static void
find_completions (
drd_info drd, tree t, hashset<string>& h, string prefix= "")
{
if (is_atomic (t)) {
string s= t->label;
int i= 0, n= N(s);
while (i<n) {
if (is_iso_alpha (s[i])) {
int start= i;
while ((i<n) && (is_iso_alpha (s[i]))) i++;
string r= s (start, i);
if (starts (r, prefix) && (r != prefix))
h->insert (r (N(prefix), N(r)));
}
else skip_symbol (s, i);
}
}
else {
int i, n= N(t);
for (i=0; i<n; i++)
if (drd->is_accessible_child (t, i))
find_completions (drd, t[i], h, prefix);
}
}
// Parses any expression.
struct ParseResult parse(const char *text) {
struct ParseResult result;
result.err_type = PARSE_SUCCESS;
const char *s = text;
s += skip_whitespace(s);
size_t len;
switch (*s) {
case '\0':
result.err_type = ERR_UNEXPECTED_EOI;
break;
case '(':
s++;
result = parse_pair(s);
s += result.chars_read;
break;
case ')':
result.err_type = ERR_UNEXPECTED_RPAREN;
break;
case '.':
result.err_type = ERR_INVALID_DOT;
break;
case '#':
len = skip_symbol(s + 1);
if (len == 1 && s[1] == 't') {
s += 2;
result.expr = new_boolean(true);
} else if (len == 1 && s[1] == 'f') {
s += 2;
result.expr = new_boolean(false);
} else if (len > 2 && s[1] == '\\') {
char c = parse_char_name(s + 2, len - 1);
if (c == '\0') {
s += 2;
result.err_type = ERR_UNKNOWN_CHARACTER;
} else {
s += 1 + len;
result.expr = new_character(c);
}
} else if (s[1] == '\\' && s[2] && !isspace(s[2])) {
result.expr = new_character(s[2]);
s += 3;
} else {
result.err_type = ERR_INVALID_LITERAL;
}
break;
case '\'':
s++;
result = parse(s);
s += result.chars_read;
if (result.err_type == PARSE_SUCCESS) {
result.expr = new_pair(
new_stdmacro(F_QUOTE),
new_pair(result.expr, new_null()));
}
break;
case '`':
s++;
result = parse(s);
s += result.chars_read;
if (result.err_type == PARSE_SUCCESS) {
result.expr = new_pair(
new_stdmacro(F_QUASIQUOTE),
new_pair(result.expr, new_null()));
}
break;
case ',':
s++;
enum StandardMacro stdmacro = F_UNQUOTE;
if (*s == '@') {
s++;
stdmacro = F_UNQUOTE_SPLICING;
}
result = parse(s);
s += result.chars_read;
if (result.err_type == PARSE_SUCCESS) {
result.expr = new_pair(
new_stdmacro(stdmacro),
new_pair(result.expr, new_null()));
}
break;
case '"':
s++;
len = skip_string(s);
if (!(s[len-1] == '\\' && (len < 2 || s[len-2] == '\\'))
&& s[len] == '"') {
result.expr = parse_string(s, len);
} else {
result.err_type = ERR_UNEXPECTED_EOI;
}
s += len;
s++;
break;
default:;
len = skip_symbol(s);
assert(len > 0);
Number number;
if (parse_number(s, len, &number)) {
result.expr = new_number(number);
} else {
InternId symbol_id = intern_string_n(s, len);
result.expr = new_symbol(symbol_id);
}
s += len;
break;
}
if (result.err_type == PARSE_SUCCESS) {
s += skip_whitespace(s);
assert(s > text);
}
result.chars_read = (size_t)(s - text);
return result;
}
