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ngspice
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Rewrite the ad hoc checks for valid infix expressions. Check the starting infix token, then for a last token being an ID, gate op, ~, lparen or rparen check that the following token is valid. This is much more systematic and easier to understand.

This commit is contained in:
Brian Taylor 2024-03-15 21:06:56 -07:00
parent e4451bf242
commit 91e49ce4d6
1 changed files with 38 additions and 30 deletions
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68
src/frontend/logicexp.c
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@ -748,36 +748,44 @@ static int infix_to_postfix(char* infix, DSTRING * postfix_p)
nlist = add_name_entry("first", NULL);
ds_clear(postfix_p);
while ( ( ltok = lexer_scan(lx) ) != 0 ) { // start while ltok loop
if (ltok == LEX_ID && last_tok == LEX_ID) {
fprintf(stderr, "ERROR (1) no gate operator between two identifiers\n");
status = 1;
goto err_return;
}
if (lex_gate_op(ltok)) {
if (lex_gate_op(last_tok)) {
fprintf(stderr, "ERROR (2) two consecutive gate operators\n");
status = 1;
goto err_return;
} else if (last_tok != LEX_ID && last_tok != ')') {
fprintf(stderr, "ERROR (2a) gate operator not after ID or rparen\n");
if (last_tok == -1) { // check starting token
if (!(ltok == LEX_ID || ltok == '~' || ltok == '(')) {
fprintf(stderr, "ERROR (1) invalid starting token\n");
status = 1;
goto err_return;
}
}
if (last_tok == '~' && ltok != LEX_ID && ltok != '(') {
fprintf(stderr, "ERROR (3) \'~\' is not followed by an ID or lparen\n");
status = 1;
goto err_return;
}
if (ltok == '~' && (last_tok == LEX_ID || last_tok == ')')) {
fprintf(stderr, "ERROR (4) \'~\' follows an ID or rparen\n");
status = 1;
goto err_return;
}
if (ltok == ')' && (lex_gate_op(last_tok) || last_tok == '~')) {
fprintf(stderr, "ERROR (5) incomplete infix sub-expression\n");
status = 1;
goto err_return;
} else {
if (last_tok == LEX_ID) { // check follower of an ID
if (!(lex_gate_op(ltok) || ltok == ')')) {
fprintf(stderr, "ERROR (2) incorrect token after ID\n");
status = 1;
goto err_return;
}
} else if (lex_gate_op(last_tok)) { // check follower of a gate op
if (!(ltok == LEX_ID || ltok == '~' || ltok == '(')) {
fprintf(stderr, "ERROR (3) incorrect token after gate op\n");
status = 1;
goto err_return;
}
} else if (last_tok == '~') { // check follower of ~
if (!(ltok == LEX_ID || ltok == '(')) {
fprintf(stderr, "ERROR (4) incorrect token after \'~\'\n");
status = 1;
goto err_return;
}
} else if (last_tok == '(') { // check follower of lparen
if (!(ltok == LEX_ID || ltok == '~' || ltok == '(')) {
fprintf(stderr, "ERROR (5) incorrect token after lparen\n");
status = 1;
goto err_return;
}
} else if (last_tok == ')') { // check follower of rparen
if (!(ltok == ')' || lex_gate_op(ltok))) {
fprintf(stderr, "ERROR (6) incorrect token after rparen\n");
status = 1;
goto err_return;
}
}
}
last_tok = ltok;
@ -832,19 +840,19 @@ static int infix_to_postfix(char* infix, DSTRING * postfix_p)
goto err_return;
}
} else {
fprintf(stderr, "ERROR (6) unexpected infix token %d \'%s\'\n",
fprintf(stderr, "ERROR (7) unexpected infix token %d \'%s\'\n",
ltok, lx->lexer_buf);
status = 1;
goto err_return;
}
} // end while ltok loop
if (lex_gate_op(last_tok) || last_tok == '~') {
fprintf(stderr, "ERROR (7) incomplete infix expression\n");
fprintf(stderr, "ERROR (8) incomplete infix expression\n");
status = 1;
goto err_return;
}
if (lparen_count != rparen_count) {
fprintf(stderr, "ERROR (8) mismatched parentheses\n");
fprintf(stderr, "ERROR (9) mismatched parentheses\n");
status = 1;
goto err_return;
}