+/*
+ * Parse a single operator, one or two characters long.
+ * If the operator is recognized, return success and advance the
+ * parse point, else return failure and let the parse point unchanged.
+ */
+static int
+roff_getop(const char *v, int *pos, char *res)
+{
+
+ *res = v[*pos];
+
+ switch (*res) {
+ case '+':
+ /* FALLTHROUGH */
+ case '-':
+ /* FALLTHROUGH */
+ case '*':
+ /* FALLTHROUGH */
+ case '/':
+ /* FALLTHROUGH */
+ case '%':
+ /* FALLTHROUGH */
+ case '&':
+ /* FALLTHROUGH */
+ case ':':
+ break;
+ case '<':
+ switch (v[*pos + 1]) {
+ case '=':
+ *res = 'l';
+ (*pos)++;
+ break;
+ case '>':
+ *res = '!';
+ (*pos)++;
+ break;
+ case '?':
+ *res = 'i';
+ (*pos)++;
+ break;
+ default:
+ break;
+ }
+ break;
+ case '>':
+ switch (v[*pos + 1]) {
+ case '=':
+ *res = 'g';
+ (*pos)++;
+ break;
+ case '?':
+ *res = 'a';
+ (*pos)++;
+ break;
+ default:
+ break;
+ }
+ break;
+ case '=':
+ if ('=' == v[*pos + 1])
+ (*pos)++;
+ break;
+ default:
+ return(0);
+ }
+ (*pos)++;
+
+ return(*res);
+}
+
+/*
+ * Evaluate either a parenthesized numeric expression
+ * or a single signed integer number.
+ */
+static int
+roff_evalpar(struct roff *r, int ln,
+ const char *v, int *pos, int *res)
+{
+
+ if ('(' != v[*pos])
+ return(roff_getnum(v, pos, res));
+
+ (*pos)++;
+ if ( ! roff_evalnum(r, ln, v, pos, res, 1))
+ return(0);
+
+ /*
+ * Omission of the closing parenthesis
+ * is an error in validation mode,
+ * but ignored in evaluation mode.
+ */
+
+ if (')' == v[*pos])
+ (*pos)++;
+ else if (NULL == res)
+ return(0);
+
+ return(1);
+}
+
+/*
+ * Evaluate a complete numeric expression.
+ * Proceed left to right, there is no concept of precedence.
+ */
+static int
+roff_evalnum(struct roff *r, int ln, const char *v,
+ int *pos, int *res, int skipwhite)
+{
+ int mypos, operand2;
+ char operator;
+
+ if (NULL == pos) {
+ mypos = 0;
+ pos = &mypos;
+ }
+
+ if (skipwhite)
+ while (isspace((unsigned char)v[*pos]))
+ (*pos)++;
+
+ if ( ! roff_evalpar(r, ln, v, pos, res))
+ return(0);
+
+ while (1) {
+ if (skipwhite)
+ while (isspace((unsigned char)v[*pos]))
+ (*pos)++;
+
+ if ( ! roff_getop(v, pos, &operator))
+ break;
+
+ if (skipwhite)
+ while (isspace((unsigned char)v[*pos]))
+ (*pos)++;
+
+ if ( ! roff_evalpar(r, ln, v, pos, &operand2))
+ return(0);
+
+ if (skipwhite)
+ while (isspace((unsigned char)v[*pos]))
+ (*pos)++;
+
+ if (NULL == res)
+ continue;
+
+ switch (operator) {
+ case '+':
+ *res += operand2;
+ break;
+ case '-':
+ *res -= operand2;
+ break;
+ case '*':
+ *res *= operand2;
+ break;
+ case '/':
+ if (0 == operand2) {
+ mandoc_msg(MANDOCERR_DIVZERO,
+ r->parse, ln, *pos, v);
+ *res = 0;
+ break;
+ }
+ *res /= operand2;
+ break;
+ case '%':
+ *res %= operand2;
+ break;
+ case '<':
+ *res = *res < operand2;
+ break;
+ case '>':
+ *res = *res > operand2;
+ break;
+ case 'l':
+ *res = *res <= operand2;
+ break;
+ case 'g':
+ *res = *res >= operand2;
+ break;
+ case '=':
+ *res = *res == operand2;
+ break;
+ case '!':
+ *res = *res != operand2;
+ break;
+ case '&':
+ *res = *res && operand2;
+ break;
+ case ':':
+ *res = *res || operand2;
+ break;
+ case 'i':
+ if (operand2 < *res)
+ *res = operand2;
+ break;
+ case 'a':
+ if (operand2 > *res)
+ *res = operand2;
+ break;
+ default:
+ abort();
+ }
+ }
+ return(1);
+}
+
git.ckatri.com / mandoc.git / blobdiff