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Frozen Fish 1: Amiga
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d105
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bison.lha
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Bison
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lex.c
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C/C++ Source or Header
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1987-10-25
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8KB
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407 lines
/* Token-reader for Bison's input parser,
copyright (C) 1984 Bob Corbett and Richard Stallman
Permission is granted to anyone to make or distribute verbatim copies of this program
provided that the copyright notice and this permission notice are preserved;
and provided that the recipient is not asked to waive or limit his right to
redistribute copies as permitted by this permission notice;
and provided that anyone possessing an executable copy
is granted access to copy the source code, in machine-readable form,
in some reasonable manner.
Permission is granted to distribute derived works or enhanced versions of
this program under the above conditions with the additional condition
that the entire derivative or enhanced work
must be covered by a permission notice identical to this one.
Anything distributed as part of a package containing portions derived
from this program, which cannot in current practice perform its function usefully
in the absense of what was derived directly from this program,
is to be considered as forming, together with the latter,
a single work derived from this program,
which must be entirely covered by a permission notice identical to this one
in order for distribution of the package to be permitted.
In other words, you are welcome to use, share and improve this program.
You are forbidden to forbid anyone else to use, share and improve
what you give them. Help stamp out software-hoarding! */
/*
lex() is the entry point. It is called from reader.c.
It returns one of the token-type codes defined in lex.h.
When an identifier is seen, the code IDENTIFIER is returned
and the name is looked up in the symbol table using symtab.c;
symval is set to a pointer to the entry found. */
#include <stdio.h>
#include <ctype.h>
#include "files.h"
#include "symtab.h"
#include "lex.h"
extern int lineno;
extern int translations;
char token_buffer[MAXTOKEN + 1];
extern bucket *symval;
int numval;
static int unlexed; /* these two describe a token to be reread */
static bucket *unlexed_symval; /* by the next call to lex */
init_lex()
{
unlexed = -1;
}
int
skip_white_space()
{
register int c;
register int inside;
c = getc(finput);
for (;;)
{
switch (c)
{
case '/':
c = getc(finput);
if (c != '*')
fatal("illegal comment");
c = getc(finput);
inside = 1;
while (inside)
{
if (c == '*')
{
while (c == '*')
c = getc(finput);
if (c == '/')
{
inside = 0;
c = getc(finput);
}
}
else if (c == '\n')
{
lineno++;
c = getc(finput);
}
else if (c == EOF)
fatal("unterminated comment");
else
c = getc(finput);
}
break;
case '\n':
lineno++;
case ' ':
case '\t':
case '\f':
c = getc(finput);
break;
default:
return (c);
}
}
}
unlex(token)
int token;
{
unlexed = token;
unlexed_symval = symval;
}
int
lex()
{
register int c;
register char *p;
if (unlexed >= 0)
{
symval = unlexed_symval;
c = unlexed;
unlexed = -1;
return (c);
}
c = skip_white_space();
switch (c)
{
case EOF:
return (ENDFILE);
case 'A': case 'B': case 'C': case 'D': case 'E':
case 'F': case 'G': case 'H': case 'I': case 'J':
case 'K': case 'L': case 'M': case 'N': case 'O':
case 'P': case 'Q': case 'R': case 'S': case 'T':
case 'U': case 'V': case 'W': case 'X': case 'Y':
case 'Z':
case 'a': case 'b': case 'c': case 'd': case 'e':
case 'f': case 'g': case 'h': case 'i': case 'j':
case 'k': case 'l': case 'm': case 'n': case 'o':
case 'p': case 'q': case 'r': case 's': case 't':
case 'u': case 'v': case 'w': case 'x': case 'y':
case 'z':
case '.': case '_':
p = token_buffer;
while (isalnum(c) || c == '_' || c == '.')
