129 lines
2.8 KiB
C
129 lines
2.8 KiB
C
/* L L l e x . c
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*
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* Very simple lexical analyzer.
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* Also contains LLmessage().
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*/
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# include <ctype.h>
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# include <stdio.h>
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# include "tunable.h"
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# include "token.h"
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# include "Lpars.h"
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struct token dot; /* current token */
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static struct token aside; /* to put currrent token aside, when a token
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* is inserted
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*/
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int newline, lineno; /* To keep track of linenumbers */
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extern FILE *input; /* file descriptor of machine table */
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LLlex() {
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register c;
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if (aside.t_tokno) { /* A token was pushed aside, return it now */
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dot = aside;
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aside.t_tokno = 0;
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return dot.t_tokno;
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}
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if (newline) { /* delayed increment of lineno, needed to give
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* correct line numbers in error messages
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*/
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lineno++;
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newline = 0;
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}
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c = getc(input);
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while (c == '/') { /* Could be a comment */
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if ((c = getc(input)) == '*') {
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/* Yes, it is a comment */
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int l;
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l = lineno;
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do {
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do {
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if (c == '\n') lineno++;
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c = getc(input);
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} while (c != '*' && c != EOF);
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if (c != EOF) c = getc(input);
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} while (c != '/' && c != EOF);
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if (c == EOF) {
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c = lineno;
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lineno = l;
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error("Unterminated comment");
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lineno = c;
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c = EOF;
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}
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else c = getc(input);
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}
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else {
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ungetc(c, stdin);
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c = '/';
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break;
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}
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}
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dot.t_tokno = c;
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dot.t_attrib = c;
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if (isupper(c) || islower(c) || c == '_') {
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dot.t_tokno = LETTER;
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return LETTER;
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}
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if (isdigit(c)) {
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dot.t_tokno = DIGIT;
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return DIGIT;
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}
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switch(c) {
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case line_term :
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dot.t_tokno = LINE_TERMINATOR;
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return LINE_TERMINATOR;
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case operand_sep :
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dot.t_tokno = OPERAND_SEPARATOR;
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return OPERAND_SEPARATOR;
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case instruction_sep :
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dot.t_tokno = INSTRUCTION_SEPARATOR;
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return INSTRUCTION_SEPARATOR;
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case '-' :
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c = getc(input);
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if (c == '>') {
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dot.t_tokno = PATTERN_SEPARATOR;
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return PATTERN_SEPARATOR;
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}
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ungetc(c,stdin);
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dot.t_tokno = OTHER;
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return OTHER;
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case open_bracket :
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dot.t_tokno = OPEN_BRACKET;
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return OPEN_BRACKET;
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case close_bracket :
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dot.t_tokno = CLOSE_BRACKET;
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return CLOSE_BRACKET;
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case '\n' :
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newline = 1;
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/* Fall through */
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case ' ' :
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case '\t' :
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dot.t_tokno = SPACE;
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return SPACE;
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case '%' :
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case EOF :
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return c;
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default :
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/* Let the C-compiler find out what is illegal! */
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dot.t_tokno = OTHER;
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return OTHER;
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}
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}
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LLmessage(d) {
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static int savlineno;
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if (savlineno != lineno) {
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/* Only an error message if on another line number */
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savlineno = lineno;
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error("Syntax error");
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}
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if (d > 0) {
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/* "d" is the token to be inserted.
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* This is the place to put the current token aside and
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* give the inserted token an attribute ... but who cares
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*/
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aside = dot;
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}
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}
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