
unary_delim = true;
code = question;
break;
case (':'):
code = colon;
unary_delim = true;
break;
case (';'):
unary_delim = true;
code = semicolon;
break;
case ('{'):
unary_delim = true;
code = lbrace;
break;
case ('}'):
unary_delim = true;
code = rbrace;
break;
case 014: /* a form feed */
unary_delim = last_u_d;
last_nl = true; /* remember this so we can set 'col_1' right */
code = form_feed;
break;
case (','):
unary_delim = true;
code = comma;
break;
case '.':
unary_delim = false;
code = period;
break;
case '-':
case '+': /* check for -, +, --, ++ */
code = (last_u_d ? unary_op : binary_op);
unary_delim = true;
if (*buf_ptr == token[0]) {
/* check for doubled character */
*tok++ = *buf_ptr++;
/* buffer overflow will be checked at end of loop */
if (last_code == ident || last_code == rparen) {
code = (last_u_d ? unary_op : postop);
/* check for following ++ or -- */
unary_delim = false;
}
}
else
if (*buf_ptr == '>' || *buf_ptr == '=')
/* check for operator -> or += */
*tok++ = *buf_ptr++;
/* buffer overflow will be checked at end of switch */
break;
case '=':
if (chartype[*buf_ptr] == opchar) {
/* we have two char assignment */
*tok++ = *buf_ptr;
/* move second character */
if (++buf_ptr >= buf_end)
fill_buffer ();
}
code = binary_op;
unary_delim = true;
if (token[1] != '<' && token[1] != '>')
/* check for possible 3 char operator */
break;
/* can drop thru!!! */
case '>':
case '<':
case '!': /* ops like <, <<, <=, !=, etc */
if (*buf_ptr == '>' || *buf_ptr == '<' || *buf_ptr == '=') {
*tok++ = *buf_ptr;
if (++buf_ptr >= buf_end)
fill_buffer ();
}
if (*buf_ptr == '=')
*tok++ = *buf_ptr++;
code = (last_u_d ? unary_op : binary_op);
unary_delim = true;
break;
default:
if (token[0] == '/' && *buf_ptr == '*') {
/* it is start of comment */
*tok++ = '*';
if (++buf_ptr >= buf_end)
fill_buffer ();
code = comment;
unary_delim = last_u_d;
break;
}
while (*(tok - 1) == *buf_ptr || *buf_ptr=='=') {
/* handle ||, &&, etc, and also things as in int *****i */
*tok++ = *buf_ptr;
if (++buf_ptr >= buf_end)
fill_buffer ();
}
code = (last_u_d ? unary_op : binary_op);
unary_delim = true;
} /* end of switch */
if (code != newline) {
l_struct = false;
last_code = code;
}
if (buf_ptr >= buf_end) /* check for input buffer empty */
fill_buffer ();
last_u_d = unary_delim;
*tok = '\0'; /* null terminate the token */
return (code);
};

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