+
+/* Return true if the lisp code read using READCHARFUN defines a non-nil
+ `lexical-binding' file variable. After returning, the stream is
+ positioned following the first line, if it is a comment, otherwise
+ nothing is read. */
+
+static int
+lisp_file_lexically_bound_p (Lisp_Object readcharfun)
+{
+ int ch = READCHAR;
+ if (ch != ';')
+ /* The first line isn't a comment, just give up. */
+ {
+ UNREAD (ch);
+ return 0;
+ }
+ else
+ /* Look for an appropriate file-variable in the first line. */
+ {
+ int rv = 0;
+ enum {
+ NOMINAL, AFTER_FIRST_DASH, AFTER_ASTERIX,
+ } beg_end_state = NOMINAL;
+ int in_file_vars = 0;
+
+#define UPDATE_BEG_END_STATE(ch) \
+ if (beg_end_state == NOMINAL) \
+ beg_end_state = (ch == '-' ? AFTER_FIRST_DASH : NOMINAL); \
+ else if (beg_end_state == AFTER_FIRST_DASH) \
+ beg_end_state = (ch == '*' ? AFTER_ASTERIX : NOMINAL); \
+ else if (beg_end_state == AFTER_ASTERIX) \
+ { \
+ if (ch == '-') \
+ in_file_vars = !in_file_vars; \
+ beg_end_state = NOMINAL; \
+ }
+
+ /* Skip until we get to the file vars, if any. */
+ do
+ {
+ ch = READCHAR;
+ UPDATE_BEG_END_STATE (ch);
+ }
+ while (!in_file_vars && ch != '\n' && ch != EOF);
+
+ while (in_file_vars)
+ {
+ char var[100], val[100];
+ unsigned i;
+
+ ch = READCHAR;
+
+ /* Read a variable name. */
+ while (ch == ' ' || ch == '\t')
+ ch = READCHAR;
+
+ i = 0;
+ while (ch != ':' && ch != '\n' && ch != EOF && in_file_vars)
+ {
+ if (i < sizeof var - 1)
+ var[i++] = ch;
+ UPDATE_BEG_END_STATE (ch);
+ ch = READCHAR;
+ }
+
+ /* Stop scanning if no colon was found before end marker. */
+ if (!in_file_vars)
+ break;
+
+ while (i > 0 && (var[i - 1] == ' ' || var[i - 1] == '\t'))
+ i--;
+ var[i] = '\0';
+
+ if (ch == ':')
+ {
+ /* Read a variable value. */
+ ch = READCHAR;
+
+ while (ch == ' ' || ch == '\t')
+ ch = READCHAR;
+
+ i = 0;
+ while (ch != ';' && ch != '\n' && ch != EOF && in_file_vars)
+ {
+ if (i < sizeof val - 1)
+ val[i++] = ch;
+ UPDATE_BEG_END_STATE (ch);
+ ch = READCHAR;
+ }
+ if (! in_file_vars)
+ /* The value was terminated by an end-marker, which
+ remove. */
+ i -= 3;
+ while (i > 0 && (val[i - 1] == ' ' || val[i - 1] == '\t'))
+ i--;
+ val[i] = '\0';
+
+ if (strcmp (var, "lexical-binding") == 0)
+ /* This is it... */
+ {
+ rv = (strcmp (val, "nil") != 0);
+ break;
+ }
+ }
+ }
+
+ while (ch != '\n' && ch != EOF)
+ ch = READCHAR;
+
+ return rv;
+ }
+}
+\f