{
if (p < token_buffer + MAXTOKEN)
*p++ = c;
c = getc(finput);
}
*p = 0;
ungetc(c, finput);
symval = getsym(token_buffer);
return (IDENTIFIER);
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
{
numval = 0;
while (isdigit(c))
{
numval = numval*10 + c - '0';
c = getc(finput);
}
ungetc(c, finput);
return (NUMBER);
}
case '\'':
translations = -1;
/* parse the literal token and compute character code in code */
c = getc(finput);
{
register int code = 0;
if (c == '\\')
{
c = getc(finput);
if (c <= '7' && c >= '0')
{
while (c <= '7' && c >= '0')
{
code = (code * 8) + (c - '0');
c = getc(finput);
}
if (c >= 128)
fatal("malformatted literal token");
}
else
{
if (c == 't')
code = '\t';
else if (c == 'n')
code = '\n';
else if (c == 'r')
code = '\r';
else if (c == 'f')
code = '\f';
else if (c == 'b')
code = '\b';
else if (c == '\\')
code = '\\';
else if (c == '\'')
code = '\'';
else fatal("invalid literal token");
c = getc(finput);
}
}
else
{
code = c;
c = getc(finput);
}
if (c != '\'')
fatal("malformatted literal token");
/* now fill token_buffer with the canonical name for this character
as a literal token. Do not use what the user typed,
so that '\012' and '\n' can be interchangeable. */
p = token_buffer;
*p++ = '\'';
if (code == '\\')
{
p = token_buffer + 1;
*p++ = '\\';
*p++ = '\\';
}
else if (code == '\'')
{
p = token_buffer + 1;
*p++ = '\\';
*p++ = '\'';
}
else if (code >= 040 && code != 0177)
*p++ = code;
else if (code == '\t')
{
p = token_buffer + 1;
*p++ = '\\';
*p++ = 't';
}
else if (code == '\n')
{
p = token_buffer + 1;
*p++ = '\\';
*p++ = 'n';
}
else if (code == '\r')
{
p = token_buffer + 1;
*p++ = '\\';
*p++ = 'r';
}
else if (code == '\b')
{
p = token_buffer + 1;
*p++ = '\\';
*p++ = 'b';
}
else if (code == '\f')
{
p = token_buffer + 1;
*p++ = '\\';
*p++ = 'f';
}
else
{
*p++ = code / 0100 + '0';
*p++ = ((code / 010) & 07) + '0';
*p++ = (code & 07) + '0';
}
*p++ = '\'';
*p = 0;
symval = getsym(token_buffer);
symval->class = STOKEN;
if (! symval->user_token_number)
symval->user_token_number = code;
return (IDENTIFIER);
}
case ',':
return (COMMA);
case ':':
return (COLON);
case ';':
return (SEMICOLON);
case '|':
return (BAR);
case '{':
return (LEFT_CURLY);
case '<':
p = token_buffer;
c = getc(finput);
while (c != '>')
{
if (c == '\n' || c == EOF)
fatal("unterminated type name");
if (p >= token_buffer + MAXTOKEN - 1)
fatal("type name too long");
*p++ = c;
c = getc(finput);
}
*p = 0;
return (TYPENAME);
case '%':
return (parse_percent_token());
default:
return (ILLEGAL);
}
}
/* parse a token which starts with %. Assumes the % has already been read and discarded. */
int
parse_percent_token ()
{
register int c;
register char *p;
p = token_buffer;
c = getc(finput);
if (c == '%')
return (TWO_PERCENTS);
if (c == '{')
return (PERCENT_LEFT_CURLY);
if (isalpha(c)) {}
else return (ILLEGAL);
while (isalpha(c) || c == '_')
{
if (p < token_buffer + MAXTOKEN)
*p++ = c;
c = getc(finput);
}
ungetc(c, finput);
*p = 0;
if (strcmp(token_buffer, "token") == 0)
return (TOKEN);
else if (strcmp(token_buffer, "nterm") == 0)
return (NTERM);
else if (strcmp(token_buffer, "type") == 0)
return (TYPE);
else if (strcmp(token_buffer, "guard") == 0)
return (GUARD);
else if (strcmp(token_buffer, "union") == 0)
return (UNION);
else if (strcmp(token_buffer, "start") == 0)
return (START);
else if (strcmp(token_buffer, "left") == 0)
return (LEFT);
else if (strcmp(token_buffer, "right") == 0)
return (RIGHT);
else if (strcmp(token_buffer, "semantic_parser") == 0)
return (SEMANTIC_PARSER);
else if (strcmp(token_buffer, "pure_parser") == 0)
return (PURE_PARSER);
else if (strcmp(token_buffer, "prec") == 0)
return (PREC);
else return (ILLEGAL);
}